JPH10190533A - Loud-speaker call device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a loud-speaker call device whereby nearly entire dual communication with the common usage of a voice switch system and an echo canceller system by improving the loud-speaker call device and estimating the performance change of an adaptive filter based on a signal referred in the past when the adaptive filter executes learning. SOLUTION: When the adaptive filter 12 executes learning, the integration value of the power of a reception signal RS referred in the past or a transmission signal TS is used so as to estimate the performance of the adaptive filter 12 and the threshold is changed in accordance with the performance change so that nearly entire dual communication where the voice switch system is commonly used with the echo canceller system is stably executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loudspeaker system, and more particularly to a system for performing two-way communication using a speaker and a microphone, such as a speakerphone or a video conference, by using a simple process to reduce the echo removal performance of an echo canceller. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loudspeaker apparatus capable of improving the estimation and voice switch performance of a voice switch.

[0002]

2. Description of the Related Art A loudspeaker, which does not have a receiver and uses a speaker and a microphone for talking, is used, for example, for a video conference system connecting a plurality of points and a car telephone for keeping a hand off a steering wheel for safety. It is applied to a wide range of fields. The problem with this loudspeaker system is that the sound output from the speaker reverberates and goes around the microphone, and the acoustic echo generated by the speaker and the voice generated by the speaker due to the impedance mismatch at the line coupling part are reflected. This is a phenomenon called line echo that occurs. Here, FIG. 6 is a diagram for simply explaining the acoustic echo and the line echo. This problem is serious because, for example, as shown in FIG.
The acoustic echo path and the line echo path are simultaneously established,
This is a case where a closed loop (a closed loop including the microphone 61, the line SP, and the speaker 62) is formed via the line. That is, when the gain of the closed loop exceeds 1, oscillation (howling) occurs in the closed loop, and in the worst case, communication becomes impossible. Even in the case where oscillation does not occur, for example, in the case of a line echo, the sound uttered by itself is output from the speaker 62 with a delay, which makes it very difficult to speak.

[0003] Devices for avoiding the effect of the echo are roughly classified into two types. One is to insert an electrical loss in the receiving path of the near-end speaker when the speaker is talking (transmitting state), and to insert it in the transmitting path of the speaker when the speaker is listening. This is a half-duplex voice switch system in which a loss is inserted (in the receiving state). In this method, the switching between the transmission state and the reception state is performed based on the voice uttered by the near-end or far-end speaker. The other is an echo canceller system that creates a signal that approximates the echo by using an adaptive filter that estimates the characteristics of the echo, and removes the echo signal from the closed loop by subtracting the signal from the transmission line. . In the echo canceller system, the echo is removed in real time, and both the transmission path and the reception path are not closed, so that full-duplex communication can be performed.

Meanwhile, the technology relating to the loudspeaker using the voice switch as described above is disclosed in, for example, Japanese Patent Publication No. 5-44
No. 221. Here, FIG. 7 is a diagram showing a schematic configuration of the loudspeaker apparatus described in the above-mentioned document. As shown in FIG. 7, in the loudspeaker apparatus 100 using the voice switch, a transmitting unit 200 includes a multiplexer 210 for temporarily storing a plurality of inputs such as a voice signal input from a microphone 111, and a computer described later. Mute control 21 for closing the transmission path according to a control signal from 110
1, a high-pass filter 212 for removing background noise included in the audio signal, and a programmable attenuator for attenuating the audio signal passing through the high-pass filter 212 in accordance with a control signal from the computer 110 213
(Corresponding to the receiving state setting means), an envelope detector 214 for detecting an envelope of the audio signal output from the high-pass filter 212, and a switching noise generated by the programmable attenuator 213. A low-pass filter 215 for shaping the output waveform of the signal and a logarithmic amplification detector 2 for logarithmically amplifying the output from the envelope detector 214
16 is provided.

[0005] Further, the receiving unit 3
Reference numeral 00 designates a multiplexer 310 for temporarily storing a plurality of inputs, such as an audio signal received via the line 102, and a control signal from the computer 110, which includes the same circuit as the transmission unit 200. A mute control 311 for closing a receiving path, a high-pass filter 312 for removing background noise included in the audio signal, and the audio signal passing through the high-pass filter 312 are controlled according to a control signal from the computer 110. Attenuator 313 (corresponding to a transmission state setting means) for providing attenuation, an envelope detector 314 for detecting an envelope of the audio signal output from the high-pass filter 312, and a programmable attenuator 3
13 includes a low-pass filter 315 for attenuating the switching noise generated at 13 and shaping the output waveform to the speaker 112, and a logarithmic amplification detector 216 for logarithmically amplifying the output from the envelope detector 314. The computer 110 (corresponding to the state switching means) converts the signals from the logarithmic amplifiers 216 and 316 into the multiplexer 1.
17, received via the A / D converter 115, and mute control 211, 311, and the programmable attenuator 21
3, 313. The computer 110 is also connected to a calibration circuit 113. The calibration circuit 113 is used to input predetermined calibration sounds to the multiplexers 210 and 310 and to estimate the characteristics of the system.

