JP2017034355A - Echo suppression device, echo suppression program, and echo suppression method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an echo suppression device capable of suppressing an acoustic echo signal, even immediately after initiating operation of the echo suppression device.SOLUTION: An echo suppression device includes: amount of frame delay estimation means for estimating an amount of frame delay based on an amplitude spectrum of an estimated echo signal estimated for a plurality of past frames and an amplitude spectrum of a near-end input signal; amount of frame delay convergence determination means for determining if the amount of frame delay is converged or not, and outputs the amount of frame delay based on the result; estimated echo path characteristic renewal means for renewing an estimated echo path characteristic using a fixed value of the amount of frame delay, and stores it, based on the determination result; and an echo suppression means for calculating an echo suppression gain with an amplitude spectrum of an estimated echo signal delayed using the amount of frame delay, and an amplitude spectrum of a near-end input signal, and for suppressing the estimated echo signal based on the amplitude spectrum of the near-end input signal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an echo suppression device, an echo suppression program, and an echo suppression method, and can be applied to, for example, an echo suppression device, an echo suppression program, and an echo suppression method used in a video conference system, a telephone conference system, and the like. .

  For example, in a loudspeaker system such as a video conference system or a telephone conference system, an acoustic echo that is emitted from a speaker (where sound includes sound, voice, etc.) wraps around a microphone and returns to the transmitting side. A signal is generated. Since the acoustic echo signal significantly hinders a call, much research and development have been conducted on the acoustic echo signal suppression method.

  One technique for suppressing the acoustic echo signal is to use an echo suppressor (echo suppressor). The echo suppressor obtains the estimated echo path characteristics, estimated echo signal, and echo suppress gain from the far end signal and the near end input signal, and suppresses the acoustic echo signal by multiplying the near end input signal and the echo suppress gain. It is a technique. Non-Patent Document 1 proposes a technique for suppressing an acoustic echo signal using this echo suppressor.

  The echo suppressor disclosed in Non-Patent Document 1 obtains an estimated echo path characteristic based on a far-end signal and a near-end input signal of a past frame. Then, the signal obtained by multiplying the obtained estimated echo path characteristic and the far-end signal is used as an estimated echo signal, and the echo suppressor obtains an echo suppression gain based on the near-end input signal and the estimated echo signal, Multiply with the end input signal to suppress the acoustic echo signal.

C. Faller and C.M. Turnery, “ESTIMATION THE DELAY AND COLORATION EFFECT OF THE ACOUSTIC ECHO PATH FOR LOW COMPLEITY ECHO SUPPRESSION”, Proc. Intl. Works. on Acoustic. Echo and Noise Control (IWAENC) 2005, pp. 53-56, Oct. 2005

  However, in the echo suppression device described in Non-Patent Document 1, when used in a device having a buffer in an input / output unit such as a softphone or a smartphone, an acoustic echo signal is output until the learning of the estimated echo path characteristics proceeds after the operation starts. I cannot suppress it. In addition to the echo suppression process, various applications and programs are running on softphones and smartphones. If the load increases, the process of saving sound data in the buffer and the process of outputting sound data from the input buffer will stop. The delay amount increases, and the variation in the delay amount increases. In the echo suppression device of Non-Patent Document 1, since the estimated echo path characteristic is calculated using the average of past frames when calculating the estimated echo signal without considering the delay amount, the echo suppression device starts operating. The acoustic echo signal immediately after being applied cannot be suppressed. Further, since the delay amount is not taken into consideration, there is a possibility that a section in which the acoustic echo signal cannot be suppressed becomes long and howling occurs.

  Therefore, an echo suppression device, an echo suppression program, and an echo suppression method that can suppress an acoustic echo signal immediately after the operation of the echo suppression device is started are desired.

  According to a first aspect of the present invention, there is provided an echo suppressor that suppresses an acoustic echo signal based on a near-end input signal and a far-end signal, and (1) an amplitude spectrum of an estimated echo signal of a plurality of past frames, A frame delay amount estimating means for estimating a frame delay amount from the amplitude spectrum; and (2) determining whether or not the frame delay amount estimated by the frame delay amount estimating means has converged, and based on the determined determination result, A frame delay amount convergence determining means for outputting the frame delay amount; and (3) updating an estimated echo path characteristic using a fixed value of the frame delay amount in accordance with the determination result in the frame delay amount convergence determining means. An estimated echo path characteristic updating means to be held; (4) an amplitude spectrum of the estimated echo signal delayed by using the frame delay amount; and an amplitude of the near-end input signal. An echo suppression gain calculated in the spectrum, and having a echo suppression means for suppressing the estimated echo signal from the amplitude spectrum of the near-end input signal.

  The echo suppression program of the second aspect of the present invention provides a computer mounted on an echo suppression apparatus that suppresses an acoustic echo signal based on a near-end input signal and a far-end signal, and (1) an estimated echo signal of a plurality of past frames. A frame delay amount estimating means for estimating a frame delay amount from the amplitude spectrum and the amplitude spectrum of the near-end input signal; and (2) determining whether or not the frame delay amount estimated by the frame delay amount estimating means has converged. A frame delay amount convergence determining means for outputting the frame delay amount based on the determined determination result; and (3) a fixed value of the frame delay amount according to the determination result in the frame delay amount convergence determining means. And (4) an estimated echo signal delayed by using the frame delay amount. The amplitude spectrum, the echo suppression gain in the amplitude spectrum of the near-end input signal is calculated, characterized in that to function as an echo suppression means for suppressing the estimated echo signal from the amplitude spectrum of the near-end input signal.

  According to a third aspect of the present invention, there is provided an echo suppression method for suppressing an acoustic echo signal based on a near-end input signal and a far-end signal, a frame delay amount estimating unit, a frame delay amount convergence determining unit, an estimated echo path characteristic updating unit, and Echo suppression means, (1) the frame delay amount estimation means estimates the frame delay amount from the amplitude spectrum of the estimated echo signal of the past plural frames and the amplitude spectrum of the near-end input signal, and (2) the above The frame delay amount convergence determination means determines whether or not the frame delay amount estimated by the frame delay amount estimation means has converged, and outputs the frame delay amount based on the determined determination result, (3) The estimated echo path characteristic updating unit uses the fixed value of the frame delay amount according to the determination result of the frame delay amount convergence determining unit. (4) The echo suppression means calculates an echo suppression gain using the amplitude spectrum of the estimated echo signal delayed using the frame delay amount and the amplitude spectrum of the near-end input signal. The estimated echo signal is suppressed from the amplitude spectrum of the near-end input signal.

  According to the present invention, an acoustic echo signal can be suppressed even immediately after the operation of the echo suppression device is started.

It is a block diagram which shows the structure of the echo suppression apparatus which concerns on 1st Embodiment. It is a processing flowchart which shows the process of the frame delay amount convergence determination part which concerns on 1st Embodiment. It is a processing flowchart which shows the process of the estimation echo path characteristic calculation part which concerns on 1st Embodiment. It is a processing flowchart which shows the process of the estimation echo path characteristic calculation part which concerns on 2nd Embodiment.

