JP2974503B2 - Echo canceller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an echo canceller, and more particularly, to an echo canceller which can be applied to a hands-free telephone.

[0002]

2. Description of the Related Art In recent years, research and development of acoustic echo cancellers for use in hands-free telephones and the like have been actively conducted.

For example, the document: Japanese Patent Laid-Open Publication No. Hei 3-80628 discloses a double talk detection system applicable to an acoustic echo canceller.

According to the above document, for example, the microphone 102 is non-directional, and the microphone 103 has a directivity different from that of the microphone 102. The sound power of the voice uttered by the near end speaker is S2 in the microphone 102, S3 in the microphone 103, and a difference in power occurs between S2 and S3. Then, the input level of the received echo signal of the microphone 102 is R2, the input level of the received echo signal of the microphone 103 is R3, and the microphone 1
Here, the noise input level at 02 is N2 and the noise input level at the microphone 103 is N3, and the above level relationships are as follows.

R2 + N2> R3 + N3 (1), S
3 + N3> S2 + N2 Equation (2), R2> R3 ...
Expression (3), S3> S2 (4) Expression.

Under the above conditions, the power ratio Srec in the receiving state (receiving state) is Srec = (R3 + N3).
/ (R2 + N2). On the other hand, considering the influence of noise, the power ratio Ssend in the transmitting state is Ssend.
(Transmission state) = (S3 + N3) / (S2 + N2). The power ratio in the double talk (transmission / reception) state is Sdouble = (R3 + S3 + N3) / (R2 +
S2 + N2). And Ssend-Sdoub
le = {R2 (S3 + N3) -R3 (S2 + N2)} /
{(S2 + N2). (R2 + S2 + N2)}. Then, according to the above equations (1) to (4), Ssend-
Sdouble> 0 and Srec-Sdouble <0. Therefore, Srec <Sdouble <Ssend
Becomes

[0007] From the above relationship, Srec, Sdoubl
A threshold is provided between e and Ssend to check which state the power ratio is closest to, and each state is identified.

[0008]

However, in the above method, even if the output of the received speaker signal is not output from the speaker 104, the Srec state (reception state) is caused by spatial noises N2 and N3. , The filter coefficients of the adaptive filter 101 are updated, the coefficients are disturbed, and stable echo cancellation cannot be performed.

Further, when the state changes from the reception state to the transmission / reception state, the tap coefficients of the adaptive filter are disturbed, so that there is a problem that stable echo cancellation cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the influence of noise and to stably perform echo cancellation even when the call state changes. It is to provide an echo canceller.

[0011]

In order to achieve the above object, the present invention provides a receiving sound output means for outputting a receiving signal as sound, a sound capturing means for capturing sound and outputting a sound signal, and An adaptive filter for estimating a received sound echo component generated by an echo due to a received sound output; a computing unit for removing the received sound echo component from the sound signal; and a receiving state, a transmitting / receiving state, a transmitting state, and a silent state.
And a call state determining means for controlling the update of the filter coefficient of the adaptive filter in accordance with the result of the determination . The echo-removed sound obtained by removing the received sound echo component from the sound signal. The echo canceller that outputs a signal is realized by the following characteristic adaptive filters, means, and configurations.

(1) The above adaptive filter and the above
And a computer based on the sound signal and the reception signal.
-Equipped with multiple echo removal units that output the removal sound signal,
(2) Further, the plurality of echo removing units are adapted for the adaptive
If the filter coefficient of the filter is at least
For example, the transmission / reception state may be included. ) When different
It is multiplexed to be updated at a certain timing,
(3) Power of echo-removed acoustic signals from each echo-removal unit
And selecting and outputting the echo-removed sound signal from any of the echo-removing units based on the

[0013]

[0014]

According to the present invention, the echo removing units are multiplexed, and the adaptive filters of the respective echo removing units are updated at least with the echo removing sound signals at different times, for example, at the time of the receiving state. In the receiving state and the transmitting and receiving state, each echo removing sound signal output based on the echo component estimated by each echo removing unit is output, and a power comparison is performed, for example, an echo removing acoustic signal having a small power is output. can do.