Hereinafter, the operation of the above-mentioned voice communication device will be described.
The following describes an example of a transmission interruption that switches from a reception state to a transmission state. FIG. 8 is a flowchart for explaining the transmission interruption operation. As shown in FIG. 8, when the loudspeaker apparatus is in the receiving state (S1001), first, the transmission signal TX-S input from the microphone 111 is set to a predetermined threshold value. It is determined whether or not the value is greater than Th times (S1002). Here, the predicted transmission signal TX-E is a signal that predicts a transmission signal generated by coupling the reception signal RX-S from the speaker 112 to the microphone 111.
That is, this step S1002 is provided to prevent the apparatus from self-switching by the reception signal RX-S output from the speaker 112 even when the near-end speaker is not speaking due to the influence of the acoustic echo. In order to In step S1002, the transmission signal TX-S is converted to the predicted transmission signal TX-E
If the transmission noise TX-N exceeds the threshold value Th, it is determined whether or not the transmission signal TX-S exceeds the transmission noise TX-N by a predetermined threshold Th. The determination here is provided to determine whether the transmission signal TX-S is a voice signal or a noise signal. In step S1003, it is confirmed that the transmission signal TX-S is an audio signal, and it is only after that whether or not the transmission signal TX-S exceeds the reception signal RX-S by a predetermined threshold Th is compared. This is performed (S1004). Then, in step 1004, if the transmission signal TX-S exceeds the reception signal RX-S, the reservation timer is initialized (S1005), and the state shifts to the transmission state (S1006). Thus, in the above-mentioned loudspeaker apparatus, erroneous switching due to acoustic echo is prevented by comparing the transmission signal TX-S with the predicted transmission signal TX-E. still,
The prevention of erroneous switching due to the line echo is in a front-to-back relationship with the case of the acoustic echo, and is substantially equivalent, and therefore description thereof is omitted.

[0007] By the way, the predicted transmission signal TX-E and the process S
The threshold value used for the determination in 1004 is the calibration circuit 11
3 is determined using the calibration sound actually emitted. More specifically, if the calibration circuit 113
A signal having an audible frequency in the range of about 3.4 kHz is regularly emitted from the speaker to the surrounding environment, and the maximum amplitude of the acoustic echo signal and the duration of reverberation are obtained based on the acoustic response measured at that time. Thus, the predicted transmission signal TX
-E and threshold are determined. The calibration sound is transmitted when no audio signal is detected on the transmission path and the reception path, and the predicted transmission signal TX-E and the threshold value can be changed in response to a change in environment. For this reason, when there is little reverberation in the surrounding environment and the sound condition is good, or when the line condition is good, the interrupt threshold value set according to the acoustic echo or the line echo is lowered, so that full duplex is achieved. Close communication can be performed.

On the other hand, the technology relating to the echo canceller
For example, it is disclosed in JP-A-61-258554. Here, FIG. 9 is a diagram showing a schematic configuration of the echo canceller disclosed in the above document. As shown in FIG. 9, the echo canceller performs a reception signal X received from a line.
An XR memory 906 for storing R in time series, and a speaker 9
A memory 907 for storing an estimated value A of the acoustic echo characteristic wrapping around from the microphone 02 to the microphone 901, an arithmetic circuit 908 for performing a convolution operation of the received signal XR and the estimated value A, and an arithmetic circuit for calculating the acoustic echo signal from the acoustic echo signal Subtraction circuit 909 for suppressing the acoustic echo signal by subtracting the output of 908
And XT memory 910 for storing transmission signal XT in time series
And an H memory 91 for storing an estimated value H of the line echo characteristic
1, an arithmetic circuit 912 for performing a convolution operation of the transmission signal XT and the estimated value H, a subtraction circuit 913 for suppressing the line echo signal by subtracting the output of the arithmetic circuit 912 from the line echo signal, Memory 906 or X
To sequentially correct the estimated value A or H stored in the A memory 907 or the H memory 911 based on the reception signal XR or transmission signal XT stored in the T memory 910 and the output of the subtraction circuit 909 or 913 Adaptive control circuit 914 for obtaining a correction coefficient of
4, an addition circuit 915 for sequentially correcting the estimated value A by adding the correction coefficient obtained in step 4, an addition circuit 916 for sequentially correcting the estimated value A by adding the correction coefficient obtained in the adaptive control circuit 914, Switches 917, 918, and 919 for selecting an input / output signal of the control circuit 914, and voice signals of a transmission signal and a reception signal are detected.
8 and 919, and a signal detection circuit 920 (corresponding to an audio signal detection unit).

The above-described echo canceller normally performs processing divided by two circuits, an adaptive control circuit for removing acoustic echo and an adaptive control circuit for removing line echo, by a signal detecting circuit 92.
0 and a single adaptive control circuit 914 whose inputs and outputs are controlled by switches 917, 918 and 919,
Although the hardware configuration is simplified, the acoustic echo cancellation and the line echo cancellation are basically the same processing. Therefore, only the acoustic echo cancellation will be described below, and the line echo cancellation is not necessary. Omitted unless otherwise noted.

In the echo canceler, when the signal detection circuit 920 detects a voice signal only in the received signal XR, adaptive learning of the echo canceller is performed.
That is, modifications obtained by the adaptive control circuit 914 coefficients .DELTA.a _n
Estimated value train a _n of the impulse response stored in the A memory 7 is modified sequentially by. For this correction, for example, a learning identification method is used. The following equation (1) specifically shows the correction by the learning identification method.

