JPH04189000A - Sound field control device - Google Patents

Abstract

PURPOSE:To improve tone at the position other than the optinum listening point by outputting direct sound from the speaker for initial reflected sound and the speaker for reverberation sound. CONSTITUTION:The above device is composed of a direct sound signal generation means 1, an initial reflection signal generation means 2, a reverberation signal generation means 3, a speaker for direct sound 4, a speaker for initial reflected sound 5, a speaker for reverberation sound 6, an initial sound correction means 7 and a reverberation sound correction means 8. If the initial reflection signal is outputted from the speaker for the initial reflected sound 5 after the initial reflection signal is mixed with direct sound signal at the initial sound correction means 7 and the reverberation signal is outputted from the speaker for reverberation sound 6 after the reverberation signal is mixed with direct sound signal at the reverberation sound correction means 8, the tone is improved as the direct sound is outputted from each speaker. Thus, the tone can be improved in the extent other than the optinum listening position.

Description

[Detailed Description of the Invention] [Summary] A sound field control device outputs direct sound, early reflected sound, and reverberant sound from their corresponding speakers, thereby adjusting the sound field at the optimum listening position (hereinafter referred to as the optimum listening point). The sound field is controlled to create a sense of presence as if you were in a concert hall. However, at positions other than the optimal listening point, particularly near the early reflection sound speaker and the reverberation sound speaker, the early reflection sound and reverberation sound components become large, and the sound quality deteriorates significantly.

Therefore, sound quality is improved at positions other than the optimal listening point by directly outputting sound from the early reflection speaker and the reverberation speaker.

[Industrial application field]

The present invention relates to a sound field control device, and more particularly to a sound field control device that makes it possible to obtain reasonably good sound quality even at positions other than the optimum listening point.

[Conventional technology]

There is an audio system called a sound field control device that installs many speakers and outputs different signals from each speaker so that even in a normal room or a car, you can hear as if you were in a concert hall. In a concert hall, etc., this includes the direct sound transmitted directly from the performance point as shown in Figure 4, the initial reflected wave group due to the first reflection mainly from the left and right side walls, and the gradual return of multiple reflections. This method measures each group of high-order reflected waves that are transmitted over a longer period of time while attenuating, and creates a signal that produces a similar acoustic effect from the acoustic signal and outputs it from each speaker. Usually, the group of early reflected waves is called early reflected sound, and the group of higher-order reflected waves is called reverberant sound.

In high-end systems, the number of speakers may be very large, but - for boat fishing, as shown in Figure 5, there are two speakers on each side for direct sound, early reflection sound, and reverberant sound, that is, six speakers in total. The system consists of several speakers. In such a sound field control device, as shown in FIG. 5, an optimum listening point 100c is set, and a desired sound field is created within that range.

A control device for performing such sound field control is composed of a circuit that generates a direct sound signal, an early reflection signal, and a reverberation signal from an acoustic signal, as shown in FIG. Actually, such a circuit exists for each left and right speaker. The direct sound signal generation circuit 1d is often an amplifier circuit that amplifies the sound signal as it is. The early reflection signal generation circuit 2d and the reverberation signal generation circuit 3d are digital signal processors (hereinafter referred to as D).
It is called SP. ), and is generally converted into an analog signal by a D/A converter after filtering.

The sampling frequency of the DSP is set at approximately 22.5 kHz due to cost considerations. Therefore, sufficient characteristics cannot be obtained in the high frequency range, but since the early reflection signal and reverberation signal generated by the DSP are reflected signals, the high frequency range is more attenuated, and the sampling frequency of the DSP becomes a big problem. It's not.

[Problem to be solved by the invention]

As shown in FIG. 5, the sound field controlled by the sound field control device is at the optimal listening point) 100 c. As a result, sound quality deteriorates significantly at positions other than the optimum listening point. In particular, at a position near the early reflected sound speaker 51C or 52C or a position near the reverberant sound speaker 61c or 62C, the ratio of early reflected sound and reverberant sound increases relatively.

As mentioned above, early reflected sounds and reverberations themselves have a low high frequency range, and the DSP does not have sufficient characteristics in the high frequency range, resulting in a muffled and unclear sound. Therefore, at positions other than the optimal listening point, the sound quality deteriorates significantly compared to conventional stereo systems that output direct sound from two speakers.