For example, the first adaptive filter of the first echo removing unit adapts a filter coefficient according to the echo removing signal of the first echo removing unit when there is a received signal (in a receiving state or a transmitting / receiving state). When the second adaptive filter of the second echo removing unit takes in the filter coefficient set in the first adaptive filter at a certain period for the own filter coefficient in the receiving state and sets it, for example, from the receiving state Even if the state changes to the transmission / reception state and the filter coefficient of the first adaptive filter is disturbed by the transmission signal, the reception acoustic echo is performed using the filter coefficient set in the past stable reception state by the second adaptive filter. The power of the echo-removed sound signal obtained by estimating the component is compared with the power of the echo-removed sound signal of the first echo-removing unit, and the echo-removed sound having the smaller power is performed. It is also possible to output a signal.

Accordingly, echo can be stably removed in the receiving state and the transmitting / receiving state.

[0017]

Next, a preferred embodiment of the echo canceller of the present invention will be described with reference to the drawings. FIG. 1 shows a functional block diagram of an adaptive filter unit and an adder applicable to an echo canceller. Prior to this description, an overall outline of the echo canceller will be described with reference to FIG.

FIG. 3 is a functional block diagram of the echo canceller of this embodiment.

In FIG. 3, the echo canceller comprises an omnidirectional microphone 1, a speaker 2, and an echo canceller main body 7. And
The output of the microphone 1 is supplied to the echo canceller main body 7. The echo canceller body 7 outputs a residual signal e as an eco-canceler output. The reception signal is supplied to the echo canceller body 7 and the speaker 2.

Further, the echo canceller main unit 7 includes an adder 3, an adaptive filter unit 4, a microphone output signal power detector 5, a tap coefficient update control unit 6, a residual signal power detector 8, a power ratio It comprises a calculator 9, a received signal power detector 10, and a call state determiner 11.

Next, the function of each section will be described. Adder 3
Calculates the difference between the transmission signal supplied from the microphone 1 and the pseudo echo signal y ^* supplied from the adaptive filter unit 4, outputs a residual signal e, and outputs the residual signal e together with the echo canceller output to the tap coefficient update control unit 6 It is also supplied to the difference power detector 8.

The adaptive filter unit 4 captures the received signal and the transmitted signal from the microphone 1 and generates and adds a pseudo echo signal y ^* based on the control of the tap coefficient control signal from the tap coefficient update control unit 6. To the difference input of the unit 3. Specific example of the configuration of the adaptive filter unit 4 will be described in detail in the description of FIG. 1 will be described later.

Microphone output signal power detector 5
Calculates the average value of the power of the supplied microphone output signal. In this averaging, a short period t (for example, 1
0 msec) average value Pt1 _ave and long period T
(For example, about 100 msec) average value _PT1ave
Is calculated. In the averaging based on these two types of time, the period is set such that there is a difference in the change of the average value with respect to the time variation of the microphone output signal, thereby improving the accuracy of signal detection. Then, the average value Pt1 _ave and the average value P
The ratio Pp1 to _T1ave is determined. This power ratio Pp1
Is greater than or equal to a predetermined threshold value Pth1. Here, when it is determined that the power ratio Pp1 is larger than the predetermined threshold value Pth1, it is considered that there is a microphone output signal, and
The microphone output signal presence information is used to determine the call state determination unit 11
To supply. Further, the averaged microphone output signal power value P1 is supplied to the power ratio calculation unit 9.

The residual signal power detector 8 has basically the same function as the microphone output signal power detector 5 described above. That is, the average value of the power of the supplied residual signal is calculated. In this averaging, a short period t (for example, 10 m
the average value _{Pt2 ave} of about sec), the long period T (e.g., calculates the average value _{P T2ave} of about 100 msec). In the averaging based on these two types of time, the period is set so that a difference in the change of the average value with respect to the time variation of the residual signal appears, thereby improving the accuracy of signal detection. Then, a power ratio Pp2 and the average value _{P T2ave} and the average value _{Pt2 ave.} This power ratio Pp2 is equal to a predetermined threshold Pth
It is determined whether it is greater than two. Where the power ratio Pp
When it is determined that 2 is larger than the predetermined threshold value Pth2, it is determined that there is a residual signal, and the residual signal presence information is supplied to the call state determiner 11. Then, the averaged residual signal power value P2 is supplied to the power ratio calculator 9.