(Equation 1) It should be noted that the above adaptive learning is performed when a voice signal is detected only in the received signal, because the voice signal uttered by the near-end speaker is originally irrelevant to the acoustic echo characteristics. This is because, when the voice signal emitted by the near-end speaker is input to the echo canceller, the voice signal emitted by the near-end speaker becomes a disturbance and hinders the learning of the echo canceller. As described above, in the loudspeaker apparatus having the above-described echo canceller, the echo can be more accurately removed as time elapses by sequentially correcting the impulse response of the adaptive filter using the learning identification method.

[0011]

By the way, if the above two systems, ie, the voice switch system and the echo canceller system, are used together, the echo is attenuated by the attenuator of the voice switch and the adaptive filter of the echo canceller is used.
Since the echo is removed to some extent, it is possible to provide a system that is nearly full duplex and is less affected by the echo. The problem is the setting of the threshold value for switching between transmission and reception in the voice switch system. In the voice switch method, as described above, the characteristics of the system can be directly measured by the calibration sound emitted from the calibration circuit 113, and the threshold value can be adjusted in accordance with the echo. When used together, the amount of echo remaining in the system changes momentarily according to the degree of learning of the adaptive filter, so adjustment is useless at a threshold value that is calibrated only during a specific period, and consequently the cause of erroneous switching. Becomes In order to solve the problems in the conventional technology, the present invention improves a loudspeaker apparatus, and estimates a performance change of the adaptive filter based on a signal referred to in the past when the adaptive filter learns. ,
It is an object of the present invention to provide a loudspeaker apparatus capable of stably performing nearly full-duplex communication using both a voice switch system and an echo canceller system.

[0012]

According to a first aspect of the present invention, there is provided a receiving state setting means for setting a receiving state in which a transmission signal input from a microphone is attenuated during transmission to a line. A transmission state setting means for setting a transmission state in which a reception signal received from a line is attenuated while being output from a speaker; and a transmission state setting means for setting an acoustic echo generated when the reception signal wraps around from a speaker to a microphone. State switching means for switching between the transmission state and the reception state based on a predetermined acoustic echo threshold value, and detecting a voice signal from the transmission and reception signals; A sound signal detecting means for changing the response based on an acoustic echo when the sound signal is detected only in the received signal by the sound signal detecting means; Having an adaptive filter for estimating sequentially,
A speech communication apparatus comprising: an acoustic echo canceling means for subtracting a pseudo acoustic echo signal obtained by inputting the reception signal to the adaptive filter from the transmission signal; a history of the reception signal output from the speaker in the past. A residual acoustic echo estimating means for estimating a residual acoustic echo signal remaining without being removed by the acoustic echo removing means on the basis of the above, and the state switching according to the residual acoustic echo signal estimated by the residual acoustic echo estimating means Means for changing the acoustic echo threshold of the means. In the loudspeaker apparatus according to the first aspect, the remaining acoustic echo signal is estimated based on the received signal output from the speaker in the past, and the acoustic echo threshold for switching between the transmission state and the reception state is estimated. Can be changed according to the remaining acoustic echo signal, so that the acoustic echo removing means and the transmitting / receiving state setting means cooperate,
It is possible to realize a comfortable two-way communication system with improved transmission / reception switching performance.

In the loudspeaker apparatus, the remaining acoustic echo signal may be, for example, a power of a received signal obtained by integrating the power of the received signal when the voice signal is detected only in the received signal by the voice signal detecting means. It can be estimated based on the value. Also, the remaining acoustic echo signal can be estimated based on the received signal detection integrated value obtained by integrating the detection time of the received signal when the voice signal is detected only in the received signal by the voice signal detecting means. .
A simple processing based on the power of the received signal and the integrated value of the detected time of the received signal reduces the amount of calculation for changing the acoustic echo threshold value, and is inexpensive and consumes less power than conventional systems. Can be provided.

According to a second aspect of the present invention, there is provided a receiving state setting means for setting a receiving state in which a transmitting signal inputted from a microphone is attenuated during transmission to a line, and a receiving signal received from the line is output from a speaker. A transmission state setting means for setting a transmission state to be attenuated during transmission, and a predetermined line echo threshold value set for a line echo generated when the transmission signal sneak from the line transmission side to the line reception side. State switching means for determining a magnitude relationship between the transmission signal and the reception signal based on the transmission signal and the reception state, and audio signal detection means for detecting an audio signal from the transmission signal and the reception signal. An adaptive filter for sequentially estimating the characteristics of the line echo by changing the response based on the line echo when the voice signal is detected only in the transmission signal by the voice signal detection means; And a line echo removing means for subtracting a pseudo-line echo signal obtained by inputting the transmission signal to the adaptive filter from the reception signal. Remaining line echo estimating means for estimating the remaining line echo signal remaining without being removed by the line echo removing means based on the history of the transmitted transmission signal, and the remaining line echo signal estimated by the remaining line echo estimating means. And a line echo threshold changing means for changing the line echo threshold of the state switching means in accordance with the above. In the loudspeaker apparatus according to the second invention, the remaining line echo signal is estimated based on a transmission signal output from the microphone to the line in the past, and the line echo threshold for switching between the transmission state and the reception state is determined. Can be changed according to the estimated remaining line echo signal, so that the line echo canceling means and the transmission / reception state setting means can cooperate to provide a comfortable two-way communication system with improved transmission / reception switching performance. Can be realized.

