JP2006033789A - Method, device, and program for estimating amount of echo path coupling; method, device, and program for controlling echoes; method for suppressing echoes; echo suppressor; echo suppressor program; method and device for controlling amount of losses on transmission lines; program for controlling losses on transmission lines; method, device, and program for suppressing multichannel echoes; and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for estimating the amount of echo path coupling which does not require determination of the double talking state and can estimate the amount of echo path coupling even under the double talking state, and to provide various devices that use the estimating method. <P>SOLUTION: The frequency for each input signal, to which a receiving signal and an echo signal are added, is analyzed, and receiving signal power and input signal power for each frequency band are computed from the frequency coefficient. The power ratio of the input signal power to the receiving signal power is computed for each frequency band; and the minimum value of the power ratio computed for each frequency band is updated, the updated minimum value of the power ratio is retained, and the minimum power ratio retained for each frequency band is output as the amount of echo path coupling for each frequency band. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an echo path coupling amount estimation method, an echo suppression method using the echo path coupling amount estimation method, an echo suppression method, a loss control method on a speech path, a multi-channel echo suppression method, and a device thereof, for example, The present invention relates to an echo suppression processing technique for suppressing acoustic echo generated in an echo path of a hands-free loudspeaking call using a microphone and a speaker, a line echo generated in a hybrid circuit of two-wire four-wire conversion, and a voice switch technique for preventing howling.

A conventional technique (Patent Document 1) relating to an echo path (acoustic) coupling amount estimation method and an echo canceling apparatus using the estimated echo path coupling amount will be described with reference to FIG. The echo cancellation apparatus 500 includes an echo cancellation unit 200 and a loss control unit 300. The loss amount determining means 310 in the loss control unit 300 is configured to estimate the echo path coupling amount and determine the loss amount based on the echo path coupling amount.
Assume that the own side that performs hands-free loudspeaking using the receiving unit 410 (speaker) and the transmitting unit 420 (microphone) is the near end, and the other side that is calling across the communication path is the far end. FIG. 6 shows the processing of the echo canceller arranged at the near end.

The received signal x (n) received from the far-end partner (speaker) via the communication path is echoed via the receiving means 410 and the echo path, and is sent to the transmitting means 420 as an echo signal y (n). Assume that the sound is picked up.
In the echo canceling unit 200, a pseudo echo signal y ^ (n) is formed from the received signal x (n) and the pseudo echo path 210, and the echo is subtracted from the microphone input signal z (n) input to the transmitting means 420. The signal y (n) is erased. The microphone input signal z (n) is composed of one or both of an echo signal y (n) and a transmission signal s (n) depending on the call state. However, when there is no received signal x (n), the echo signal y (n) does not exist at the same time.

The estimation means 220 uses the error signal e (n) after subtracting the pseudo echo signal y ^ (n) from the received signal x (n) and the microphone input signal z (n), and the pseudo echo path h ^ (n ) And the pseudo echo path 210 is updated (corrected). The echo canceling unit 200 outputs an error signal e (n) and a microphone input signal z (n).
The loss determination unit 310 in the loss control unit 300 receives the received signal x (n), the error signal e (n), and the microphone input signal z (n). The loss amount determining means 310 first determines the double talk state.

The double talk state is a state in which two-way conversation is performed simultaneously (that is, the other party and the other party speak together), and the transmitting means 420 has an echo signal y (n) and a transmitted signal s (n). Are simultaneously input (sound collection). Short-time powers Px (n), Pz (n), and Pe (n) of the received signal x (n), the input signal z (n), and the error signal e (n) are calculated.
If the received signal short-time power Px (n) exceeds a predetermined threshold value xth and a threshold value Th set to 1 or less, a relationship of Pe (n)> Th × Pz (n) is established. It is determined not to be in a double talk state. If the relationship of Px (n)> xth and Pe (n)> Th × Pz (n) is established, it is determined that the double talk state or the echo path has changed. Next, when it is determined that the state is not the double talk state, the echo path coupling amount is obtained from Pz (n) / Px (n), and the reciprocal number Px (n) / Pz (n) is determined as the loss amount. To do. The determined loss amount is input to the loss amount control unit 330, and the loss is inserted into at least one of the reception signal side and the transmission signal side by the loss device 10 or the loss device 20. As a result, it is controlled that howling occurs when the gain (circular amplification amount) of the communication path (loop) that makes a round between the far end and the near end exceeds 1.
Japanese Patent No. 3268572

The echo path coupling amount is a power change rate when the received signal x (n) becomes the echo signal y (n) via the echo path, and is equal to the ratio Py (n) / Px (n). That is, if it can be determined that the state is a single talk state in which only the echo signal is input to the transmitting means 420, the echo path coupling amount can be calculated because Py (n) and Px (n) can be measured independently. However, the condition for enabling the measurement is based on the premise that the single talk state can be determined.
In the double talk state, not only the echo signal but also the transmission signal s (n) is input to the transmission means 420, and Py (n) cannot be measured alone. It becomes.