The sound field control device is intended to perform control only at the optimal listening point, and the above-mentioned deterioration in sound quality at positions other than the optimal listening point is considered to be natural.

However, when actually using a sound field control device, a certain level of sound quality may be required not only at the optimum listening point but also over a wider range.

For example, in a Joe room or the like, it is required to maintain the original sound quality at the optimal listening point, and it is also necessary to not give a bad impression even when moving within the room. The same applies when there are more than a certain number of people in the room. However, conventional sound field control devices have been insufficient to meet the above requirements because of the large difference in sound quality between the optimum listening point and other positions.

The present invention has been made in view of the above problems, and an object of the present invention is to improve the sound quality at positions other than the optimal listening point while maintaining the sound quality at the optimal listening point.

[Means to solve the problem]

In order to solve the above problems, the sound field control device of the present invention improves the sound quality at positions other than the optimum listening point by directly outputting sound from the early reflection sound speaker and the reverberation sound speaker. FIG. 1 is a diagram showing the basic configuration of a sound field control device according to the present invention. In other figures, parts that perform the same functions are indicated by the same numbers with a suffix of the alphabet.

In FIG. 1, reference numeral 1 denotes a direct sound signal generating means, which generates a direct sound signal output from a direct sound speaker 4. As shown in FIG.

Reference numeral 2 denotes an early reflection signal generating means, which generates an early reflection signal output from the early reflection sound speaker 5. Reference numeral 3 denotes a reverberation signal generation means, which generates a reverberation signal that is emitted from the reverberation sound speaker 6. The sound field at the optimal listening position is controlled by these direct sound signals, early reflection signals, and reverberation signals.

and 7 is an initial sound correction means, which generates a corrected initial signal by adding the direct sound signal of the first ratio and the initial reflection signal,
It is output to the speaker 5 for early reflection sound.

Reference numeral 8 denotes a reverberation sound correction means, which generates a corrected reverberation signal by adding the second proportion of the direct sound signal and the reverberation signal, and outputs the corrected reverberation signal to the reverberation sound speaker 6 . The feature is that this improves the sound quality in a range other than the optimal listening position.

Oral effect: Good sound quality can only be obtained when direct sound, early reflection sound, and reverberant sound are balanced. Therefore, at positions other than the optimal listening point, these balances will be disrupted. - In the case of boat fishing as shown in Figure 5, the ratio of sound output from each speaker as it approaches the direct sound speakers 41C and 42C1, the early reflection sound speakers 51c and 52C1, the reverberant sound speakers 61C and 62C, respectively. increases.

Of course, the balance between left and right will also change.

When direct sound increases, the sense of reverberation decreases, but the sound itself can be heard clearly, and the sound quality does not deteriorate significantly. However, as mentioned above, early reflections and reverberations have large attenuation in the high frequency range, making them muffled and unclear sounds, so if the proportion of early reflections and reverberations increases, the sound quality will deteriorate significantly. . If sound is output directly from the early reflection speaker 5 and the reverberation speaker 6, the proportion of direct sound near these speakers will increase, making it possible to hear clearer sound and improving sound quality. do. Therefore, the initial sound correction means 7 mixes the direct sound signal with the early reflection signal and outputs it from the early reflection sound speaker 5, and the reverberation sound correction means 8 mixes the direct sound signal with the reverberation signal and outputs it from the reverberation sound speaker 6. If you output, the sound will be output directly from each speaker, improving the sound quality.

However, the purpose of the sound field control device is to control the sound field at the optimal listening point, and the direct sound output from the early reflection speaker 5 and the reverberant speaker 5 should not have a negative effect on the sound quality at the optimal listening point. is necessary. Fifth
In the case shown in the figure, the early reflection sound speaker 51c
Since there is a distance from the 52C1 reverberant speakers 61C and 62C to the optimal listening point, even if the volume of the direct sound is effective near each speaker, it will not have much effect on the optimal listening point.
Deterioration in sound quality at the optimal listening point is small.

