JP5889233B2 - Acoustic coupling amount estimating apparatus, echo canceling apparatus, method and program thereof - Google Patents

Description

  The present invention relates to an echo canceling device for canceling acoustic echoes that cause acoustic feedback and cause acoustic disturbances, for example, used in a teleconference system having an acoustic reproduction system, and acoustic coupling amount estimation for estimating an echo path used at that time. The present invention relates to an apparatus, a method thereof, and a program.

  Echo suppression processing based on short-time spectral amplitude (STSA) estimation is based on the fact that the human auditory characteristics are insensitive to the phase and the statistical characteristics of the echo, and the amplitude of the echo in the frequency domain. This is achieved by subtracting the components. A conventional echo canceling apparatus 100 that suppresses echoes in the frequency domain is described in Patent Document 1, for example.

FIG. 1 shows a functional configuration example of the echo canceling apparatus 100, and its operation will be described. The echo canceling apparatus 100 is input to the receiving end 1 and is a reproduction signal x that is converted into an acoustic signal by the speaker 2.
(K) and a collected sound signal y (k) in which an echo component influenced by an indoor impulse response (transfer function) (not shown) is superimposed on a reproduction signal x (k) converted into an acoustic signal output from the microphone 3. Are input signals. The output signal e (k) output from the echo canceller 100 to the transmitting end 4 is a signal in which the echo component of the collected sound signal y (k) is suppressed.

  The echo cancellation apparatus 100 includes a first frequency analysis unit 81, a second frequency analysis unit 82, an acoustic coupling amount calculation unit 13, an echo power calculation unit 14, a gain calculation unit 85, an integration unit 86, and a frequency synthesis unit 87.

The first frequency analysis unit 81 receives the reproduction signal x (k) as an input and outputs a reproduction signal spectrum X _ω (i). The second frequency analysis unit 82 receives the collected sound signal y (k) and outputs a collected sound signal spectrum Y _ω (i). Here, k is a sample point number indicating a discrete time of a predetermined interval, and the reproduction signal x (k) and the sound collection signal y (k) are digital signals. In FIG. 1, an A / D converter that converts an analog signal input to the speaker 2 and an analog signal output from the microphone 3 into a digital signal is omitted. In the reproduction signal spectrum X _ω (i) and the collected sound signal spectrum Y _ω (i), ω is a frequency value, which is a frequency number of the spectrum obtained at a predetermined frequency interval. I is a frame number. The time length of the frame is, for example, 16 ms when the sampling frequency is 16 kHz and the data amount of frequency analysis is 256 points.

The acoustic coupling amount calculator 13 receives the collected sound signal spectrum Y _ω (i) and the reproduction signal spectrum X _ω (i) as inputs, and uses the equation (1) to estimate the acoustic coupling amount | H ^ _ω (i, m ) | ² (The symbol “^” used in the text should be described immediately above the character immediately before, but is described immediately after the character due to restrictions on the text notation. These symbols are written in their original positions).

Here, ^* is a conjugate complex number. m is a value that takes an integer value of m = 0, 1,..., M−1, and the reproduction signal spectrum X _ω (ij−m) is obtained with respect to the collected sound signal spectrum Y _ω (ij). This represents the number of frames to be shifted to the past time. Therefore, M represents a range shifted to the past time. In other words, M is the number of frames determined by the reverberation time. For example, when the frame shift width is 8 ms and the reverberation time is 160 ms, M = 20. N (m) is a predetermined number of frames and represents a frame width for obtaining an estimated value of the acoustic coupling amount (hereinafter also simply referred to as “acoustic coupling amount estimation value”). C (m) is an adjustment constant, for example, C (m) = 1. The adjustment constant C (m) may be set to a different value depending on m. For example, if m is large, the past frame time becomes a calculation target, so that the SN ratio is relatively lower than the acoustic coupling amount when m is small. Therefore, when m is large, for example, C (m) may be decreased. That is, the weight for the past is reduced. Similarly, since the SN ratio of the past frame time decreases, the predetermined number of frames N (m) may be changed depending on the value of m. For example, if m is large, N (m) is also large. By doing so, since the cross spectrum addition value and the power value are further averaged, an improvement in accuracy can be expected.