The reception signal power detector 10 has basically the same function as the microphone output signal power detector 5 and the residual signal power detector 8 described above. That is, the average value of the power of the supplied residual signal is calculated. This averaging, short-period t (e.g., about 10 msec) for calculating the average value _{Pt3 ave} of the long period T (e.g., about 100 msec) and a mean value _P T _{3 ave} of. In the averaging based on the two types of time, a period is set such that a change in the average value with respect to the time variation of the received signal is different, thereby improving the accuracy of signal detection. Then, the average value _{P T3a ve} the ratio Pp3 and the average value _{Pt3 ave.} It is determined whether this power ratio Pp3 is greater than a predetermined threshold value Pth3. Here, when it is determined that the power ratio Pp3 is larger than the predetermined threshold value Pth3, it is determined that there is a reception signal, and the reception signal presence information is supplied to the call state determination unit 11.

The power ratio calculator 9 takes in the transmission signal power value P1 from the transmission signal power detector 5, takes in the residual signal power value P2 from the residual power detector 8, and obtains the echo cancellation amount Ys. Specifically, the echo canceling amount Y
s is, for example, Ys = 10 × log ₁₀ (P1 / P2)
, And supplies the echo cancellation amount Ys to the call state determination unit 11. For example, when there is only a reception signal, the echo cancellation amount Ys changes to take a value near a certain steady value V1. For example, Ys can be represented by a curve shown in FIG.

The call state judging unit 11 takes in the presence / absence information of the microphone signal from the microphone signal power detector 5, takes in the presence / absence information of the residual signal from the residual signal power detector 8, and receives the received signal power detector 10. , And generates a coefficient update / stop control signal for controlling whether or not to perform update control of the filter tap coefficient based on the information, and supplies the generated signal to the tap coefficient update control unit 6. . Further, the echo canceling amount Ys supplied from the power ratio calculating unit 9 is fetched, and a constant value V
Until the value becomes 1, the coefficient update control signal is supplied to the tap coefficient update control unit 6. FIG. 4 shows a characteristic diagram of an example of the echo cancellation amount Ys.

Further, the call state determiner 11 is, for example,
When the reception state is determined by the supply of the reception signal presence information, the coefficient update control signal is supplied to the tap coefficient update control unit 6. When it is determined that there is a microphone signal, a reception signal, and a residual signal (in the case of the double talk state, the two-way communication state, and the transmission / reception state), the coefficient update stop control is supplied to the tap coefficient update control unit 6. I do. When it is determined that there is a microphone signal and a residual signal, a coefficient update stop signal is supplied to the tap coefficient update controller 6. When it is determined that there is neither a transmission signal nor a reception signal, a coefficient update stop signal is supplied to the tap coefficient update controller 6. In addition, the presence / absence information of the microphone signal
The microphone output signal power detector 5, the residual signal power detector 8, the received signal power detector 10 so that other combinations based on the reception signal presence / absence information and the residual signal presence / absence information cannot occur. It is assumed that the respective thresholds are set. Therefore, a state other than the above-mentioned combinations cannot occur in this embodiment.

The tap coefficient update control unit 6 basically takes in the residual signal e output from the adder 3 and
Control is performed based on the coefficient update / stop control signal supplied from 1 and a tap coefficient control signal is supplied to the adaptive filter unit 4 so that the residual signal e is minimized. In the tap coefficient control algorithm, for example, the control can be performed by a learning identification method.

Therefore, from the start-up of the initial state until the echo canceling amount Ys takes a constant value V1, the above-mentioned control algorithm performs the sequential processing and updates the tap coefficients. After the echo elimination amount Ys takes a value near the constant value V1, a method of updating the tap coefficient will be described later with reference to FIGS.

FIG. 5 is an explanatory diagram showing the time relationship between the change in the amount of echo cancellation and the detection of the microphone output signal in this embodiment.

FIG. 5A shows a curve of an example of a temporal change in the amount of echo cancellation in the power ratio calculator 9. (B) shows an example of a waveform diagram of a microphone output signal from the microphone 1 in a relationship corresponding to the above curve (A). (C) is a diagram showing a state of presence / absence of a signal with / without detection of sound / non-sound by the microphone output signal power detector 5 corresponding to the output signal of the microphone 1 of (B). Here, the time from when the microphone 1 captures a sound or the like and the microphone output signal starts to be output (B in FIG. 5B) to when the signal is determined and output (A in FIG. 5C). To T
1 (detection response time T1).

FIG. 1 is a functional block diagram of an example of the adaptive filter section 4 and the adder 3 according to this embodiment.

[0034] In FIG. 1, the adder 3, FIG 3
The same part as the adder 3 in the figure is shown, and specifically, the adder 3 includes adders 507 and 508. Portions other than the adder 3 represent internal functional blocks of the adaptive filter unit 4. The adaptive filter unit 4 includes tap coefficient multiplication registers 503 and 504,
A reference signal register 505, adders 501 and 502,
It comprises a switch 506, an average power comparator 509, and switches SW1, SW2, SW3, SW4.

