HK1068761A

HK1068761A - Electroacoustical transducing with low frequency augmenting devices

Info

Publication number: HK1068761A
Application number: HK05100967.4A
Authority: HK
Inventors: J．理查德．艾尔沃德; 查尔斯．R．巴克第三
Original assignee: 伯斯有限公司
Priority date: 2002-12-03
Filing date: 2005-02-04
Publication date: 2005-04-29

Description

Electroacoustic transduction with low frequency amplification device

This application claims priority to U.S. patent application No. 10/309395, filed 12, 3, 2002, under 35 USC § 119(e), the contents of which are incorporated herein by reference in their entirety.

Technical Field

The present invention relates to electro-acoustic transduction (transduction) with low frequency amplification devices, more particularly to the use of directional arrays with low frequency devices, and still more particularly to the use of directional arrays with low frequency devices applied to multimedia entertainment equipment.

It is an important aspect of the present invention to provide an improved method for utilizing a directional array with low frequency amplification devices and for integrating the directional array in multimedia entertainment devices such as gambling machines and video games.

Disclosure of Invention

According to the present invention, a method for processing an audio signal comprises the steps of: receiving a first channel audio signal; the first audio channel signal is separated into a first channel first spectral portion and a first channel second spectral portion. The method further comprises a processing of a first spectral portion of the first channel signal according to a first processing, represented by a first non-integer non-zero transfer function, to provide a first channel first processed signal; a first processing unit configured to provide a first channel first processed signal according to a first processed first spectral portion of the first channel, the first processing unit being represented by a first conversion function; the first channel first processed signal is combined with the first channel second spectral portion to provide a first channel first combined signal. The method further comprises transducing the first combined signal with a first electro-acoustic transducer; combining the first channel second processed signal with the first channel second spectral portion to provide a first channel second combined signal; and converting the second combined signal by a second electro-acoustic transducer.

In another aspect of the present invention, a method for processing a multi-channel audio signal includes: separating the first audio channel signal stream into a first channel first spectral portion and a first channel second spectral portion; separating the second audio channel signal stream into a second channel first spectral portion and a second channel second spectral portion; processing a first spectral portion of the first channel signal according to a first process represented by a first non-integer non-zero transfer function to provide a first processed signal; processing the first spectral portion of the first audio channel signal according to a second processing to provide a second processed signal, the second processing being represented by a second transfer function different from the first transfer function; processing the second channel first spectral portion according to a third process represented by a third non-integer non-zero transfer function to provide a third processed signal; the second channel signal first spectral portion is processed by a fourth process represented by a fourth transfer function different from the third transfer function to provide a fourth processed signal. The method further comprises combining the first channel second spectral portion with the second channel second spectral portion to provide a combined first channel second spectral portion; transducing, by a first electro-acoustic transducer, a second spectral portion of the first channel combination and one of the first channel first processed signal, the first channel second processed signal, the first channel third processed signal, and the first channel fourth processed signal.

In another aspect of the invention, an electro-acoustic apparatus includes a first directional array. The first directional array includes a first electro-acoustic transducer and a second electro-acoustic transducer. Each of the first and second electro-acoustic transducers includes a first radiating surface and a second radiating surface. The apparatus further comprises a low frequency amplifying structure having an exterior and an interior, wherein the electro-acoustic device is constructed and arranged such that the first electro-acoustic transducer first radiating surface and the second electro-acoustic transducer first radiating surface face the ambient environment, and such that the first electro-acoustic transducer second radiating surface and the second electro-acoustic transducer second radiating surface face the interior of the low frequency amplifying structure.

In another aspect of the present invention, a method for operating a multi-channel sound system including first and second electro-acoustic transducers and an acoustic waveguide, the method comprising the steps of: positioning the first transducer and the second transducer at separate points in the waveguide such that the first radiating surface of the first transducer and the first radiating surface of the second transducer radiate acoustic waves to the acoustic waveguide; separating the first channel signal into a first channel high frequency audio signal and a first channel low frequency audio signal; separating the second channel signal into a second channel high frequency audio signal and a second channel low frequency audio signal; and combining the first channel low frequency audio signal with the second channel low frequency audio signal to form a common low frequency audio signal. The method further comprises the steps of: transmitting the common low frequency audio signal to the first transducer and the second transducer; transmitting the first channel high frequency audio signal to the first transducer; transmitting the second channel high frequency audio signal to the second transducer; radiating, by the first transducer, acoustic waves corresponding to the first channel high frequency signal and the common low frequency audio signal to the waveguide; radiating, by the second transducer, acoustic waves corresponding to the second channel high frequency signal and the common low frequency audio signal to the waveguide.

In another aspect of the invention, a method for operating a multimedia entertainment device having a sound system including first and second speaker arrays and first and second audio channels, each of the first and second audio channels having a high frequency portion and a low frequency portion, the multimedia entertainment device including an associated listening space, the method comprising the steps of: directionally radiating, by the first speaker array, sound waves corresponding to a high frequency portion of the first audio channel toward the listening space; directionally radiating, by the second speaker array, sound waves corresponding to a high frequency portion of the second audio channel toward the listening space; non-directionally radiating the first channel low frequency portion and the second channel low frequency portion through the first speaker array and the second speaker array.

In another aspect of the invention, an entertainment zone includes a first multimedia entertainment device including a sound system. The sound system includes a first audio channel and a second audio channel. The first audio channel and the second audio channel each include a high frequency portion and a low frequency portion, and the first multimedia entertainment device includes a first speaker array and a second speaker array. The entertainment zone comprises a listening space connected to said first multimedia entertainment device. The zone also includes a second multimedia entertainment device of the sound system. The sound system includes a first audio channel and a second audio channel. Each of the first audio channel and the second audio channel includes a high frequency portion and a low frequency portion. The second multimedia entertainment device includes a first speaker array and a second speaker array. The entertainment zone comprises a listening space connected to said second multimedia entertainment device; the first multimedia entertainment device and the second multimedia exercise device are in a common viewing and listening area. The first multimedia entertainment device is constructed and arranged to directionally radiate sound waves corresponding to a first channel high frequency portion of said first device and to directionally radiate sound waves corresponding to a second channel high frequency portion of said first device such that said sound waves corresponding to said first channel high frequency portion of said first device and said sound waves corresponding to said second channel high frequency portion of said first device are more clearly audible in said listening space associated with said first device than in said listening space associated with said second device. The second multimedia entertainment device is constructed and arranged to directionally radiate sound waves corresponding to a first channel high frequency portion of said second device and to directionally radiate sound waves corresponding to a second channel high frequency portion of said second device such that said sound waves corresponding to said first channel high frequency portion of said second device and said sound waves corresponding to said second channel high frequency portion of said second device are more clearly audible in said listening space associated with said second device than in said listening space associated with said first device.

In another aspect of the invention, a sound system for radiating sound waves corresponding to a first audio signal and a second audio signal includes an indicator for indicating directional radiation pattern selection. The indicator has at least two states. The sound system comprises a detector for detecting the indicator; and a directional array for radiating acoustic waves in a plurality of directional radiation patterns. The directional array is constructed and arranged to radiate acoustic energy upon detection of a first indicator state according to a first directional radiation pattern and upon detection of a second indicator state according to a second directional radiation pattern.

A sound system for radiating sound waves corresponding to a first audio signal and a second audio signal includes an indicator for indicating a directional radiation pattern selection. The indicator has at least two states. The sound system includes: a detector for detecting the indicator; and a directional array for radiating acoustic waves in a plurality of directional radiation patterns. The directional array is constructed and arranged to radiate acoustic energy upon detection of a first indicator state according to a first directional radiation pattern and upon detection of a second indicator state according to a second directional radiation pattern.

In another aspect of the present invention, a method for dynamically balancing an audio signal includes the steps of: providing an audio signal; first attenuating said audio signal by a variable factor G to provide a first attenuated signal, wherein 0 < G < 1; second attenuating said audio signal by a variable factor 1-G to provide a second attenuated signal. The method further comprises balancing the first attenuated signal to provide a balanced first attenuated signal; and combining the balanced first attenuated signal with the second attenuated signal to provide an output signal.

In another aspect of the present invention, a method for clipping and post-clipping an audio signal, comprises the steps of: clipping the audio signal to provide a clipped audio signal; filtering the audio signal by a first filter to provide a filtered, non-clipped audio signal; the audio signal is filtered by a second filter to provide a filtered limited audio signal. The method further comprises differentially combining the filtered limited audio signal with the limited audio signal to provide a differentially combined audio signal; and combining the filtered non-clipped audio signal with the differentially combined audio signal to provide an output signal.

In another aspect of the invention, a method for controlling the directionality of a sound radiation pattern comprises the steps of: the audio signal is provided to a first attenuator, a delay, and a first summer. The method further comprises first attenuating said audio signal by a variable factor G via said first attenuator to provide a first variably attenuated audio signal, wherein 0 < G < 1; second attenuating said audio signal by a variable factor (1-G) to provide a second variably attenuated audio signal; delaying said first audio signal to provide a delayed audio signal; third attenuating said delayed audio signal by a variable factor H to provide a first variably attenuated delayed audio signal; the fourth attenuation is by a variable factor (1-H) to provide a second variably attenuated delayed audio signal. The method further comprises combining the first variably attenuated audio signal with the second variably attenuated delayed audio signal to provide a first transduction audio signal; and combining the second variably attenuated audio signal with the first variably attenuated delayed audio signal to provide a second exchangeable audio signal.

In another aspect of the invention, a wagering apparatus includes an associated listening space and sound system. The sound system includes a directional speaker array having a plurality of transducers. Acoustic waves radiated by a first of the plurality of transducers combine constructively in a first direction and destructively in a second direction. The first direction is directed towards the listening space.

Other features, aspects, and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.

Drawings

FIG. 1A shows a block diagram of an audio signal processing system embodying the present invention;

FIG. 1B illustrates a block diagram of an alternative implementation of the audio signal processing system of FIG. 1A;

FIG. 2 shows a block diagram of another alternative implementation of the audio signal processing system of FIG. 1A;

FIG. 3A shows a simplified diagram of an implementation of the audio signal processing system of FIG. 2;

FIG. 3B shows a simplified diagram of another implementation of the audio signal processing system of FIG. 2;

FIG. 3C shows a simplified diagram of an arrangement of electro-acoustic transducers used in a directional array;

FIG. 4 shows a simplified diagram of a networked plurality of audio signal processing systems;

FIG. 5 shows a simplified diagram of an alternative implementation of the audio signal processing system of FIG. 3A;

FIG. 6 shows a block diagram of another audio signal processing system embodying the present invention;

FIG. 7 shows a diagram of one implementation of the embodiment of FIG. 6;

FIG. 8A shows a block diagram of another audio signal processing system embodying the present invention;

FIG. 8B shows a block diagram of an alternative circuit for processing the center channel signal;

FIG. 8C shows a block diagram of an alternative implementation of the embodiment of FIG. 8A;

FIG. 9 shows a simplified diagram of an audio signal processing system implementing FIGS. 8A and 8C;

FIGS. 10A and 10B together illustrate a block diagram of another audio signal processing system embodying the present invention;

FIG. 11 shows a simplified diagram of an implementation of the audio signal processing system of FIGS. 10A and 10B;

FIG. 12 shows a block diagram of an audio processing system including an alternative arrangement of some elements of the previous features and showing some additional features of the invention;

13A-13C are block diagrams illustrating some of the elements of FIG. 12 in greater detail;

FIG. 14 is another block diagram showing the elements of FIG. 12 in greater detail;

15A and 15B show another block diagram of the elements of FIG. 12;

FIG. 15C shows a frequency response curve illustrating the operation of the circuit of FIGS. 15A and 15B;

FIG. 16 shows another block diagram of the elements of FIG. 12;

FIGS. 17A and 17B show diagrams of another audio signal processing system embodying the present invention;

FIG. 18 shows a diagram of another implementation of the audio signal processing system of FIGS. 17A and 17B;

fig. 19 shows an alternative implementation of the audio signal processing system of fig. 18.