FIG. 2 shows a functional configuration example of the echo power calculation unit 14. The echo power calculation unit 14 includes a reproduction signal spectrum power calculation unit 140, a reproduction signal power recording unit 141, and a multiplication / accumulation unit 142. The reproduction signal spectrum power calculation unit 140 squares the input reproduction signal spectrum X _ω (i) to obtain the reproduction signal spectrum power | X _ω (i) | ² . The reproduction signal spectral power | X _ω (i) | ² is recorded in the reproduction signal power recording unit 141. The multiplication / accumulation unit 142 calculates the acoustic coupling amount estimated value | H ^ _ω (i, m) | ² and the reproduction signal spectral power from the present recorded in the reproduction signal power recording unit 141 to the past for M−1 frames | _Xω (i) | ² , | X _ω (i−1) | ² ,..., | X _ω (i−M + 1) | ² are used as inputs, and the echo power estimated value | D ^ _ω ( i) | ² is calculated.

As described above, the echo power calculation unit 14 determines the acoustic coupling amount estimated value | H ^ _ω (i, 0) | ² and the reproduction signal spectral power | X _{ω for} the current time frame (im) (m = 0). (I−m) | ² and the acoustic coupling amount estimated value at the same time within the range of the past time frame (im) (m = 1 to M−1) | H ^ _ω ( i, m) | ² and the reproduction signal spectral power | X _ω (i−m) | ² are added together to obtain an echo power | D ^ _ω (i) | ² .

The gain calculation unit 85 receives the echo power estimated value | D ^ _ω (i) | ² and the collected sound signal spectrum Y _ω (i) as input, and calculates the gain coefficient G _ω (i) by the equation (3).

The gain coefficient G _ω (i) takes a real value between 0 and 1, and is small when the collected sound signal spectrum Y _ω (i) has many echo components, and large when there are many components other than the echo components. Value.

Integrating unit 86 outputs the sound collection signal spectrum Y ω _(i) the gain coefficient G ω _(i) integrating to the echo-canceled signal spectrum E _{ω (i).}

The frequency synthesizer 87 re-synthesizes and outputs the output signal e (k) in the time domain from the echo cancellation signal spectrum E _ω (i) corresponding to the frequency value ω.

JP 2010-187086 A

  In order to consider the case where the impulse response length of the echo path is longer than the frame length, the conventional technique performs a convolution operation in the power spectrum region between the acoustic coupling amount estimation value and the reproduction signal spectrum power (see Expression (2)). ). In this model, there is a problem that the optimum value of the acoustic coupling amount estimation value is not uniquely determined by the approximation in which the phase information is removed. However, since the conventional acoustic coupling amount estimation method does not consider this problem, the estimation accuracy of the echo power may not be sufficient, and problems such as the echo remaining unerased or musical noise may occur. was there.

  The present invention has been made in view of the above points, and a technique for accurately estimating an echo path when the impulse response length of the echo path is longer than the frame length, and an echo cancellation technique using the echo path estimation value The purpose is to provide.

In order to solve the above-described problem, according to the first aspect of the present invention, the acoustic coupling amount estimation apparatus is configured such that M is a range in which the reproduction signal spectrum is shifted to a past time with respect to the collected signal spectrum, m = 0. , 1,..., M−1, X _ω (i) is the reproduction signal spectrum at the frequency ω of frame i, Y _ω (i) is the collected signal spectrum at the frequency ω of frame i, L is the number of added frames, ^H Is the complex conjugate transpose, and the first to Mth echo path estimation values H ^ _ω (i, m) are obtained by the following equations.

In order to solve the above problem, according to another aspect of the present invention, an acoustic coupling amount estimation method includes a range in which the reproduction signal spectrum is shifted to a past time with respect to the collected sound signal spectrum, M = 0, 1,..., M−1, X _ω (i) is the reproduction signal spectrum at the frequency ω of frame i, Y _ω (i) is the collected sound signal spectrum at the frequency ω of frame i, L is the number of frames added, and ^H is The complex conjugate transpose is used, and the first to Mth echo path estimation values H ^ _ω (i, m) are obtained by the following equations.

  According to the present invention, the first to M-th echo path estimation values are collectively calculated by the least square solution between the collected sound signal spectrum and the estimation value of the echo spectrum. As a result, the first to Mth echo path estimation values are calculated in consideration of calculating the echo power estimation value closest to the true value for each frame. Therefore, it is possible to obtain an echo power estimation value that is more accurate than that of the prior art, which can sufficiently suppress the echo as compared to the prior art, and is more robust against voice distortion and performs echo cancellation with less deterioration in sound quality. it can.