The second FI comprising the reference signal register 505, the switch 506, the tap coefficient multiplication register 503, and the adder 501 of the adaptive filter section 4
A pseudo echo y2 ^* is generated by the R-type filter 530. Also, a pseudo echo y1 ^* is generated by a first FIR filter 520 including a reference signal register 505, a tap coefficient multiplication register 504, and an adder 502.

Therefore, the reference signal register 505 is shared by the second FIR filter 530 and the first FIR filter 520.

The time lag (T) register length of the reference signal register 505 is such that the time lag registers 505a to 505n can hold sample data for a period (T2 ≧ 2 × T1) at least twice the time T1 (detection response time). And In the adaptive filter section 4, the T1 time is defined as the time from the supply of the microphone output signal to the determination of the double talk or the determination of the transmission state by the call state determiner 11 as T.
It is set to 1.

For example, if the sampling frequency is fHz (for example, about 8 kHz), the reference signal register 50
5 is f × T2 (for example, 8 kHz × 0.05 sec)
= About 400) time lag registers 505a-50
5n. Then, the above time T1 and T2
An example of the relationship is also shown in FIG.

The switch 506 constituting a part of the second FIR filter 530 is on / off controlled by a control signal A1 from the tap coefficient update control unit 6. The supply timing of the control signal A1 is, for example, the time TP shown in FIG. 6D in the operation timing chart of FIG.
1, TP2 (in the receiving state, every 2 × T2).

Each time the switch 506 is turned on once during the T2 period, the tap coefficient at that time is read from the tap coefficient register 504 of the first FIR filter 520, and the second FIR filter 530 The data is transferred to the tap coefficient multiplication register 503 and set. While the switch 506 is turned on, the reception signal from the reference signal register 505 is added to the tap coefficient multiplication register 503.
And multiplied by the set tap coefficient,
The addition is performed by the adder 501 to generate a pseudo echo signal y2 ^* .

Then, the generated pseudo echo signal y2 ^*
Is supplied to the difference input of the adder 507, where the difference from the signal from the microphone 1 (transmission signal S + echo signal y) is obtained, the residual signal e2 is output, and the average power comparator 509 and , Switch SW1.

On the other hand, the first FIR filter 520 is
While the control signal A1 is turned on from the tap coefficient update control unit 6 to the switch SW3 (in the receiving state), the control signal A1 is sequentially supplied with the value of the residual signal e1 generated by the supply of the echo signal from the microphone 1 while being supplied. The coefficient value of the tap coefficient register 504 is updated, and the pseudo echo signal y1 ^* generated with the update of the coefficient value also changes. Therefore,
If the transmission is suddenly started in the receiving state, the adder 50
The eight-output residual signal e1 is disturbed, and the disturbed residual signal e1 is disturbed.
The tap coefficient of the tap coefficient multiplication register 504 is updated, the pseudo echo signal y1 ^* is also disturbed, the power of the residual signal e1 increases, and the average power comparator 509
Is determined in the past reception state of the second FIR filter 530, and it is determined that the residual signal e2 due to the pseudo echo y2 ^* generated by the tap coefficient of the tap coefficient multiplication register 503 has lower power. Then, the residual signal e2 is output as an echo canceller output.

The average power comparator 509 has a predetermined threshold value S1 set in advance, and receives the supplied residual signals e1 and e1.
2 and S1, the residual signal e1 or e2 having the smaller residual echo component is determined and selected. In order to make this determination, in the case of a power relationship of (e2) ² + s1 <(e1) ² , in order to select the residual signal e2,
Supply an ON control signal to the switch SW1 to turn on the switch SW1,
In addition, an OFF control signal is supplied to the switch SW2 to turn it off, and the tap coefficient update control
The control signal A3 for turning on the power supply is supplied. Upon receiving this control signal, the tap coefficient update control unit 6 sets the switch 506
Is supplied with an ON control signal A2 to turn it ON.

