JPH11262081A - Delay time setting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce setting a delay time corresponding to respective loudspeakers when plural speakers are employed and to set an accurate delay time. SOLUTION: An HPF 30 and a delay device 10 connect to a pre-stage of a tweeter 40, a BPF 32 and a delay device 12 connect to a pre-stage of a loudspeaker 42, and an LPF 34 and a delay device 14 connect to a pre-stage of a woofer 44 respectively. A delay time calculation setting section 52 calculates the delay time until the sound wave emitted from any of the speakers 40-44 receiving a prescribed signal outputted from a delay time measurement sound source 50 reaches a microphone 46 at a listening point. Furthermore, the delay time calculation setting section 52 sets the delay times of the delay devices 10-14, so that the arrival timings of the sound waves to the microphone 46 coincide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a delay time setting method in an audio system that outputs a plurality of channels of sound from a plurality of speakers.

[0002]

2. Description of the Related Art It is preferable that a speaker used in an audio device can output sound in an audible band evenly. However, in practice, it is difficult to output sound in the entire frequency band with a single speaker. 2 with different characteristics
One or three speakers are used in combination. For example, when three speakers are used, a high-range speaker, a middle-range speaker, and a low-range speaker are combined.

[0003] By the way, sound waves corresponding to audio signals having different frequency bands are separately emitted from each of these two or three speakers. However, in order for a listener to listen to music without a sense of incongruity, the listener is required to listen to the music. It is necessary to match the arrival times of the sound waves at the points.

In particular, in an audio system for a vehicle,
Since it is not easy to secure a space for installing speakers, it is often difficult to install a plurality of speakers having different frequency characteristics in the same place, and each speaker may be installed in a different place. In such a case,
If the distance from each speaker to the listening point is different, the time required for the sound waves radiated from each speaker to reach the listening point will be shifted, and the reproduced sound will be distorted. The arrival time of the sound wave of each frequency component is matched.

Conventionally, the delay time of each of these delay devices is calculated by the user who installs the speaker himself / herself calculating the distance from each speaker to the listening position, and based on the calculated value. Thus, even if the installation locations of the speakers are significantly different, the time at which the sound waves radiated from each speaker reach the listening position can be made to substantially coincide.

[0006]

By the way, in setting the delay time of the delay unit described above, the user himself / herself calculates the distance from the speaker to the listening position and inputs the result to a speaker system or the like by a digital processor. Since it is necessary, there is a problem that the setting operation is complicated.

Further, the time from when an audio signal is actually output from an audio device to when a sound wave of each corresponding frequency component reaches a listening position is only a difference due to a difference in distance from each speaker to the listening position. In addition, the difference between the time when an audio signal is input to each speaker and the time when a sound wave is radiated should be considered, but this is not taken into account in the past, and accurate delay time can be set. Did not. For example, a bass speaker requires a longer time from the input of an audio signal to the actual emission of a sound wave, compared to a speaker for a middle tone or a treble. In such a delay device, it is necessary to set the delay time by subtracting this time difference. Also, the delay time varies when the length of the wiring connecting the audio device and the speaker greatly changes depending on the installation position of the speaker. However, the delay time of each delay device is set in consideration of the variation. Therefore, it was not possible to set an accurate delay time.

The present invention has been made in view of the above points, and has as its object to reduce the trouble of setting a delay time corresponding to each speaker when a plurality of speakers are used. Another object of the present invention is to provide a delay time setting method capable of setting an accurate delay time.

[0009]

In order to solve the above-mentioned problem, in the delay time setting method of the present invention, a sound collecting means is provided at a listening position, and a plurality of speakers installed in an acoustic space are provided. Each of them receives a delay time measuring signal and detects sound waves actually emitted from each speaker by a sound collecting means. Then, based on the detection result, the delay time from when the delay time measuring signal is input to each speaker to when the corresponding sound wave is detected by the sound collecting means is calculated by the delay time calculating means. Based on this, each delay time of the delay means connected in front of each speaker is set by the delay time setting means. In this way, the signal for delay time measurement is actually input to each speaker, and the corresponding sound wave is radiated into the acoustic space. This is detected by the sound collecting means at the listening position, and the delay time is measured, and the measurement result is obtained. , The delay time of each delay means is set, and it is possible to set an accurate delay time. In particular, it is possible to set a highly accurate delay time in consideration of not only the difference between the distance between each speaker and the sound collecting means but also the type of the speaker and the difference in the wiring length. Further, since the delay time of each delay unit is automatically set, there is no need for the user to make various settings manually, and the labor required for setting the delay time can be reduced.