(A) First Embodiment Hereinafter, a first embodiment of an echo suppression device, an echo suppression program, and an echo suppression method of the present invention will be described in detail with reference to the drawings.

  The first embodiment exemplifies a case where the present invention is applied to, for example, an echo suppression device, an echo suppression program, and an echo suppression method of an audio transmission / reception device of a loudspeaker communication system such as a video conference system or a telephone conference system.

(A-1) Configuration of First Embodiment FIG. 1 is a block diagram showing a configuration of an echo suppression apparatus 100 according to an embodiment of the present invention.

  The echo suppressor 100 according to the first embodiment of the present invention is implemented with the above-described echo suppressor of the present invention, and the far-end signal transmits the near-end side space and is used as an acoustic echo signal. Even when the signal is input around the side microphone, echo suppression processing is performed on the near-end input signal to appropriately suppress the acoustic echo signal.

  The echo suppression apparatus 100 according to the first embodiment may be configured as a dedicated board, for example, or may be realized by writing an echo suppression program to a DSP (digital signal processor). Although it may be realized by a CPU and software (echo suppression program) executed by the CPU, it can be functionally represented in FIG.

  In FIG. 1, an echo suppression apparatus 100 according to the first embodiment includes a far-end signal input terminal 101, an output buffer 102, a DA converter 103, a speaker 104, a microphone 105, an AD converter 106, an input buffer 107, and a far end. Signal frequency domain transform unit 108, far end signal amplitude spectrum calculation unit 109, estimated echo path characteristic update unit 110, estimated echo signal calculation unit 111, estimated echo signal holding unit 112, near end input signal frequency domain transform unit 113, near end input Signal amplitude spectrum calculation unit 114, frame delay amount estimation unit 115, frame delay amount convergence determination unit 116, estimated echo signal delay unit 117, echo suppression gain calculation unit 118, echo suppression unit 119, near-end output signal time domain conversion unit 120 , Near-end signal output terminal 121, far-end signal holding unit 122, near-end output signal amplitude spectrum Torr calculation unit 123 has a single-talk determination unit 124.

  The far-end signal input terminal 101 is connected to, for example, a network such as an Internet protocol (IP) network or a radio wave of a wireless network such as a mobile phone. ) Is input.

  The far-end signal input to the far-end signal input terminal 101 is temporarily held in the output buffer 102 and the far-end signal is output to the DA converter 103 as soon as the DA converter 103 is ready for processing. , The digital sound signal is converted into an analog sound signal and output to the near end through the speaker 104.

  The output buffer 102 is a buffer for waiting for processing of the echo suppression apparatus 100.

  On the other hand, a sound signal such as a voice uttered by a speaker on the near end side, an environmental sound, an acoustic echo signal (for example, an analog sound signal output from the speaker 104 is transmitted around the space on the near end side and wraps around. ) Etc. are received by the microphone 105, converted into a digital sound signal by the AD converter 106, temporarily held in the input buffer 107, and the digital sound signal is ready as soon as the echo suppressor 100 is ready. Is input to the echo suppression apparatus 100 as a near-end input signal.

  The input buffer 107 is a buffer for waiting for processing of the echo suppression apparatus 100.

  The far-end signal frequency domain transforming unit 108 transforms the far-end signal from a time-domain signal to a frequency-domain signal by, for example, fast Fourier transform (FFT), and outputs a frequency spectrum of the far-end signal.

  The far-end signal amplitude spectrum calculation unit 109 calculates the amplitude spectrum of the far-end signal based on the frequency spectrum of the far-end signal, and outputs the calculated amplitude spectrum of the far-end signal.

  The estimated echo path characteristic updating unit 110 holds the estimated echo path characteristic in the previous frame, and outputs it to the held estimated echo path characteristic.

  Further, when the single-talk determining unit 124 determines that single-talk is determined, the estimated echo path characteristic updating unit 110 is based on the amplitude spectrum of the far-end signal and the amplitude spectrum of the near-end input signal delayed by the estimated frame delay amount. The estimated echo path characteristic of the current frame is calculated, the estimated echo path characteristic is updated based on the calculated estimated echo path characteristic of the current frame and the estimated echo path characteristic held in the estimated echo path characteristic update unit 110, and the updated estimated echo path characteristic is The estimated echo path characteristic update unit 110 stores the result.

  The estimated echo signal calculation unit 111 calculates the amplitude spectrum of the estimated echo signal by multiplying the amplitude spectrum of the far-end signal and the estimated echo path characteristic, and outputs the calculated amplitude spectrum of the estimated echo signal.

  The estimated echo signal holding unit 112 holds the amplitude spectrum of the estimated echo signal for a predetermined time, and the frame delay amount estimating unit 115 outputs a plurality of past estimated echo signals in order to estimate the frame delay amount. Further, the estimated echo signal holding unit 112 outputs an estimated echo signal delayed by a frame delay amount output from a frame delay amount convergence determination unit 116 described later.

  The near-end input signal frequency domain conversion unit 113 converts the near-end input signal from a time-domain signal to a frequency-domain signal by, for example, fast Fourier transform, and outputs a frequency spectrum of the near-end input signal.

  The near-end input signal amplitude spectrum calculation unit 114 calculates the amplitude spectrum of the near-end input signal based on the frequency spectrum of the near-end input signal, and outputs the calculated near-end input signal amplitude spectrum.

  The frame delay amount estimation unit 115 estimates the frame delay amount based on the amplitude spectrum of the estimated echo signal of the past plural frames and the amplitude spectrum of the near-end input signal of the past plural frames, and outputs the estimated frame delay amount.

  The frame delay amount convergence determination unit 116 determines whether or not the estimated frame delay amount has converged. If the estimated frame delay amount has not converged, a fixed value is substituted for the frame delay amount and output. The estimated echo path characteristic update unit 110 outputs the frame delay amount estimated by the frame delay amount estimation unit 115 if the frame delay amount estimated by the frame has converged. Further, the frame delay amount convergence determination unit 116 outputs the convergence determination result to the estimated echo path characteristic update unit 110.

  The estimated echo signal delay unit 117 reads the amplitude spectrum of the estimated echo signal of the frame delayed by the frame delay amount from the estimated echo signal holding unit 112 using the frame delay amount, and outputs it as the amplitude spectrum of the delayed estimated echo signal. .

  The echo suppression gain calculation unit 118 calculates an echo suppression gain for suppressing the acoustic echo signal superimposed on the near-end input signal, using the amplitude spectrum of the near-end input signal and the amplitude spectrum of the delay estimation echo signal. The calculated echo suppression gain is output.

  The echo suppression unit 119 obtains a frequency spectrum in which the acoustic echo signal superimposed on the near-end input signal is suppressed by multiplying the echo suppress gain and the frequency spectrum of the near-end input signal, and obtains the frequency spectrum of the near-end output signal. Output.

  The near-end output signal time domain conversion unit 120 converts the frequency spectrum of the near-end output signal into a digital sound signal in the time domain by, for example, inverse fast Fourier transform (Inverse FFT), and outputs it as a near-end output signal.