Detailed Description

Referring now to the drawings, and in particular to FIG. 1A, there is shown an audio signal processing system 1 according to the present invention. The input terminals 10, 12 receive audio signals corresponding to two channels a and B of a stereo or multi-channel sound system. The inputs 10 and 12 are connected to a filtering and combining circuit 14 which outputs modified audio signals on audio signal lines 16, 18 and 20. The audio signal line 16 is connected to the processing blocks 23-26 of the audio signal processing circuit 22. The signal processing block 23 is connected to an adder 27A, which is connected to an electroacoustic transducer 27B. The signal processing block 24 is connected to an adder 28A, which is connected to an electroacoustic transducer 28B. The signal processing block 25 is connected to an adder 29A, which is connected to an electroacoustic transducer 29B. The signal processing block 26 is connected to an adder 30A, which is connected to an electroacoustic transducer 30B. The audio signal line 18 is connected to the processing blocks 31 to 34 of the audio signal processing circuit 22. The signal processing block 31 is connected to the adder 27A. The signal processing block 32 is connected to the adder 28A. The signal processing block 33 is connected to the adder 29A. The signal processing block 34 is connected to the adder 30A. The audio signal line 20 is connected to the processing block 35 of the audio signal processing circuit 22. Processing block 35 is coupled to adders 27A-30A.

The combining and filtering circuit 14 may include a high pass filter 36 connected to the input 10 and a high pass filter 40 connected to the input 12. The combining and filtering circuit 14 may also comprise an adder 38, which is optionally connected to the input 10 and the input 12, respectively, by means of a phase shifter 37A or 37B. The adder 38 is connected to a low-pass filter 41, which outputs to the signal line 20. The characteristics and functionality of phase shifters 37A and 37B are described in co-pending U.S. patent application No. 09/735123. Phase shifters 37A and 37B have similar or different parameters as long as they have the overall effect described in co-pending U.S. patent application No. 09/735123 over a range of frequencies in the passband of low pass filter 41. The system of fig. 1A may also include conventional elements such as DACs and amplifiers, which are not shown in this view.

In operation, the combining and filtering circuit 14 outputs a high frequency channel a signal [ Ahf ] on signal line 16, a high frequency channel B signal [ Bhf ] on signal line 18, and a combined low frequency signal [ (a + B) lf ] on third signal line 20. In processing blocks 23-26, the audio signals on signal line 16 are processed separately in a manner represented by transfer functions H1(s) -H4(s) (where s is the laplace frequency variable j ω and ω is 2 π f, so that H(s) is a frequency domain representation of the transfer function) and output to summers 27A-30A and then to electro-acoustic transducers 27B-30B, respectively. In processing blocks 31-34, the signal on signal line 18 is processed in a manner represented by transfer functions H5(s) -H8(s) and output to summers 27A-30A and then to electro-acoustic transducers 27B-30B, respectively. In processing block 35, the signal on signal line 20 is processed in a manner represented by transfer function H9(s) and output to summers 27A-30A and then to electro-acoustic transducers 27B-30B, respectively. The processing result of the system of FIG. 1A is that each of transducers 27B-30B may receive signals Ahf and Bhf processed according to different transfer functions, and that each of transducers 27B-30B receives a combined (A + B) lf signal.

As a result of the processing of the system of fig. 1A, transducer 27B receives signal H1(s) Ahf + H5(s) Bhf + + H9(s) (a + B) lf; transducer 28B receives signals H2(s) Ahf + H6(s) Bhf + H9(s) (A + B) lf; transducer 29B receives signal H3(s) Ahf + H7(s) Bhf + H9(s) (a + B) lf; and transducer 30B receives signal H4(s) Ahf + H8(s) Bhf + H9(s) (a + B) lf. If either or both phase shifters 37A or 37B are present, a phase shift may be included in the signals received by several transducers.

The transfer functions H1(s) -H9(s) may represent one or more attenuations/amplifications; a time delay; phase shifting; balance, HRTF processing (explained below in the discussion of fig. 17A and 17B), or other linear or non-linear signal processing functions. The transfer functions H1(s) -H9(s) may also represent no change (or be mathematically represented as a single value), or may be absent (or mathematically represented as zero); examples of these two conditions will be described below. Additionally, each of the transducers 27B-30B may be individually equalized in addition to the equalization that may be implemented in the processing blocks 23-26 and 31-35. Single transducer balancing may be most conveniently performed by a processor associated with the single transducer.

The system of FIG. 1A is a logical block diagram. In FIG. 1A and the other logical block diagrams below, there may or may not be physical elements corresponding to each of the elements of FIG. 1A. For example, the inputs 10 and 12 may be implemented as a single physical input for receiving a digitally encoded signal stream. Elements such as high pass filters 36 and 40, or processing blocks 23-26 and 31-35, or other elements may be implemented by Digital Signal Processors (DSPs) operating on digitally encoded data. In addition, other circuit arrangements may produce substantially the same results as the arrangement of FIG. 1A. For example, channels a and B may be filtered by a low pass filter, such as filter 41, before being combined. The high pass filters 36 and 40 may be implemented as low pass filters with a differential sum of the unfiltered signals, as shown in fig. 14 below. A single element may represent more than one block, or may merge blocks; for example, exemplary high pass filters 36 and 40 may be incorporated into the conversion functions of blocks 23-26 and 31-34, and low pass filter 41 may be incorporated into the conversion function of block 35.

As used herein, "connected" means "communicatively connected," i.e., two connected components are configured to communicate audio signals. The connected components may be physically connected by electrical wires or optical transmission fibers, or may be communicatively connected by wireless techniques such as infrared or Radio Frequency (RF) or other signal communication techniques. If the elements are implemented as DSPs operating on digitally encoded signals, "connected" means that the DSPs are capable of operating on digitally encoded audio signals in the manner indicated by the elements and described in the relevant portions of the disclosure. Similarly, a "signal line" as used herein refers to any transmissible path including an electrical wire, an optical transmission fiber, a wireless communication path, or other type of signal transmission path for transmitting analog or digitally encoded audio signals.

As used herein, "directional" is such that at frequencies having respective wavelengths that are relatively long with respect to the size of the radiating surface, the amplitude of sound radiated in the maximum radiation direction is at least 3dB greater than the amplitude of sound radiated in the minimum radiation direction. "oriented (or more) in direction X" means that the radiation level is more audible in direction X than in some other direction, even if direction X is not the direction of maximum radiation. Directional sound devices typically include elements that change the radiation pattern of the transducer so that radiation from the transducer is more audible in some locations in space than in others. Two types of directional devices are waveguide devices and interference devices. The waveguide device includes obstructions that cause the acoustic waves to radiate with greater amplitude in some directions than in others. Waveguide devices are particularly effective for radiation having wavelengths comparable to or smaller than the dimensions of the waveguide device. Examples of waveguide devices are horn radiators and acoustic lenses. In addition, the acoustic drivers become directional at frequencies having wavelengths comparable to or shorter than their diameters. As used herein, "non-directional" means that the magnitude of sound radiated in the maximum radiation direction is less than 3dB greater than the magnitude of sound radiated in the minimum radiation direction at frequencies having respective wavelengths that are relatively long relative to the size of the radiating surface. As used herein, "listening space" refers to the portion of space typically occupied by a single listener. Examples of listening spaces include seats in movie theaters, easy chairs, lounges, or sofa locations in home entertainment rooms, seating locations in the passenger compartment of a vehicle, single listener wagering apparatus, or video games played by a person, etc. Sometimes, there may be multiple people in a listening space, such as when two people are playing the same video game. As used herein, "listening zone" refers to a collection of acoustically contiguous listening spaces, i.e., not isolated by acoustic obstructions.

The interference device has at least two radiating elements, which may be two acoustic drivers, or two radiating surfaces of a single acoustic driver. Both radiating elements radiate acoustic waves that interfere in a frequency range having a wavelength greater than the diameter of the radiating element. The destructive interference of the sound waves in some directions is greater than in other directions. In other words, the amount of destructive interference is a function of the angle relative to the midpoint between the drives. The term "low frequency" as used herein refers to frequencies up to about 200Hz (which has a corresponding wavelength of 5.7 feet or 1.7 meters) or up to about 400Hz (which has a corresponding wavelength of 2.8 feet or 86 centimeters). As used herein, "high frequency" refers to frequencies having wavelengths above the low frequency range. For a conical electro-acoustic transducer having a cone diameter of about 4 inches, the typical high frequency range is above about 200 Hz. As used herein, "very high frequencies" are a subset of high frequencies, and refer to frequencies in the acoustic spectrum that have corresponding wavelengths that are smaller than the diameter of the transducer used to radiate them (above about 3.5KHz for an electroacoustic transducer having a conical diameter of about 4 inches).

The audio signal processing system according to fig. 1A is advantageous in that multiple transducers may use signal processing techniques to radiate directionally sound waves corresponding to high frequency audio signals in order to produce destructive interference. Destructive interference is more fully described in us patent 5809153 and us patent 5870484. At the same time, the multiple transducers may radiate sound waves in coordination corresponding to low frequency audio signals within the range of frequencies at which the sound waves constructively combine, thereby providing more sound energy in the low frequency range.

Referring to FIG. 1B, an alternative implementation of the embodiment of FIG. 1A is shown. In fig. 1B, a delay is provided in the signal path between processing block 35 and one or more transducers. For example, processing block 35 may be coupled to adders 29A and 30A via delay 61. Alternatively, processing block 35 may be coupled to adder 29A via delay 62 and to adder 30A via delay 63. Delays similar to delays 61, 62 and 63 may be inserted between processing block 35 and transducers 27B and 28B. More delays may be inserted in the processing blocks 23-26 and 31-34 of fig. 1A. The delay may be implemented as an all-pass filter, a complementary all-pass filter, a non-minimized phase filter, or a delay. The delay may be used to generate a relative time difference between the signals provided to the transducers.

Referring now to fig. 2, an implementation of the audio signal processing system of fig. 1A is shown. In the embodiment of fig. 2, inputs 10 and 12 represent the left (L) and right (R) inputs of a conventional multi-channel system. The transfer functions H1(s) and H8(s) in processing blocks 23 and 34, respectively, represent no change (have a single value); the transfer functions H3(s), H4(s), H5(s) and H6(s) in processing blocks 25, 26, 31 and 32 have zero values and are not shown. The processing block 35, which includes the transfer function H9(s), affects the lf signal that is sent on average to the four transducers. The transfer functions H2(s) and H7(s) in processing blocks 24 and 33 represent inverse (indicated with negative sign) and time shifts (Δ t2 and Δ t7, respectively). As a result of the signal processing of the embodiment of FIG. 2, transducer 27B radiates acoustic waves corresponding to the signal combination Lhf + (L + R) lf; transducer 28B radiates acoustic waves corresponding to the signal combination-Lhf Δ t2+ (L + R) lf; transducer 29B radiates acoustic waves corresponding to signal combination-Rhf Δ t7+ (L + R) lf; and transducer 30B radiates acoustic waves corresponding to signal combination Rhf + (L + R) lf.