The above-described delay time setting means searches the longest delay time from the plurality of delay times calculated by the delay time calculation means corresponding to each of the plurality of speakers, and finds the longest delay time. It is preferable to calculate the difference from the other delay times based on the above, and set these difference values as the delay time of each delay unit. Since the difference in the arrival time of the sound wave to the different sound collecting means for each speaker can be reflected in the delay time of each delay means, the arrival timing of the sound wave radiated from each speaker at the listening position can be accurately adjusted. Can be.

The delay time calculating means receives the signal for measuring the delay time and the output signal of the sound collecting means, and calculates the delay time based on the time at which the cross-correlation between these two signals is maximum. Preferably, the calculation is performed. The sound wave radiated from the speaker is distorted in waveform by the propagation characteristics from the speaker to the sound collecting means, but the point of time when the sound wave having the highest cross-correlation is received is considered to be the arrival time. By detecting, the delay time until the sound wave reaches the sound collecting means can be accurately calculated.

The delay time calculating means receives the delay time measuring signal and the output signal of the sound collecting means, and performs adaptive equalization processing so that the power of an error signal between these two signals is minimized. It is preferable to calculate the delay time based on the filter coefficient of the adaptive filter to be performed. Since the filter coefficient of the adaptive filter reproduces the impulse response detected by the sound collecting means, the time until the sound wave reaches the sound collecting means accurately is detected by detecting the time at which the filter coefficient becomes maximum. Time can be calculated.

In particular, when calculating these delay times, it is preferable to use a white noise signal as the delay time measurement signal. The white noise signal contains frequency components from the low band to the high band, and when several types of speakers with different frequency characteristics are used in combination,
A sound wave corresponding to the delay time measurement signal can be emitted from each speaker, and the delay time can be reliably calculated.

A time stretched pulse may be used as the delay time measuring signal. In this case, the delay time calculating means performs a convolution operation on a signal obtained by inverting the time stretched pulse on the time axis with respect to the output signal of the sound collecting means, and obtains a time at which the convolution operation result becomes maximum. It is preferable to calculate the delay time. By performing such a convolution operation, an impulse response can be obtained. Therefore, by detecting the maximum value, a delay time until a sound wave reaches the sound collecting means can be accurately calculated. The time-stretched pulse is a signal having a predetermined time width and a frequency component dispersed on the time axis, and has an advantage that it is hardly affected by sudden noise.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An audio system according to an embodiment to which a delay time setting method according to the present invention is applied includes a plurality of speakers having different frequency characteristics, and an audio signal is actually input and emitted from each speaker. It is characterized in that the time required for the sound wave to reach the listening point is automatically measured, and the delay time of a delay device provided in the preceding stage of each speaker is set based on the measurement result. Hereinafter, an audio system according to an embodiment will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an audio system according to an embodiment to which the present invention is applied. The on-vehicle audio system shown in FIG. 1 includes an audio device 100 such as a tuner or a CD player, three delay devices 10, 12, and 14 to which an audio signal output from the audio device 100 is input, and these delay devices. Four switches 20, 22, 24,
26, a high-pass filter (HPF) 30 that passes only high-frequency components from the input audio signal, and a band-pass filter (BPF) that passes only mid-frequency components
32, a low-pass filter (LPF) 34 for passing only low-frequency components, three speakers 40, 42, and 44 having different frequency characteristics, a microphone 46 set at a listening position of audio sound, and a delay time measuring device. A delay time measuring sound source 50 for generating a predetermined signal;
6 and a delay time calculating / setting unit 52 for calculating the delay time of the sound wave via each speaker 40 and the like and setting the delay time of each delay unit 10 and the like based on the output signal of the sixth embodiment.

The delay units 10, 12, and 14 can arbitrarily set their respective delay times, and each delay time is set by the delay time calculation / setting unit 52. The audio signal output from the delay unit 10 is input to a high-pass filter 30 via a switch 20, and a high-frequency component sound wave is radiated from a high-frequency loudspeaker 40 connected to a subsequent stage into the vehicle interior acoustic space. Similarly, the audio signal output from the delay unit 12 is input to the band-pass filter 32 via the switch 22, and the middle-range component sound wave is output from the middle-tone speaker 42 connected to the subsequent stage, Is radiated. The audio signal output from the delay unit 14 is input to a low-pass filter 34 via a switch 24, and a low-frequency component sound wave is radiated from a low-frequency loudspeaker 44 connected to the subsequent stage into the vehicle interior acoustic space.