The average power comparator 509 determines (e2) ² to determine and select the residual signal e1 or e2.
+ S1 ≧ (e1) If it is determined that the power relationship is ² , the switch SW is selected to select the residual signal e1.
1, an off control signal is supplied to turn off the switch SW2, and an on control signal is supplied to the switch SW2 to turn on the switch SW2.
The control signal A3 for turning off the power supply is supplied. Upon receiving this control signal, the tap coefficient update control unit 6 sets the switch 506
Is supplied to turn on the switch SW3, and the switch SW3 is supplied with the on control signal A1 to turn on the switch SW3. When the switch SW3 is turned on, each coefficient of the tap coefficient multiplication register 504 is updated by the residual signal e1.

FIG. 6 is an operation timing chart of this embodiment.

In FIG. 6, (A) shows an example of a state transition, that is, a transition from a receiving state to a double talk state to a transmitting state to a silent state. (B) shows the result of the presence / absence detection of the microphone output signal in the microphone output signal power detector 5. (C) shows the result of the presence / absence detection of the reception signal in the reception signal power detector 10.

FIG. 6D shows the ON / OFF state of the switch 506 of the second FIR filter 530 of the adaptive filter unit 4.
This shows the timing of the off control. Switch 506
Is turned on by a control signal A2 from the tap coefficient update control unit 6 in the transmission / reception state (double talk state). In other than the transmission / reception state (double talk state), off control is performed.

FIG. 6E shows the timing of the on / off control of the switch SW1 of the adaptive filter unit 4. When it is determined in the double talk state that the average power of the residual signal e2 is smaller than the average power of the residual signal e1, in the double talk state, for example, the switch SW1 is turned on and outputs the residual signal e2. When the average power of the residual signal e1 is smaller, the switch SW2 is turned on.

FIG. 6F shows the timing of the on / off control of the switch SW2 of the adaptive filter unit 4.
That is, for example, in the receiving state, the switch SW2
Is turned on to output the residual signal e1 as an echo canceller output. Further, in the transmission state and the silent state, the switch SW2 is turned on to output the residual signal e1 or output the silent state.

FIG. 6G shows the timing of the on / off control of the switch SW3 of the adaptive filter unit 4.
That is, the SW3 is turned on by the control signal A1 from the tap coefficient update control unit 6 while the reception signal is being supplied to the echo canceller main body 7, so that the SW3 is turned on in the reception state and during double talk. Then, for example, when the switch SW3 is turned on in the reception state, control is performed such that the tap coefficient of the tap coefficient multiplication register 504 of the first FIR filter 520 is updated by the residual signal e1. Also in the double talk state, SW3 is controlled to be ON, and the tap coefficient of the tap coefficient multiplication register 504 is updated by the residual signal e1.

FIG. 6H shows the timing of the on / off control of the switch SW4 of the adaptive filter unit 4.
The switch SW4 is turned on by a control signal A4 from the tap coefficient update control unit 6 in the receiving state and the transmitting / receiving state. That is, it is turned on when there is a reception signal (or an echo signal). Further, in the transmission state and the silent state, the off control is performed. That is, when there is no reception signal (or echo signal), the off control is performed.

FIG. 6 (J) shows the tap coefficient copy transfer timing from the tap coefficient register 504 of the first FIR filter 520 of the adaptive filter unit 4 to the tap coefficient multiplication register 503 of the second FIR filter 530. Represents. Then, in the receiving state, 1 in the 2 × T2 period.
Each time (TP1, TP2), the tap coefficient of the tap coefficient register 504 of the first FIR filter 520 is set to the second
Coefficient multiplication register 5 of FIR type filter 530
03 is copied and set. This is the first
Of the tap coefficient of the second FIR filter 530 is affected when the tap coefficient of the FIR filter 520 is disturbed (for example, when the tap coefficient is disturbed when shifting from the receiving state to the transmitting / receiving state). 503.

According to the above embodiment, since the echo cancellation is performed using one omnidirectional microphone 1, it is hardly affected by the location of the noise source.
Even if there are a plurality of speakers, the detection accuracy of double talk is hardly deteriorated.

Also, based on the presence / absence information of the microphone output signal, the presence / absence information of the reception signal, and the presence / absence information of the residual signal, whether the state is the reception state, the transmission state, the transmission / reception state, or the silent state Therefore, when there is no reception signal (e.g., echo signal), it is possible to reduce the possibility that the tap coefficient of the adaptive filter unit 4 is inappropriately updated due to erroneous detection of a call state due to transmission noise or the like. Can be.