In the conventional method, a case where the state is not a double talk state (that is, a single talk state) is determined, and an echo path coupling amount is determined only at that time. However, since the conventional method uses a threshold value for discrimination of double talk, there is no guarantee that the discrimination can always be made accurately in various environments such as the gain setting of the input means and the state of the echo path. In addition, when the double talk state continues, the echo path coupling amount cannot be calculated.
On the other hand, when the received signal is made up of a plurality of channels and each of them is reproduced as sound, the one-channel method cannot be applied as it is. Specifically, the amount of acoustic coupling cannot be estimated independently for each pair of monaural channels for reproduction and sound collection. This is because a single microphone picks up a plurality of echoes from a plurality of speakers. When estimation similar to monaural is performed with a pair of playback-sound pickup signals (1-channel playback-1 channel sound pickup), echoes amplified from other than the target speaker are added. The amount will be greatly estimated. Then, the performance of echo suppression is degraded due to the influence of the estimation error.

  An object of the present invention is to use an echo path coupling amount estimation method and apparatus that require discrimination of a double talk state and that can estimate an echo path coupling amount even in the double talk state, and further uses this echo path coupling amount estimation method. The present invention proposes an echo suppression method and apparatus, an echo suppression method and echo suppressor, a loss control method and apparatus on a communication path, a multi-channel echo suppression method, and a multi-channel echo suppression apparatus.

  In this invention, in the echo path coupling amount estimation method for estimating the echo path coupling amount between the receiving end and the transmitting end, the received signal is converted into the frequency domain, and the received signal power for each frequency band is calculated from the frequency coefficient of the received signal. A process for calculating, an input signal obtained by adding an echo signal transmitted through an echo path to a transmission signal, converting the frequency signal into a frequency domain, and calculating an input signal power for each frequency band from a frequency coefficient of the input signal; Processing to calculate the power ratio of input signal power to signal power for each frequency band, update the minimum value of power ratio calculated for each frequency band, and maintain the updated minimum value of power ratio for each frequency band The present invention proposes an echo path coupling amount estimation method including a process of outputting a minimum power ratio held for each frequency band as an echo path coupling quantity for each frequency band.

According to the present invention, in the above-described echo path coupling amount estimation method, the maximum value of the echo path coupling amounts for each frequency band is output as the echo path coupling amount of the frequency bands collectively. Propose.
In the present invention, in an echo path coupling amount estimation device for estimating the echo path coupling amount between the receiving end and the transmitting end, the first frequency analyzing means for converting the received signal into a frequency coefficient, and the first frequency analyzing means analyzed First-band power calculation means for calculating received signal power for each frequency band from the frequency coefficient of the received signal, and an input signal obtained by adding an echo signal transmitted through the echo path to the transmitted signal into a frequency coefficient. Two-frequency analysis means, second-band power calculation means for calculating the power of the input signal for each frequency band from the frequency coefficient of the input signal analyzed by the second frequency analysis means, and the input signal power relative to the received signal power The second band power ratio calculation means for calculating the power ratio for each frequency band and the minimum power ratio calculated for each frequency band are updated, and the power ratio for each frequency band is updated. Maintain the minimum value, update the minimum value of power ratio calculated for each frequency band using the minimum power ratio held for each frequency band as the amount of echo coupling for each frequency band, and the minimum held for each frequency band The present invention proposes an echo path coupling amount estimation device comprising: a power ratio minimum value holding unit for each band that outputs a power ratio as an echo path coupling amount for each frequency band.

In the present invention, in the above echo path coupling amount estimation device, the maximum value of the power ratio is extracted from the power ratio minimum value for each frequency band output by the power ratio minimum value holding unit for each band, and the power ratio The present invention proposes an echo path coupling amount estimation device comprising band collective echo coupling amount calculation means for outputting a maximum value of the power ratio extracted from among the minimum values as a band collective echo coupling amount.
The present invention further proposes an echo path coupling amount estimation program that is described in a computer-readable program language and that causes the computer to function as any of the above echo path coupling amount estimation devices.

  The present invention further converts the received signal into the frequency domain, calculates the received signal power for each frequency band from the frequency coefficient of the received signal, and the input obtained by adding the echo signal via the echo path to the transmitted signal. The process of converting the signal to the frequency domain and calculating the input signal power for each frequency band from the frequency coefficient of the input signal, the process of calculating the power ratio of the input signal power to the received signal power for each frequency band, and each frequency Update the minimum value of the power ratio calculated for each band, hold the updated minimum value of the power ratio for each frequency band, and connect the minimum power ratio held for each frequency band to the echo path for each frequency band The echo for each band is superimposed by superimposing the received signal power for each band obtained by frequency analysis of the received signal on the echo coupling amount for each band calculated by the echo path coupling amount estimation method including the processing to output as a volume. Suppression for each frequency band based on the ratio of the input signal power for each band and the echo signal power for each band obtained by frequency analysis of the input signal obtained by calculating the signal power and adding the echo signal transmitted through the echo path to the transmitted signal Obtain the gain, superimpose the suppression gain on the amplitude component of the input signal frequency coefficient, suppress the echo signal for each frequency band, synthesize the frequency coefficient obtained by suppressing the echo signal, and output the time signal with the echo signal suppressed We propose an echo suppression method characterized by