  The far end signal holding unit 122 holds the amplitude spectrum of the far end signal for the same predetermined time as the estimated echo signal holding unit 112. Then, the far end signal holding unit 122 outputs the amplitude spectrum of the far end signal delayed by the estimated frame delay amount.

  The near-end output signal amplitude spectrum calculation unit 123 calculates the amplitude spectrum of the near-end output signal based on the frequency spectrum of the near-end output signal, and outputs the calculated amplitude spectrum of the near-end output signal.

  The near-end output signal amplitude spectrum calculation unit 123 calculates the amplitude spectrum of the near-end output signal based on the frequency spectrum of the near-end output signal, and outputs the calculated amplitude spectrum of the near-end output signal.

  The single talk determination unit 124 determines whether single talk or other than single talk using the amplitude spectrum of the near-end input signal and the amplitude spectrum of the near-end output signal, and outputs a single talk determination result.

(A-2) Operation of the First Embodiment Next, the operation of echo suppression processing in the echo suppression device 100 according to the first embodiment will be described in detail.

(A-2-1) Echo Suppression Processing First, when the operation of the echo suppression device 100 is started, it is connected to, for example, a radio wave of a network such as the Internet Protocol (IP) network or a wireless network such as a mobile phone. The far-end signal on the far-end side is input to the far-end signal input terminal 101 through the connected line.

  The far-end signal input to the far-end signal input terminal 101 is temporarily held in the output buffer 102, and the far-end signal is output to the DA converter 103 as soon as the DA converter 103 is ready for processing. In the DA converter 103, the far-end signal is converted from a digital sound signal to an analog sound signal and output to the near-end side through the speaker 104.

  On the other hand, a sound signal such as a voice uttered by a speaker on the near end side, an environmental sound, an acoustic echo signal (for example, an analog sound signal output from the speaker 104 is transmitted around the space on the near end side and wraps around. ) And the like are received by the microphone 105 and converted into a digital sound signal by the AD converter 106. The digital sound signal is temporarily held in the input buffer 107, and as soon as the echo suppressor 100 is ready, the digital sound signal is input to the echo suppressor 100 as a near-end input signal.

  The far-end signal frequency domain transform unit 108 transforms the far-end signal from a time-domain signal to a frequency-domain signal by, for example, fast Fourier transform (FFT), and the frequency spectrum ROUT (i) of the transformed far-end signal. , Ω) is output to the far-end signal amplitude spectrum calculation unit 109.

  The far-end signal amplitude spectrum calculation unit 109 obtains the far-end signal amplitude spectrum | ROUT (i, ω) | according to the equation (1) using the frequency spectrum ROUT (i, ω).

ここで、ｉはフレーム、ωは周波数ビン、ＲＯＵＴ＿ｒｅａｌ（ｉ，ω）とＲＯＵＴ＿ｉｍａｇｅ（ｉ，ω）は、フレームｉにおける周波数ビンωの遠端信号の周波数スペクトルの実数部と虚数部を示しており、遠端信号の周波数スペクトルＲＯＵＴ（ｉ，ω）は、（２）式で表すことができる。

Here, i is a frame, ω is a frequency bin, and ROUT_real (i, ω) and ROUT_image (i, ω) indicate the real part and imaginary part of the frequency spectrum of the far-end signal of the frequency bin ω in frame i. The frequency spectrum ROUT (i, ω) of the far-end signal can be expressed by equation (2).

（２）式のｊは虚数を表している。そして、遠端信号振幅スペクトル計算部１０９により求められた遠端信号の振幅スペクトル｜ＲＯＵＴ（ｉ，ω）｜は、推定エコー信号計算部１１１、遠端信号保持部１２２に出力する。

(2) j represents an imaginary number. Then, the far-end signal amplitude spectrum | ROUT (i, ω) | obtained by the far-end signal amplitude spectrum calculating unit 109 is output to the estimated echo signal calculating unit 111 and the far-end signal holding unit 122.

  The estimated echo path characteristic update unit 110 outputs the stored echo path characteristic | H (i−1, ω) | estimated for the previous frame to the estimated echo signal calculation unit 111.

  The estimated echo signal calculation unit 111 uses the echo path characteristic | H (i−1, ω) | estimated for the previous frame and the amplitude spectrum | ROUT (i, ω) | Thus, the amplitude spectrum | ECHO (i, ω) | of the estimated echo signal is obtained.

（３）式は遠端信号の振幅スペクトル｜ＲＯＵＴ（ｉ，ω）｜に、前フレームに推定したエコーパス特性｜Ｈ（ｉ−１，ω）｜の対応する周波数ビンを乗じて、当該周波数ビンの推定エコー信号の振幅スペクトル｜ＥＣＨＯ（ｉ，ω）｜を求めるという式である。そして、推定エコー信号計算部１１１により求められた推定エコー信号の振幅スペクトル｜ＥＣＨＯ（ｉ，ω）｜を推定エコー信号保持部１１２に出力する。

Equation (3) is obtained by multiplying the amplitude spectrum | ROUT (i, ω) | of the far-end signal by the corresponding frequency bin of the echo path characteristic | H (i−1, ω) | estimated for the previous frame. This is an equation for obtaining the amplitude spectrum | ECHO (i, ω) | of the estimated echo signal. Then, the amplitude spectrum | ECHO (i, ω) | of the estimated echo signal obtained by the estimated echo signal calculation unit 111 is output to the estimated echo signal holding unit 112.

  The estimated echo signal holding unit 112 writes the amplitude spectrum | ECHO (i, ω) | of the estimated echo signal output from the estimated echo signal calculation unit 111 into the amplitude spectrum buffer ECHO_Buffer (n, ω) of the estimated echo signal, The amplitude spectrum | ECHO (i, ω) | of the estimated echo signal is held in the past plural frames.

（４）式のｎは推定エコー信号保持部１１２の推定エコー信号の振幅スペクトルバッファの書込み位置であり、推定エコー信号の振幅スペクトル｜ＥＣＨＯ（ｉ，ω）｜が書込まれるとインクリメントされ、ｎが推定エコー信号の振幅スペクトルバッファの大きさと同じになると、ｎに０が代入され上書き保持される。書込みが完了すればフレーム遅延量推定部１１５に推定エコー信号保持部１１２が保持している過去の推定エコー信号の振幅スペクトルを複数フレーム出力する。

N in the equation (4) is the writing position of the amplitude spectrum buffer of the estimated echo signal of the estimated echo signal holding unit 112, and is incremented when the amplitude spectrum | ECHO (i, ω) | of the estimated echo signal is written, and n Is the same as the magnitude of the amplitude spectrum buffer of the estimated echo signal, 0 is substituted for n and overwritten. When the writing is completed, a plurality of frames of the amplitude spectrum of the past estimated echo signal held by the estimated echo signal holding unit 112 are output to the frame delay amount estimating unit 115.

  On the other hand, the near-end input signal frequency domain conversion unit 113 converts the near-end input signal from a time-domain signal to a frequency-domain signal by, for example, fast Fourier transform (FFT). The converted frequency spectrum SIN (i, ω) of the near-end input signal is output to the near-end input signal amplitude spectrum calculation unit 114 and the echo suppression unit 119.