In the loudspeaker apparatus, the remaining line echo signal is, for example, a speech signal obtained by integrating the power of the transmission signal when the speech signal is detected only in the speech signal by the speech signal detection means. It can be estimated based on the signal power integrated value. Further, the remaining line echo signal is estimated based on a transmission signal detection integrated value obtained by integrating the detection time of the transmission signal when the voice signal is detected only in the transmission signal by the voice signal detecting means. You can also.
By a simple process based on the power of the transmission signal and the integrated value of the detected time of the transmission signal, the amount of calculation for changing the line echo threshold is reduced. Fewer systems can be provided.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
It should be noted that the following embodiments are examples embodying the present invention, and do not limit the technical scope of the present invention. Here, FIG. 1 is a diagram showing a schematic configuration of a loudspeaker apparatus according to an embodiment of the present invention, FIG. 2 is a flowchart for explaining the operation of the loudspeaker apparatus, and FIG. FIG. 4 is a diagram illustrating a temporal performance change of the canceller, and FIG. 4 is a diagram illustrating a state of threshold adjustment using signal power in a time series.

As shown in FIG. 1, the voice communication apparatus according to the present embodiment has a general configuration in which a voice switch unit VS is connected to a transmission signal TS input from a microphone 1 by, for example, a two-wire to four-wire converter. A receiving state setting means 2 for setting a receiving state to be attenuated during transmission to the line SP, and a transmitting state setting for setting a transmitting state to attenuate a receiving signal RS received from the line SP to the speaker 3 during output. Means 4, a signal level detector 5 for detecting the signal levels of the transmission signal TS and the reception signal RS, and setting for a line echo generated when the transmission signal TS wraps around from the line transmitting side 20 to the line receiving side 21. A line echo transmission / reception determination means 6 for determining the magnitude relationship between the reception signal RS and the transmission signal TS based on the determined predetermined line echo threshold GRS, and the reception signal RS sneaking into the microphone 1 from the speaker 3. An acoustic echo transmission / reception determination means 7 for determining the magnitude relationship between the transmission signal TS and the reception signal RS based on a predetermined acoustic echo threshold GTS set for the acoustic echo generated in A voice signal detecting means 8 for detecting a voice signal from the signal RS, and a transmission state setting when the transmission signal TS is determined to be larger or smaller than the reception signal RS by the line echo transmission / reception determination means 6 in the transmission priority mode. The transmitting state or the receiving state is set by the means 4 or the receiving state setting means 2, and when the voice signal is detected from the transmitting signal TS or the receiving signal RS by the voice signal detecting means 8, the transmitting state or the receiving state is changed. The first transmission / reception state in which the signal is maintained and, if it is determined that the signal is a noise signal, the attenuation in the reception state setting means 2 and the transmission state setting means 4 is shifted to the intermediate state. A receiving means 9 (corresponding to a state switching means) and a receiving state setting means 2 or a transmitting state when the acoustic echo transmission / reception determining means 7 determines that the received signal RS is larger or smaller than the transmitted signal TS in the receiving priority mode. The receiving state or the transmitting state is set by the setting unit 4, and the receiving signal R is set by the voice signal detecting unit 8.
If a voice signal is detected from S or the transmission signal TS, the reception state or the transmission state is maintained, and if it is determined that the signal is a noise signal, the reception state setting means 2 and the transmission state setting means The second to shift the amount of attenuation in 4 to the intermediate state
Transmission / reception state switching means 10 (corresponding to state switching means), and the first transmission / reception state switching means 9 causes the line echo transmission / reception determination means 6 to transmit the transmission signal TS to the reception signal RS.
If it is determined to be smaller than the above, and the state is set to the receiving state or the intermediate state, the next processing is transferred to the second transmitting / receiving state switching means 11, and the second transmitting / receiving state switching means 11 The reception signal R is determined by the echo transmission / reception determination means 7.
If it is determined that S is smaller than the transmission signal TS and the transmission state or the intermediate state is set, the processing transition means 1 for transitioning the next processing to the first transmission / reception state switching means 9
1, and the line echo threshold GRS and the acoustic echo threshold GTS can be changed by the line echo threshold changing unit 17 and the acoustic echo threshold changing unit 15 described later. Further, the above-mentioned voice communication device has a voice switch unit VS,
There is provided a transmission / reception determination means 18 for checking the presence or absence of the transmission signal TS or the reception signal RS after removing the influence of the gain of the system based on the transmission side gains Gt and Gr set in advance.