The present invention further includes first frequency analysis means for converting the received signal into a frequency coefficient, and first band-specific calculation for calculating received signal power for each frequency band from the frequency coefficient of the received signal analyzed by the first frequency analyzing means. From the power calculation means, the second frequency analysis means for converting the input signal obtained by adding the echo signal transmitted through the echo path to the transmission signal into the frequency coefficient, and the frequency coefficient of the input signal analyzed by the second frequency analysis means Second-band power calculation means for calculating the power of the input signal for each frequency band; and second-band power ratio calculation means for calculating the power ratio of the input signal power to the received signal power for each frequency band; The minimum power ratio calculated for each frequency band is updated, the updated minimum value of the power ratio for each frequency band is maintained, and the minimum power ratio is maintained for each frequency band. Update the minimum power ratio calculated for each frequency band as the amount of echo coupling for each frequency band, and output the minimum power ratio stored for each frequency band as the amount of echo coupling for each frequency band. Equipped with an echo path coupling amount estimation device constituted by a power ratio minimum value holding means,
The echo signal power calculation for each band calculates the echo signal power for each band by superimposing the received signal power for each band obtained by frequency analysis of the received signal on the echo path coupling amount for each band calculated by this echo path coupling amount estimation device. And the input signal power for each band obtained by frequency analysis of the input signal obtained by adding the echo signal transmitted through the echo path to the transmission signal, and for each band calculated by the above-mentioned echo signal power calculation means for each band. A suppression gain calculation means for obtaining an echo suppression gain for each frequency band based on a ratio to the echo signal, and an echo suppression gain for each frequency band calculated by the suppression gain calculation means and the frequency coefficient of the input signal are superimposed to each frequency. Echo suppression means for suppressing echoes by band and time signal synthesis means for synthesizing frequency coefficients with echoes suppressed by echo suppression means and combining them with time signals Suggest composed echo suppressor by.

The present invention further proposes an echo suppression program that is described in a computer-readable program language and causes the computer to function as the echo suppression device.
The present invention further calculates the power of the received signal, multiplies the received signal power by the echo band coupling amount of the frequency band collectively calculated by the echo path coupling amount estimating means, obtains the reciprocal thereof to obtain the loss amount, An echo suppression method is proposed in which an echo signal included in an input signal is suppressed by multiplying an input signal obtained by adding this loss amount to a transmission signal and an echo signal that has passed through an echo path.

In the present invention, the received signal power calculating means for calculating the power of the received signal, the echo path coupling amount of the frequency bands collectively calculated by the echo path coupling amount estimating device, and the received signal power calculated by the received signal power calculating unit, And a loss means for calculating the reciprocal number as a loss amount and a loss means for multiplying the microphone input signal by the loss amount counted by the loss amount calculation unit and outputting the signal as an echo signal suppressed. Propose an echo suppressor.
The present invention further proposes an echo suppressor program that is written in a computer-readable program language and that causes the computer to function as the echo suppressor.

In the present invention, the loss amount to be inserted into the communication loop is further calculated from the band collective echo path coupling amount calculated by the above echo path coupling amount estimation method, and the loss amount of the lossr inserted into the communication path according to the calculated loss amount We propose a loss control method on the communication path that controls
The present invention further includes a loss amount calculating means for calculating a loss amount to be inserted into the communication loop from the band collective acoustic coupling amount calculated by the echo path coupling amount estimating device, and a loss amount calculated by the loss amount calculating means. A loss control device on a communication path, comprising: loss control means for determining whether to be inserted into the receiver side or transmitter side and controlling the loss amount of any of the lossers inserted into the receiver side and transmitter side according to the determination suggest.

The present invention further proposes a loss control program on a speech path which is described in a computer-readable program language and allows the computer to function as a loss control device on the communication path.
The present invention further provides a multi-channel echo suppression method for suppressing a plurality of echoes generated when an N-channel (N> 1) received signal is reproduced and an M-channel (M> 1) input signal is picked up. A multi-channel echo suppression method is proposed in which echoes are suppressed for each M channel by the above echo suppression method using an added reception signal obtained by adding N channel reception signals and M input signals. .

The present invention further provides a multi-channel echo suppressor that reproduces an N-channel (N> 1) received signal and suppresses a plurality of echoes generated when an M-channel (M> 1) input signal is picked up. , An adder for adding N-channel received signals, and the echo suppressor for suppressing each echo for each M channel using the added received signal added by the adder and M input signals. A multi-channel echo suppressor is proposed.
The present invention further proposes a multi-channel echo suppression program that is written in a computer-readable program language and causes the computer to function as the multi-channel echo suppression device.

  The present invention further comprises a computer-readable recording medium, and at least the echo path coupling amount estimation program, the echo suppression program, or the echo suppressor program, the loss control program on the communication path, A recording medium on which any one of the above multi-channel echo suppression programs is recorded is proposed.