  The near-end input signal amplitude spectrum calculation unit 114 uses the frequency spectrum SIN (i, ω) of the near-end input signal and calculates the amplitude spectrum | SIN (i, ω) | of the near-end input signal according to the equation (5). Ask.

ここで、ＳＩＮ＿ｒｅａｌ（ｉ，ω）とＳＩＮ＿ｉｍａｇｅ（ｉ，ω）は、フレームｉにおける周波数ビンωの近端入力信号の周波数スペクトルの実数部と虚数部を示しており、近端入力信号の周波数スペクトルＳＩＮ（ｉ，ω）は、式（６）で表すことができる。

Here, SIN_real (i, ω) and SIN_image (i, ω) indicate a real part and an imaginary part of the frequency spectrum of the near-end input signal of the frequency bin ω in the frame i, and the frequency spectrum of the near-end input signal. SIN (i, ω) can be expressed by Equation (6).

（６）式のｊは虚数を表している。そして、近端入力信号振幅スペクトル計算部１１４により求められた近端入力信号の振幅スペクトル｜ＳＩＮ（ｉ，ω）｜は、フレーム遅延量推定部１１５、エコーサプレスゲイン計算部１１８、シングルトーク判定部１２４、及び推定エコーパス特性更新部１１０に出力される。

(6) j represents an imaginary number. Then, the amplitude spectrum | SIN (i, ω) | of the near-end input signal obtained by the near-end input signal amplitude spectrum calculation unit 114 is a frame delay amount estimation unit 115, an echo suppression gain calculation unit 118, and a single talk determination unit. 124 and the estimated echo path characteristic update unit 110.

  The frame delay amount estimation unit 115 includes a plurality of frames ECHO_Buffer (n−k) (0 ≦ k ≦ N) of the amplitude spectrum of the past estimated echo signal output from the estimated echo signal holding unit 112 and the amplitude spectrum of the near-end input signal. The frame delay amount is estimated from | SIN (i, ω) |. The estimation method of the frame delay amount is, for example, a plurality of frames ECHO_Buffer (n−k) of the amplitude spectrum of the past estimated echo signal output from the estimated echo signal holding unit 112 and the amplitude spectrum | SIN (i, The error of ω) | is obtained according to the equation (7) for each frame.

（７）式のＦｓはサンプリング周波数である。そして、フレーム遅延量推定部１１５は、（８）式に従い、フレーム誤差Ｅｒｒｏｒ（ｉ，ｋ）が最小になるフレーム遅延量ｄｅｌａｙ（ｉ）を求める。

In the equation (7), Fs is a sampling frequency. Then, the frame delay amount estimation unit 115 obtains a frame delay amount delay (i) that minimizes the frame error Error (i, k) according to the equation (8).

（８）式のａｒｇｍｉｎ（ｘ（ｋ））という関数は、ｘ（ｋ）が最小になる引数を出力する関数であり、フレーム誤差Ｅｒｒｏｒ（ｉ，ｋ）が最小になるフレーム遅延量を出力し、ｄｅｌａｙ（ｉ）に代入するという式である。

The function argmin (x (k)) in equation (8) is a function that outputs an argument that minimizes x (k), and outputs a frame delay amount that minimizes the frame error Error (i, k). , Delay (i).

  Note that various methods can be widely applied to the method of estimating the frame delay amount. For example, a plurality of frames ECHO_Buffer (n−k) of the amplitude spectrum of the estimated echo signal and the amplitude spectrum | SIN ( i, ω) | may be calculated for each frame, a frame having the highest correlation may be obtained, and the frame having the highest correlation may be used as the frame delay amount delay (i). The frame delay amount estimation unit 115 estimates and outputs the estimated frame delay amount delay (i).

  The frame delay amount convergence determination unit 116 determines whether or not the frame delay amount delay (i) estimated by the frame delay amount estimation unit 115 has converged. If the estimated frame delay amount has not converged, the frame delay amount delay ( Assign a fixed value to i) and output. If the estimated frame delay amount has converged, the estimated frame delay amount delay (i) is output to the estimated echo path characteristic updating unit 110, the estimated echo signal delay unit 117, and the far-end signal holding unit 122. Further, the frame delay amount convergence determination unit 116 outputs the convergence determination result to the estimated echo path characteristic update unit 110.

  The estimated echo signal delay unit 117 reads out a frame obtained by delaying the amplitude spectrum of the past estimated echo signal held in the estimated echo signal holding unit 112 by the frame delay amount using the frame delay amount delay (i). The delayed estimated echo signal. This delayed estimated echo signal can be expressed by equation (9).

推定エコー信号遅延部１１７は、遅延した推定エコー信号の振幅スペクトル｜ＥＣＨＯ＿ＤＥＬＡＹ（ｉ、ω）｜をエコーサプレスゲイン計算部１１８に出力する。

The estimated echo signal delay unit 117 outputs the amplitude spectrum | ECHO_DELAY (i, ω) | of the delayed estimated echo signal to the echo suppression gain calculation unit 118.

  The echo suppression gain calculation unit 118 obtains the amplitude spectrum | SIN (i, ω) | of the near-end input signal and the amplitude spectrum | ECHO_DELAY (i, ω) | of the delayed estimated echo signal to obtain the equation (10). The echo suppression gain G (i, ω) is obtained according to

（１０）式は、周波数ビン毎に近端入力信号の振幅スペクトル｜ＳＩＮ（ｉ，ω）｜から推定エコー信号の振幅スペクトル｜ＥＣＨＯ＿ＤＥＬＡＹ（ｉ，ω）｜を差し引いた振幅スペクトルを、近端入力信号の振幅スペクトル｜ＳＩＮ（ｉ，ω）｜で除することで、エコーサプレスゲインＧ（ｉ，ω）を求めるという式である。エコーサプレスゲイン計算部１１８により求められたエコーサプレスゲインＧ（ｉ，ω）は、エコーサプレス部１１９に出力する。

Equation (10) is obtained by subtracting the amplitude spectrum | ECHO_DELAY (i, ω) | of the estimated echo signal from the amplitude spectrum | SIN (i, ω) | of the near-end input signal for each frequency bin. This is an equation for obtaining the echo suppression gain G (i, ω) by dividing by the amplitude spectrum of the signal | SIN (i, ω) |. The echo suppression gain G (i, ω) obtained by the echo suppression gain calculation unit 118 is output to the echo suppression unit 119.

  The echo suppress unit 119 uses the near-end input signal spectrum SIN (i, ω) and the echo suppress gain G (i, ω) according to the equations (11) and (12), and the near-end input signal spectrum. The acoustic echo signal superimposed on SIN (i, ω) is suppressed.

ここで、ＳＯＵＴ＿ｒｅａｌ（ｉ，ω）とＳＯＵＴ＿ｉｍａｇｅ（ｉ，ω）は、フレームｉにおける周波数ビンωの近端出力信号の周波数スペクトルの実数部と虚数部を示しており、近端出力信号の周波数スペクトルＳＯＵＴ（ｉ，ω）は（１３）式で表すことができる。

Here, SOUT_real (i, ω) and SOUT_image (i, ω) indicate the real part and the imaginary part of the frequency spectrum of the near-end output signal of the frequency bin ω in the frame i, and the frequency spectrum of the near-end output signal. SOUT (i, ω) can be expressed by equation (13).

