JP3390574B2 - Adaptive sound image reproduction device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound image reproducing apparatus for reproducing the same sound image as the original sound field in a reproduced sound field by using an acoustic signal or an encoded acoustic signal.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a configuration of a conventional sound image reproducing apparatus, in which 401 is an audio signal input terminal to which an encoded audio signal is input, 402 is a decoder, 403 is a reflected sound adder, 404 is a D / A converter, 405 is a low pass filter (LPF),
Reference numeral 406 is an amplifier, 407 is a speaker, and 408 is a reproduced sound field.

Next, the operation of the conventional sound image reproducing apparatus will be described. In FIG. 4, when the encoded acoustic signal is input to the acoustic signal input terminal 401, the input signal is the decoder 4
02 is decoded into a digital acoustic signal, and an appropriate reflected sound is added by a reflected sound adder 403. The signal to which the reflected sound is added is converted into an analog signal by the D / A converter 404, and the LPF which is a smoothing filter is used.
405 attenuates components above the Nyquist frequency,
The amplified signal is amplified by the amplifier 406 and radiated to the reproduced sound field 408 by the speaker 407.

As described above, even in the conventional sound image reproducing apparatus, the sound is reproduced in the reproduced sound field 408 by appropriately setting the delay time and the amplitude of the reflected sound added by the reflected sound adder 403. It is possible to control the distance and spread of the sound image.

[0005]

However, in the conventional sound image reproducing apparatus described above, when the state of the reproduced sound field, for example, the position of the listener or the position of the speaker changes, a sound image different from the sound image to be reproduced is received. There was a problem of being perceived by the listener.

The present invention solves such a conventional problem and provides an excellent adaptive sound image reproducing apparatus capable of faithfully reproducing the sound image of the current sound field even when the state of the reproduced sound field changes. That is the purpose.

[0007]

In order to achieve the above-mentioned object, the present invention transmits an element sense signal such as a spread, a direction and a distance of a sound image of an original sound field encoded in an auditory discrimination limit unit together with an acoustic signal. In the coming system, a microphone installed near the listener and an adaptive sound image reproducer that controls the elemental sense of the sound image according to the output signal of the microphone are installed to reproduce the sound image of the original sound field in the reproduced sound field. It is the one.

[0008]

Therefore, according to the adaptive sound image reproducing apparatus of the present invention, even if the state of the reproduced sound field changes, the microphone senses the change and changes the control amount of the sound image according to the change amount. The listener has the effect of always perceiving the same sound image as the original sound field.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention. 101 is an acoustic signal input terminal, 102 is a control signal, that is, an input of a control signal to which an element sense signal of an encoded sound image is input. Terminals, 103 are decoders for acoustic signals, 104 are decoders for control signals, 105 and 106 are FIR filters for control, 107, 108, 109, 110, 111 and 112 are FIR filters,
Reference numeral 113 is an adaptive processor, 114 and 115 are subtractors, 116 is a coefficient replacement unit, 117 is a coefficient storage unit, 118 is an adaptive sound image reproducer, and 119 and 1
20 is a D / A converter, 121 and 122 are LPFs, 123 and 124 are amplifiers, 125 and 126 are A / D converters, 127 and 128 are LPFs, 12
Reference numerals 9 and 130 are amplifiers, 131 and 132 are speakers, 133 is a dummy head microphone (DHM), and 134 is a reproduced sound field.

Next, the operation of the first embodiment will be described.

In FIG. 1, the acoustic signal recorded in the original sound field is encoded and transmitted, and is input to the acoustic signal input terminal 101. The coded acoustic signal input from the acoustic signal input terminal 101 is decoded by the decoder 103. The decoded signal is made into desired amplitude and phase characteristics by the control FIR filters 105 and 106, and then the D / A converter 11
9 and 120 convert to analog signals, LPFs 121 and 122, which are smoothing filters, attenuate components above the Nyquist frequency, amplifies them by amplifiers 123 and 124, and outputs them to the speaker 13
At 1 and 132, the sound is radiated to the reproduction sound field 134 and reaches the DHM 133 installed near the listener.