The figure which shows the function structural example of the echo cancellation apparatus which concerns on a prior art. The figure which shows the function structural example of the echo power calculation part which concerns on a prior art. The figure which shows the function structural example of the echo cancellation apparatus which concerns on 1st embodiment. The figure which shows the example of the processing flow of the echo cancellation apparatus which concerns on 1st embodiment.

Hereinafter, embodiments of the present invention will be described. In the drawings used for the following description, constituent parts having the same function and steps for performing the same process are denoted by the same reference numerals, and redundant description is omitted. In the following explanations, the symbols “^”, “~”, “ ^→ ”, etc. used in the text should be written directly above the previous character. Immediately after. In the formula, these symbols are written in their original positions. Further, the processing performed for each element of a vector or matrix is applied to all elements of the vector or matrix unless otherwise specified.

<First embodiment>
FIG. 3 is a diagram illustrating a functional configuration example of the echo cancellation apparatus 200 according to the first embodiment. FIG. 4 shows the processing flow.

  The echo cancellation apparatus 200 includes a first frequency analysis unit 81, a second frequency analysis unit 82, an acoustic coupling amount calculation unit 23, an echo power calculation unit 14, a gain calculation unit 85, an integration unit 86, and a frequency synthesis unit 87. The echo canceller 200 has a new acoustic coupling amount calculator 23, and the other configurations are the same as those of the conventional echo canceller 100. About the same part as the past, the same reference numerals are used to simplify the description.

<First Frequency Analysis Unit 81 and Second Frequency Analysis Unit 82>
The first frequency analysis unit 81 outputs a reproduction signal spectrum X _ω (i) obtained by frequency conversion of the reproduction signal x (k) (s1). The second frequency analysis unit 82 outputs the collected sound signal spectrum Y _ω (i) obtained by frequency-converting the collected sound signal y (k) (s2).

<Acoustic coupling amount calculation unit 23>
The acoustic coupling amount calculator 23 receives the reproduction signal spectrum X _ω (i) and the collected sound signal spectrum Y _ω (i) as inputs, and the first to Mth acoustic coupling amount estimation values | H ^ (i, m) | ² is obtained (s3) and output.

The acoustic coupling amount calculation unit 23 calculates first to Mth acoustic coupling amount estimated values | H ^ _ω (i, m) | ² corresponding to the least squares solution based on the collected sound signal spectrum and the estimated value of the echo spectrum. Ask. For example, first to M-th echo path estimation values H _ω (corresponding to the least squares solution of the following equation based on the collected sound signal spectrum Y _ω (i) and the echo spectrum estimation value D _ω ^ (i). i, m) is obtained, and the absolute value square value of the echo path estimated value H ^ _ω (i, m) is obtained as an acoustic coupling amount estimated value | H ^ _ω (i, m) | ² .

It is. Here, || · || is the norm, L is the number of frames added, l = 0,1, ..., L , M are collected sound signal spectrum Y _{ω (i)} the reproduction signal spectrum X _omega (i ) Represents the range to shift. Equation (11) corresponds to obtaining the first to M-th echo path estimation values H ^ _ω (i, m) so that the difference between the collected sound signal spectrum and the estimated value of the echo spectrum is minimized. The first to Mth echo path estimation values | H ^ _ω (i, m) | ² correspond to the least squares solution obtained so that the difference between the collected sound signal spectrum and the estimated value of the echo spectrum is minimized. For example, the first to Mth acoustic coupling amount estimated values | H ^ _ω (i, m) | ² corresponding to the least squares solution are obtained as follows.

First, the acoustic coupling amount calculation unit 23 calculates the autocorrelation matrix R ^→ _ω (i) and the vector norm _y˜ω (i) according to the equations (12) and (13), respectively.

Next, the acoustic coupling amount calculating unit 23 calculates the product [Phi _omega of the autocorrelation matrix R ^→ _omega (i) a (i) by the following equation (14).

Here, ^H represents a complex conjugate transpose.

The acoustic coupling amount calculation unit 23 uses the autocorrelation matrix R ^→ _ω (i), the product Φ _ω (i), and the vector norm _y˜ω (i) to calculate the first to M-th echo path estimation values H ^. (I, m) is calculated by the following equation (15) and output.

  In addition, Formula (15) is equal to the solution of the simultaneous equation model of following Formula (16).

  Equation (15) is also a value corresponding to the least squares solution of Equation (11).