Further, the above-mentioned loudspeaker apparatus changes the response based on an acoustic echo or a line echo when the voice signal is detected only in the received signal RS or the transmitted signal TS by the voice signal detecting means 8, and Adaptive filter 12 (12a, 12a, 12a)
b), a pseudo acoustic or line echo signal obtained by inputting the reception signal RS or the transmission signal TS to the adaptive filter 12 (12a, 12b) and subtracting the acoustic or line echo signal from the transmission signal TS or the reception signal RS. Canceller 13a or 1
3b (corresponding to acoustic or line echo removing means). And, the above-mentioned voice communication device has a voice switch unit V
In order to make S cooperate with the acoustic echo canceller unit 13a and the line echo canceller unit 13b, based on the history of the received signal RS output from the speaker in the past, the remaining sound that has not been removed by the acoustic echo canceller unit 13a. Residual acoustic echo estimation means 14 for estimating an echo signal
An acoustic echo threshold changing means 15 for changing the acoustic echo threshold GTS of the acoustic echo transmission / reception determining means 7 in accordance with the residual acoustic echo signal estimated by the residual acoustic echo estimating means 14; The remaining line echo estimating means 16 for estimating the remaining line echo signal remaining without being removed by the line echo canceller unit 13b based on the history of the output transmission signal TS, and the above-mentioned estimated by the remaining line echo estimating means 16 A line echo threshold value changing means for changing a line echo threshold value of the line echo transmission / reception determining means in accordance with the remaining line echo signal;

Referring now to FIG. 2, a description will be given of the transmission / reception switching operation of the above-described loudspeaker apparatus and the change of the threshold value.
In the following, the case where the attenuation amount of the receiving state setting means 2 is 0 and the attenuation amount of the transmitting state setting means 4 is the maximum is the transmitting state, and the amount of attenuation of the receiving state setting means 2 is half the maximum value. The case where the amount of attenuation of the talking state setting means 4 is half the maximum value is a transmission waiting state, the case where the amount of attenuation of the receiving state setting means 2 is maximum and the amount of attenuation of the transmitting state setting means 4 is 0, the receiving state, The case where the attenuation amount of the receiving state setting means 2 is half the maximum value and the attenuation amount of the transmitting state setting means 4 is half the maximum value is referred to as a reception waiting state. Further, the transmission state and the transmission waiting state are collectively referred to as transmission priority, and the reception state and the reception waiting state are collectively referred to as reception priority.

When the power of the apparatus is turned on and the loudspeaker apparatus is connected to a general line, the loudspeaker apparatus is normally set to the reception priority. Here, the switching operation in the transmission priority state is performed. That is, the operation of the first transmission / reception state switching means 9 will be described first. First, the mode setting is confirmed in the first transmission / reception state switching means 9 (S1).
01). Next, based on the line echo threshold GRS, the line echo transmission / reception determination means 6 makes a comparison determination of the signal levels of the transmission signal TS and the reception signal RS (S102),
If the transmission signal TS is larger than the reception signal RS, step S1
03, if it is smaller, the process proceeds to step S104. By the way, in step S102, it is shown that the transmission priority processing is continued unless the voice of the far end speaker clearly exceeds the line echo. For this reason, in the voice switch unit VS, the transmission priority processing is maintained even when there is a situation in which the near end speaker is silent for a while due to the transmission priority.

In step S103, the transmission priority flag is set again, and then the audio signal of the transmission signal TS is detected by the audio signal detection means 8 (S105).
The detection by the audio signal detecting means 8 is performed, for example, by using the transmission signal TS.
Is larger than the noise signal threshold, the signal is performed as a voice signal. In step S105,
When it is determined that the transmission signal TS is a voice signal, the reception state setting means 2 and the transmission state setting means 4 are set to the transmission state (S106). Step S102 and step S102
In the state where the detection of the voice signal is confirmed only in the transmission signal TS by the determination of 105, the remaining line echo signal remaining without being removed by the line echo canceller 13b is estimated by the remaining line echo estimating means 16 (S10).
7).

Here, based on FIGS. 3 and 4, it is shown that the performance of the adaptive filter 12 used in the echo canceller can be almost estimated by the characteristics of the input signal referred to for adaptive learning of the adaptive filter 12. FIG. 3 shows a state in which the remaining line echo signal decreases as time passes. On the other hand, FIG. 4A shows the signal power of the input signal referred to by the adaptive filter 12 during the adaptive learning, and FIG. 4B shows the time integral of the signal power of the transmission signal TS. I have. Further, from FIGS. 3 and 4B, it can be understood that the degree of learning of the adaptive filter 12 increases as the integrated value of the power of the input signal referred to increases. For this input signal, for example, a transmission signal when a voice signal is detected only in the transmission signal TS may be used, and thus no special measuring means is required. Therefore, the input signal (here,
An operation is performed such that the output decreases as the integrated value of the power of the transmission signal TS) increases. FIG. 4C shows the results in a time series. The actual residual line echo amount shown in FIG. 3 and the estimation of the residual line echo shown in FIG. 4 (c) agree in that tendency, and are sufficient for use in correcting the line echo threshold. It is about. Then, in response to the remaining line echo signal estimated by the remaining line echo estimation unit 16, the line echo threshold GRS is changed by the line echo threshold changing unit 17 as shown in FIG.
It is changed as shown in (d) (S108). As described above, it is possible to easily estimate the performance change of the echo canceller based on the past input signal referred to by the adaptive filter 12 at the time of learning. Also, no special measuring means for performing calibration is required for the estimation.

In step S104, the transmission signal T
If it is determined that S is a noise signal, the receiving state setting means 2 and the transmitting state setting means 4 are set to the intermediate state (S109). When continuing the determination processing after the end of step S106 and step S109, the process returns to step S101.