（１３）式のｊは虚数を表している。（１１）式と（１２）式は、周波数スペクトルの実数部、虚数部にエコーサプレスゲインＧ（ｉ，ω）を周波数ビン毎に乗じて、音響エコー信号を抑圧した近端出力信号の周波数スペクトルを求める。そして、エコーサプレス部１１９により求められた音響エコー信号が抑圧された近端出力信号の周波数スペクトルＳＯＵＴ（ｉ，ω）を近端出力信号時間領域変換部１２０、及び近端出力信号振幅スペクトル計算部に出力する。

In equation (13), j represents an imaginary number. Equations (11) and (12) are obtained by multiplying the real part and imaginary part of the frequency spectrum by the echo suppression gain G (i, ω) for each frequency bin, and the frequency spectrum of the near-end output signal in which the acoustic echo signal is suppressed. Ask for. Then, the near-end output signal time domain transform unit 120 and the near-end output signal amplitude spectrum calculation unit convert the frequency spectrum SOUT (i, ω) of the near-end output signal in which the acoustic echo signal obtained by the echo suppression unit 119 is suppressed. Output to.

  In the near-end output signal time domain conversion unit 120, the spectrum SOUT (i, ω) of the near-end output signal is converted into a digital sound signal in the time domain by, for example, inverse fast Fourier transform (Inverse FFT), and converted. The near end output signal is output to the near end signal output terminal 121.

  The near-end signal output terminal 121 is connected to, for example, a radio wave of a network such as an Internet protocol (IP) network or a wireless network such as a mobile phone, and a call is made via a line connected to the near-end output signal. Outputs to the far end that is the other party.

  The far-end signal holding unit 122 writes the amplitude spectrum | ROUT (i, ω) | of the far-end signal output from the far-end signal amplitude spectrum calculating unit 109 in the same writing frame as the estimated echo signal holding unit 112.

そして、遠端信号保持部１２２は、（１５）式に従い、フレーム遅延量ｄｅｌａｙ（ｉ）だけ遅延させた遠端信号の振幅スペクトル｜ＲＯＵＴ＿ＤＥＬＡＹ（ｉ，ω）｜を推定エコーパス特性更新部１１０に出力する。

Then, the far-end signal holding unit 122 outputs the amplitude spectrum | ROUT_DELAY (i, ω) | of the far-end signal delayed by the frame delay amount delay (i) to the estimated echo path characteristic updating unit 110 according to the equation (15). To do.

近端出力信号振幅スペクトル計算部１２３では、近端出力信号の周波数スペクトルＳＯＵＴ（ｉ，ω）を用いて、（１６）式に従い、近端出力信号の振幅スペクトル｜ＳＯＵＴ（ｉ，ω）｜が求められる。

The near-end output signal amplitude spectrum calculation unit 123 uses the frequency spectrum SOUT (i, ω) of the near-end output signal to obtain the amplitude spectrum | SOUT (i, ω) | of the near-end output signal according to the equation (16). Desired.

そして、近端出力信号振幅スペクトル計算部１２３により求められた近端入力信号の振幅スペクトル｜ＳＯＵＴ（ｉ，ω）｜は、シングルトーク判定部１２４に出力される。

Then, the amplitude spectrum | SOUT (i, ω) | of the near-end input signal obtained by the near-end output signal amplitude spectrum calculation unit 123 is output to the single talk determination unit 124.

  The single talk determination unit 124 determines whether the near-end input signal is a single talk or other than a single talk using the amplitude spectrum of the near-end input signal and the amplitude spectrum of the near-end output signal. As a method for determining whether it is single talk or other than single talk, for example, there is a method for determining whether it is single talk or other than single talk according to the equation (17).

（１７）式のＦｓはサンプリング周波数、ＴＨ１は閾値である。つまり、（１７）式の条件が真のときはシングルトークと判定し、偽のときはシングルトーク以外として判定する。閾値ＴＨ１は、（１７）式の場合、シングルトーク時は（１７）式の左辺が小さい値になるので、小さい固定値（例えばＴＨ１＝０．３）やフレームで変化する変数などにしても良い。なお、シングルトークかシングルトーク以外かの判定の手段は、種々の方法を広く適用することができ、例えば、遠端信号の振幅スペクトルと推定したフレーム遅延量だけ遅延させた近端信号の振幅スペクトルとの相闘を求め、その相関値が高いときはシングルトークとする方法で判定しても良い。シングルトーク判定部１２４は、シングルトーク判定結果を推定エコーパス特性更新部１１０に出力する。

In the equation (17), Fs is a sampling frequency, and TH1 is a threshold value. That is, when the condition of the expression (17) is true, it is determined as single talk, and when it is false, it is determined as other than single talk. In the case of the expression (17), the threshold value TH1 may be a small fixed value (for example, TH1 = 0.3) or a variable that changes in the frame because the left side of the expression (17) becomes a small value during single talk. . Note that various methods can be widely applied as means for determining whether single talk or other than single talk, for example, the far-end signal amplitude spectrum and the near-end signal amplitude spectrum delayed by the estimated frame delay amount. If the correlation value is high, it may be determined by a method of single talk. The single talk determination unit 124 outputs the single talk determination result to the estimated echo path characteristic update unit 110.

  The estimated echo path characteristic update unit 110 outputs a fixed value of the echo path characteristic to the estimated echo signal calculation unit 111 in the next frame while the frame delay amount convergence determination unit 116 determines that the frame delay amount has not converged. To do. At the same time, the estimated echo path characteristic update unit 110 for the frame determined as single talk by the single talk determination unit 124, the amplitude spectrum of the far end signal obtained by delaying the estimated echo path characteristic of the current frame from the far end signal holding unit 122. And using the amplitude spectrum of the near-end output signal from the near-end output signal amplitude spectrum calculation unit 123, the estimated echo path characteristic held in the estimated echo path characteristic update unit 110 and held one frame before is read, and the echo path characteristic Update.

  On the other hand, if the frame delay amount convergence determination unit 116 determines that the frame delay amount has converged, the estimated echo path characteristic update unit 110 determines the current frame of the frame determined as single talk by the single talk determination unit 124. An estimated echo path characteristic is obtained using the delayed far-end signal amplitude spectrum from the far-end signal holding unit 122 and the near-end output signal amplitude spectrum from the near-end output signal amplitude spectrum calculating unit 123, and the estimated echo path characteristic. The estimated echo path characteristic held one frame before held in the update unit 110 is read, and the echo path characteristic is updated.

(A-2-2) Processing of Frame Delay Amount Convergence Determination Unit Next, the processing of the frame delay amount convergence determination unit 116 in the echo suppression apparatus 100 according to the first embodiment will be described in detail with reference to the drawings. .

  FIG. 2 is a process flow diagram illustrating a process flow of the frame delay amount convergence determination unit 116 of the echo suppressor 100 according to the first embodiment.