The microphone 46 includes speakers 40 to 44
Sound waves emitted from any of the above. The delay time calculation / setting unit 52 measures a delay time from when a predetermined signal for delay time measurement is output from the delay time measurement sound source 50 to when a sound wave corresponding to the signal is detected by the microphone 46 ( Calculation), and based on this measurement result, the delays of the delay units 10 to 14 are adjusted so that the time from when the audio signal is input from the audio device 100 to when the sound wave in each frequency range reaches the microphone 46 coincides. Set the time. The detailed configuration of the delay time calculation / setting unit 52 will be described later.

The delay units 10, 12, and 14 are used as delay means, the microphone 46 is used as sound collecting means, the sound source 50 for measuring delay time is used as signal generating means, and the delay time calculating / setting unit 52 is used.
Correspond to the delay time calculating means and the delay time setting means, respectively.

The audio system of the present embodiment has such a configuration. Next, each of the filters 30, 32, 3
The delay times t1, t2, and t3 from when the signal is input to the speaker 4 to when the sound waves emitted from the speakers 40 to 44 reach the microphone 46 are measured, and the respective delay times of the delay units 10 to 14 are set. The operation will be described.

First, the switches 20, 22, and 24 are switched to connect the filters 30 to 34 to the delay units 10 to 1, respectively.
Change from the 4 side to the delay time measurement sound source 50 side. Then, by switching the switch 26, the sound source 5 for delay time measurement
A predetermined signal output from 0 is input to the high-pass filter 30. The switching operation of each of these switches is performed in response to an operation instruction from the delay time calculation / setting unit 52 or a control unit (not shown).

In such a connection state of each switch, a predetermined signal for delay time measurement is output from the sound source for delay time measurement 50, and a corresponding sound wave is radiated from the speaker 40 to the acoustic space in the vehicle compartment. Delay time calculation / setting unit 52
Calculates a delay time t1 from when a predetermined signal is output from the delay time measurement sound source 50 to when a corresponding detection signal is output from the microphone 46.

When the calculation of the delay time t1 is completed, the switch 26 is switched to change the state in which a predetermined signal output from the delay time measuring sound source 50 is input to the bandpass filter 32. In this state, a predetermined signal for delay time measurement is output from the delay time measurement sound source 50, and a corresponding sound wave is emitted from the speaker 42 into the vehicle interior space. The delay time calculation / setting unit 52 outputs a predetermined signal from the sound source 50 for delay time measurement,
6 to the output of the corresponding detection signal t
2 is calculated.

When the calculation of the delay time t2 is completed, the switch 26 is further switched, and the sound source 50 for delay time measurement is turned on.
Is changed to a state in which the predetermined signal output from is input to the low-pass filter 34. In this state, a predetermined signal for delay time measurement is output from the delay time measurement sound source 50, and a corresponding sound wave is emitted from the speaker 44 into the vehicle interior space. The delay time calculation / setting unit 52 calculates a delay time t3 from when a predetermined signal is output from the delay time measurement sound source 50 to when a corresponding detection signal is output from the microphone 46.

Thus, three delay times t1, t
After the calculation of 2, t3 is completed, the delay time calculation / setting unit 52 calculates 3 based on the three delay times t1 to t3.
Each delay time of one of the delay units 10 to 14 is set. For example, when the delay time T1 is the longest, the delay time of the corresponding delay unit 10 is set to 0, and the delay time of the delay unit 12 is set to (t1
At (t2), the delay time of the delay unit 14 is set to (t1-t3).

Next, the above-described delay time calculation / setting unit 52
, Three specific configuration examples will be described.

Configuration Example 1 of Delay Time Calculation / Setting Unit The delay time from when a signal is input to each of the filters 30 to 34 to when a corresponding sound wave reaches the microphone 46 is determined by the input to each of the filters 30 to 34. It can be calculated by calculating the cross-correlation between the signal and the output signal of the microphone 46 and determining the time when the maximum value is obtained.

FIG. 2 is a diagram showing the configuration of the delay time calculating / setting unit 52 when calculating the delay time using the cross-correlation. The delay time calculation / setting unit 52 shown in FIG. 3 includes a cross-correlation calculation unit 60, a cross-correlation function maximum value / delay time search unit 62, and a delay time setting unit 64. Also,
The sound source 50 for delay time measurement combined with the delay time calculation / setting unit 52 outputs a white noise signal as a predetermined signal for delay time measurement.