Referring to fig. 3A, an implementation of the embodiment of fig. 2 is shown, which illustrates one use of the present invention. Transducers 27B and 28B may be conventional four inch diameter conical acoustic drivers mounted such that one radiating face of each transducer radiates acoustic energy into waveguide 39A directly or through an acoustic tank (acoustcvolumn) 80 or some other acoustic element. The other radiating surface of each transducer radiates acoustic energy directly to the external environment. The characteristics of the transfer functions H1(S) and H2(S), including the delay at 2 and the position and orientation of the transducers 27B and 28B, are set so that the front faces of the transducers 27B and 28B act as a directional array radiating sound waves corresponding to the high frequency spectral components of the left channel in a radiation pattern (e.g., cardioid 40) in which more acoustic energy is radiated in a direction 44 generally directed toward a listener 46 in a listening position associated with the audio signal processing system 1 than in some other direction. Transducers 29B and 30B may be conventional four inch diameter conical acoustic drivers mounted such that one radiating face of each transducer radiates acoustic energy into waveguide 39A directly or through acoustic tank 82 or some other acoustic element. The other radiating surface of each transducer radiates acoustic energy directly to the external environment. The characteristics of the transfer functions H7(S) and H8(S), including the delay at 7 and the position and orientation of the transducers 29B and 30B, are set so that the front faces of the transducers 29B and 30B act as a directional array radiating sound waves corresponding to the high frequency spectral components of the left channel in a radiation pattern (e.g., cardioid 42) in which more acoustic energy is radiated in a direction 48 generally directed toward a listener 46 in a listening position associated with the audio signal processing system 1 than in some other direction. Directional arrays are discussed in more detail in us patents 5809153 and 5870484. The sound waves, particularly low frequency sound waves, radiated from the conical back surface to the waveguide amplify the low frequency sound waves radiated from the conical front surface. In this implementation of the embodiment of fig. 2, transducers 29B and 30B are acoustically coupled to waveguide 39A near the closed end of the waveguide, and transducers 27B and 28B are acoustically coupled to waveguide 39A approximately midway between the two ends of the waveband. With the transducers positioned in this manner, the waveguide 39A and the transducers operate in the manner described in copending application S/N09/753167. Acoustic volumes 80 and 82 act as acoustic low pass filters, as described in co-pending application S/N09/886868. The low pass filtering effect of containers 80 and 82 is particularly advantageous in the present invention because the amplification effect of waveguide 39A is more important at low frequencies than at high frequencies. Combinations including waveguides and transducers may also include other elements to reduce high frequency resonance; such elements may include, for example, strategically placed foam sections. The closed substantially constant cross-sectional area waveguide may be replaced by some other form of waveguide, such as an open waveguide or a tapered or stepped waveguide as described in U.S. patent application 09/146662. Low frequency acoustic energy may be radiated non-directionally.

In one variation of the implementation of FIG. 3A, the characteristics of the transfer functions H1(S) -H8(S) are set so that transducers 27B and 28B and transducers 29B and 30B radiate high frequency acoustic energy non-directionally. Non-directional radiation patterns can be achieved by setting the transfer functions H1(S) and H2(S) so that the audio signals arrive at transducers 27B and 28B and transducers 29B and 30B simultaneously and are in phase. In another implementation of fig. 3A, the characteristics of the transfer functions H1(S) -H8(S) may vary such that transducers 27B and 28B and transducers 29B and 30B may have one mode of operation in which the radiation pattern is directed and a second mode of operation in which the radiation pattern is not directed, or so transducers 29B and 30B may have one mode of operation in which the radiation pattern is directed in one direction and a second mode of operation in which the radiation pattern is directed in a second direction. In addition, the transfer functions H1(S) -H8(S) can be formulated such that the directionality is incrementally or continuously changed between the two modes by incrementally or continuously changing the transfer functions H1(S) -H8 (S).

Fig. 3B illustrates another implementation of the embodiment of fig. 2. In the implementation of FIG. 3B, transducer 28B is acoustically coupled to waveguide 39A proximate the first end of the waveguide, transducer 27B is acoustically coupled to waveguide 39A approximately one-quarter of the distance from the first end to the second end of the waveguide, transducer 30B is coupled to waveguide 39A approximately one-half of the distance from the first end to the second end, and transducer 29B is coupled to waveguide 39A approximately three-quarters of the distance from the first end to the second end. By varying the geometry of the waveguides and the mounting points of the transducers, a combination of directional array behavior and waveguide behavior can be achieved. The transducers may be connected to the waveguide by containers, such as containers 84-87.

Practical considerations may be made for complex waveguide/transducer structures, such as the structure of fig. 3B, which is difficult to implement. In this case, the delays 61-63 of FIG. 1B may be advantageously utilized to change the effective position in the waveguide of one or more transducers.

The graph showing the radiation pattern is diagrammatic and the transducer arrangement shown need not be the one used to produce the radiation directionality pattern shown. The directivity mode can be controlled in a number of ways. One way is by changing the arrangement of the transducers. Some examples of different transducer arrangements for controlling the directivity pattern are shown in fig. 3C. The distance between the transducers may be varied, as shown in arrangements 232 and 234; the transducer may be acoustically coupled to the waveguide by an acoustic capsule or some other acoustic element, as shown in arrangement 236; or the positioning of the transducers to the listening space may be changed, the positioning of the transducers relative to each other may be changed or additional transducers may be added, as shown in one or more of the arrangements 238, 240 and 242; and many other arrangements may be devised using different arrangements of transducers or combinations of arrangements shown in figure 3C. The directional pattern may also be changed by signal processing methods such as changing the phase between signals or changing the time of arrival of a signal at a transducer, changing the amplitude of signals sent to two transducers, changing the relative polarity of two signals, other signal processing methods alone or in a combined group. Controlling radiation directionality patterns is discussed more fully in U.S. patents 5809153 and 5870484.

At very high frequencies, the transducer tends to become directional in the axial direction of the transducer face, i.e. in the direction of the cone motion. For arrangements such as arrangements 238, 240 and 242 having a transducer 244 with an axis 246 generally directed toward a listening space associated with the sound system, additional circuitry and signal processing may pad out (roll off) signals to the transducer 248 that are not directed toward the listening space, so that at very high frequencies, sound waves are radiated only by the transducer 244 having an axis 246 generally directed toward the listening space, providing directional radiation at very high frequencies. Alternatively, an additional transducer having a small radiating surface may be added in close proximity to the listening space for radiating very high frequency sound energy at a low level, so that significantly more very high frequency sound waves are heard in the listening space associated with the sound system than in the listening space associated with an adjacent listening space.

Referring to fig. 4, a number of audio signal processing systems according to the embodiment of fig. 3A are shown, illustrating an intended use of the invention, and disclosing another feature of the invention. In fig. 4, nine audio signal processing systems 1A-1H, each having a corresponding listener 46A-46H, are placed in the acoustically open area. Each audio signal processing system may connect it to a video device (not shown) that, together with the audio signal processing system and a user interface, allows a listener to operate an interactive multimedia entertainment device. An example of a multimedia entertainment device is a video game (for home or online use). The second category of multimedia entertainment is gambling machines (e.g., slot machines, bingo devices, video lottery terminals, poker machines, gambling rooms, or local or wide area progressive gambling machines), especially those used in a casino environment, which includes many gambling machines in acoustically open areas. Each sound system 1A-1H may also have two modes of operation as described in the variant discussion of fig. 3A. Sound systems 1A-1D and 1F-1H operate in a mode in which transducers 27A and 28A and transducers 29A and 30A radiate high frequency acoustic energy directionally so that listeners associated with the sound systems hear significantly more sound radiated by each sound system than listeners associated with the other sound systems. Sound system 1E radiates high frequency sound waves non-directionally so that listener 46E does not hear significantly more high frequency sound waves radiated by system 1E than listeners associated with other systems. The audio signal processing system 1A-1H may be configured to operate in a first mode under some conditions and in a second mode under other conditions, or to switch between modes in case some event occurs. Switching between modes may be achieved by digital signal processing or manual or automatic analog or digital switching or by modifying signal processing parameters. There are many ways to modify the signal processing parameters, such as manual control, voltage controlled filters or voltage controlled amplifiers, or conversion function factor updates or modifications. The sound systems 1A-1H may be networked to each other and to the controller 2 so that they may be controlled locally by the sound systems or remotely by the controller 2. The sound systems 1A-1E may also be networked so that the sound system sources may be remote, local, or partially remote and partially local. In fig. 4, audio system 1E may operate in a mode responsive to the occurrence of a condition or an event such that the array comprising transducers 27A and 28A and the array comprising transducers 29A and 30A radiate high frequency acoustic energy non-directionally. For example, in a video casino (arcade) implementation, the sound system may operate in a directional mode under normal conditions and switch to a non-directional mode for a predetermined period of time if the player has reached a certain level of performance. In a playroom implementation, the sound system may operate in a directional mode under normal conditions and switch to a non-directional mode for a predetermined period of time if the player clicks "jackpot," thereby providing stimulation and encouragement to all listeners in the vicinity of the sound system 1E.

One embodiment of the present invention is particularly advantageous in a casino environment. It is desirable to place as many machines in a space as possible, to make a sufficient level of sound for each machine to sustain stimulation, and to listen to more of the acoustic energy radiated by each machine in the listening space associated with a device than in the listening space associated with an adjacent device.

In another implementation, the directivity pattern may be continuously or incrementally varied between directional and non-directional, or continuously or incrementally between radiating directionally in one direction and directional radiation in another direction. One method for providing a continuous orientation or incremental change is illustrated in fig. 16 below, and the corresponding portions of the present disclosure.

Referring to fig. 5, a diagram of an alternative implementation of fig. 3A is shown. Corresponding reference numerals in fig. 5 refer to like-numbered elements of fig. 3. In the implementation of FIG. 5, transducers 27B, 28B, 29B and 30B are mounted in a housing 39B having a port 50. Transducers 27B and 28B are conical acoustic drivers mounted such that one conical surface radiates acoustic waves to the ported enclosure and one conical surface radiates acoustic waves to the atmosphere. The values of delay at 2 of fig. 2, the characteristics of the transfer functions H1(s) and H2(s) of fig. 2, and the positions and orientations of transducers 27B and 28B are set so that the front surfaces of transducers 27B and 28B act as a directional array for radiating sound waves corresponding to the high frequency spectral components of the left channel in a radiation pattern (e.g., cardioid 40) that is oriented in a direction 44 that is generally oriented toward a listener 46 in a listening position associated with audio signal processing system 1. The delay values at 7, the characteristics of the transfer functions H7(s) and H8(s), and the positions and orientations of the transducers 29B and 30B are set so that the front surfaces of the transducers 29B and 30B act as a directional array for radiating sound waves corresponding to the high frequency spectral components of the right channel in a radiation pattern (e.g., cardioid 42) that is oriented in a direction 48 that generally orients a listener 46 in a listening position associated with the audio signal processing system 1. The sound waves, especially low frequency sound waves, radiated by the back surface of the cone to the housing with the ports amplify the sound waves radiated by the front surface of the cone.

Referring now to FIG. 6, another embodiment of the present invention is shown. In the embodiment of fig. 6, the inputs represent the left and left surround inputs of a surround sound system. The transfer functions H1(s) and H6(s) represent no change (have a single value); the transfer functions H3(s), H4(s), H7(s) and H8(s) in processing blocks 25, 26, 33 and 34 (of fig. 1A) are absent (have mathematical zero values) and are not shown. The transfer function H9(s) of processing block 35 likewise affects the lf signal sent to the transducer. The transfer functions H2(s) and H5(s) represent the inverse (indicated by the minus sign) and time shifts (Δ t2 and Δ t 5). As a result of the signal processing of the embodiment of FIG. 2, transducer 27B radiates sound waves corresponding to the signal combination Lhf-LShf Δ t5+ (L + LS) lf, and transducer 28B radiates sound waves corresponding to the signal combination LShf-Lhf Δ t2+ (L + LS) lf. There may be the same audio signal processing system for the right and right surround channels.