[Excuse side] As mentioned above, it is desirable that the direct sound output from the early reflection speaker and the reverberation speaker do not excessively affect the sound quality at the optimal listening point, but depending on the size of the room. The effect varies depending on the placement of the sheath speakers. FIG. 2 shows a circuit of an embodiment in which the ratio of direct sound addition can be changed depending on the situation.

Similar to the speaker system shown in FIG. 5, this embodiment is a system in which there are two speakers each for direct sound, early reflection sound, and reverberant sound. In this embodiment, as shown in FIG.
It produces a channel direct sound signal and an Rch direct sound signal.

Note that in FIG. 2, components not directly related to the present invention, such as amplifiers, are omitted. Reference numeral 9a indicates a DSP section that is composed of an A/D converter, a DSP, and a D/A converter, which is similar to that of a conventional sound field control device. If Lc
If the audio signals of h and Rch are digital signals from a CD device, etc., an A/D converter is not necessary, but the D
/A converter is required.

The Lch direct sound signal in the form of an analog signal and the Lch early reflection signal are mixed by an addition circuit using an ob-amp as shown in the Lch initial sound correction circuit 71a. The ratio of direct sound is adjusted by the variable resistor in the figure according to the size of the room, etc. The circuit configurations of the Rch initial sound correction circuit 72a, the Lch reverberation sound correction circuit 81a, and the Rch reverberation sound correction circuit 82a are similar to the Lch initial sound correction circuit 71a.

In FIG. 2, the direct sound signal is output as is without being processed by the DSP 9a, and the synthesis with the early reflection signal and the reverberation signal is also performed by an analog circuit, so that the problem of deterioration in the high frequency range does not occur. However, it is necessary to provide a separate analog adder circuit. Therefore, cost reduction can be achieved by sharing the synthesis of the direct sound signal, the early reflection signal, and the reverberation signal with the DSP that generates the early reflection signal and the reverberation signal. FIG. 3 shows an example of the circuit configuration of the synthesis portion of the direct sound, early reflected sound, and reverberant signal in this embodiment.

The direct sound signal is an A/D converted acoustic signal,
The early reflection signal and reverberant signal are converted to DS using the same method as before.
Generated by P. 9Ib and 93b are variable amplifiers, and 92b and 94b are adders.

95b is a D/A converter that converts each signal into an analog signal. Although this embodiment has the problem of deterioration in the high frequency range related to sampling in digital processing, it has a great advantage in that existing DSPs can be used in common.

〔Effect of the invention〕

According to the present invention, it is possible to improve the deterioration in sound quality at positions other than the optimal listening point caused by conventional sound field control devices.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of a sound field control device according to the present invention, and FIG. 2 shows an example of a sound field control device having a correction circuit configured with an analog circuit and having a variable ratio of direct sound. 3 is a diagram illustrating an example of a circuit for configuring a correction circuit using a DSP, and FIG. 4 is a diagram illustrating an example of a circuit for configuring a correction circuit with a DSP, and FIG. FIG. 5 is a diagram illustrating a general example of sound; FIG. 5 is a diagram illustrating an example arrangement of speakers in sound field control; FIG. 6 is a diagram illustrating a conventional configuration example of a sound field control device. In the figure, l: Direct sound signal generation means, 2: Early reflection signal generation means, 3: Reverberation signal generation means, 4: Direct sound speaker, 5: Early reflection sound speaker, 6... Reverberation sound speaker, 7... Initial sound correction means, 8... Reverberation sound correction means, 9a... DSP section.

Claims (1)

[Claims] 1. A direct sound signal generating means (1) for generating a direct sound signal output from a direct sound speaker (4), and an initial reflection signal output from an early reflection sound speaker (5). and a reverberation signal generation means (3) for generating a reverberation signal output from a reverberation sound speaker (6), and controlling a sound field at an optimal listening position. a control device for generating a corrected initial signal by adding a first proportion of the direct sound signal and the early reflection signal;
an initial sound correction means (7) for outputting the direct sound signal to the reverberation signal; and a reverberation correction means for generating a corrected reverberation signal by adding the direct sound signal at a second ratio and the reverberation signal, and outputting the corrected reverberation signal to the reverberation sound speaker (6). A sound field control device comprising (8), characterized in that sound quality is improved in a range other than the optimum listening position. 2. The sound field control device according to claim 1, wherein the first ratio and the second ratio are variable.