The coefficients of the control FIR filters 105 and 106 are
It is updated by the adaptive processor 113. The decoded acoustic signal is made into the target characteristic by the FIR filters 111 and 112 showing the target characteristic, and becomes one input of the subtracters 114 and 115.
The signals input to the DHM133 are amplified by the amplifiers 129 and 130, and the LPFs 127 and 128 which are aliasing filters.
Causes components above the Nyquist frequency to be attenuated, resulting in A / D
It is converted into a digital signal by the converters 125 and 126 and becomes the other input of the subtractor 114. The subtractor 114 calculates the difference between the target characteristic and the DHM output signal and inputs it to the adaptive processor 113. In addition, the decoded acoustic signal is transmitted to the speakers 131, 1
FIR filter representing transfer function from 32 to DHM133 1
07-110, characterized by the location of DHM133,
This is the other input to the adaptive processor 113. Adaptive processor 113
Is a control FIR filter 105, 1 according to the input signal.
Update the coefficient of 06.

On the other hand, the sound image perceived in the original sound field is coded for each discrimination limit of the elemental sense (spreading, distance, direction) of the sound image, and is input to the control signal input terminal 102 as a control signal. The signal input to the control signal input terminal 102 is the decoder 104
Is decrypted by. The coefficient replacing unit 116 reads the characteristic to be reproduced at the listener position in the reproduced sound field 134 from the coefficient storing unit 117 by the decoded control signal, and the FIR filter 1
Swap the coefficients of 11 and 112. The coefficient storage 117 stores the target characteristic to be reproduced for each discrimination limit of each element sense.

The transfer function matrix of the decoded acoustic signal is x,
If the transfer function matrix of the control FIR filters 105 and 106 is W, the transfer function matrix from the speakers 131 and 132 to the DHM 133 in the reproduced sound field 134 is C, and the target transfer function matrix is d, then W is

[0016]

[Equation 1] If W = C to ¹ · d,

[0017]

[Formula 2] C · W · x = d · x holds, and the target characteristic can be realized at the position of the DHM133 placed near the listener. Further, the adaptive processor 113 updates W so that the target characteristic can be accurately reproduced even if the state of the reproduced sound field 134, that is, C changes. The coefficient update formula is
According to the Filtered x LMS algorithm, it is expressed by (Equation 3).

[0018]

## EQU3 ## W _{n + 1} = W _n −μ · e · C · x where e is the output of the subtracters 114 and 115, and W _n is the transfer function of the control FIR filters 105 and 106 at the current sample. Matrix, W _{n + 1} is the control FIR filter 105 at the next sample,
There are 106 transfer function matrices.

As described above, according to the first embodiment, the characteristics to be reproduced at the listener position set by the control signal,
Since the coefficient of the control FIR filter is updated based on the difference from the current characteristic, the target characteristic can always be reproduced at the listener's position even if the state of the reproduced sound field changes, and the listener always hears the same sound as the original sound field. It has the effect of being able to perceive the field.

FIG. 2 is a block diagram showing the configuration of the second embodiment of the present invention. 201 is an audio signal input terminal, 202 is a control signal input terminal, 203 is an audio signal decoder, and 204 is a direction controller. , 205 is a distance controller, 206 is a spread controller, 207 is a control signal decoder, 208, 209 and 210 are subtractors, 211 is a spread amount calculator, 212 is a distance amount calculator, and 213 is a direction amount calculator. Bowl, 21
4 is an adaptive sound image reproducer, 215 and 216 are D / A converters, 217 and 21
8 is LPF, 219, 220 is amplifier, 221, 222 is A / D converter, 223, 224 is LPF, 225, 226 is amplifier, 227, 228 is speaker, 229 is dummy head microphone (DHM), 2
30 is a reproduction sound field.

Next, the operation of the second embodiment will be described.

In FIG. 2, the acoustic signal recorded in the original sound field is encoded and transmitted, and is input to the acoustic signal input terminal 201. The coded acoustic signal input from the acoustic signal input terminal 201 is decoded by the decoder 203. The direction signal of the decoded signal in the reproduced sound field 230 is controlled by the direction controller 204, the distance of the sound image is controlled by the distance controller 205, and the spread of the sound image is controlled by the spread controller 206. The signal with controlled sense of sound image is
The analog signals are converted into analog signals by the D / A converters 215 and 216, components above the Nyquist frequency are attenuated by the smoothing filters LPFs 217 and 218, amplified by the amplifiers 219 and 220, and reproduced by the speakers 227 and 228 in the reproduced sound field 230. It is emitted and reaches the DHM229 installed near the listener.