The cross-correlation calculating section 60 performs a cross-correlation calculation between the white noise signal output from the delay time measuring sound source 50 and the output signal of the microphone 46. This cross-correlation calculation is performed according to the following equation (1).

[0030]

(Equation 1)

Here, h (n) is a white noise signal, g (n) is a detection signal of the microphone 46, N is a length of time taken into the cross-correlation calculator 60, and τ is a sampling time interval. Is shown.

Maximum value of cross-correlation function / delay time search section 62
Is obtained by searching the value of m at which the cross-correlation R (mτ) becomes maximum based on the result of performing the cross-correlation calculation by sequentially changing the value of m in the equation (1) by the cross-correlation calculator 60. Is the delay time t1 (or t2, t3).

The delay time setting section 64 extracts the maximum value from the three delay times t1, t2, and t3 obtained by the cross-correlation function maximum value / delay time search section 62, and uses the maximum value as a reference to determine the remaining value. Is calculated with the delay time.
As described above, when the delay time t1 is the maximum value, the difference (t1-t) between the remaining two delay times t2 and t3 is obtained.
2), (t1-t3) are calculated. Further, the delay time setting unit 64 determines whether the three delay units 10
-14 are set.

Configuration Example 2 of Delay Time Calculation / Setting Unit The delay time from when a signal is input to each of the filters 30 to 34 to when a corresponding sound wave reaches the microphone 46 is determined by the impulse response detected by the microphone 46. Can be calculated by measuring the time at which the maximum is obtained.

FIG. 3 is a diagram showing a configuration of the delay time calculating / setting unit 52 when calculating a delay time using an impulse response. Delay time calculation / setting unit 52 shown in FIG.
Is an analog-to-digital (A / D) converter 70, a memory control unit 72, a memory 74, an averaging processing unit 76, a convolution operation unit 78, and an impulse response maximum value / delay time search unit 8
0 and a delay time setting unit 82. Further, a time-stretched pulse (time-stretched pulse) is output from the delay-time measuring sound source 50 combined with the delay-time calculating / setting unit 52.

The time stretched pulse is a signal whose frequency characteristic H (k) is expressed as follows.

[0037]

(Equation 2)

Here, m is a coefficient indicating the degree of shifting the phase of each frequency within the time stretched pulse,
Take any integer value. N is a coefficient that defines the time of generation of the time stretched pulse. Also, k is from 0 to N-
A is an integer up to 1, and a is determined by the third expression included in Expression (2) if m and N are determined. For example, when m = 0, a = 0, so that H (k) = e for all k.
xp (0) = 1, and each frequency component becomes an impulse concentrated without being dispersed.

The actual time-stretched pulse output from the delay time measuring sound source 50 is a signal obtained by performing an inverse Fourier transform on the above equation (2), an example of which is shown in FIG. The time-stretched pulse shown in FIG.
= 256, and a signal in which each frequency component is dispersed for a predetermined time corresponding to the value of N and the value of m. Therefore, by setting the value of N to be large and the value of m to be large, the energy of each frequency component can be dispersed over a long period of time. Since the time required for measuring the delay time becomes longer as the occurrence time of the error becomes longer, it is necessary to set appropriate values of N and m within a range where the occurrence time does not become too long.

The A / D converter 70 samples and quantizes the output signal of the microphone 46 at predetermined time intervals, and outputs data of a predetermined number of bits. The memory control unit 72 sequentially stores data output from the A / D converter 70 at predetermined time intervals in the memory 74. When the time stretched pulse is output once, the microphone 46 responds to the time stretched pulse.
Is converted into digital waveform data (hereinafter, this data is referred to as “time-stretched pulse response data”) by the A / D converter 70 and stored in a predetermined area of the memory 74. In the memory 74, such storage areas are secured for L pieces, and when the L time stretched pulses are repeatedly output from the delay time measuring sound source 50, the corresponding time stretched pulse responses are obtained. Data is stored in each of the L storage areas described above.

The averaging section 76 averages L time-stretched pulse response data stored in the memory 74. The averaged response data is q
(N), assuming that the i-th response data is q _i (n),

[0042]

(Equation 3)

Is as follows. The averaging unit 76 calculates (3)
By performing an averaging process on the L pieces of time-stretched pulse response data according to the formula, response data from which the influence of sudden noise has been removed can be obtained.