Finally, the acoustic coupling amount calculation unit 23 calculates and outputs the absolute value square value of the echo path estimation value H ^ _ω (i, m) as the acoustic coupling amount estimation value | H ^ _ω (i, m) | ^2. .

<Echo power calculation unit 14>
The echo power calculator 14 receives the reproduction signal spectrum X _ω (i) and the first to Mth acoustic coupling amount estimation values | H ^ _ω (i, m) | ² as inputs, and inputs the first to Mth acoustic couplings. Each of the quantity estimated values | H _ω ^ (i, m) | ² is multiplied by the power | X _ω (im) | ² of the reproduction signal spectrum corresponding to the value of m (m = 0 to M−1). The sum of the obtained values is obtained as an echo power estimated value | _Dω ^ (i) | ² (see equation (2), s4) and output.

<Gain calculation unit 85>
The gain calculation unit 85 obtains a gain coefficient G _ω (i) by using the collected sound signal spectrum Y _ω (i) and the echo power estimated value | D _ω ^ (i) | ² as input (see Expression (3), s5). ,Output.

<Integration unit 86>
The accumulator 86 multiplies the collected sound signal spectrum Y _ω (i) by the gain coefficient G _ω (i) (s6), and outputs the multiplication value as an echo cancellation signal spectrum E _ω (i).

<Frequency synthesizer 87>
The frequency synthesizer 87 frequency synthesizes the echo cancellation signal spectrum E _ω (i) (s7) and outputs an output signal e (k) in the time domain.

<Effect>
In this way, the echo canceller 200 obtains the first to Mth echo path estimation values by shifting the reproduction signal spectrum with respect to the collected sound signal spectrum in the past. Then, the total of the values obtained by multiplying each of the acoustic coupling amount estimated values, which are the absolute value square values of the echo path estimated values, by the power of the reproduction signal spectrum X _ω (i) corresponding to the value of m is obtained as the echo power estimation. Output as a value. Therefore, even when the impulse response length of the echo path is longer than the frame, the echo power can be estimated with high accuracy.

  Further, with such a configuration, the first to Mth echo path estimation values can be calculated together by a least square solution between the collected sound signal spectrum and the estimated value of the echo spectrum. As a result, the first to Mth echo path estimation values are calculated in consideration of calculating the echo power estimation value closest to the true value for each frame. Therefore, it is possible to obtain an echo power estimation value that is more accurate than that of the prior art, which can suppress the echo sufficiently compared to the prior art, and can perform echo cancellation that is more robust against voice distortion and less deteriorated in sound quality. it can.

<Modification>
An echo canceller including an adaptive filter may be provided in the previous stage of the echo canceller 200. In that case, the echo canceling apparatus 200 suppresses the reverberant echo remaining in the output value of the echo canceling apparatus including the adaptive filter.

The acoustic coupling amount calculation unit 23 is not part of the echo canceller 200 but receives the collected sound signal spectrum Y _ω (i) and the reproduction signal spectrum X _ω (i) as input, and first to Mth echo path estimations You may comprise separately as an acoustic coupling amount estimation apparatus which outputs a value.

In the present embodiment, the acoustic coupling amount calculator 23 includes first to Mth echoes corresponding to the least squares solution based on the collected sound signal spectrum Y _ω (i) and the estimated value D _ω ^ (i) of the echo spectrum. path estimate H ^ ω _(i, m) is seeking, collected sound signal spectral power ^| Y ω _(i) | ² and the estimated value of the echo spectrum power ^| D ω ^ _(i) | minimum based on ² and It is good also as a structure which calculates | requires the 1st thru | or Mth acoustic coupling amount estimated value | H ^ ( _omega ) (i, m) | ² corresponding to a square solution.

<Second embodiment>
A description will be given centering on differences from the first embodiment.

The inverse matrix operation for obtaining the inverse matrix Φ _ω ⁻¹ (i) of the product Φ _ω (i) of the autocorrelation matrix R ^→ _ω (i) in Expression (15) requires a large amount of computation. In the second embodiment, the inverse matrix Φ _ω ⁻¹ (i) is obtained recursively using the Recursive Least-Squares (RLS) algorithm (see Reference 1).
(Reference 1) S. Qiao, “Fast adaptive RLS algorithms: a generalized inverse approach and analysis”, IEEE Trans. Signal Process., June 1991, vol. 39, no. 6, pp. 1455-1459

In the second embodiment, the acoustic coupling amount calculator 23 calculates the product Φ _ω (i) of the autocorrelation matrix R ^→ _ω (i) using the forgetting factor β as in the following equation.