The signal input to the DHM229 is supplied to the amplifier 22.
L is an aliasing filter that is amplified by 5,226
Components above the Nyquist frequency are attenuated by the PFs 223 and 224, converted into digital signals by the A / D converters 221 and 222, and input to the spread amount calculator 211, the distance amount calculator 212, and the direction amount calculator 213. The spread amount calculator 211 calculates the amount of spread perceived by the listener in the current reproduction sound field 230 from the output signal of the DHM 229 in the discrimination limit unit, and the subtracter 210
To enter. Similarly, the distance amount calculator 212 and the direction calculator 213 also calculate the distance amount and the direction amount and input them to the subtracters 208 and 209.

On the other hand, the sound image perceived in the original sound field is encoded for each discrimination limit of the elemental sense (spreading, distance, direction) of the sound image, and is input to the control signal input terminal 202 as a control signal. The signal input to the control signal input terminal 202 is output to the decoder 2
Decrypted by 07. The decoded signal is used as a subtractor 208, 2
One of 09 and 210 inputs. The subtractors 208 to 210 calculate the difference between the element sense signal of the sound image to be reproduced and the output signals of the spread amount calculator 211, the distance amount calculator 212, and the direction calculator 213, and the spread controller 206 and the distance, respectively. Input to the controller 205 and the direction controller 204. Direction controller 204, distance controller 205,
The spread controller 206 uses the difference to control the amount of direction,
Change the amount of distance and the amount of spread.

As described above, according to the second embodiment, the difference between the elemental sense amount of the sound image to be reproduced at the listener position set by the control signal and the elemental sense amount of the sound image in the current reproduced sound field is calculated. Since the control amount of each controller is changed based on this, there is an effect that the same sound field as the original sound field can always be reproduced even if the state of the reproduced sound field changes.

FIG. 3 is a block diagram showing the configuration of the third embodiment of the present invention. 301 is an audio signal input terminal, 302 is a control signal input terminal, 303 is an audio signal decoder, and 304 is direction control. , 305 is a distance controller, 306 is a spread controller, 307 is a control signal decoder, 308, 309 and 310 are subtractors, 311 is a spread amount calculator, 312 is a distance amount calculator, and 313 is a direction amount. Calculator,
314 and 315 are LPFs, 316 and 317 are adders, 318 is an adaptive sound image reproducer, 319 and 320 are D / A converters, 321 and 322 are LPFs,
323, 324 are amplifiers, 325, 326 are A / D converters, 327, 328
Are LPFs, 329 and 330 are amplifiers, 331 and 332 are speakers, and 33
3 is a dummy head microphone (DHM), and 334 is a reproduced sound field.

Next, the operation of the third embodiment will be described.

In FIG. 3, LPFs 314 and 315 and an adder 31
The operation other than 6,317 is the same as the operation of the second embodiment. The cutoff frequencies of the LPFs 314 and 315 are set to around 1600 Hz so that only signals in a frequency band having a high correlation with the spread and direction of the sound image are passed. A signal whose band is limited by the LPF 314 is input to the direction controller 304 and the spread controller 306, and a signal whose band is not limited is input to the distance controller 305. Similarly, the direction amount calculator 313 and the spread amount calculator 311 are input with the signal band-limited by the LPF 315, and the distance calculator 312 is input with the signal not band-limited. The adders 316 and 317 add the signal in which the sense amount related to the sound image whose band is limited is controlled and the signal in which the sense amount related to the sound image is not limited to the band.

Therefore, in the third embodiment, the second
In addition to the effect of the embodiment, since the signal band is limited by the LPFs 314 and 315, the calculation amount of the direction controller 304, the spread controller 306, the spread amount calculator 311, and the direction amount calculator 313 can be reduced. Has the effect.

[0030]

As described above, according to the invention described in each claim, the difference between the sound image being reproduced in the reproduction sound field and the sound image to be reproduced is calculated, and the control amount is set according to the difference. Since the change is made, there is an effect that the sound image to be reproduced can be accurately reproduced even if the state of the reproduced sound field changes.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of an adaptive sound image reproducer of the present invention.