Referring now to fig. 7, an implementation of the embodiment of fig. 6 is shown. In the embodiment of FIG. 7, transducers 27B-L ("L" for left/left surround audio signal processing system) and 28B-L are mounted in a housing 52L having an opening. The enclosure with the opening is configured to amplify the low frequency acoustic waves radiated by the transducers 27B-L and 28B-L. The spacing of the transducers and the value of Δ t2 are set so that the acoustic wave corresponding to the Lhf signal radiates directionally toward the listener 46 as indicated by arrow 54. The spacing of the transducers and the value of Δ t5 are set so that the sound waves corresponding to the LShf signal radiate directionally in a direction 56 that is not directed toward the listener so that the sound waves arrive at the listener after reflection from the house boundary and objects in the house. Similarly, transducers 27B-R ("R" refers to right/right surround audio signal processing system) and 28B-R are mounted in a housing 52R having an opening. The enclosure with the opening is configured to amplify the low frequency sound waves radiated by the transducers 27B-R and 28B-R. The spacing of the transducers and the value of Δ t2 are set so that the sound wave corresponding to the Rhf signal radiates directionally toward the listener 46 as indicated by arrow 58. The spacing of the transducers and the value of Δ t5 are set so that the sound waves corresponding to the RShf signal radiate in a direction that is not directed toward the listener so that the sound waves arrive at the listener after reflection from the house boundary and objects in the house. In another implementation of fig. 6, such as the implementation of fig. 4, the signal processing, transducer spacing, and values of Δ t2 and Δ t5 are set so that the acoustic waves corresponding to the L and LS signals and the R and RS signals radiate into the listening space occupied by the listener 46. If there is a center channel, the center channel may be radiated by a single centrally located transducer, a device similar to that shown in FIG. 7, or the center channel may be down-combined (downmix), as shown in FIG. 8B.

Referring to fig. 8A, another embodiment of the present invention is shown. In the embodiment of fig. 8, the inputs 10 and 12 may represent inputs of a conventional stereo sound system or L and R inputs of a conventional multi-channel sound system. A center channel input 70, which may be the center channel of a multi-channel sound system, may also be included. In the embodiment of fig. 8A, the high and low frequency spectral components of the audio signal are not separated, and thus the combining and filtering circuits and adders of other embodiments are not required. The input 10 is connected to an electroacoustic transducer 27B via a processing block 23. Input 12 is connected to electro-acoustic transducer 28B through processing block 34. The input 70 is connected to an electro-acoustic transducer 74 through a processing block 72. The transfer functions H1(s) (L signal provided to processing block 23), H8(s) (R signal provided to processing block 34) and H10(s) (C signal provided to processing block 72) may include functions such as single channel equalization, single equalization of transducers to account for room effects, volume or balance control, and image spreading, or other similar functions, or may represent no change. The sound wave corresponding to the full range left channel signal is radiated by transducer 28B and the sound wave corresponding to the full range center audio signal is radiated by transducer 74. More details of this embodiment are shown in fig. 9.

Fig. 8B shows an alternative processing circuit for processing the center channel signal. In the system of fig. 8B, the center channel may be combined down into left and right channels at adders 76 and 78. The down-combining may include scaling of the center channel signal and may be performed according to conventional techniques.

Fig. 8C shows an alternative embodiment of fig. 8A. The implementation of fig. 8C includes the elements of fig. 8A, plus additional circuitry to process the low frequency signals, such as combining and filtering circuit 14 connected to inputs 10 and 12. The combining and filtering circuit 14 includes the adder 38, the low pass filter 41, the high pass filters 36 and 40, and the signal lines 16, 18 and 20 of fig. 1, 2 and 6. In addition, the implementation of fig. 8A may include phase shifters, such as phase shifters 37A and 38B (not shown in this view) of the previous embodiment connecting inputs 10, 12 and 70 to summer 38, and a high pass filter 142 for the center channel signal. The relative phases provided by the phase shifters, if any, may be set so that the signals from inputs 10, 12 and 70 are combined in a normal phase relationship. Summers 27A, 28A and 74A connect the elements of audio signal processing circuit 22 with transducers 27B, 28B and 74B for the left, right and center channels, respectively. The embodiment of fig. 8C functions the same as the embodiment of fig. 8A, except that the bass portions of the three channel signals are combined and sent to each transducer.

Referring now to fig. 9, an implementation of the embodiment of fig. 8A and 8C is shown. In the embodiment of FIG. 9, transducers 27B, 28B and 74 are located in waveguide 39A such that one side of the cone of each transducer faces the outside environment and the other side of the cone of each transducer is acoustically connected to the waveguide. In this embodiment, the transducer may be acoustically connected to the waveguide by acoustic volumes 80, 82, and 84 according to the principles described above in the discussion of fig. 3A and 3B. The transducer may be connected to the waveguide 39A at approximately one-quarter, one-half, and three-quarters of the distance between the two ends of the waveguide as shown, or at other locations, selected empirically or by simulation, which mitigates undesirable resonant effects of the waveguide.

Referring to fig. 10A and 10B, another embodiment of the present invention is shown. The inputs 110, 113 and 115 receive audio signals corresponding to the left, left surround, right surround, and center channels, respectively, of a surround sound system. The input terminals 110 and 113 and 115 are connected to a combining and filtering circuit 114 that outputs a high-frequency L signal (Lhf) on a first signal line 116, a high-frequency LS signal (LShf) on a second signal line 117, a high-frequency R signal (Rhf) on a signal line 118, a high-frequency RS signal (RShf) on a signal line 119, a high-frequency C signal (Chf) on a signal line 121, and a combined low-frequency signal (C + L + LS + R + RS) lf on a signal line 120. The signals on signal lines 116 and 121 are processed by processing circuit 122. The signal on signal line 116 is processed in a manner represented by transfer functions H1(s) and H2(s) in processing blocks 123 and 124 and output to adders 127A and 128A and then to electro-acoustic transducers 127B-128B, respectively. The signal on the signal line 117 is processed in a manner represented by the transfer functions H3(s) and H4(s) in processing blocks 125 and 126 and output to adders 127A and 128A and then to electro-acoustic transducers 127B and 128B, respectively. The signal on signal line 118 is processed in a manner represented by transfer functions H5(s) and H6(s) in processing blocks 131 and 132 and output to summers 129A and 130A and then to electro-acoustic transducers 129B and 130B, respectively. The signal on signal line 119 is processed in a manner represented by transfer functions H7(s) and H8(s) in processing blocks 133 and 134 and output to summers 129A and 130A and then to electro-acoustic transducers 129B and 130B, respectively. The signal on signal line 120 is processed in a manner represented by transfer function H9(s) in processing block 135 and output to adders 127A-130A and 173A and then to electro-acoustic transducers 127B-130B and 173B, respectively. The signal on signal line 121 is processed in a manner represented by transfer function H10(s) in processing block 172 and output to adder 173A and then to electro-acoustic transducer 173B. As a result of the processing of the systems of fig. 10A and 10B, the transducers 127B and 128B may receive signals Lhf and LShf processed according to different transfer functions; transducers 129B and 130B may receive signals Rhf and RShf sounds processed according to different transfer functions; transducer 173B may receive the processed Chf channel signal; and each of transducers 127B-130B and 173B may receive a combined (C + L + LS + R + RS) lf signal processed according to the same transfer function.

As with the embodiment of fig. 1A, an optional phase shifter such as elements 37A and 37B of fig. 1A may be used when any combination of lf, LSlf, then f, and RSlf are combined to provide a phase relationship that produces a suitable combination of signals. If the sound system does not have a separate center channel transducer 173B, the center channels may be downcombined as shown in FIG. 8B.

One topology for implementing the combining and filtering circuit 114 is shown in fig. 10A and 10B. Input 110 is coupled to a high pass filter 136 and a summer 138. Input 111 is coupled to a high pass filter 137 and an adder 138. The input 112 is connected to a high pass filter 240 and to the adder 138. Input 113 is coupled to a high pass filter 143 and to an adder 138. The connection from either end to summer 138 may be through a phase shifter such as phase shifter 37A or 37B shown in fig. 1A. The adder 138 is connected to a low pass filter 141, which outputs to the signal line 120. Another filter topology may produce substantially the same result; for example, the channels may be low pass filtered before they are combined, or the high pass filter may be implemented as a low pass filter using differential summing of the unfiltered signals, as shown in FIG. 14. The transfer functions H1(s) -H10(s) may represent one or more attenuations/amplifications; delaying time; phase shifting; equalization, or other acoustic signal processing functions. The transfer functions H1(s) -H9(s) may also represent no change (or be mathematically represented as a single value), or may be absent (or be mathematically represented as a zero value); examples of these two cases will be described below. The system of fig. 10A and 10B may also include conventional elements, such as DACs and amplifiers, which are not shown in this view. Additionally, each electro-acoustic transducer 27B-30B may be individually equalized in addition to any equalization that may be implemented in processing blocks 23-26 and 31-35. In fig. 10A and 10B, other topologies may provide the same result. For example, the low pass filter 141 between the adder 138 and the signal line 120 may be replaced by a low pass filter between each input and the adder 138.

In one embodiment of the invention, the transfer functions H1(s), H4(s), H6(s) and H7(s) represent no change (mathematically expressed as a single value), and the transfer functions H2(s), H3(s), H5(s) and H8(s) represent inversion (indicated by negative sign) and delay (indicated by Δ tn, where n is 2, 3, 6 and 7, respectively).

From the perspective of the electro-acoustic transducer, transducer 127B receives the combined signal Lhf-LShf Δ t3+ + (L + LS + R + RS + C) lf; transducer 128B receives the combined signal LShf-Lhf Δ t2+ (L + LS + R + + RS + C) lf; transducer 129B receives the combined signal RShf-Rhf Δ t5+ (L + LS + R + RS + C) lf; transducer 130B receives combined signal Rhf-RShf Δ t8+ (L + LS + R + RS + C) lf; and transducer 173B receives combined signal Chf + (C + L + LS + RS) lf.

Referring to fig. 11, an implementation of the embodiment of fig. 10A and 10B is shown. The delay values Δ t2, the characteristics of the transfer functions H1(S) and H2(S), and the positions and directions of the transducers 127B and 128B are set so that the front surfaces of the transducers 127B and 128B radiate sound waves as a directional array corresponding to the high frequency spectral components of the left channel in a radiation pattern that is generally directed in a direction 54 that is directed toward the listener 46 in the listening position associated with the audio signal processing system 1. The delay values at 3, the characteristics of the transfer functions H3(S) and H4(S), and the locations and directions of the transducers 127B and 128B are set so that the front faces of the transducers 127B and 128B act as a directional array radiating sound waves corresponding to the high frequency spectral components of the left surround channel in a radiation pattern that is generally directed in a direction 56 other than direction 54, in this example outward. Alternatively, the delay value Δ t3, the characteristics of the transfer functions H3(S) and H4(S), and the positions and orientations of transducers 127B and 128B are set so that the front faces of transducers 27B and 28B act as a directional array radiating sound waves corresponding to the high frequency spectral components of the left surround channel in a radiation pattern that is directional in direction 54, inward in this example. The delay values Δ t6, the characteristics of the transfer functions H5(S) and H6(S), and the positions and directions of the transducers 129B and 130B are set so that the front surfaces of the transducers 129B and 130B act as a directional array radiating sound waves corresponding to the high frequency spectral components of the right channel in a radiation pattern that is generally directed in the direction 58 directed toward the listener 46 in the listening position associated with the audio signal processing system 1. The delay value Δ t7, the characteristics of the transfer functions H7(S) and H8(S), and the positions and orientations of transducers 129B and 130B are set so that the front surfaces of transducers 129B and 130B act as a directional array radiating sound waves corresponding to the high frequency spectral components of the right surround channel in a radiation pattern that is generally directional in a direction 60 other than direction 58, outward in this example. Alternatively, the delay value Δ t7, the characteristics of the transfer functions H7(S) and H8(S), and the positions and orientations of transducers 129B and 130B are set so that the front surfaces of transducers 129B and 130B act as a directional array radiating sound waves corresponding to the high frequency spectral components of the right surround channel in a radiation pattern that is directional in direction 58, in this example inward.