According to the echo path coupling amount estimation method of the present invention, it is not necessary to determine the double talk state, and the echo path coupling amount can be estimated even in the double talk state. Therefore, by applying the echo path coupling amount estimation method of the present invention to the echo suppression technique, the echo suppression technique, and the loss control technique on the communication path for suppressing howling, even if the double talk state continues for a long time, the control state Is maintained, and the echo suppression state and the howling suppression state can be stably maintained.
Furthermore, according to the multi-channel echo suppression method and apparatus according to the present invention, a plurality of reproduced signals are added to make a virtual monaural signal, and the acoustic coupling amount is estimated by the method proposed in the previous monaural. Next, also for echo suppression, echo suppression processing is performed by adding a plurality of reproduction signals to calculate a suppression gain. As a result, it is possible to estimate the acoustic coupling amount of one microphone for all of the plurality of speakers and independently suppress the echo without obtaining the acoustic coupling amount of the plurality of echo paths between the speaker and the microphone independently. It becomes.

  The echo path coupling amount estimation device, the echo suppression device, the echo suppressor, and the loss amount control device on the communication path according to the present invention can be realized by assembling dedicated hardware, but are generally proposed in the present invention. The echo path coupling amount estimation program, echo suppression program, echo suppressor program, and loss control program on the communication path are installed in the computer, and each installed program is decoded and executed by a CPU (central processing unit) provided in the computer. The embodiment realized by this is the best mode.

A first embodiment of the present invention will be described with reference to FIGS. The first embodiment shows an embodiment of the echo path coupling amount estimation device proposed in claim 3 of the present invention and the echo suppression device proposed in claim 7 for realizing the echo suppression method proposed in claim 6. .
The near side is the own side that conducts a hands-free loudspeaking call using the receiving means 410 (speaker) and the sending means 420 (microphone), and the far side that is talking across the call path is the far end. FIG. 1 shows the processing of the echo suppressor 301 arranged at the near end.
In the transmitting means 420, the received signal x (n) received from the far-end partner (speaker) via the speech path is echoed through the receiving means 410 and the echo path y (n). Alternatively, one or both of the transmission signals s (n) or both (double talk state) are input (sound picked up) to become a microphone input signal z (n). If there is no received signal x (n), the echo signal y (n) does not exist at the same time. The echo path coupling amount estimation apparatus 100 estimates the echo path coupling amount by the following processing regardless of whether or not it is in the double talk state.

The echo path coupling amount estimation apparatus 100 receives the received signal x (n) and the microphone input signal z (n).
The received signal x (n), which is a time signal, is cut into frames by the frequency analysis means 110 on the received signal side, converted into frequency domains, and each frequency band is divided, and a received signal frequency coefficient X (m, f) is output. To do. Here, m represents the number of the current frame, and f represents a number (frequency) indicating each band in the frequency domain.
The band-by-band power calculation means 130 on the reception signal side calculates the band-by-band reception signal power PX (m, f) from the reception signal frequency coefficient X (m, f).

The frequency analysis means 120 on the microphone input signal side converts the input signal z (n) into the frequency domain and outputs the input signal frequency coefficient Z (m, f).
The band-specific power calculation means 140 on the microphone input signal side calculates the band-specific input signal power PZ (m, f) from the input signal frequency coefficient Z (m, f).
The power ratio calculation unit 150 for each band calculates the power ratio of PZ (m, f) / PX (m, f) for each band, and outputs the power ratio A (m, f) for each band.
The band-specific power ratio minimum value holding unit 160 compares the input band-specific power ratio A (m, f) with the held minimum band-specific power ratio C (m-1, f). When A (m, f) <C (m−1, f), the minimum value is updated and held as C (m, f) = A (m, f). When A (m, f)> C (m−1, f), the minimum value is not updated and is held as C (m, f) = C (m−1, f). Then, the held power ratio C (m, f) for each minimum band is output as an echo path coupling amount for each frequency band.

  Here, the principle of the processing performed by the band-specific power ratio calculation unit 150 and the band-specific power ratio minimum value holding unit 160 will be described. The echo signal and the transmitted voice have different frequency characteristics (voice prints) due to the voices of different speakers. Specifically, the harmonic structure of the voice (peak value on the frequency axis) is almost never the same position (because each voice signal has a characteristic of sparsity). That is, even in the double talk state, only the peak of the echo signal power generated by the echo of the received signal exists in the band with the peak of the received signal power, and the peak of the transmitted signal power does not exist. Therefore, if the power ratio for each band is calculated only in the band where the peak of the received signal exists, the ratio of the echo signal power to the received signal power, that is, the amount of echo path coupling in that band can be specified.