  In FIG. 2, the frame delay amount convergence determination unit 116 performs a frame delay amount convergence determination 201, a frame delay amount fixed value output 202, and a frame delay amount estimated value output 203.

  The frame delay amount convergence determination 201 determines whether the estimated frame delay amount has converged or has not converged, and outputs a convergence determination result.

  The frame delay amount fixed value output 202 operates when the frame delay amount convergence determination 201 determines that the frame delay amount has not converged, and outputs a fixed value of the frame delay amount.

  The frame delay amount estimated value output 203 operates when the frame delay amount convergence determination 201 determines that the frame delay amount has converged, and outputs the estimated frame delay amount.

(A-2-3) Detailed Processing of Frame Delay Amount Convergence Determination Unit Next, the processing operation of the frame delay amount convergence determination unit 116 in the echo suppressor 100 according to the first embodiment will be described in detail.

  In frame delay amount convergence determination 201, it is determined whether the estimated frame delay amount has converged or has not converged. For example, according to (18), the convergence determination method obtains a value delay_TC (i) smoothed by a time constant filter of the frame delay amount.

ａは時定数フィルタの係数であり、０より大きく、１より小さい値であって、エコーパス特性の更新を遅くしたい場合は１に近い値が望ましく（例えば、ａ＝０．９９等の値）、更新を早くしたい場合は０に近い値が望ましい（例えば、ａ＝０．０１等の値）。

a is a coefficient of the time constant filter, and is a value larger than 0 and smaller than 1, and is preferably a value close to 1 (for example, a = 0.99) when it is desired to delay the update of the echo path characteristics. A value close to 0 is desirable when the update is desired to be accelerated (for example, a = 0.01 or the like).

  Then, the frame delay amount convergence determination 201 counts when the difference between the smoothed value delay_TC (i) and the estimated frame delay amount delay (i) is equal to or smaller than the threshold value according to the equation (19).

（１９）式のＴＨ２は閾値である。ＴＨ２はｄｅ１ａｙ＿ＴＣ（ｉ）とｄｅｌａｙ（ｉ）との差が小さいか判定できれば良く、値が小さい固定値（例えば、ＴＨ２＝０やＴＨ２＝１など）とする。ｄｅｌａｙ＿ＴＣ（ｉ）とｄｅｌａｙ（ｉ）の差が閾値ＴＨ２より小さいときはｃｏｕｎｔをインクリメントする。

TH2 in the equation (19) is a threshold value. It is only necessary to determine whether TH2 has a small difference between de1ay_TC (i) and delay (i), and is a fixed value having a small value (for example, TH2 = 0 or TH2 = 1). When the difference between delay_TC (i) and delay (i) is smaller than the threshold value TH2, count is incremented.

  The frame delay amount convergence determination 201 determines that the frame delay amount has not converged when the count of the equation (19) is smaller than the specified number of times (for example, count = 100), and the count becomes larger than the specified number of times. It is determined that the frame delay amount has converged. The frame delay amount convergence determination result is also used by the estimated echo path characteristic update unit 110.

  The frame delay amount fixed value output 202 operates when the frame delay amount convergence determination 201 determines that the frame delay amount has not converged, and outputs a fixed value for the frame delay amount de1ay (i). The fixed value of the frame delay amount may be a frame delay amount calculated from the distance between the speaker and the microphone of the echo suppression device, for example. Note that various methods can be widely applied to the fixed value determining means, and may be, for example, the minimum value of the frame delay amount of the echo suppression device.

  The frame delay amount estimated value output 203 operates when the frame delay amount convergence determination 201 determines that the frame delay amount has converged, and outputs the frame delay amount delay (i) estimated by the frame delay amount convergence determination 201. To do.

(A-2-4) Process of Estimated Echo Path Characteristic Update Unit Next, the process of the estimated echo path characteristic update unit in the echo suppressor 100 according to the first embodiment will be described in detail with reference to the drawings.

  FIG. 3 is a process flow diagram showing a process flow of the estimated echo path characteristic update unit 110 of the echo suppressor 100 according to the first embodiment of the present invention.

  3, the estimated echo path characteristic update unit 110 of the echo suppressor 100 of the present invention includes a frame delay amount convergence determination confirmation 301, an estimated echo path characteristic update 302 when the frame delay amount has not converged, a single talk determination confirmation 303, and a frame delay. An estimated echo path characteristic update 304 at the time of convergence is performed.

  The frame delay amount convergence determination check 301 uses the determination result of the frame delay amount convergence determination unit 116 to check whether the frame delay amount has converged or has not converged.

  The estimated echo path characteristic update 302 when the frame delay amount has not converged operates when the frame delay amount has not converged in the frame delay amount convergence determination confirmation 301, and calculates an echo path characteristic using a fixed frame delay amount.

  The single talk determination confirmation 303 confirms whether single talk or other than single talk is used by using the result of the single talk determination unit 124 when the frame delay amount converges in the frame delay amount convergence confirmation confirmation 301.

  The estimated echo path characteristic update 304 at the time of frame delay convergence is operated when the frame delay amount has converged in the frame delay amount convergence determination confirmation 301 and the current frame is single talk in the single talk determination confirmation 303, and the estimated echo path characteristic is updated. Update.

(A-2-5) Detailed Process of Estimated Echo Path Characteristic Update Unit Next, the operation of the process of the estimated echo path characteristic update unit 110 in the echo suppressor 100 according to the first embodiment will be described in detail.

  The frame delay amount convergence determination confirmation 301 uses the determination result of the frame delay amount convergence determination unit 116 to check whether the frame delay amount has converged or has not converged. The echo path characteristic is updated, and the echo path characteristic is calculated using a fixed frame delay amount. When the frame delay amount has converged, single talk determination is confirmed.

The estimated echo path characteristic update 302 when the frame delay amount has not converged operates when the frame delay amount has not converged in the frame delay amount convergence determination confirmation 301, and the estimated echo path characteristic | H (i , Ω) | is calculated and held. The estimated echo path characteristic update 302 when the frame delay amount has not converged includes the amplitude spectrum | ROUT_DELAY (i, ω) | of the far-end signal delayed by a fixed value and the amplitude spectrum of the near-end output signal | SIN (i, ω) | Is used to obtain the estimated echo path characteristic | H ₁ (i, ω) | of the current frame according to the equation (20).

そして、フレーム遅延量未収束時の推定エコーパス特性更新３０２は、現フレームの推定エコーパス特性｜Ｈ_１（ｉ，ω）｜が求まれば、推定エコーパス特性更新部１１０に保持されている１フレーム前に保持した推定エコーパス特性｜Ｈ（ｉ−１，ω）｜を読み出し、｜Ｈ（ｉ−１，ω）｜と、｜Ｈ_１（ｉ，ω）｜を用いて、推定エコーパス特性を（２１）式に従って更新する。

Then, the estimated echo path characteristic update 302 when the frame delay amount has not converged is performed one frame before the estimated echo path characteristic update unit 110 holds the estimated echo path characteristic | H ₁ (i, ω) | of the current frame. The estimated echo path characteristic | H (i−1, ω) | held in is read, and | H (i−1, ω) | and | H ₁ (i, ω) | ) Update according to formula.