Directional arrays are discussed in more detail in us patents 5809153 and 5870484. The sound waves, particularly low frequency sound waves, radiated from the conical back surface to the waveguide amplify the low frequency sound waves radiated from the conical front surface. In this implementation of the embodiment of FIG. 11, transducers 129B and 130B are located near the closed end of the waveguide, and transducers 127B and 128B are located approximately midway between the two ends of the waveguide. With the transducer positioned in this manner, the waveguide 139A and transducer operate in the manner described in co-pending U.S. patent application S/N09/753167. The components comprising the waveguide and transducer may also include elements to reduce high frequency resonance; those elements may include, for example, strategically placed foam sections.

In addition to the directionality direction shown in FIG. 11, the display mode signal processing method of co-pending U.S. patent application S/N09/886868 may be used to produce different combinations of directionality patterns for the L, LS, R, and RS channels.

Referring now to fig. 12, a sound system including an alternative configuration of the combining and filtering circuit 114 and the audio processing circuit 122, and including additional features of the present invention, is shown. Input terminal 10 is connected to a signal conditioner 89 which is connected to a combining and filtering circuit 14 via signal line 210. Input 12 is connected to a signal conditioner 90 which is connected to combining and filtering circuit 14 by signal line 212. The combining and filtering circuit 14 is connected to the directivity control circuit 91 of the audio signal processing circuit 22. The directivity control circuit 91 is connected to signal summers 27A and 28A, each of which is in turn connected to a corresponding electroacoustic transducer 27B and 28B. The combining and filtering circuit 14 is also connected to the directivity control circuit 92 of the audio signal processing circuit 22. The directionality control circuit 92 is connected to signal summers 29A and 30A, each of which is in turn connected to a respective electro-acoustic transducer 29B and 30B. The combining and filtering circuit 14 is also connected to a processing block 35 of the audio signal processing circuit 22, which is in turn connected to signal adders 27A-30A, each of which is in turn connected to an electroacoustic transducer 27B-30B.

In the discussion of fig. 13-16, a more detailed description of the elements of fig. 12 and their operation may be found.

Referring now to fig. 13A-13C, signal conditioner 89 is shown in greater detail. The signal conditioner 89 includes a signal compressor 160 and a level dependent dynamic equalizer 162. The compressor 160 comprises a multiplexer 164 which is connected to the input 10 and differentially connected to an adder 166. Input terminal 10 is also coupled to adder 166. The adder is connected to an amplifier 168 which is connected to the level dependent dynamic equalizer 162 via signal line 169. The level dependent dynamic equalizer 162 includes an input signal line connected to a multiplexer 170 and an adder 172. The multiplexer 170 is differentially connected to an adder 172 and an adder 174. Summer 172 is coupled to an equalizer 176, and equalizer 176 is coupled to summer 174.

Signal modulation will be described by way of exampleThe operation of the section 89, where the input 10 is the left end of a stereo or multi-channel system, where L and R are the left and right channel signals, respectively, and L and R are the amplitudes of the left and right channel signals, respectively. The system can also be applied to other combinations of channels, such as surround channels. In operation, the multiplexer 164 of the compressor 160 provides a coefficient, or attenuation factorTo the input signal where Y ═ L | + | R | and K1 is a constant that depends on the degree of dynamic range compression desired. Typical values for K1 are in the range of 0.09. The adder 166 differentially sums the output signal of the multiplexer 164 with the input signal so that the signal provided to the amplifier 168 is compressed by a factor ofIs determined by the number of values of (c). The amplitude L of the input signal L is effectively attenuated by a factorAnd amplified by a factor K2 to provide the amplitude L of the compressed signal_comThereby compressing the amplitude L of the signal_comIs thatExpression formulaReduced toSo that the amplitude L of the compressed signal_comIs also described asMagnitude valueIs sent to the level dependent dynamic equalizer 162.

If the values of | L | and | R | are large relative to K1, thenIs close to 1, andis close to 0 and the signal is therefore sufficiently compressed. If the values of | L | and | R | are both small, thenIs close to 1 and the signal is rarely compressed. A typical value for the gain K2 of the amplifier is 5.

The multiplexer 170 of the level dependent dynamic equalizer 162 provides a coefficientWherein K3 is a signal that is applied to the sum of the audio signal andis measured as a related constant, andcan be expressed asA typical value for K3 is 0.025. The adder 172 combines the output signal from the multiplexer 170 with the compressed signal L_comDifferentially combined so that the signal output from summer 172 is effectively attenuated by a factorThe signal from summer 172 is then balanced by equalizer 176 and combined with the unequalized output of multiplexer 170 at summer 174, thereby passing the signal that has been attenuated by a factorAnd an equalized signal attenuated by an equalization factorAnd the equalized signals are combined to form the output signal of signal conditioner 89. In order to equalize the large value of the coefficient value Y2 close to 0, equalization is applied to a small portion of the signal. For small values of Y2, the coefficient value is close to 1 and equalization is applied to most of the input signal.

Signal conditioner 90 may have elements that correspond to elements in signal conditioner 89, which are arranged in a substantially identical manner and perform substantially the same function in a substantially similar manner.

Fig. 14 shows the combining and filtering circuit of fig. 12 in more detail. The signal line 210 is connected to the all-pass filter 94, which is differentially connected to the adder 96. The signal line 210 is also connected to a low pass filter 98 which is connected to the all pass filter 140 and the adder 96. The adder 96 is connected to the signal processing block 91 of the audio processing circuit 22. The all-pass filter 140 of phase shifter 37A is connected to the all-pass filter 142 of phase shifter 37A. The all-pass filter 142 is connected to the adder 38. The signal line 212 is connected to an all-pass filter 95 which is differentially connected to the adder 97. The adder 97 is connected to the signal processing block 92 of the audio signal processing circuit 22. The signal line 212 is also connected to a low pass filter 99 which is connected to the all pass filter 144 and the adder 97. The all-pass filter of phase shifter 37B is connected to all-pass filter 146 of phase shifter 37B. An all-pass filter 146 is coupled to the summer 38. The adder 38 is connected to the signal processing block 35 of the audio signal processing circuit 22.

The characteristics of the all-pass filter are shown in the following table:

filter with a filter element having a plurality of filter elements	Electrode for electrochemical cell	Zero point
	Electrode for electrochemical cell	Zero point	140	-8	8
142	-133	133	140	-8	8

144	-37	37
144	-37	37	146	-589	589
94，95	-400	400	146	-589	589

Phase shifters 37A and 37B may also be implemented as two all-pass filters as shown, or may be implemented as more or less than two all-pass filters, depending on the frequency range over the relative phase difference desired. The filter may have a singular point (singularity) different from that listed in the table. The low pass filters 98 and 99 may be second order low pass filters with a cutoff frequency of about 200 Hz. Other cut-off frequencies and other filter orders may be used depending on the transducer used and signal processing considerations. The signal blocks 91 and 92 will be described in fig. 16.

Lowpass filters 98 and 99, phase shifters 37A and 37B, and adder 38 perform functions similar to lowpass filters 41, phase shifters 37A and 38B, and adder 38 of fig. 1A and 1B, except that the signals are lowpass filtered prior to their combination. The combination of low pass filter 98 and adder 96 and the combination of low pass filter 99 and adder 97 perform functions similar to high pass filters 36 and 40 of fig. 1A and 1B, respectively. The all-pass filters 94 and 95 provide proper phase alignment when combining the high frequency signals in a subsequent stage of the apparatus.

Referring to FIG. 15A, processing block 35 of the embodiment of FIG. 12 is shown in greater detail. The signal line from the adder 38 is connected to a limiter 190 and a notch filter 192. The output of the slicer 190 is connected to a notch filter 194 and an adder 196. The output of notch filter 194 is differentially connected to a summer 196. The output of summer 196 and the output of notch filter 192 are coupled to a summer 198. For illustration, some nodes are identified in FIG. 15A. Node 200 is on the signal line between the input and limiter 190 and between the input and notch filter 192. Node 202 is on the signal line between limiter 190 and notch filter 192 and between limiter 190 and adder 196. Node 204 is on the signal line between notch filter 194 and summer 196. Node 206 is on the signal line between notch filter 192 and adder 198. Node 208 is on the signal line between adders 196 and 198. Node 209 is on the signal line between the adder 198 and the output.

Fig. 15B shows a variation of the circuit of fig. 15A. In the circuit of fig. 15B, the adders 196 and 198 of fig. 15A are combined into an adder 197. The circuits of fig. 15A and 15B perform substantially the same function.

Referring to fig. 15C and 15A, exemplary frequency response patterns at the node of fig. 15A are shown. Curve 210 is the frequency response of the audio signal. Curve 212 is the frequency response curve at node 202. After clipping, curve 212 has an undesirable distortion 214. Curve 216 is the frequency response at node 204 after notch filter 194. Curve 220 illustrates the summation by adder 196. Curve 216' is an inverted curve 216 representing the differential sum. Curve 222 is the frequency response at node 208 after summing at summer 196. Curve 224 is the frequency response at node 206 after notch filter 192. Curve 226 illustrates the summation by adder 198. Curve 228 is the frequency response at node 209 after the summing by the adder.

Notch filters 192 and 194 may be centered at approximately the maximum excursion frequency of the electro-acoustic transducer, or at other significant frequencies, such as approximately at frequencies where the impedance is low and power is provided. The limiter 190 may be a dipole limiter, or some other form of limiter that limits the signal amplitude to a small frequency band. Notch filters 192 and 194 may be notch filters as shown, or may be bandpass filters or lowpass filters.

In operation, the circuits of fig. 15A and 15B effectively decompose and recombine an input signal as a function of frequency by using both clipped and non-clipped signal portions. The distortion-prone limited signal portion used is close to the maximum offset frequency of the electro-acoustic transducer or transducers where it may be desirable to limit the maximum signal provided. The larger portion of the recombined frequency response curve comes from the un-clipped frequency response curve, which typically contains less distortion than the clipped frequency response curve. The circuit may also be modified to clip more than one frequency, or to clip frequencies other than the maximum offset frequency. In some applications, the notch filter may be replaced by a low pass filter or a band pass filter. The circuits of fig. 15A and 15B limit the maximum amplitude signal at one or more predetermined frequencies, do not limit other frequencies, and provide clipping in a manner that introduces minimal distortion.

The signal conditioners 89 and 90 and the combining and filtering circuit 14 of fig. 12 and their constituent elements may be modified and reconfigured in a number of ways. For example, signal conditioners 89 and 90 may be used alone; i.e. one element may be used alone. In a system having both signal conditioners 89 and 90 and combining and filtering circuit 14, the order may be reversed; that is, the signals may be combined and filtered first, and then conditioned. Either element of the signal conditioner (compressor 160 and level dependent dynamic equalizer 162 of fig. 13A) may be used alone; i.e. one element may be used alone.

Referring to FIG. 16, the directionality control circuit 91 is shown in greater detail. The signal lines from the adder 96 of the combining and filtering circuit 14 of fig. 14 are connected to a delay 230, a multiplexer 232 and an adder 234. Delay 230 is coupled to multiplexer 236 and adder 238. Multiplexer 232 is differentially coupled to adder 234 and additionally to adder 27A. Multiplexer 236 is differentially coupled to adder 238 and additionally to adder 28A. Adder 234 is coupled to adder 28A. Adder 238 is coupled to adder 27A. The adder 27A is connected to the electroacoustic transducer 27B. The adder 28A is connected to the electroacoustic transducer 28B. Processing block 35 of fig. 14 (not shown) is connected to adders 27A and 28A.