Further, as shown in FIG. 1 , the configuration of the adaptive filter section 4 includes a first FIR filter 520 and a second FIR filter 520.
And a type filter 530, and 2
The second FIR filter 53 with a cycle of once every × T2
The tap coefficient of 0 is copied and transferred and set in the tap coefficient multiplication register 503 of the second FIR filter 530,
Even if the tap coefficient of the first FIR filter 520 is disturbed when the state changes from the receiving state to the double talk state, the pseudo echo y2 ^* is used using the tap coefficient set in the second FIR filter 530 ^. it is possible to perform a stable echo cancellation by the.

Therefore, the present invention is effective when applied to a hands-free telephone or the like.

In the above embodiment, the microphone output signal power detector 5, the residual signal power detector 8,
Short period t = 10 msec of the reception signal power detector 10,
Although the long period T is set to 100 msec, it is not limited to this.

Further, in the above embodiment, the detection of the power change of the microphone output signal power detector 5, the residual signal power detector 8, and the reception signal power detector 10 is detected by the predetermined threshold value. The threshold may be different for each of the power detectors 5, 8, 10.

Further, in the above embodiment, the configuration of the adaptive filter section 4 is as shown in FIG. 1 , but it is not limited to this configuration. For example, although the FIR filter is used, the filter may be another IIR filter. Also, set the sampling frequency to 8k
Hz, and the reference signal register length T2 is set to 0.05 sec. However, the present invention is not limited to this.

Further, in the above-described embodiment, the tap coefficient update control unit 6 exemplifies the learning similarity method, but the present invention is not limited to this.

In the above embodiment, the echo removing units (the adaptive filters 520 and 530 and the adder 50) are used.
7, 508) has been shown as an example of duplexing, but the present invention is not limited to this. In other words, the present invention can be applied to a configuration in which the configuration is tripled or more.

In the above embodiment, the microphone output signal power detector 5 and the residual signal power detector 8 shown in FIG. 3 detect the presence or absence of a signal based on the detection of power. However, the present invention is not limited to this. Absent. In addition, a detection method using, for example, autocorrelation may be used.

[0063]

According As described above, according to the present invention to the present invention, small
At least in the listening state, the multiplexed echo canceller is
The filter coefficients of each of the last adaptive filters are different
And updated from each echo and output from each echo canceller
Either of the echoes is
Selects and outputs the echo removal sound signal, so
Selects echo-removed sound signal that is less affected by data coefficient disturbance
Yes, the call state between the above-mentioned receiving state and other call states
Even if there is a change in state or noise, the echo-removed sound signal
Enables stable echo cancellation using
Become.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an adaptive filter unit and an adder of an echo canceller according to one embodiment of the present invention.

FIG. 2 is a functional block diagram of a conventional acoustic echo canceller.

FIG. 3 is a functional block diagram of the echo canceller of one embodiment.

FIG. 4 is a characteristic diagram of the amount of echo cancellation in one embodiment.

FIG. 5 is an operation explanatory diagram of one embodiment.

FIG. 6 is an operation timing chart of one embodiment.

[Explanation of symbols]

501, 502, 507, 508... Adders, 503, 5
04: Tap coefficient multiplication register, 505: Reference signal register, 509: Average power comparator, 520: First FI
R type filter, 530... Second FIR type filter, SW
1 to SW4 switches.

Claims (2)

(57) [Claims] 1. A receiving sound output means for outputting a receiving signal as sound, a sound capturing means for capturing a sound and outputting a sound signal, and an adaptive filter for estimating a receiving sound echo component generated by an echo by the receiving sound output. a calculator for removing the received acoustic echo components from the acoustic signal, receiving
A call state determination unit that determines a call state including a talk state, a transmission / reception state, a transmission state, and a silent state, and performs update control of a filter coefficient of the adaptive filter according to a result of the determination. An echo canceller that outputs an echo-removed acoustic signal in which the received acoustic echo component has been removed from a signal, the echo canceller including the adaptive filter and the arithmetic unit,
Output echo-reduced sound signal based on
The number of echo cancellers, and the plurality of echo cancellers is
When the filter coefficients of at least
Multiplexed so that they are updated at different timings, and based on the power of the echo-removed sound signal from each echo-removal unit.
Zui, the echo canceller, characterized in that selects and outputs the echo cancellation audio signal from any of the echo cancellation unit. 2. The echo canceller according to claim 1,
And the power of the acoustic signal and the power of the echo-removed acoustic signal.
Comprising a calculating means for calculating the echo cancellation amount based on chromatography, and at least listen state, yet the echo cancellation
While the volume has not reached the specified value,
An echo canceller characterized by continuously updating the filter coefficient of a filter .