On the other hand, in step S102, the transmission signal TS
Is smaller than the reception signal RS, the transmission / reception determination means 18 compares the transmission signal TS with the reception signal RS based on the transmission side gain Gt and the reception side gain Gr (S104). In this step S104, the possibility of reception is checked by removing the gain of the system. here,
If the transmitting side is larger, the process returns to step S103 and the presence or absence of the transmitted voice is set. If the receiving side is larger, a flag is set to the receiving priority in step S110, and the next step S111
The presence or absence of the received voice is checked at. In step S111, the audio signal of the reception signal RS is detected by the audio signal detection means 8. The judgment of the audio signal detecting means 8 is as follows.
As in the case of the transmission signal TS, the determination is made based on whether the reception signal RS is larger or smaller than the noise signal threshold. Process S
If it is determined in step 111 that the reception signal RS is a voice signal, the reception state setting means 2 and the transmission state setting means 4 are set to the reception state (S112). Also, as in the case of changing the line echo threshold, steps S113 and S11
4 changes the acoustic echo threshold value. When it is determined that the transmission signal TS is a noise signal, the reception state setting means 2 and the transmission state setting means 4 are set to the intermediate state (S115). Then, step S112 and step S1
When the determination process is continued after the end of step 15, the process returns to step S101. Here, when returning to step S101, the acoustic echo threshold value or the line echo threshold value is set low with the improvement of the performance of the echo canceller. It is also possible to do.

In the determination process in the first transmission / reception state switching means 9, if a flag is set for the reception priority, the processing transition means 11 switches the first transmission / reception state switching means 9 to the second transmission / reception state switching means 9. The determination process is shifted to the means 10. Note that the determination processing performed by the first transmission / reception state switching means 9 and the second transmission / reception state switching means 10 are in front and back, and are substantially equivalent. When the mode shifts from the transmission priority to the reception priority by, for example, uttering the far-end speaker, first, the acoustic echo transmission / reception determination means 7 determines the size of the reception signal RS and the transmission signal TS based on the acoustic echo threshold GTS. The relationship is determined (S202). When it is determined in step S202 that the reception signal RS is larger than the transmission signal TS, the process proceeds to step S203, and when it is determined that the reception signal RS is smaller, the process proceeds to S204. By the way, in step S202,
This indicates that the reception priority processing is continued unless the sound of the near end speaker clearly exceeds the acoustic echo. For this reason, in the voice switching device, the reception priority processing is maintained even when there is a situation in which the far-end speaker is silent for a while with the reception priority. In step S203, the reception priority flag is set again. In this step, it is specified that the determination processing is performed by the second transmission / reception state switching means 10 when the processing is continued.

Next, it is determined by the voice signal detecting means 8 whether or not the received signal RS has a voice signal (S2).
05). If it is determined in step S205 that the reception signal RS is a voice signal, the reception state setting means 2 and the transmission state setting means 4 are set to the reception state (S206). Also, as in the above case, step S207
Then, the acoustic echo threshold value is changed in step S208. If it is determined that the reception signal RS is a noise signal, the reception state setting means 2 and the transmission state 4 are set to the intermediate state (S209). After the state setting in step S206 or step S209, if the process is to be continued, the process returns to step S101. On the other hand, step S20
2, if it is determined that the received signal RS is smaller than the transmitted signal TS, the transmitted / received
The comparison between S and the reception signal RS is performed based on the transmission side gain Gt and the reception side gain Gr (S204). This step S
At 204, the possibility of transmission is checked by removing the gain of the system. Here, if the receiving side is larger, the process returns to step S203 to determine whether or not there is a received voice, and if the transmitting side is larger, the flag is switched from receiving priority to transmitting priority in step S210, and the next step S211. In step (1), the presence or absence of a transmission voice is checked. In step S210, it is specified that the next processing determination is to be transferred to the first transmission / reception state switching means 9.

In step S211, the audio signal detection means 8 determines whether the transmission signal TS has an audio signal or a noise signal. If the determination in step S211 is a voice signal, the receiving state setting means 2 and the transmitting state setting means 4 are set to the transmitting state (S212). Also, as in the above case, the line echo threshold is changed in steps S213 and S214. If the transmission signal TS is a noise signal, the reception state setting means 2 and the transmission state setting means 4 are set to the intermediate state (S215). Step S212
Alternatively, if the process is continued after the state setting in step S215 is completed, the process returns to step S101. Here, when returning to step S101, the acoustic echo threshold value or the line echo threshold value is set low with the improvement of the performance of the echo canceller. It is also possible to do. As described above, in the above-described loudspeaker apparatus, since the performance change of the echo canceller can be estimated from the integrated value of the power of the input signal referred to by the adaptive filter 12 at the time of learning, the echo canceller and the voice switch are coordinated. It is possible to realize a comfortable two-way communication system with improved transmission / reception switching performance. In addition, since the estimation of the performance change of the echo cassella is performed by a simple arithmetic processing, an inexpensive device with low power consumption can be realized. Further, since the threshold value is changed according to the performance of the echo canceller that changes with time during a call, there is no need to use an unpleasant calibration sound.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the loudspeaker apparatus according to the above embodiment, a loudspeaker apparatus capable of changing the acoustic echo threshold (corresponding to the first invention) and a loudspeaker apparatus capable of changing the line echo threshold ( (Corresponding to the second aspect of the present invention). However, for example, when the distance between the microphone 1 and the speaker 3 is so long that the acoustic echo can be ignored, or when a short-range call is made and a two-wire circuit is used. If the line echo that can be directly connected can be ignored, the loudspeaker that can change the acoustic echo threshold and the loudspeaker that can change the line echo threshold can be used independently. It is. In this case, since the threshold value correction processing may be performed for either the acoustic echo or the line echo, the cost can be further reduced. Such a loudspeaker apparatus is also an example of the loudspeaker apparatus in the present invention. Further, in the above embodiment, the performance change of the adaptive filter 12 is estimated using the integrated value of the power of the past input signal, but as shown in FIG. The above estimation may be performed based on the above.
The time when the power of the signal is assumed to be constant corresponds to the estimation based on the integrated value of time. When the estimation is performed based on the integrated value of time, the amount of calculation is further reduced. Such a loudspeaker apparatus is also an example of the loudspeaker apparatus in the present invention.