Since time and phase may be correlated in a known manner, delay 230 may be implemented in the form of one or more phase shifters. Non-minimum phase devices may also be used to achieve the delay. In DSP-based systems, latency can be achieved by directly delaying data samples by a large number of clock cycles. The phase shifter may be implemented as an all-pass filter or a complementary all-pass filter.

In operation, the audio signal from the adder 96 of the combining and filtering circuit 14 is attenuated by the multiplexer 232 by an attenuation factorAnd differentially combined with the unattenuated signal at adder 234. The combined signal is then sent to adder 28A. In addition, the output of the multiplexer 232 is sent to the adder 27A. The audio signal from the adder 96 of the combined filter circuit 14 is delayed by a delay 230 and attenuated by an attenuation factor by a multiplexer 236And differentially combined with the unattenuated signal at summer 238. The combined signal is then sent to adder 27A. In addition, the output of multiplexer 236 is sent to adder 28A. Adders 27A and 28A may also receive low-frequency audio signals from processing block 35 of audio signal processing circuit 22. The combined signal at summers 27A and 28A is then radiated by electro-acoustic transducers 27B and 28B, respectively. The delay at, spacing, and orientation of the transducers 27B and 28B may be arranged to radiate acoustic energy directionally as described in U.S. patents 5809153 and 5870484, and as implemented in the systems of fig. 3A, 3B, 4, 5, 6, 7, and 11,

the directivity of the array of electro-acoustic transducers 27B and 28B can be controlled by controlling the correlation, amplitude and phase relationship of the L and R signals. Two cases are illustrated at the bottom of fig. 16. If L ═ R (i.e., the mono signal, in phase), the value of the attenuation factor is zero, and a signal substantially free of L signals-L Δ t is sent to transducer 27B, and a signal L substantially free of-L Δ t is sent to transducer 28B. If L ═ R (i.e., same amplitude, and opposite phase), the coefficient value is 1, and a signal substantially free of L signal-L Δ t is sent to transducer 28B, and a signal substantially free of-L Δ t is sent to transducer 27B, resulting in a substantially different directivity pattern.

The result of the processing of the circuit of fig. 16 is attenuated by a factorIs added to a delayed or phase shifted signal and a low frequency audio signal from element 35 at adder 27A and transduced by transducer 27B, the delayed or phase shifted signal being attenuated by a factorAnd inverted (indicated by minus signs). Has been attenuated by a factorIs combined with a delayed signal, which is attenuated by a factor, and a low frequency audio signal from element 35 at adder 28A and transduced by transducer 27BAnd inverted (indicated by minus signs). As described in the discussion of fig. 4, varying the amplitude, correlation, and phase of the L and R signals can result in different radiation patterns. In addition to the signal dependent directivity control of fig. 16, other arrangements such as a user-contactable switch or an automatic switch or signal processing may change the directivity pattern continuously or incrementally, and may be formed upon the occurrence of some event.

The directivity control circuit 92 has substantially the same elements as the directivity control circuit 91, which are arranged in substantially the same structure and perform the same operation in substantially the same manner.

In addition, the directivity control circuit of fig. 16 may be used for other channels, such as surround channels. The surround channel signals may be processed to be radiated by the transducers 27B and 28B, or may be processed to be radiated by other transducers.

Referring to fig. 17A and 17B, another embodiment of the present invention is shown. Sound system 300A includes a front sound system 301A having inputs 310L, 310C and 310R for the left (L), center (C) and right (R) channels of a multi-channel sound system. Each input is connected to a high pass filter 312L, 312C and 312R, each of which is in turn connected to one of the processing blocks 313L, 313C and 313R. Each processing block 313L, 313C, and 313R is connected to a summer 314L, 314C, and 314R, each summer 314L, 314C, and 314R being connected to an electroacoustic transducer 316L, 316C, and 316R, respectively. Electro-acoustic transducers 316L, 316C, and 316R are mounted such that they radiate acoustic waves to a low frequency amplification device, such as waveguide 318. Inputs 310L, 310C, and 310R are coupled to an adder 320, and adder 320 is coupled to a low pass filter 311. The low-pass filter 311 is connected to a processing block 313LF, which is in turn connected to adders 314L, 314C and 314R, respectively. As shown in the previous figures, some or all of the inputs 310L, 310C, and 310R may be connected to the adder 320 through phase shifters such as elements 37A and 37B of fig. 1A. These elements may be arranged in a different order. Filters 312L, 312C, and 312R may be incorporated in the transfer functions of processing blocks 313L, 313C, and 313R. The transfer function may incorporate processing such as phase shifting, time delaying, signal conditioning, compression, clipping, equalization, HRTF processing, etc., or may represent a zero or integer. Additionally, the transducers 316L, 316C, and 316R may be mounted such that they radiate sound waves through the acoustic enclosure to the waveguide 318, as shown in the previous figures.

Front sound system 301A operates in the manner described in the previous figures, e.g., fig. 3C. Each of the electro-acoustic transducers 316L, 316C and 316R radiates a channel high frequency acoustic wave (Lhf, Chf and Rhf, respectively) and also radiates a combined low frequency acoustic wave (L + R + C) lf. A low frequency amplification device, such as waveguide 318, amplifies the products of the low frequency acoustic wave.

Sound system 300A may also include a rear (rear) sound system 302A as shown in fig. 17B. Rear sound system 302A has inputs 330LR and 330RR for the Left Rear (LR) and Right Rear (RR) channels of a multi-channel sound system. Each input is connected to one of the high pass filters 332LR and 332RR, which in turn are connected to one of the processing blocks 333LR and 333 RR. Each summer 334LR and 334RR is connected to an electro-acoustic transducer 336LR and 336RR, respectively. Electro-acoustic transducers 336LR and 336RR are mounted such that they radiate acoustic waves to a low frequency amplification device such as a housing 338 having an outlet. Each input 330LR and 330RR is also connected to an adder 340, which adder 340 is connected to a low pass filter 341. The low pass filter 341 is connected to a processing block 333LR which is in turn connected to adders 334LR and 334 RR. As shown in the previous figures, one or both of the inputs 330LR and 330RR may be connected to the summer 340 by a phase shifter such as elements 37A and 37B of fig. 1A. These elements may be arranged in a different order. Filters 332LR and 332RR may be incorporated in the transfer functions of processing blocks 333LR and 333 RR. The transfer function may incorporate processing such as phase shifting, time delaying, signal conditioning, compression, clipping, equalization, etc., or may represent a zero or integer. In addition, transducers 336LR and 336RR may be mounted such that they radiate acoustic waves to a low frequency amplification device, such as a container with an opening or a housing with a passive radiator.

The rear sound system 302A operates in a manner similar to the embodiment described in the previous figures and may also operate in a manner similar to the rear acoustic radiating apparatus of co-pending U.S. patent application 10/309395. The LR signal and RR signal may include left surround and right surround channel audio signals, respectively, and may also include Head Related Transfer Function (HRTF) elements, such as a binaural time difference, a binaural phase difference, a binaural level difference, or a monaural frequency spectrum, suggesting a more accurate placement of the image of the sound source for the listener 322. The transducers may also be connected to other elements by circuitry such as described above so that they are able to radiate sound having varying degrees of directivity.

The sound system according to the embodiment of fig. 17A and 17B is advantageous for the reasons previously set forth. Further, the sound system according to fig. 17A and 17B can radiate real position information to the listener 22, and can radiate different position information to listeners of many multimedia entertainment apparatuses in the same listening zone. Due to the natural directionality close to the listener and at very high frequencies of the transducer, each listener hears the sound associated with the corresponding multimedia device more clearly than listeners capable of hearing the sound associated with other multimedia entertainment devices.

Referring to fig. 18, another implementation of the embodiment of fig. 17A and 18A is shown. In fig. 18, a signal processing system utilizing the circuit of fig. 2 provides a left signal L, a right signal R, a left rear signal LR, and a right rear signal RR. The transducer 316C may be the same as in fig. 17A, or could be replaced with a directional array, or the center channel could be combined down as shown in fig. 8B, and the description of the transducer 316C of fig. 17A omitted. The transducers 316L, 316R, 336LS and 336RS of fig. 17A and 17B are replaced by directional arrays. The implementation of fig. 18 may use two signal processing systems similar to the systems of fig. 1A and 1B or fig. 2, one for the front and the other for the rear to accommodate the front and rear radiation. Transducer 316L and summer 314L of fig. 17A are replaced by a directional array comprising transducers 316L-1 and 316L-2 and corresponding signal summers 314L-1 and 314L-2 in common. Transducer 316R and summer 314R of fig. 17A are replaced by a directional array comprising transducers 316R-1 and 316R-2 and corresponding signal summers 314R-1 and 314R-2 in common. Transducers 316L-1, 316L-2, 316R-1 and 316R-2 may be mounted such that one radiating surface of each transducer radiates sound waves to the external environment and such that one radiating surface of each transducer radiates sound waves to a low frequency radiation amplification device, such as sound waveguide 318. Similarly, transducer 336R and summer 334LR of FIG. 17B are replaced by a directional array including transducers 336LR-1 and 336RR-1 in common with corresponding signal summers 334LR-1 and 334 LR-2. Transducer 336RR may be replaced by a directional array that includes transducer 336RR-1 and transducer 336RR-2, with transducer 336RR-1 receiving audio signals from summer 334RR-1 and transducer 336RR-2 receiving audio signals from summer 334 RR-2. Transducers 336LR-1, 336LR-2, 336RR-1 and 336RR-2 may be mounted such that one radiating face of each transducer radiates acoustic waves to the outside environment and such that one radiating face of each transducer radiates acoustic waves to a low frequency radiation amplification device such as enclosure 340 having an opening.

In the implementation of FIG. 18, transducers 316L-1, 316L-2, 316R-1 and 316R-2 all receive combined left and right low frequency signals (L + R) lf. Additionally, transducer 316L-1 receives high frequency left signal Lhf; transducer 316L-2 receives the high frequency Lhf signal with polarity reversed and time delayed; transducer 316R-1 receives high frequency signal Rhf; transducer 316R-2 receives the polarity reversed and time delayed signal Rhf. The transducers 316L-1 and 316L-2 operate as a directional array that radiates sound waves corresponding to the Lhf signal in such a way as to radiate more acoustic energy to the listener 322 than to a listener in an adjacent listening space. Similarly, transducers 316R-1 and 316R-2 operate as a directional array that radiates sound waves corresponding to the Rhf signal in such a way as to radiate more acoustic energy to listener 322 than to a listener in an adjacent listening space. Acoustic waveguide 318 works in conjunction with transducers 316L-1, 316L-2, 316R-1 and 316R-2 to amplify the radiation of low frequency acoustic energy.

The transducers 336LR-1, 336LR-2, 336RR-1, and 336RR-2 all receive a combined left rear and right rear low frequency signal (LR + RR) lf. Additionally, transducer 336LR-1 receives high frequency left signal LRhf; transducer 336LR-2 receives the polarity reversed and time delayed high frequency LRhf signal; transducer 336RR-1 receives high frequency signal Rhf; and transducer 336RR-2 receives the polarity reversed and time delayed signal RRhf. Transducers 336LR-1 and 336LR-2 operate as a directional array radiating sound waves corresponding to LRhf signals in such a way as to radiate more acoustic energy to listener 322 than to a listener in an adjacent listening space. Similarly, transducers 336RR-1 and 336RR-2 operate as a directional array that radiates sound waves corresponding to RRhf signals in such a way as to radiate more acoustic energy to listener 322 than to a listener in an adjacent listening space. The enclosure 340 with openings works in conjunction with the transducers 316LR-1, 316LR-2, 316RR-1, and 316RR-2 to amplify the radiation of low frequency acoustic energy.