When there is no peak of the received signal power (the level is small) and there is a peak of the transmitted signal power, the power ratio for each band increases, and the true echo path coupling amount cannot be obtained. However, since the frequency characteristics (peak position) of the received signal change with time (for example, the vowels uttered in normal conversation differ), the above-mentioned frame processing is repeated several times to update the minimum power value for each band. By holding, it is possible to estimate the echo path coupling amount of all the bands.
The echo path coupling amount C (m, f) for each band estimated as described above is input to the echo suppression unit 600.

  As shown in FIG. 2, the echo suppression unit 600 includes a band-specific echo signal power calculation unit 601, a suppression gain calculation unit 602, and a gain control unit 603, and the band-specific echo power signal calculation unit 601 includes an echo path for each band. In addition to the coupling amount C (m, f), the reception signal power PX (m, f) for each band of the reception signal x (n) is fetched from the power calculation unit 130 for each band, and the reception signal power PX (m, f) for each band. Is superimposed on the band-by-band echo path coupling amount C (m, f) to calculate the band-by-band echo signal power PE (m, f), and the band-by-band signal power PE (m, f) is sent to the suppression gain calculation means 602. input. At the same time, the suppression gain calculation means 602 fetches the band-specific input signal power PZ (m, f) from the band-specific power calculation means 140, and the band-specific echo signal power PE (m) for the band-specific input signal power PZ (m, f). , F) ratio (PE (m, f) / PZ (m, f)) is a value obtained by subtracting 1 from 1- (PE (m, f) / PZ (m, f)). Ask for.

The suppression gain obtained by the suppression gain calculation unit 602 is input to the gain control unit 603. The gain control means 603 takes the input signal frequency coefficient Z (m, f) from the frequency analysis means 120, superimposes the suppression gain on the amplitude component of the input signal frequency coefficient Z (m, f), and suppresses the echo signal for each frequency band. To do.
The input signal frequency coefficient Z (m, f), in which the echo signal is suppressed for each frequency band, is input to the time signal synthesis unit 700 (FIG. 1), and the time signal synthesis unit 700 synthesizes (inversely converts) the frequency coefficient to echo. Output as a time signal after processing with the signal suppressed.

Since the echo suppression device 301 shown in FIG. 1 uses the echo path coupling amount C (m, f) estimated by the echo path coupling amount estimation device 100, the echo path coupling amount C (m, f) is used even in a double talk state. Can be obtained. As a result, even if the double talk state continues for a long time, there is an advantage that the echo suppression state can be stably maintained.
Note that the echo suppression processing described above is performed in the frequency domain. Here, this type of echo suppression processing is referred to as echo suppression processing, an echo suppression device, or the like. On the other hand, a method of performing echo suppression processing in the time domain described below is referred to as an echo suppression method or an echo suppressor here.

Embodiment 2 shows an embodiment of an echo path coupling amount estimation device which is a main part of the present invention and an echo suppressor proposed in claim 10. Even in the second embodiment, the configuration and operation of the echo path coupling amount estimation apparatus 100 are the same as those in the first embodiment, and therefore, redundant description thereof is omitted here. In this embodiment, the output of the echo path coupling amount estimation apparatus 100 is omitted. On the side, a band collective echo path coupling amount calculation unit 800 is provided.
The band collective echo coupling amount calculation unit 800 outputs the maximum value of the respective echo coupling amounts C (m, f) as the echo coupling amount C (n) representative of all the bands collectively for each band. Execute the process.

Here, the reason why the maximum value among the echo path coupling amounts C (m, f) calculated for each band is the echo path coupling amount C (n) representative of all the bands collectively will be described below. This is to match the suppression of echoes under the worst condition (band in the maximum coupling state) of the echo path in the echo suppressor.
In FIG. 3, the received signal x (n) input to the receiving end and the microphone input signal z (n) output from the transmitting means 420 are passed through the frequency analyzing means 110 and 120, respectively, unlike the case of FIG. Instead, it is directly input to the receiving means 410 from the receiving end, and is also output from the transmitting means 420 through the losser 20. Thereby, the signal from the receiving end to the receiving means 410 and the signal output from the transmitting means 420 through the losser 20 are time domain signals, and the echo suppressor 302 performs the echo suppression operation in the time domain. It means that.

The received signal x (n) is input to the received signal power calculator 820, and the received signal power Px (n) for each sampling time n is calculated and output.
Loss amount calculation section 810 receives band collective echo path coupling amount c (n) and received signal power Px (n). The reciprocal of the power obtained by multiplying the band collective echo path coupling amount c (n) by the received signal power Px (n) is defined as a loss amount M (n).
The loss unit 20 receives the loss amount M (n) and the microphone input signal z (n), and outputs a value obtained by multiplying the microphone input signal z (n) by the loss amount M (n).

  The principle of the echo suppressor 302 will be described below. In the loss amount calculation unit 810, a value obtained by multiplying the band collective echo path coupling amount c (n) and the received signal power Px (n) is equal to the echo signal power Py (n). This is because the received signal x (n) becomes the echo signal y (n) through the echo path, and the power fluctuation (maximum or decrease) at that time is proportional to the echo path coupling amount c (n). That is, if the microphone input signal z (n) is multiplied by the loss amount M (n) that is the reciprocal of the power Py (n) of the echo signal, it matches the echo signal y (n) included in the microphone input signal z (n). The amount of loss is inserted. Thereby, the echo signal y (n) can be suppressed.