  β is a value satisfying 0 <β ≦ 1, and is determined according to the number of added frames L. For example, it is determined so as to satisfy L = 1 / (1-β), and β = 0.99 when L = 100.

Next, the acoustic coupling amount calculation unit 23 calculates the inverse matrix Φ _ω ⁻¹ (i) by the following expression using the product Φ _ω (i) calculated from the expression (21).

The acoustic coupling amount calculator 23 uses the inverse matrix Φ _ω ⁻¹ (i), the autocorrelation matrix R ^→ _ω (i), and the vector norm _y˜ω (i) to calculate the first to Mth echo path estimation values. H ^ (i, m) is calculated by equation (15).

By setting it as such a structure, the amount of calculations required when calculating | requiring inverse matrix (PHI) _omega- ¹ (i) can be reduced.

<Third embodiment>
A description will be given centering on differences from the first embodiment.

When the echo canceller 200 performs frequency analysis / frequency synthesis such as FFT / IFFT using overlap addition, calculation of the amount of acoustic coupling for overlap may be omitted. For example, in the case of Q% frame overlap, the echo power calculation unit 14 calculates an echo power estimated value | D ^ _ω (i) | ² using the following equation.

In addition, the acoustic coupling amount calculation unit 23 uses the obtained echo path estimation value H _ω (i, m) and the reproduction signal spectrum X _ω (im) to calculate the echo power estimation value | D ^ _{ω according} to the following equation. (I) It is good also as a structure which calculates | ² .

  With such a configuration, the amount of calculation can be reduced. Note that this embodiment may be combined with the second embodiment.

<Fourth embodiment>
A description will be given centering on differences from the first embodiment.

Acoustic coupling amount calculation unit 23, estimated first to acoustic coupling estimation value of the _{M | H ^ ω (i,} m) | 2 , the size by using the adjustment constant C (m) as: You may adjust the thickness.

  For example, C (m) = 1. The adjustment constant C (m) may be set to a different value depending on m. For example, if m is large, the past frame time becomes a calculation target, so that the SN ratio is relatively lower than the acoustic coupling amount when m is small. Therefore, when m is large, for example, C (m) may be decreased. That is, the past weight may be reduced.

  With such a configuration, it is possible to estimate the acoustic coupling amount with higher accuracy. In addition, you may combine this embodiment with 2nd embodiment or 3rd embodiment.

<Fifth embodiment>
A description will be given centering on differences from the first embodiment.

  In the fifth embodiment, the echo power calculation unit 14 is replaced with an echo power calculation unit 24.

<Echo power calculation unit 24>
The echo power calculation unit 24 receives the reproduction signal spectrum X _ω (i) and the first to Mth echo path estimation values H _ω (i, m) as inputs, and uses the first to Mth The total square value of values obtained by multiplying each of the echo path estimation values H _ω ^ (i, m) by the corresponding reproduction signal spectrum X _ω (im) by the value of m (m = 0 to M−1). Is obtained as an echo power estimated value | D _ω ^ (i) | ² and output.

  Moreover, you may adjust a magnitude | size using adjustment constant C (m) like following Formula.

  Further, in combination with the third embodiment, calculation of the amount of acoustic coupling for the overlap may be omitted as in the following equation.

In the present embodiment, the acoustic coupling amount calculator 23 replaces the first to Mth acoustic coupling amount estimated values | H _ω ^ (i, m) | ² with the first to Mth echo path estimated values H _ω. ^ (I, m) may be output, and the process of calculating the absolute value square value of the first to Mth echo path estimation values _Hω ^ (i, m) may be omitted.

<Other variations>
The present invention is not limited to the above-described embodiments and modifications. For example, the various processes described above are not only executed in time series according to the description, but may also be executed in parallel or individually as required by the processing capability of the apparatus that executes the processes. In addition, it can change suitably in the range which does not deviate from the meaning of this invention.

<Program and recording medium>
In addition, various processing functions in each device described in the above embodiments and modifications may be realized by a computer. In that case, the processing contents of the functions that each device should have are described by a program. Then, by executing this program on a computer, various processing functions in each of the above devices are realized on the computer.