FIG. 2 is a block diagram showing the configuration of a second embodiment of the adaptive sound image reproducer of the present invention.

FIG. 3 is a block diagram showing a configuration of a third embodiment of the adaptive sound image reproducer of the present invention.

FIG. 4 is a block diagram showing a configuration of a conventional adaptive sound image reproducing device.

[Explanation of symbols]

101, 201, 301 ... Acoustic signal input terminal, 102, 202, 302 ...
Control signal input terminal 103, 203, 303 ... Decoder for acoustic signal, 104, 207, 307 ... Decoder for control signal, 105, 106
... Control FIR filter, 107-112 ... FIR filter, 113 ... Adaptive processor, 114, 115, 208-210, 308-
310 ... Subtractor, 116 ... Coefficient interchanger, 117 ... Coefficient storage, 118, 214, 318 ... Adaptive sound image reproducer, 119, 12
0,215,216,319,320 ... D / A converter, 121,122,1
27, 128, 217, 218, 223, 224, 314, 315, 321, 322, 3
27,328 ... LPF, 123,124,129,130,219,220,2
25,226,323,324,329,330 ... Amplifier, 125,126,2
21, 222, 325, 326 ... A / D converter, 131, 132, 227,
228, 331, 332 ... speaker, 133, 229, 333 ... dummy head microphone (DHM), 134, 230, 334 ... reproduced sound field, 204, 304 ... direction controller, 205, 305 ... distance controller, 206, 306 ... Spread controller, 211, 311 ... Spread amount calculator, 212, 312 ... Distance amount calculator, 213, 313 ... Direction amount calculator, 316, 317 ... Adder.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-59200 (JP, A) JP-A-6-121395 (JP, A) JP-A-6-245300 (JP, A) JP-A-6- 178396 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04S 1/00 H04R 5/027 H04S 7/00

Claims (7)

(57) [Claims] 1. A sound image is generated from an audio signal or an encoded audio signal, and a control signal of a sound image to be reproduced or a control signal obtained by encoding a sense of spread, distance, and direction of elemental sense in units of auditory discrimination limit. A sound image reproducing device for reproducing is provided with a speaker for reproducing an acoustic signal, a microphone installed in the vicinity of a listener, and an adaptive sound image reproducing device for controlling element sense of a sound image according to an output signal of the microphone. Adaptive sound image reproducing device. 2. A sound image control FIR (Finite Impluse R)
esponse) filter and an FIR filter whose coefficient is a target characteristic to be reproduced at the microphone position, calculates the difference between the target characteristic and the output characteristic of the microphone, and changes the control amount according to the difference. The adaptive sound image reproducing device according to claim 1, wherein 3. An adaptive processor for updating the coefficient of the sound image control FIR filter, a coefficient storage for storing a target characteristic corresponding to the control signal, a coefficient stored in the coefficient storage, and this coefficient. 3. The adaptive sound image according to claim 2, further comprising: a coefficient transposition device that transposes a coefficient of the FIR filter having a target characteristic, and the coefficient of the sound image control FIR filter is updated according to the control signal. Playback device. 4. The auditory sense is provided with a controller for controlling the elemental sense of the sound image in the unit of discriminant limit of hearing and a calculator for calculating the amount of elemental sense of the sound image in the unit of discriminative limit of hearing from the output signal of the microphone. 2. The adaptive sound image reproducing apparatus according to claim 1, wherein the control amount of the controller is changed according to the difference between the control signal encoded in the discrimination limit unit and the calculator. 5. The controller is a direction controller, a distance controller,
The adaptive sound image reproducing apparatus according to claim 4, further comprising a spread controller, wherein the calculator includes a direction amount calculator, a distance amount calculator, and a spread amount calculator. 6. A calculation amount for controlling a sound image and calculating an element feeling amount of a sound image, comprising a low-pass filter for separating the sound input signal and an output signal of the microphone into a signal having only a frequency component highly correlated with sound image localization. The adaptive sound image reproducing device according to claim 4 or 5, characterized in that 7. The cutoff frequency of the low-pass filter
7. The adaptive sound image reproducing device according to claim 6, wherein the adaptive sound image reproducing device is set to about 1600 Hz.