  Since the echo path coupling amount estimation apparatus 100 is applied to the echo suppressor 302, the band collective echo path coupling amount C (n) is always calculated even in a double talk situation. A predetermined amount of loss is given. Therefore, even if the double talk state continues for a long time, an appropriate echo suppression control state can be maintained.

FIG. 4 shows a third embodiment of the present invention. This embodiment corresponds to the embodiment of the loss amount control apparatus on the communication path proposed in claim 13 of the present invention. The loss amount controller 303 on the communication path is provided with the loss units 10 and 20 on both the receiving side and the transmission side, and by appropriately controlling the loss amounts of these loss units 10 and 20, the coupling amount of the echo path Even if becomes larger, the loop gain on the communication path is suppressed to “1” or less, and howling is suppressed.
In this embodiment as well, the band collective echo coupling amount calculation unit 800 uses the echo path coupling amount C () that represents the maximum value of the echo coupling amounts C (m, f) of each band collectively. n).

The loss amount calculation unit 810 determines the reciprocal of the band collective echo path coupling amount c (n) as the band collective loss amount L (n). The determined loss amount L (n) is input to the loss amount control unit 830, and the loss is inserted into at least one of the reception signal side and the transmission signal side by the loss device 10 or the loss device 20. As a result, it is possible to suppress the occurrence of howling by the gain (round-trip amplification amount) of the communication path (loop) that makes a round between the far end and the near end exceeding 1.
In the band collective echo path coupling amount calculation unit 800, the maximum value of the band-specific echo path coupling amount C (m, f) is set as the total echo path coupling amount for all bands, which may cause howling in the frequency characteristics of the loop loop. This is because the amount of loss is determined in accordance with a certain worst case (maximum gain).

As a fourth embodiment of the present invention, a configuration diagram of a multi-channel echo suppressor 304 is shown in FIG. In addition, the same code | symbol is attached | subjected about the part corresponding to FIG.
FIG. 5 shows a multi-channel hands-free reproduction of N-channel reproduction M-channel sound using the receiving means 410-1 to 410-N (N speakers) and the transmitting means 420-1 to 420-M (M microphones). The process of the multi-channel echo suppression device 304 at the near end (self side) when performing a voice call is shown. In the transmitting means 420-1 to 420-M, received signals x1 (n) to xN (n) received from the far-end partner (speaker) via the communication path are received means 410-1 to 410-1 to 410-1. 410-N and echo signals y1-1 (n) to yN-M (n) or transmission signals s1 (n) to sM (n) reverberated via a plurality of echo paths, or both (double Talk state) is input (sound collection) and becomes microphone input signals z1 to zM (n). The echo path coupling amount estimation apparatuses 100-1 to 100-M estimate the echo path coupling amount by the following processing regardless of whether or not the state is a double talk state.

In the echo path coupling amount estimation apparatuses 100-1 to 100-M, the signals XSUM (n) obtained by adding the reception signals x1 (n) to xN (n) and the microphone input signals z1 (n) to zM (n) are respectively received. input.
The echo path coupling amount estimation apparatuses 100-1 to 100-M respectively have band-specific echo path coupling amounts CX1 (m, f) to CXM (m, f) and band-specific received signal powers PX1 (m, f) to PXM. (M, f), band-specific input signal powers PZ1 (m, f) to PZM (m, f), and input signal frequency coefficients Z1 (m, f) to ZM (m, f) are output, and the echo suppressor 600 Input to -1 to 600-M. The internal processes of the echo suppression units 600-1 to 600-M and the time signal synthesis units 700-1 to 700-M are the same as those in the first embodiment. The time signal after the M channel processing in which the echo signal is suppressed is output from each of the time signal synthesis units 700-1 to 700-M.

  The echo path coupling amount estimation device 100, the echo suppression device 301, the echo suppressor 302, and the communication path loss amount control device 303 described above are each an echo path coupling amount estimation program written in a computer-readable program language. This is realized by installing an echo suppression program, an echo suppressor program, a loss control program on the communication path, and a multi-channel echo suppression program, causing a central processing unit called a CPU included in the computer to decode and execute the program. The program is recorded on a computer-readable recording medium such as a magnetic disk or a CD-ROM, installed in the computer from these recording medium or communication line, and decrypted by a CPU provided in the computer so as to have the above-described response. It can function as a path coupling amount estimation device, an echo suppression device, an echo suppressor, a loss control device on a communication path, a multi-channel echo suppression device, and the like.

  The echo path coupling amount estimation method and apparatus, echo suppression method and apparatus, echo suppression method and echo suppressor, loss amount control method and apparatus on a communication path according to the present invention perform hands-free loudspeaking as in a multipoint telephone conference system. Used in the field.