The left rear LR and right rear RR signals may correspond to the left and right surround signals, or may include other or additional information such as HRTF information in fig. 17B and 18B, or other information such as personalized channels or audio messages.

Another implementation of the system of fig. 17A and 17B and the system of fig. 18 may be implemented by combining the front sound system 301A of fig. 17A with the rear sound system 302B of fig. 18, or by combining the rear sound system 302A of fig. 17A with the front sound system 301B of fig. 18. In the implementations of fig. 17A, 17B, and 18, features of other embodiments may be used, such as the level dependent dynamic equalizer and compressor of fig. 13A-13C or the variable directivity component of fig. 16.

Fig. 19 illustrates another implementation of the system of fig. 17A and 17B and 18. In the implementation of fig. 19, the rear audio system 302C low frequency amplification device of fig. 17B and 340 of fig. 18 are omitted. The transducers 336LR-1, 336LR-2, 336RR-1, and 336RR-2 may be placed in a small enclosure, preferably near the head of the listener 322. The LR signal includes the high frequency portion of the LS signal, with HTRF processing as described in U.S. patent application 10/309395, if desired. The RR signal includes the high frequency portion of the RS signal, with HRTF processing if desired. The low frequency portions of signals LS and RS may be sent to summers 314L-1, 314L-2, 314R-1, and 314R-2 so that all of the low frequency acoustic energy is radiated by the transducers of front sound system 301B.

In the alternative configuration of fig. 19, the front sound system may be similar to the front sound system 301A of fig. 17A or 301B of fig. 18. In another alternative configuration of fig. 19, the front low frequency amplification device, such as waveguide 318, may be omitted and all low frequency signals may be radiated by a rear sound system, such as 302A of fig. 17B, 302B or 302C of fig. 18.

The implementations according to fig. 17A and 17B or fig. 18 are particularly suitable for situations where a large number of sound sources playing different audio program substances, such as gambling machines or video games or other multimedia entertainment equipment, are relatively close to a common listening area. The implementation according to fig. 17A and 17B or fig. 18 allows radiating all surround channels and accurately locating the sound image and sufficient low frequency radiation without the need for separate woofers.

It is apparent to those skilled in the art that numerous uses of, and departures from, the specific apparatus and techniques disclosed herein may be made without departing from the inventive concepts. The invention, therefore, is to be construed as embracing each and every novel feature and novel combination of features disclosed herein and limited only by the spirit and scope of the appended claims.

Claims

1. A multimedia entertainment system comprising

First and second multimedia entertainment devices, each device comprising:

a first input for receiving a first channel audio signal;

a second input for receiving a second channel audio signal;

a dynamic balancing circuit for dynamically balancing the first channel audio signal and the second channel audio signal to provide a dynamically balanced first channel signal and a dynamically balanced second channel signal, the dynamic balancing circuit comprising:

a first attenuator for attenuating the dynamic equalizer input audio signal by a variable factor G to provide a first attenuated dynamic equalizer signal, wherein 0 < G < 1;

a second attenuator attenuating the dynamic equalizer input audio signal by a variable factor of 1-G to provide a second attenuated dynamic equalizer signal;

an equalizer for equalizing said first attenuated dynamic equalizer signal to provide an equalized first attenuated dynamic equalizer signal; and

a dynamic equalizer combiner for combining the equalized first attenuated dynamic equalizer signal with the second attenuated signal to provide a dynamic equalizer output signal;

a clipping and post-clipping processing circuit for clipping the dynamically balanced first channel signal and the dynamically balanced second channel signal to provide a clipped first channel signal and a clipped second channel signal, the clipping and post-clipping processing circuit comprising:

a limiter for limiting the limiter input audio signal to provide a limited audio signal;

a first clipping filter for filtering the clipper input audio signal to provide a filtered, non-clipped audio signal;

a second clipping filter for filtering the clipped audio signal to provide a filtered clipped audio signal;

a first limiter combiner for differentially combining the filtered limited audio signal and the limited audio signal to provide a differentially combined limiter audio signal; and

a second slicer combiner for combining said filtered non-sliced audio signal and said differentially combined audio signal to provide a slicer output signal;

a first splitter for splitting the first limited first channel audio signal into a first channel high frequency signal and a first channel low frequency signal;

a second separator for separating the clipped second channel signal into a second channel high frequency signal and a second channel low frequency signal;

a first processor for processing said first channel high frequency signal to provide a processed first channel signal and a first channel cancellation signal, wherein said first channel cancellation signal is delayed and reversed in polarity with respect to said processed first channel signal;

a second processor for processing said second channel high frequency signal to provide a processed second channel signal and a second channel cancellation signal, wherein said second channel cancellation signal is delayed and inverted in polarity with respect to said processed second channel signal;

a first signal combiner for combining the processed first channel signal and the first channel low frequency signal to provide a first channel output signal;

a second signal combiner for combining the first channel cancellation signal and the first channel low frequency signal to provide a first channel cancellation output signal;

a third signal combiner for combining the processed second channel signal and the second channel low frequency signal to provide a second channel output signal;

a fourth signal combiner for combining the second channel cancellation signal and the second channel low frequency signal to provide a second channel cancellation output cancellation signal;

a first electro-acoustic transducer for transducing the first channel output signal to provide a first channel acoustic wave;

a second electro-acoustic transducer for transducing the first channel canceling output signal to provide a first channel canceling output sound wave, wherein the first electro-acoustic transducer and the second electro-acoustic transducer are positioned such that the first channel canceling output sound wave destructively interferes in a first direction and not destructively interferes in a second direction, wherein the second direction is directed toward a listening space associated with the multimedia entertainment device, and wherein the first electro-acoustic transducer and the second electro-acoustic transducer are mounted on a low frequency amplifying means such that the first channel output sound wave and the first channel canceling sound wave are radiated to the low frequency amplifying means;

a third electroacoustic transducer for transducing the second channel output signal to provide a second channel acoustic wave;

a fourth electro-acoustic transducer for transducing the second channel canceling output signal to provide a second channel canceling output acoustic wave, wherein the third electro-acoustic transducer and the fourth electro-acoustic transducer are positioned such that the second channel canceling output acoustic wave destructively interferes in a third direction and does not destructively interfere in a fourth direction, wherein the fourth direction is directed toward a listening space associated with the multimedia entertainment device, and wherein the third electro-acoustic transducer and the fourth electro-acoustic transducer are mounted on a low frequency amplification means such that the second channel output acoustic wave and the second channel canceling acoustic wave are radiated to the low frequency amplification means;

circuitry for modifying the first channel output signal and the first channel cancellation output signal so as to modify the orientation of the first direction; and

circuitry for modifying the second channel output signal and the second channel cancellation output signal so as to modify an orientation of the third direction;

a network for communicatively connecting the first and second multimedia entertainment devices.

2. A method for processing an audio signal, comprising the steps of:

receiving a first channel audio signal;

separating the first audio channel signal into a first channel first spectral portion and a first channel second spectral portion;

processing a first spectral portion of said first channel signal in accordance with a first processing to provide a first channel first processed signal, said first processing being represented by a first non-integer non-zero transfer function;

a first processing unit configured to provide a first channel first processed signal according to a first processed first spectral portion of the first channel, the first processing unit being represented by a first conversion function;

combining the first channel first processed signal with the first channel second spectral portion to provide a first channel first combined signal;

transducing the first combined signal with a first electro-acoustic transducer;

combining the first channel second processed signal with the first channel second spectral portion to provide a first channel second combined signal; and

the second combined signal is transduced by a second electro-acoustic transducer.

3. The method for processing an audio signal according to claim 2, wherein said first conversion function comprises delaying said first channel first spectral portion such that said first channel first processed signal is delayed with respect to said first channel second processed signal, and wherein said first conversion function comprises reversing a polarity of said first channel audio signal first spectral portion such that said first channel first processed signal is reversed in polarity with respect to said first channel second processed signal.

4. A method for processing an audio signal according to claim 3, wherein the first transfer function and the second transfer function comprise head-related transfer functions.

5. The method for processing an audio signal according to claim 2, further comprising:

receiving a second channel audio signal;

separating the second channel audio signal into a second channel first spectral portion and a second channel second spectral portion;

processing the second channel first spectral portion according to a first process represented by a third non-integer non-zero transfer function to provide a second channel first processed signal;

processing the second channel audio signal first spectral portion according to a second processing represented by a fourth transfer function different from the third transfer function to provide a second channel second processed signal;

combining the second channel first processed signal with the second channel second spectral portion to provide a second channel first combined signal;

transducing, by a third electro-acoustic transducer, a signal of the second channel first combination;

combining the second channel audio second processed signal with the second channel second spectral portion to provide a second channel second combined signal; and

transducing a second combined signal of the second channel by a fourth electro-acoustic transducer.

6. The method for processing an audio signal according to claim 5, wherein the third transfer function comprises delaying the second channel first spectral portion such that the second channel first processed signal is delayed relative to the second channel second processed signal, and wherein the third transfer comprises reversing a polarity of the second channel first spectral portion such that the second channel first processed signal is reversed in polarity relative to the second channel second processed signal.

7. The method for processing an audio signal according to claim 6, wherein the third transfer function and the fourth transfer function comprise head-related transfer functions.

8. A method for processing a multi-channel audio signal, comprising the steps of:

separating the first audio channel signal stream into a first channel first spectral portion and a first channel second spectral portion;

separating the second audio channel signal stream into a second channel first spectral portion and a second channel second spectral portion;

processing a first spectral portion of the first channel signal according to a first process represented by a first non-integer non-zero transfer function to provide a first processed signal;

processing the first spectral portion of the first audio channel signal according to a second processing to provide a second processed signal, the second processing being represented by a second transfer function different from the first transfer function;

processing the second channel first spectral portion according to a third process represented by a third non-integer non-zero transfer function to provide a third processed signal;

processing the second channel signal first spectral portion by a fourth process represented by a fourth transfer function different from the third transfer function to provide a fourth processed signal;

combining the first channel second spectral portion with the second channel second spectral portion to provide a combined first channel second spectral portion;

transducing, by a first electro-acoustic transducer, a second spectral portion of the first channel combination and one of the first channel first processed signal, the first channel second processed signal, the first channel third processed signal, and the first channel fourth processed signal.

9. The method for processing a multi-channel audio signal stream according to claim 8, further comprising the steps of: transducing a second spectral portion of the first channel combination and a second one of the first, second, third, and fourth processed signals with a second electro-acoustic transducer.

10. The method for processing a multi-channel audio signal stream according to claim 9, wherein said first and second channels are a left channel and a right channel, and wherein said first and second electro-acoustic transducers are located in front of a listener, said method further comprising the steps of:

separating the third audio channel signal into a third channel first spectral portion and a third channel second spectral portion;

separating the fourth audio channel signal into a fourth channel first spectral portion and a fourth channel second spectral portion;

processing the third audio channel signal first spectral portion according to a fifth process represented by a fifth non-integer non-zero transfer function to provide a fifth processed signal;

processing the third channel first spectral portion according to a sixth process represented by a conversion function different from the fifth conversion function to provide a sixth processed signal;

processing the fourth channel signal first spectral portion according to a seventh process represented by a seventh non-integer non-zero transfer function to provide a seventh processed signal;

processing the fourth audio channel first spectral portion by an eighth process represented by a conversion function different from the seventh conversion function to provide an eighth processed signal;

combining the third audio channel second spectral portion with the fourth audio channel second spectral portion to provide a second combined second spectral portion;

transducing the second combined second spectral portion and one of the fifth processed signal, the sixth processed signal, the seventh processed signal, and the eighth processed signal with a third electro-acoustic transducer located behind the listener.