The convolution operation unit 78 calculates the averaged time-stretched pulse response data q calculated by the equation (3).
(N) is convolved with data p (−n) obtained by inverting the time stretched pulse p (n) on the time axis.
FIG. 5 is a diagram showing a signal obtained by inverting the time stretched pulse on the time axis, and shows a waveform obtained by inverting the time stretched pulse corresponding to N = 256 shown in FIG. The data p (-n) actually used in the convolution operation unit 78 is obtained by converting the signal waveform shown in FIG. 5 into digital waveform data, and the sampling interval is A
This is the same as the sampling interval in the / D converter 70.

The convolution operation by the convolution operation unit 78 is performed based on the following equation.

[0046]

(Equation 4)

According to the equation (4), an impulse response is obtained by convolving the time-stretched pulse response signal with a signal obtained by inverting the original time-stretched pulse on the time axis. The convolution operation unit 78 performs a convolution operation using the N pieces of data by sequentially shifting data output from the averaging processing unit 76, and outputs a plurality of operation results.

Maximum impulse response value / delay time search section 8
In the case of 0, a plurality of operation results by the convolution operation unit 78 are input, and by searching for an operation result with the maximum impulse response, the arrival timing of time-stretched pulse response data corresponding to this operation result is obtained. ,
After the time-stretched pulse is input to the high-pass filter 30 or the like, a sound wave corresponding to this is input to the microphone 46.
Is calculated until the delay time t reaches.

The delay time setting section 82 sets each delay time of the three delay units 10 to 14 based on the delay time t1 and the like calculated by the maximum impulse response / delay time search section 80.

Configuration Example 3 of Delay Time Calculation / Setting Unit As described above , the delay time from when a signal is input to each of the filters 30 to 34 to when a corresponding sound wave reaches the microphone 46 is determined by the microphone 46. It can be calculated by measuring the time at which the detected impulse response is maximum, and an adaptive filter can be used to measure the time at which the impulse response is maximum.

FIG. 6 shows delay time calculation and delay time calculation when an impulse response is obtained by an adaptive filter to calculate a delay time.
FIG. 3 is a diagram showing a configuration of a setting unit 52. The delay time calculation / setting unit 52 shown in FIG.
t Mean Square) Algorithm processing unit 92, adder 9
4. It is configured to include a filter coefficient maximum value / delay time search unit 96 and a delay time setting unit 98. The delay time measurement sound source 50 combined with the delay time calculation / setting unit 52 outputs white noise as a predetermined signal for delay time measurement.

The adaptive filter 90 has a FIR (Finite Imp
ulse response) type digital filter configuration, and uses a tap coefficient vector (filter coefficient) W set by the LMS algorithm processing unit 92 for a white noise signal input from the sound source 50 for delay time measurement. To perform predetermined adaptive processing.

The LMS algorithm processing unit 92
Controls the filter coefficient W of the adaptive filter 90 so that the power of the error signal e obtained by subtracting the output signal of the adaptive filter 90 from the output signal of the microphone 46 by the adder 94 is minimized. Therefore, the microphone 4
6 and the output signal of the adaptive filter 90 are substantially the same, and the filter coefficient W of the adaptive filter 90 has substantially the same characteristics as the impulse response detected by the microphone 46.

Filter coefficient maximum value / delay time search section 96
Is the time when the maximum value of the impulse response is obtained, that is, the high-pass filter 30
For example, a time t1 from when a signal is input to the corresponding sound wave to when the sound wave reaches the microphone 46 is calculated.

The delay time setting unit 98 calculates the delay time t calculated by the filter coefficient maximum value / delay time search unit 96.
Based on 1, etc., the respective delay times of the three delay units 10 to 14 are set.

As described above, in the audio system of this embodiment, a predetermined signal for delay time measurement is output from the sound source 50 for delay time measurement, and the three speakers 40, 42, and 44 having different frequency characteristics respectively output the signals. The sound wave corresponding to the signal is actually radiated, and the output signal of the microphone 46 installed at the listening position is calculated by the delay time calculating / setting unit 52.
To each speaker 4 by performing a predetermined calculation.
The actual delay time corresponding to each of 0 and the like is calculated, and the delay time of each of the delay units 10 to 14 inserted in the preceding stage of each speaker 40 etc. is automatically set based on the calculation result. .

Therefore, as in the conventional case, the user measures the distance between each speaker 40 and the like and the listening position, and inputs the measured value to the speaker system and the like to set the delay time. The troublesome work is not required, and the work required for setting the delay time can be greatly reduced.