FIG. 9 is a block diagram for explaining an embodiment in which an echo path coupling amount estimation device proposed in claim 3 of the present invention and an echo suppression device proposed in claim 7 are combined; The block diagram for demonstrating the internal structure of the echo suppression apparatus shown in FIG. FIG. 11 is a block diagram for explaining an embodiment in which an echo path coupling amount estimation device proposed in claim 3 of the present invention and an echo suppressor proposed in claim 10 are combined; FIG. 15 is a block diagram for explaining an embodiment in which an echo path coupling amount estimation apparatus proposed in claim 3 of the present invention and a loss amount control apparatus on a communication path proposed in claim 13 are combined; The block diagram for demonstrating implementation of the multi-channel echo suppression apparatus of this invention. The block diagram for demonstrating the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,20 Loss device 600 Echo suppression part 100 Echo path coupling amount estimation apparatus 601 Echo signal 110,120 according to band Frequency analysis means Power calculation means 130,140 Power calculation means according to band 602 Suppression gain calculation means 150 Power ratio calculation means according to band 603 Gain control means 160 Band-specific power ratio minimum value holding means 301 Echo suppression device 700 Time signal synthesis section 302 Echo suppressor 800 Band collective echo path coupling 303 Loss amount controller on communication path Quantity calculation section 330 Loss amount control means 810 Loss amount Calculation unit 410 Reception means 420 Transmission means

Claims (18)