11. The method for processing a multi-channel audio signal according to claim 8, wherein said step of processing a first spectral portion of said first audio channel comprises at least one of a group of processes consisting of attenuation, amplification, delay, and equalization.

12. An electro acoustic apparatus comprising:

a first directional array comprising a first electro-acoustic transducer and a second electro-acoustic transducer, each of the first and second electro-acoustic transducers comprising a first radiating surface and a second radiating surface; and

having an external and an internal low frequency amplifying structure,

wherein said electro-acoustic apparatus is constructed and arranged such that said first electro-acoustic transducer first radiating surface and said second electro-acoustic transducer first radiating surface face the ambient environment and such that said first electro-acoustic transducer second radiating surface and said second electro-acoustic transducer second radiating surface face said low frequency amplifying structure inside.

13. The electro acoustic equipment according to claim 12, further comprising:

a second directional array comprising a third electro-acoustic transducer and a fourth electro-acoustic transducer, each of the third and fourth electro-acoustic transducers comprising a first radiating face and a second radiating face;

wherein said electro-acoustic apparatus is constructed and arranged such that said third electro-acoustic transducer first radiating surface and said fourth electro-acoustic transducer first radiating surface face said ambient environment, and such that said third electro-acoustic transducer second radiating surface and said fourth electro-acoustic transducer second radiating surface face said internal low frequency amplifying structure.

14. The electro acoustic equipment according to claim 12, wherein said low frequency amplifying device comprises one of an acoustic waveguide and a housing having an outlet.

15. A method for operating a multi-channel sound system comprising first and second electro-acoustic transducers and an acoustic waveguide, the method comprising the steps of:

positioning the first transducer and the second transducer at separate points in the waveguide such that the first radiating surface of the first transducer and the first radiating surface of the second transducer radiate acoustic waves to the acoustic waveguide;

separating the first channel signal into a first channel high frequency audio signal and a first channel low frequency audio signal;

separating the second channel signal into a second channel high frequency audio signal and a second channel low frequency audio signal;

combining the first channel low frequency audio signal with the second channel low frequency audio signal to form a common low frequency audio signal;

transmitting the common low frequency audio signal to the first transducer and the second transducer;

transmitting the first channel high frequency audio signal to the first transducer;

transmitting the second channel high frequency audio signal to the second transducer;

radiating, by the first transducer, acoustic waves corresponding to the first channel high frequency signal and the common low frequency audio signal to the waveguide;

radiating, by the second transducer, acoustic waves corresponding to the second channel high frequency signal and the common low frequency audio signal to the waveguide.

16. The method for operating a sound system in accordance with claim 15, the acoustic waveguide having an effective length, wherein the positioning step comprises positioning a first transducer such that when the first transducer radiates a first acoustic wave having substantially the same wavelength as the effective length into the waveguide, the second transducer radiates a second acoustic wave into the waveguide such that the second acoustic wave has substantially the opposite phase as the first acoustic wave.

17. The method for operating a sound system as claimed in claim 16, the first transducer being positioned such that the second radiating surface of the first transducer radiates sound waves to the external environment through a direct path absent the waveguide.

18. A method for operating a multimedia entertainment device having a sound system including first and second speaker arrays and first and second audio channels, each of the first and second audio channels having a high frequency portion and a low frequency portion, the multimedia entertainment device including an associated listening space, the method comprising the steps of:

directionally radiating, by the first speaker array, sound waves corresponding to a high frequency portion of the first audio channel toward the listening space;

directionally radiating, by the second speaker array, sound waves corresponding to a high frequency portion of the second audio channel toward the listening space;

non-directionally radiating the first channel low frequency portion and the second channel low frequency portion through the first speaker array and the second speaker array.

19. The method for operating a multimedia entertainment device according to claim 18, wherein the multimedia entertainment device is a video game.

20. The method for operating a multimedia entertainment device according to claim 18, wherein the multimedia entertainment device is a gambling machine.

21. An entertainment area comprising:

a first multimedia entertainment device comprising a sound system, the sound system comprising a first audio channel and a second audio channel, each of the first audio channel and the second audio channel comprising a high frequency portion and a low frequency portion, the first multimedia entertainment device comprising a first speaker array and a second speaker array, the entertainment zone comprising a listening space connected to the first multimedia entertainment device;

a second multimedia entertainment device comprising a sound system, the sound system comprising a first audio channel and a second audio channel, each of the first audio channel and the second audio channel comprising a high frequency portion and a low frequency portion, the second multimedia entertainment device comprising a first speaker array and a second speaker array, the entertainment zone comprising a listening space connected to the second multimedia entertainment device;

wherein the first multimedia entertainment device and the second multimedia exercise device are in a common viewing and listening area;

wherein said first multimedia entertainment device is constructed and arranged to directionally radiate sound waves corresponding to a first channel high frequency portion of said first device and to directionally radiate sound waves corresponding to a second channel high frequency portion of said first device such that said sound waves corresponding to said first device first channel high frequency portion and said sound waves corresponding to said first device second channel high frequency portion are more clearly audible in said listening space associated with said first device than in said listening space associated with said second device; and

wherein said second multimedia entertainment device is constructed and arranged to directionally radiate sound waves corresponding to a first channel high frequency portion of said second device and to directionally radiate sound waves corresponding to a second channel high frequency portion of said second device such that said sound waves corresponding to said second device first channel high frequency portion and said sound waves corresponding to said second device second channel high frequency portion are more clearly audible in said listening space associated with said second device than in said listening space associated with said first device.

22. An entertainment zone according to claim 21, wherein said entertainment zone is a gambling casino and wherein said first and second multimedia entertainment devices are gambling devices.

23. An entertainment zone according to claim 22, further comprising a control device, wherein the gaming devices are networked to each other and to the control device such that the first multimedia gaming device and the second multimedia gaming device are controllable from the control device.

24. An entertainment zone according to claim 21, further comprising a control device, wherein said first and second multimedia entertainment devices are networked to each other and to said control device, whereby the first multimedia entertainment device and said second multimedia gaming device are controllable from said control device.

25. A sound system for radiating sound waves corresponding to a first audio signal and a second audio signal, the sound system including an indicator for indicating directional radiation pattern selection, the indicator having at least two states, the sound system comprising:

a detector for detecting the indicator;

a directional array for radiating acoustic waves in a plurality of directional radiation patterns,

wherein the directional array is constructed and arranged to radiate acoustic energy upon detection of a first indicator state according to a first directional radiation pattern and to radiate acoustic energy upon detection of a second indicator state according to a second directional radiation pattern.

26. A sound system as claimed in claim 25, wherein the indicator comprises the relative phase of the first audio channel and the second audio channel.

27. A sound system according to claim 25, wherein the indicator comprises an absolute value of the signal amplitude.

28. A sound system as in claim 25, wherein said directional radiation pattern is continuously variable between said first directional radiation pattern and said second directional radiation pattern.

29. A sound system as claimed in claim 25, wherein the directional radiation pattern is incrementally varied between the first directional radiation pattern and the second directional radiation pattern.

30. A sound system as in claim 25, wherein said directional array is constructed and arranged to radiate more acoustic energy in a first direction in accordance with said first signal than in a second direction in accordance with said first radiation pattern, and wherein said directional array is constructed and arranged to radiate more acoustic energy in said second direction in accordance with said first signal than in said first direction in accordance with said second radiation pattern.

31. A sound system as claimed in claim 30, wherein said first signal comprises an audio channel signal and said second signal comprises a delayed version of said audio channel signal.

32. A sound system as claimed in claim 30, wherein said directional array is constructed and arranged to radiate more acoustic energy in a second direction in dependence on said second signal than in said first direction in dependence on said first radiation pattern, and to radiate more acoustic energy in said first direction in dependence on said second channel signal than in said second direction in dependence on said second radiation pattern.

33. A sound system as claimed in claim 32, wherein said first signal comprises an audio channel signal and said second signal comprises a delayed version of said audio channel signal.

34. A sound system as claimed in claim 25, wherein the first directional pattern is oriented in a first direction and the second directional pattern is substantially unoriented.

35. A method for dynamically balancing an audio signal, comprising the steps of:

providing an audio signal;

first attenuating said audio signal by a variable factor G to provide a first attenuated signal, wherein 0 < G < 1;

second attenuating said audio signal by a variable factor 1-G to provide a second attenuated signal;

balancing the first attenuated signal to provide a balanced first attenuated signal; and

combining the balanced first attenuated signal with the second attenuated signal to provide an output signal.

36. The method for dynamically balancing audio signals according to claim 35, wherein the second attenuating step comprises:

differentially combining the first attenuated audio signal with the first audio signal to provide the second attenuated signal.

37. A method for balancing an audio signal according to claim 35, wherein the audio signal is a compressed audio signal, and wherein the step of providing the signal comprises:

attenuating the input audio signal by a factor C in response to the amplitude of said input audio signal to provide an attenuated input audio signal;

a gain K2 is provided to the attenuated input audio signal to provide the compressed audio signal.

38. A method for balancing audio signals according to claim 37, wherein the value of the factor C is responsive to the absolute value of the amplitude of the input audio signal.

39. A method for balancing audio signals according to claim 38, wherein the value of said factor G is responsive to said value of said factor C.

40. A method for balancing an audio signal according to claim 35, wherein the value of the factor G is responsive to the amplitude of the audio signal.

41. A method for clipping and post-clipping an audio signal, comprising the steps of:

clipping the audio signal to provide a clipped audio signal;

filtering the audio signal by a first filter to provide a filtered, non-clipped audio signal;

filtering the audio signal by a second filter to provide a filtered limited audio signal;

differentially combining the filtered limited audio signal with the limited audio signal to provide a differentially combined audio signal; and

combining the filtered non-clipped audio signal with the differentially combined audio signal to provide an output signal.

42. The method for clipping an audio signal according to claim 41, wherein the first filter is a notch filter.

43. The method for clipping an audio signal according to claim 42, wherein the second filter is a notch filter.

44. The method for clipping an audio signal according to claim 43, wherein the first filter and the second filter have substantially the same notch filter rate.

45. A method for controlling the directionality of a sound radiation pattern, comprising the steps of:

providing the audio signal to a first attenuator, a delay, and a first summer;

first attenuating said audio signal by a variable factor G by said first attenuator to provide a first variably attenuated audio signal, wherein 0 < G < 1;

second attenuating said audio signal by a variable factor (1-G) to provide a second variably attenuated audio signal;

delaying said first audio signal to provide a delayed audio signal;

third attenuating said delayed audio signal by a variable factor H to provide a first variably attenuated delayed audio signal;

fourth attenuating by a variable factor (1-H) to provide a second variably attenuated delayed audio signal;

combining the first variably attenuated audio signal with the second variably attenuated delayed audio signal to provide a first transduced audio signal; and

combining the second variably attenuated audio signal with the first variably attenuated delayed audio signal to provide a second exchangeable audio signal.

46. A method for controlling the directionality of a sound radiation pattern according to claim 45, wherein the second attenuation step includes:

differentially combining the first variably attenuated audio signal and the input audio signal to provide the second variably attenuated audio signal.

47. A method for controlling the directionality of sound radiation patterns according to claim 46, wherein the fourth attenuating step includes:

differentially combining the first variably attenuated delayed audio signal with the delayed audio signal to provide the second attenuated delayed audio signal.

48. The method for controlling the directionality of the sound radiation pattern of claim 47, wherein G-H.

49. A method for controlling directionality of a speaker array according to claim 48, whereinWhere L is the amplitude of the first channel audio signal and R is the amplitude of the second channel audio signal.

50. A wagering apparatus comprising:

an associated listening space; and

a sound system comprising a directional loudspeaker array comprising a plurality of transducers, and wherein sound waves radiated by a first of the plurality of transducers combine constructively in a first direction and destructively in a second direction, and wherein the first direction is directed toward the listening space.