ｂは時定数フィルタの係数であり、０より大きく、１より小さい値であって、エコーパス特性の更新を遅くしたい場合は１に近い値が望ましく（例えば、ｂ＝０．９９等の値）、更新を早くしたい場合は０に近い値が望ましい（例えば、ｂ＝０．０１等の値）。フレーム遅延量未収束時の推定エコーパス特性更新３０２は、更新した推定エコーパス特性を推定エコーパス特性更新部１１０に保持させる。

b is a coefficient of the time constant filter, and is a value larger than 0 and smaller than 1, and is preferably a value close to 1 (for example, a value such as b = 0.99) when it is desired to delay the update of the echo path characteristic. A value close to 0 is desirable when it is desired to update faster (for example, a value such as b = 0.01). The estimated echo path characteristic update 302 when the frame delay amount has not converged causes the estimated echo path characteristic update unit 110 to retain the updated estimated echo path characteristic.

  The single talk determination confirmation 303 operates when the frame delay amount has converged, and uses the result of the single talk determination unit 124 to confirm whether the current frame is a single talk or a single talk. The single talk determination confirmation 303 updates the estimated echo path characteristic if the current frame is a single talk, and does not update the estimated echo path characteristic if the current frame is not a single talk.

The estimated echo path characteristic update 304 at the time of frame delay convergence is the far-end signal delayed when the frame delay converges in the frame delay convergence confirmation 301 and the current frame is single talk in the single talk determination 303. Using the amplitude spectrum | ROUT_DELAY (i, ω) | and the amplitude spectrum | SIN (i, ω) | of the near-end output signal according to the above equation (20), the estimated echo path characteristic | H ₁ (i , Ω) |

The estimated echo path characteristic update 304 at the time of frame delay convergence converges one frame before the estimated echo path characteristic update unit 110 if the estimated echo path characteristic | H ₁ (i, ω) | of the current frame is obtained. The stored estimated echo path characteristic | H (i−1, ω) | is read out, and estimated using | H (i−1, ω) | and | H ₁ (i, ω) | according to the equation (22). Update echo path characteristics.

ｃは時定数フィルタの係数であり、０より大きく、１より小さい値であって、エコーパス特性の更新を遅くしたい場合は１に近い値が望ましく（例えば、ｃ＝０．９９等の値）、更新を早くしたい場合は０に近い値が望ましい（例えば、ｃ＝０．０１等の値）。フレーム遅延量収束時の推定エコーパス特性更新３０４は、更新した推定エコーパス特性を推定エコーパス特性更新部１１０に保持させる。

c is a coefficient of the time constant filter, and is a value larger than 0 and smaller than 1, and is preferably a value close to 1 (for example, a value such as c = 0.99) when it is desired to delay the update of the echo path characteristic. A value close to 0 is desirable when the update is desired to be accelerated (for example, a value such as c = 0.01). The estimated echo path characteristic update 304 at the time of frame delay convergence causes the estimated echo path characteristic update unit 110 to retain the updated estimated echo path characteristic.

(A-3) Effects of the First Embodiment As described above, according to the first embodiment, the fixed value of the frame delay amount and the fixed estimated echo path characteristic are used even immediately after the echo suppressor starts operating. Thus, the acoustic echo signal can be suppressed, and if the frame delay amount converges, the acoustic echo signal can be suppressed using the estimated frame delay amount and the estimated echo path characteristic. That is, the echo suppression device of the first embodiment can maintain the echo suppression performance continuously immediately after the operation is started.

(B) Second Embodiment of the Present Invention Next, an echo suppression device, an echo suppression program, and an echo suppression method according to a second embodiment of the present invention will be described in detail with reference to the drawings.

(B-1) Configuration of Second Embodiment The echo suppression apparatus 100 according to the second embodiment is characterized in that the estimated echo path characteristic update unit 200 is a constituent element instead of the estimated echo path characteristic update unit 110 in the first embodiment. This is different from the echo suppressor 100 of the form. The other components are the same as or correspond to the components of the echo suppression apparatus 100 of FIG. 1 according to the first embodiment.

(B-2) Operation of Second Embodiment (B-2-1) Process of Estimated Echo Path Characteristic Updating Unit FIG. 4 is a process of the estimated echo path characteristic updating unit 200 of the echo suppressor 100 according to the second embodiment. It is a processing flowchart which shows a flow.

  In FIG. 4, the estimated echo path characteristic update unit 200 according to the second embodiment includes an estimated echo path characteristic update 302 when the frame delay amount has not converged, in addition to the estimated echo path characteristic update unit 110 described in the first embodiment. In place of, smoothed echo path characteristic update 401 is performed.

  In FIG. 4, the same or corresponding components as those of the echo suppression apparatus 100 according to the first embodiment are denoted by the same reference numerals. Detailed descriptions of the same or corresponding components as those in the first embodiment are duplicated, and are omitted here.

  The smoothing echo path characteristic update 401 smoothes the amplitude spectrum of the far-end signal and the amplitude spectrum of the near-end output signal delayed by a fixed value when the frame delay amount has not converged in the frame delay amount convergence determination confirmation 301, The smoothed estimated echo path characteristic is calculated using the smoothed and delayed far-end signal amplitude spectrum and the smoothed near-end output signal amplitude spectrum.

(B-2-2) Detailed Process of Estimated Echo Path Characteristic Update Unit Next, the operation of the process of the estimated echo path characteristic update unit 200 in the echo suppressor 100 according to the second embodiment will be described in detail. Here, the processing operation in the smoothed echo path characteristic update 401 of the echo suppression apparatus 100 according to the second embodiment will be described in detail.

  The smoothed echo path characteristic update 401 operates when the frame delay amount has not converged in the frame delay amount convergence determination confirmation 301, and calculates the smoothed estimated echo path characteristic | H_TC (i, ω) |. The smoothed estimated echo path characteristic is expressed by the following equation (23), from the delayed far-end signal amplitude spectrum | ROUT_DELAY (i, ω) | and the near-end output signal amplitude spectrum | SIN (i, ω) | ) To obtain the amplitude spectrum | ROUT_DELAY_TC (i, ω) | of the delayed far end signal smoothed for each frequency bin and the amplitude spectrum | SIN_TC (i, ω) | of the near end output signal smoothed for each frequency bin. .