[0029]

As described above, the first aspect of the present invention is a receiving state setting means for setting a receiving state for attenuating a transmission signal input from a microphone during transmission to a line, and a receiving state received from the line. A transmission state setting means for setting a transmission state in which a signal is attenuated while being output from the speaker, and a predetermined acoustic echo threshold value set for an acoustic echo generated when the received signal is transmitted from the speaker to the microphone. State switching means for determining the magnitude relationship between the transmission signal and the reception signal and switching between the transmission state and the reception state; voice signal detection means for detecting a voice signal from the transmission signal and the reception signal; An adaptive filter for changing a response based on an acoustic echo when the audio signal is detected only in the received signal by the audio signal detecting means and sequentially estimating the characteristics of the acoustic echo And a sound echo removing means for subtracting a pseudo acoustic echo signal obtained by inputting the reception signal to the adaptive filter from the transmission signal. A remaining acoustic echo estimating means for estimating a residual acoustic echo signal remaining without being removed by the acoustic echo removing means on the basis of a signal history; and a residual acoustic echo signal estimated by the residual acoustic echo estimating means. An acoustic echo threshold changing means for changing an acoustic echo threshold of the state switching means is provided as a voice communication device. In the loudspeaker apparatus according to the first aspect, the remaining acoustic echo signal is estimated based on the received signal output from the speaker in the past, and the acoustic echo threshold for switching between the transmission state and the reception state is estimated. Since it can be changed according to the remaining acoustic echo signal, the acoustic echo canceling means and the transmission / reception state setting means cooperate to realize a comfortable two-way communication system with improved transmission / reception switching performance. Can be.

In the loudspeaker apparatus, the remaining acoustic echo signal is, for example, a received signal power integration obtained by integrating the power of the received signal when the voice signal is detected only in the received signal by the voice signal detecting means. It can be estimated based on the value. Also, the remaining acoustic echo signal can be estimated based on the received signal detection integrated value obtained by integrating the detection time of the received signal when the voice signal is detected only in the received signal by the voice signal detecting means. .
A simple processing based on the power of the received signal and the integrated value of the detected time of the received signal reduces the amount of calculation for changing the acoustic echo threshold value, and is inexpensive and consumes less power than conventional systems. Can be provided.

According to a second aspect of the present invention, there is provided a receiving state setting means for setting a receiving state in which a transmitting signal inputted from a microphone is attenuated during transmission to a line, and a receiving signal received from the line is output from a speaker. A transmission state setting means for setting a transmission state to be attenuated during transmission, and a predetermined line echo threshold value set for a line echo generated when the transmission signal sneak from the line transmission side to the line reception side. State switching means for determining a magnitude relationship between the transmission signal and the reception signal based on the transmission signal and the reception state, and audio signal detection means for detecting an audio signal from the transmission signal and the reception signal. An adaptive filter for sequentially estimating the characteristics of the line echo by changing the response based on the line echo when the voice signal is detected only in the transmission signal by the voice signal detection means; And a line echo removing means for subtracting a pseudo-line echo signal obtained by inputting the transmission signal to the adaptive filter from the reception signal. Remaining line echo estimating means for estimating the remaining line echo signal remaining without being removed by the line echo removing means based on the history of the transmitted transmission signal, and the remaining line echo signal estimated by the remaining line echo estimating means. And a line echo threshold changing means for changing the line echo threshold of the state switching means in accordance with the above. In the loudspeaker apparatus according to the second invention, the remaining line echo signal is estimated based on a transmission signal output from the microphone to the line in the past, and the line echo threshold for switching between the transmission state and the reception state is determined. Can be changed according to the estimated remaining line echo signal, so that the line echo canceling means and the transmission / reception state setting means can cooperate to provide a comfortable two-way communication system with improved transmission / reception switching performance. Can be realized.

In the loudspeaker apparatus, the remaining line echo signal may be, for example, a speech signal obtained by integrating the power of a speech signal when the speech signal is detected only in the speech signal by the speech signal detection means. It can be estimated based on the signal power integrated value. Further, the remaining line echo signal is estimated based on a transmission signal detection integrated value obtained by integrating the detection time of the transmission signal when the voice signal is detected only in the transmission signal by the voice signal detecting means. You can also.
By a simple process based on the power of the transmission signal and the integrated value of the detected time of the transmission signal, the amount of calculation for changing the line echo threshold is reduced. Fewer systems can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a loudspeaker apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the loudspeaker apparatus.