Further, since the delay time actually generated by emitting the sound wave from each speaker 40 and the like is calculated, the wiring length to each speaker 10 and the like and the response time of each speaker 10 and the like (after the signal is input) The delay time of each of the delay units 10 and the like can be accurately set in consideration of the variation in the time until the sound wave is emitted, and the sound quality at the listening position can be improved.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. For example, in the above-described embodiment, an audio system in which three speakers 40 to 44 having different frequency characteristics are installed in a vehicle compartment has been described, but the number of speakers may be two or four or more. In addition to the case where a plurality of speakers having different frequency characteristics are combined, a delay time of a delay unit inserted before a plurality of speakers having the same frequency characteristic may be set. In addition, it is not limited to audio systems for vehicles,
The present invention can also be applied to an indoor or outdoor audio system or the like.

[0060]

As described above, according to the present invention, a signal for measuring delay time is actually input to each speaker, a corresponding sound wave is radiated into an acoustic space, and the sound wave is collected at a listening position. The delay time is detected and measured, and the delay time of each delay unit is set based on the result of the actual measurement, so that the delay time can be set accurately. In particular, it is possible to set a highly accurate delay time in consideration of not only the difference between the distance between each speaker and the sound collecting means but also the type of the speaker and the difference in the wiring length. Further, since the delay time of each delay unit is automatically set, there is no need for the user to make various settings manually, and the labor required for setting the delay time can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an audio system according to an embodiment to which the present invention is applied.

FIG. 2 is a diagram illustrating a configuration of a delay time calculation / setting unit when calculating a delay time using a cross-correlation.

FIG. 3 is a diagram illustrating a configuration of a delay time calculation / setting unit when calculating a delay time using an impulse response.

FIG. 4 is a diagram illustrating an example of a time stretched pulse.

FIG. 5 is a diagram showing a signal obtained by inverting a time stretched pulse on a time axis.

FIG. 6 is a diagram illustrating a configuration of a delay time calculating / setting unit when calculating an impulse response by an adaptive filter to calculate a delay time.

[Explanation of symbols]

 10, 12, 14 Delay device 20, 22, 24, 26 Switch 30 High pass filter (HPF) 32 Band pass filter (BPF) 34 Low pass filter (LPF) 40, 42, 44 Speaker 46 Microphone 50 Delay time measurement sound source 52 Delay Time calculation / setting unit

Claims (6)

[Claims] 1. A plurality of speakers installed at a predetermined position in an acoustic space; a sound collection unit installed at a listening position in the acoustic space; A plurality of delay units that can set a delay time; a signal generation unit that inputs a predetermined delay time measurement signal to each of the plurality of speakers; and a plurality of speaker units based on an output signal of the sound collection unit. A delay time calculating means for calculating a delay time from when the delay time measuring signal is input to the corresponding sound wave is detected by the sound collecting means, based on a calculation result by the delay time calculating means, A delay time setting means for setting a delay time of each of the plurality of delay means. 2. The delay time setting unit according to claim 1, wherein the delay time setting unit searches for a longest delay time from a plurality of delay times calculated by the delay time calculation unit corresponding to each of the plurality of speakers. Calculating a difference from the other delay times based on the longest delay time, and setting the calculated difference value as each delay time of the plurality of delay means corresponding to each of the plurality of speakers. Delay time setting method. 3. The delay time calculation means according to claim 1, wherein the delay time measurement signal output from the signal generation means and the output signal of the sound collection means are input to the delay time calculation means. By determining the time at which the cross-correlation of the two signals is maximized, the delay time from when the delay time measurement signal is input to each of the plurality of speakers until the corresponding sound wave is detected by the sound collection means is determined. A delay time setting method that performs calculation. 4. The delay time calculating means according to claim 1, wherein the delay time calculating means receives the delay time measuring signal output from the signal generating means and an output signal of the sound collecting means. An adaptive filter that performs an adaptive equalization process so that the power of the error signal of the two signals is minimized. Based on the filter coefficient of the adaptive filter, the delay time measurement signal is supplied to each of the plurality of speakers. Calculating a delay time from when the sound is input to when the corresponding sound wave is detected by the sound collecting means. 5. The delay time setting method according to claim 3, wherein the delay time measurement signal output from the signal generation means is a white noise signal. 6. The signal according to claim 1, wherein the delay time measurement signal output from the signal generation means is a time stretched pulse, and the delay time calculation means outputs
The signal obtained by inverting the time-stretched pulse on the time axis is subjected to a convolution operation, and the time at which the convolution operation result is maximized is obtained, so that the delay time measurement signal is input to each of the plurality of speakers. A delay time setting method for calculating a delay time until a corresponding sound wave is detected by the sound collecting means.