ｄは時定数フィルタの係数であり、０より大きく、１より小さい値であって、エコーパス特性の更新を遅くしたい場合は１に近い値が望ましく（例えば、ｄ＝０．９９等の値）、更新を早くしたい場合は０に近い値が望ましい（例えば、ｄ＝０．０１等の値）。そして、平滑化エコーパス特性更新４０１は、周波数ビン毎に平滑化した遅延遠端信号の振幅スペクトル｜ＲＯＵＴ＿ＤＥＬＡＹ＿ＴＣ（ｉ，ω）｜と周波数ビン毎に平滑化した近端出力信号の振幅スペクトル｜ＳＩＮ＿ＴＣ（ｉ，ω）｜を使用して（２５）、（２６）式に従って平滑化推定エコーパス特性を求め、平滑化推定エコー信号を保持する。

d is a coefficient of the time constant filter, and is a value larger than 0 and smaller than 1, and is preferably a value close to 1 (for example, a value such as d = 0.99) when it is desired to delay the update of the echo path characteristic. A value close to 0 is desirable when the update is desired to be accelerated (for example, a value such as d = 0.01). Then, the smoothed echo path characteristic update 401 includes the amplitude spectrum | ROUT_DELAY_TC (i, ω) | of the delayed far-end signal smoothed for each frequency bin and the amplitude spectrum | SIN_TC () of the near-end output signal smoothed for each frequency bin. i, ω) | is used to obtain a smoothed estimated echo path characteristic according to equations (25) and (26), and a smoothed estimated echo signal is held.

(B-3) Effect of Second Embodiment As described above, according to the second embodiment, the fixed value of the frame delay amount and the smoothed estimated echo path characteristic can be obtained even immediately after the echo suppressor starts operating. The acoustic echo signal can be suppressed by use, and if the frame delay amount converges, the acoustic echo signal can be suppressed by using the estimated frame delay amount and the estimated echo path characteristic. That is, the echo suppression device of the second embodiment can maintain the echo suppression performance continuously immediately after the operation is started.

(C) Other Embodiments In the above-described embodiments, various modified embodiments have been described, but the present invention can also be applied to the following modified embodiments.

  The echo suppression device described in each of the above-described embodiments may be mounted on a device including a voice communication device used in a video conference system, a telephone conference system, or the like. Further, the echo suppression device of the present invention may be mounted on a mobile terminal such as a mobile phone or a smartphone.

  DESCRIPTION OF SYMBOLS 100 ... Echo suppression apparatus, 101 ... Far end signal input terminal, 102 ... Output buffer, 103 ... DA converter, 104 ... Speaker, 105 ... Microphone, 106 ... AD converter, 107 ... Input buffer, 108 ... Far end signal frequency Area conversion calculation unit 109 ... far-end signal amplitude spectrum calculation unit 110 110 estimated echo path characteristic update unit 111 111 estimated echo signal calculation unit 112 112 estimated echo signal holding unit 113 113 near-end input signal frequency domain conversion unit 114 ... Near-end input signal amplitude spectrum calculation unit, 115 ... Frame delay amount estimation unit, 116 ... Frame delay amount convergence determination unit, 117 ... Estimated echo signal delay unit, 118 ... Echo suppression gain calculation unit, 119 ... Echo suppression unit, 120 ... Near-end output signal time domain conversion unit, 121 ... Near-end signal output terminal, 122 ... Far-end signal holding unit, 123 ... Edge output signal amplitude spectrum calculation unit, 124 ... single talk determination unit, 201 ... frame delay amount convergence determination, 202 ... frame delay amount fixed value output, 203 ... frame delay amount estimated value output, 301 ... frame delay amount convergence determination confirmation, 302 ... Update of estimated echo path characteristics when frame delay amount has not converged, 303 ... Confirm single talk determination, 304 ... Update echo path characteristics when frame delay amount converges, 401 ... Update smoothed echo path characteristics.

Claims (5)

In an echo suppression device that suppresses an acoustic echo signal based on a near-end input signal and a far-end signal,
A frame delay amount estimating means for estimating a frame delay amount from the amplitude spectrum of the estimated echo signal of the past plural frames and the amplitude spectrum of the near-end input signal;
Determining whether the frame delay amount estimated by the frame delay amount estimation means has converged, and based on the determined determination result, a frame delay amount convergence determination means for outputting the frame delay amount;
In accordance with the determination result in the frame delay amount convergence determination means, estimated echo path characteristic update means for updating and holding the estimated echo path characteristic using a fixed value of the frame delay amount;
The echo suppression gain is calculated from the amplitude spectrum of the estimated echo signal delayed using the frame delay amount and the amplitude spectrum of the near-end input signal, and the estimated echo signal is suppressed from the amplitude spectrum of the near-end input signal. And an echo suppression means. The estimated echo path characteristic update means includes:
If the frame delay amount convergence determining means determines that the frame delay amount has not converged, the estimated echo path characteristic when the frame delay amount has not converged is updated and held using the fixed value of the frame delay amount. Update section,
When the frame delay amount convergence determining means determines that the frame delay amount has converged, it further performs single talk determination. If it is determined as single talk by the single talk determination, the frame delay amount convergence determining means The echo suppression apparatus according to claim 1, further comprising: an estimated echo path characteristic updating unit at the time of frame delay amount convergence that updates and holds the estimated echo path characteristic using the output frame delay amount.   When the estimated echo path characteristic update unit when the frame delay amount has not converged determines that the frame delay amount has not converged, the far-end signal amplitude spectrum delayed by a fixed value of the frame delay amount, and the echo The amplitude spectrum of the near-end output signal in which the estimated echo signal of the near-end input signal is suppressed by the suppression means is smoothed, and the smoothed amplitude spectrum of the far-end signal and the amplitude spectrum of the near-end output signal are The echo suppression apparatus according to claim 2, wherein the estimated echo path characteristic is updated and held by using. A computer mounted in an echo suppression device that suppresses an acoustic echo signal based on the near-end input signal and the far-end signal,
A frame delay amount estimating means for estimating a frame delay amount from the amplitude spectrum of the estimated echo signal of the past plural frames and the amplitude spectrum of the near-end input signal;
Determining whether the frame delay amount estimated by the frame delay amount estimation means has converged, and based on the determined determination result, a frame delay amount convergence determination means for outputting the frame delay amount;
In accordance with the determination result in the frame delay amount convergence determination means, estimated echo path characteristic update means for updating and holding the estimated echo path characteristic using a fixed value of the frame delay amount;
The echo suppression gain is calculated from the amplitude spectrum of the estimated echo signal delayed using the frame delay amount and the amplitude spectrum of the near-end input signal, and the estimated echo signal is suppressed from the amplitude spectrum of the near-end input signal. An echo suppression program that functions as an echo suppression means. In an echo suppression method for suppressing an acoustic echo signal based on a near-end input signal and a far-end signal,
A frame delay amount estimation unit, a frame delay amount convergence determination unit, an estimated echo path characteristic update unit, and an echo suppression unit,
The frame delay amount estimating means estimates the frame delay amount from the amplitude spectrum of the estimated echo signal of the past plural frames and the amplitude spectrum of the near-end input signal,
The frame delay amount convergence determination means determines whether or not the frame delay amount estimated by the frame delay amount estimation means has converged, and outputs the frame delay amount based on the determined determination result,
The estimated echo path characteristic update unit updates and holds the estimated echo path characteristic using a fixed value of the frame delay amount according to the determination result in the frame delay amount convergence determination unit,
The echo suppression means calculates an echo suppression gain from the amplitude spectrum of the estimated echo signal delayed using the frame delay amount and the amplitude spectrum of the near-end input signal, and calculates the echo suppression gain from the amplitude spectrum of the near-end input signal. An echo suppression method comprising suppressing the estimated echo signal.

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