FIG. 3 is a diagram showing a change in performance of the echo canceller in a time series.

FIG. 4 is a diagram for explaining estimation of the performance change based on an integrated value of power of an input signal.

FIG. 5 is a diagram for explaining estimation of the performance change based on an integrated value of the audio signal detection time.

FIG. 6 is a diagram for briefly explaining an echo phenomenon.

FIG. 7 is a diagram showing a schematic configuration of a conventional voice switch communication device of a voice switch type.

FIG. 8 is a flowchart for explaining the operation of the above-mentioned conventional voice communication device.

FIG. 9 is a diagram illustrating a schematic configuration of a conventional loudspeaker apparatus including an echo canceller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Microphone 2 ... Reception state setting means 3 ... Speaker 4 ... Transmission state setting means 6 ... Line echo transmission / reception determination means (line echo threshold) 7 ... Acoustic echo transmission / reception determination means (acoustic echo threshold) 8 ... Voice signal detection Means 9, 10 ... Transmission / reception state setting means (state switching means) 12 ... Adaptive filters 13a, 13b ... Echo removal means 14 ... Remaining acoustic echo estimation means 15 ... Acoustic echo threshold value changing means 16 ... Remaining line echo estimation means 17 ... Line Echo threshold changing means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Akira Nakazumi, Inventor Kobe Steel, Ltd. Osaka Branch, 4-3-1 Bingocho, Chuo-ku, Osaka-shi, Osaka

Claims (6)

[Claims] 1. A receiving state setting means for setting a receiving state for attenuating a transmission signal inputted from a microphone during transmission to a line, and a transmitting means for attenuating a reception signal received from the line during output from a speaker. A transmission state setting means for setting a talking state; and a magnitude of the transmission signal and the reception signal based on a predetermined acoustic echo threshold value set for an acoustic echo generated when the reception signal wraps around from the speaker to the microphone. State switching means for judging the relationship and switching between the transmission state and the reception state, audio signal detection means for detecting an audio signal from the transmission signal and the reception signal, and only the reception signal by the audio signal detection means An adaptive filter for changing the response based on the acoustic echo when the voice signal is detected and sequentially estimating the characteristics of the acoustic echo; A loudspeaker communication device comprising: an acoustic echo removing means for subtracting a pseudo acoustic echo signal obtained by inputting a speech signal from the transmission signal, based on a history of a reception signal output from a speaker in the past. Residual acoustic echo estimating means for estimating a residual acoustic echo signal remaining without being removed by the echo removing means, and an acoustic echo threshold value of the state switching means according to the residual acoustic echo signal estimated by the residual acoustic echo estimating means And an acoustic echo threshold value changing means for changing the threshold value. 2. The apparatus according to claim 1, wherein said residual acoustic echo estimating means integrates the power of the received signal when the voice signal is detected only in the received signal by the voice signal detecting means, based on the integrated power of the received signal. The loudspeaker apparatus according to claim 1, wherein the remaining acoustic echo signal is estimated. 3. The apparatus according to claim 2, wherein said remaining acoustic echo estimating means is based on a received signal detection integrated value obtained by integrating detection time of the received signal when only the received signal is detected by said voice signal detecting means. 2. The loudspeaker apparatus according to claim 1, wherein the remaining acoustic echo signal is estimated by using the following method. 4. A receiving state setting means for setting a receiving state in which a transmitting signal inputted from a microphone is attenuated during transmission to a line, and a transmitting means for attenuating a receiving signal received from the line during outputting from a speaker. Transmitting state setting means for setting a talking state; and the transmitting signal based on a predetermined line echo threshold value set for a line echo generated when the transmitting signal goes from the line transmitting side to the line receiving side. State switching means for judging the magnitude relationship between the transmission signal and the reception signal, switching between the transmission state and the reception state, audio signal detection means for detecting an audio signal from the transmission signal and the reception signal, and the audio signal detection means Changes the response based on the line echo when a voice signal is detected only in the above-mentioned transmission signal,
A loudspeaker having an adaptive filter for sequentially estimating the characteristics of the line echo, and a line echo removing means for subtracting a pseudo line echo signal obtained by inputting the transmission signal to the adaptive filter from the received signal; A remaining line echo estimating unit for estimating a remaining line echo signal remaining without being removed by the line echo removing unit based on a history of a transmission signal output from the microphone to the line in the past, and the remaining line echo A loudspeaker apparatus comprising: a line echo threshold changing unit that changes a line echo threshold of the state switching unit according to the remaining line echo signal estimated by the estimating unit. 5. A transmission signal power integrated value obtained by integrating the power of a transmission signal when a voice signal is detected only in the transmission signal by the voice signal detecting means, wherein the remaining line echo estimating means integrates the power of the transmission signal. 5. The loudspeaker apparatus according to claim 4, wherein the remaining line echo signal is estimated based on the following equation. 6. A transmission signal detection integration obtained by integrating the detection time of a transmission signal when an audio signal is detected only in the transmission signal by the audio signal detection means. 5. The loudspeaker apparatus according to claim 4, wherein said remaining line echo signal is estimated based on a value.