In the echo path coupling amount estimation method for estimating the echo path coupling amount between the receiving end and the transmitting end,
A process of converting the received signal into the frequency domain and calculating the received signal power for each frequency band from the frequency coefficient of the received signal;
A process of converting an input signal obtained by adding an echo signal via an echo path to a transmission signal into a frequency domain, and calculating an input signal power for each frequency band from a frequency coefficient of the input signal;
Processing for calculating the power ratio of the input signal power to the received signal power for each frequency band;
Updates the minimum value of the power ratio calculated for each frequency band, maintains the updated minimum value of the power ratio for each frequency band, and reflects the minimum power ratio held for each frequency band for each frequency band. Processing to output as a road coupling amount;
The echo path coupling | bonding amount estimation method characterized by including these.   2. The echo path coupling amount estimation method according to claim 1, wherein a maximum value among the echo path coupling quantities for the respective frequency bands is output as an echo path coupling quantity for the frequency bands collectively. Quantity estimation method. In the echo path coupling amount estimation device for estimating the echo path coupling amount between the receiving end and the transmitting end,
First frequency analysis means for converting the received signal into a frequency coefficient;
Power calculating means for each first band for calculating received signal power for each frequency band from the frequency coefficient of the received signal analyzed by the first frequency analyzing means;
Second frequency analysis means for converting an input signal obtained by adding a reverberation signal via an echo path to a transmission signal into a frequency coefficient;
Second-band power calculation means for calculating the power of the input signal for each frequency band from the frequency coefficient of the input signal analyzed by the second frequency analysis means;
A second band power ratio calculation means for calculating a power ratio of the input signal power to the received signal power for each frequency band;
Update the minimum value of the power ratio calculated for each frequency band, hold the updated minimum value of the power ratio for each frequency band, and combine the minimum power ratio for each frequency band for each frequency band Updating the minimum value of the power ratio calculated for each frequency band as a quantity, and outputting the minimum power ratio held for each frequency band as the amount of echo path coupling for each frequency band;
An echo path coupling amount estimation apparatus comprising:   4. The echo path coupling amount estimation device according to claim 3, wherein a maximum value of the power ratio is extracted from the power ratio minimum value for each frequency band output by the band-specific power ratio minimum value holding means, and the power ratio minimum An echo path coupling amount estimation device, comprising: a band collective echo path coupling amount calculation means for outputting a maximum value of the power ratio extracted from the values as a band collective echo path coupling amount.   An echo path coupling amount estimation program that is described in a computer readable program language and causes the computer to function as the echo path coupling amount estimation device according to claim 3.   Converts the received signal to the frequency domain, calculates the received signal power for each frequency band from the frequency coefficient of the received signal, and the input signal obtained by adding the echo signal sent through the echo path to the transmitted signal in the frequency domain A process for converting and calculating the input signal power for each frequency band from the frequency coefficient of the input signal, a process for calculating the power ratio of the input signal power to the received signal power for each frequency band, and for each frequency band Update the minimum value of the calculated power ratio, hold the updated minimum value of the power ratio for each frequency band, and output the minimum power ratio held for each frequency band as the amount of echo path coupling for each frequency band Echo signal power for each band by superimposing the received signal power for each band obtained by frequency analysis of the received signal on the echo coupling amount for each band calculated by the echo path coupling amount estimation method Calculate the suppression gain for each frequency band based on the ratio of the input signal power for each band obtained by frequency analysis of the input signal obtained by adding the echo signal sent through the echo path to the transmitted signal and the echo signal power for each band. The above-mentioned suppression gain is superimposed on the amplitude component of the input signal frequency coefficient, the echo signal is suppressed for each frequency band, the frequency coefficient obtained by suppressing the echo signal is synthesized, and the time signal with the echo signal suppressed is output. Characteristic echo suppression method. A first frequency analyzing means for converting the received signal into a frequency coefficient; a first band-specific power calculating means for calculating the received signal power for each frequency band from the frequency coefficient of the received signal analyzed by the first frequency analyzing means; Second frequency analysis means for converting an input signal obtained by adding a reverberation signal via an echo path to a transmitted signal into a frequency coefficient, and a frequency coefficient of the input signal analyzed by the second frequency analysis means for each frequency band. Second-band power calculation means for calculating the power of the input signal, second-band power ratio calculation means for calculating the power ratio of the input signal power to the received signal power for each frequency band, and calculation for each frequency band Update the minimum value of the power ratio, maintain the updated minimum value of the power ratio for each frequency band, and maintain the minimum power ratio for each frequency band for each frequency band. The minimum power ratio value calculated for each frequency band is updated as the amount of resonance path coupling, and the minimum power ratio stored for each frequency band is output as the amount of echo path coupling for each frequency band. And an echo path coupling amount estimation device constituted by means,
The echo signal power calculation for each band calculates the echo signal power for each band by superimposing the received signal power for each band obtained by frequency analysis of the received signal on the echo path coupling amount for each band calculated by this echo path coupling amount estimation device. Means,
The input signal power for each band obtained by frequency analysis of the input signal obtained by adding the echo signal transmitted through the echo path to the transmitted signal, and the echo signal for each band calculated by the above-mentioned echo signal power calculation means for each band A suppression gain calculation means for obtaining an echo suppression gain for each frequency band by the ratio of
Echo suppression means for superimposing the echo suppression gain for each frequency band calculated by the suppression gain calculation means and the frequency coefficient of the input signal, and suppressing echo for each frequency band;
A time signal synthesizing unit that synthesizes a frequency coefficient in which echo is suppressed by the echo suppression unit, and synthesizes the time coefficient;
Echo suppression device composed of.   8. An echo suppression program that is written in a computer-readable program language and causes the computer to function as the echo suppression device according to claim 7.   The power of the received signal is calculated, the received signal power is multiplied by the echo path coupling amount of the frequency bands collectively calculated by the echo path coupling amount estimating means according to claim 2, and the reciprocal thereof is obtained to obtain the loss amount. An echo suppression method comprising: multiplying an input signal obtained by adding an amount of loss to a transmission signal and an echo signal transmitted through an echo path to suppress an echo signal included in the input signal. A reception signal power calculation means for calculating the power of the reception signal;
A loss amount calculation for multiplying the echo path coupling amount of the frequency bands calculated by the echo path coupling amount estimation device according to claim 4 by the reception signal power calculated by the reception signal power calculation unit and obtaining an inverse thereof as a loss amount Means,
Loss means for multiplying the microphone input signal by the loss amount counted by the loss amount calculation unit and outputting the signal as a signal in which the echo signal is suppressed,
Echo suppressor configured by.   An echo suppressor program, which is written in a computer-readable program language and causes the computer to function as the echo suppressor according to claim 10.   The loss amount to be inserted into the communication loop is calculated from the band collective echo path coupling amount calculated by the echo path coupling amount estimation method according to claim 2, and the loss amount of the loss device inserted into the communication path is calculated according to the calculated loss amount. A loss amount control method on a communication path, characterized by controlling. Loss amount calculation means for calculating a loss amount to be inserted into the communication loop from the band collective acoustic coupling amount calculated by the echo path coupling amount estimation device according to claim 4;
Loss control that determines whether the loss amount calculated by this loss amount calculation means should be inserted on the receiver side or transmitter side, and controls the loss amount of the losser inserted on the receiver side and transmitter side according to the determination Means,
A loss control device on a communication path, comprising:   14. A loss control program on a communication path, which is written in a computer-readable program language and causes the computer to function as a loss control device on a communication path according to claim 13. A multi-channel echo suppression method for suppressing a plurality of echoes generated when an N-channel (N> 1) reception signal is reproduced and an M-channel (M> 1) input signal is picked up,
7. A multi-channel echo suppression method, wherein echoes are suppressed for each M channel by the echo suppression method according to claim 6 using an added reception signal obtained by adding N channel reception signals and M input signals. . A multi-channel echo suppression apparatus that reproduces an N-channel (N> 1) received signal and suppresses a plurality of echoes generated when an M-channel (M> 1) input signal is picked up.
An adder for adding N-channel received signals, and an echo suppressor according to claim 7 for suppressing each echo for each M channel using the added received signals added by the adder and M input signals. Multi-channel echo suppressor configured.   A multi-channel echo suppression program that is written in a computer-readable program language and causes the computer to function as the multi-channel echo suppression device according to claim 16.   A recording medium readable by a computer, and at least the echo path coupling amount estimation program according to claim 5, the echo suppression program according to claim 8, or the echo suppressor program according to claim 11, A recording medium recording any one of the loss control program on a communication path according to claim 14 and the multi-channel echo suppression program according to claim 17.

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