  The program describing the processing contents can be recorded on a computer-readable recording medium. As the computer-readable recording medium, for example, any recording medium such as a magnetic recording device, an optical disk, a magneto-optical recording medium, and a semiconductor memory may be used.

  The program is distributed by selling, transferring, or lending a portable recording medium such as a DVD or CD-ROM in which the program is recorded. Further, the program may be distributed by storing the program in a storage device of the server computer and transferring the program from the server computer to another computer via a network.

  A computer that executes such a program first stores, for example, a program recorded on a portable recording medium or a program transferred from a server computer in its storage unit. When executing the process, this computer reads the program stored in its own storage unit and executes the process according to the read program. As another embodiment of this program, a computer may read a program directly from a portable recording medium and execute processing according to the program. Further, each time a program is transferred from the server computer to the computer, processing according to the received program may be executed sequentially. Also, the program is not transferred from the server computer to the computer, and the above-described processing is executed by a so-called ASP (Application Service Provider) type service that realizes the processing function only by the execution instruction and result acquisition. It is good. Note that the program includes information provided for processing by the electronic computer and equivalent to the program (data that is not a direct command to the computer but has a property that defines the processing of the computer).

  In addition, although each device is configured by executing a predetermined program on a computer, at least a part of these processing contents may be realized by hardware.

Claims (5)

M is a range in which the reproduction signal spectrum is shifted to the past time with respect to the collected sound signal spectrum, m = 0, 1,..., M−1, X _ω (i) is the reproduction signal spectrum at the frequency ω of frame i, Y _ω (i) is the collected sound signal spectrum at frequency ω of frame i, L is the number of frames to be added, ^H is a complex conjugate transpose, and the first to Mth echo path estimation values H _ω (i, m) are Calculate by formula

Acoustic coupling amount estimation device. An echo canceling unit that cancels an echo component included in the collected sound signal using the first to Mth echo path estimation values H ^ _ω (i, m) obtained by the acoustic coupling amount estimation device according to claim 1. A device,
The reproduction signal spectrum X ω _(i) and said echo path estimate of first to _{M H ^ ω (i, m} ) the acoustic coupling amount estimating value is an absolute value square value of _{| H ^ ω (i, m} ) | as input ^2, the first through the acoustic coupling estimation value of the _{M | H ^ ω (i,} m) | 2 of the respective power of the reproduced signal spectrum corresponding with the value of m | X _omega (i- m) | An echo power calculation unit that outputs a sum of values multiplied by ² as an echo power estimation value;
A gain calculation unit that outputs the gain coefficient with the collected sound signal spectrum and the echo power estimation value as inputs,
An accumulator for outputting an echo cancellation signal spectrum obtained by multiplying the collected sound signal spectrum by the gain coefficient;
A frequency synthesizer that synthesizes the frequency of the echo cancellation signal spectrum and outputs an output signal in the time domain;
Echo canceller including An echo canceling unit that cancels an echo component included in the collected sound signal using the first to Mth echo path estimation values H ^ _ω (i, m) obtained by the acoustic coupling amount estimation device according to claim 1. A device,
The reproduction signal spectrum X _omega wherein the (i) first to the echo path estimation value of the _{M H ^ ω (i, m} ) as an input, the first to the echo path estimation value of the M H ^ _ω (i, an echo power calculation unit that outputs a square value of the sum of values obtained by multiplying each of m) by the reproduction signal spectrum X _ω (i−m) corresponding to the value of m as an echo power estimated value;
A gain calculation unit that outputs the gain coefficient with the collected sound signal spectrum and the echo power estimation value as inputs,
An accumulator for outputting an echo cancellation signal spectrum obtained by multiplying the collected sound signal spectrum by the gain coefficient;
A frequency synthesizer that synthesizes the frequency of the echo cancellation signal spectrum and outputs an output signal in the time domain;
Echo canceller including M is a range in which the reproduction signal spectrum is shifted to the past time with respect to the collected sound signal spectrum, m = 0, 1,..., M−1, X _ω (i) is the reproduction signal spectrum at the frequency ω of frame i, Y _ω (i) is the collected sound signal spectrum at frequency ω of frame i, L is the number of frames to be added, ^H is a complex conjugate transpose, and the first to Mth echo path estimation values H _ω (i, m) are Calculate by formula

Acoustic coupling amount estimation method.   A program for causing a computer to function as the acoustic coupling amount estimation device according to claim 1 or the echo cancellation device according to claim 2 or claim 3.

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