JPH07226698A - Acoustic echo canceler having sound field simulator and changing-over method for sound field simulator/acoustic echo canceler - Google Patents

Abstract

PURPOSE:To suppress cost, to perform an echo canceling at the time of a public address speech and to add echos in the case of the appreciation of music, etc. CONSTITUTION:A pseudo echo signal generation means 320 for obtaining a pseudo echo signal is shared by an acoustic echo canceler 100 and a sound field simulator. A switch means 310 switching to the acoustic echo canceler 100 or the sound field simulator 200 according to use purposes is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acoustic echo canceller having a sound field simulator and a sound field simulator / acoustic echo canceller switching method, and particularly to a cause of howling in a two-wire four-wire conversion system and a loud voice communication system. And an acoustic echo canceller having a sound field simulator in combination with a sound field simulator having a function of adding a sense of realism when listening to music, etc. by providing an acoustic echo canceller that eliminates or suppresses echo signals that impair hearing. And a sound field simulator / acoustic echo canceller switching method.

[0002]

2. Description of the Related Art FIG. 4 is a conceptual diagram of a conventional voice call system. The system shown in the figure includes a microphone 1, a speaker 2, amplifiers 5 and 6 and a switch 12 on the side of a speaker 10.
A, 12B, communication network 9, and exchange 12 on the receiving side 11
B, amplifiers 7 and 8, speaker 4, and microphone 3.

The transmitted voice, which is generated by the transmitter 10 from the transmitting microphone 1, is amplified by a transmitting signal amplifier 5,
It is transmitted to the receiving side via the exchange 12A, the transmission path 9, and the exchange 12B. The transmitted signal is amplified by the amplifier 8, input to the receiving speaker 4, and reproduced.

When the transmitter 10 makes a call connection request to the receiver 11, the exchange 12A is connected to the receiver 11 from the receiver side exchange 12B via the communication network 9. The talker is
A voice signal is sent to the exchange 12A via the microphone 1. The exchange 12A inputs a voice signal to the exchange 12B via the communication network 9. The exchange 12B is the receiver 11
A voice signal from the talker is transmitted to. Here, when the listener 11 receives the voice signal from the speaker 10, the voice from the speaker 10 reverberates through the echo path 13b and is sent to the speaker 10 along with the utterance of the listener 11. . Also,
Even if the listener 11 does not speak, the voice of the sender 10 reverberates through the echo path 13b and is input to the microphone 3 on the listener 11 side. This echo signal is passed through the amplifier 7
Through the switch 12B, the communication network 9, the switch 12A, and the amplifier 6, the speaker 2 on the speaker side 10 outputs howling the voice uttered by the speaker 10 itself.

As described above, in the voice communication system, the problem is that the voice transmitted from the transmitting side to the receiving side is re-input from the microphone 3 on the receiving side and reverberates to the transmitting side. For the speaker 10, this reverberation phenomenon is called an acoustic echo or the like because the voice generated by the speaker 10 is reproduced from the speaker 2, and causes adverse effects such as a call disturbance and discomfort. Furthermore, the sound reproduced from the speaker 2 is the microphone 1
Is received by and forms a closed loop of the signal. When the loop gain is larger than 1, the howling phenomenon occurs and the call becomes impossible.

In recent years, an acoustic echo canceller has been used in order to solve the above-mentioned problems of the voice communication system.

FIG. 5 shows an example of a conventional acoustic echo canceller. In the figure, an acoustic echo canceller 21
Is composed of a pseudo echo path convolution operation circuit 22, an echo path estimation circuit 23, and a subtractor 24.

The acoustic echo canceller 21 estimates the impulse response of the echo path in the echo path estimation circuit 23 and transfers the estimated value h ^ (n) to the pseudo echo path convolution circuit 22. Next, the pseudo echo path convolution operation circuit 22 performs a convolution operation of the impulse response estimated value h ^ (n) and the received signal x (n) to synthesize the pseudo echo signal y ^ (n), Is output to the subtractor 24. The subtractor 24 calculates the pseudo echo path signal y ^ (n) from the output signal of the microphone 3.
Deduct. If the echo path impulse response is well estimated, the echo signal y (n) and the pseudo echo signal y ^
(N) becomes substantially equal. The result of this subtraction is e
If (n) = 0, the echo signal y (n) included in the output of the microphone 3 is deleted.

Here, the estimated value h of the echo path impulse response
^ (N) needs to follow the temporal change of the echo path characteristic h (n). Therefore, the echo path estimation circuit 23 estimates the echo path impulse response using an adaptive algorithm. The adaptive algorithm uses the received signal x (n) and the error signal e (n) (e (n) = y (n) -y ^ (n), where y
(N) = h (n) * x (n)) is used to estimate the impulse response h ^ so that the power of e (n) is minimized.
This is an algorithm that determines (n). As the algorithm, there are an LMS method, a learning identification method, an ES method and the like.

Next, a conventional sound field simulator will be described. FIG. 6 shows the configuration of a conventional sound field simulator. In the figure, the amplifier is omitted for simplicity. The sound field simulator 33 shown in the figure comprises a pseudo echo path convolution operation circuit 22 and a pseudo echo path storage circuit 35. The sound field simulator 33 is used together with a reproducing device such as a CD player, and, for example, as the input signal x (n),
A music signal or the like is input. The input signal x (n) is convolved with the pseudo echo path by the pseudo echo path convolution operation circuit 22, and the echo added signal y ′ (n) is output to the speaker 4. In addition, the user may previously use the pseudo echo path storage circuit 35.
It is possible to select a desired pseudo echo path using the pseudo echo path selection circuit 36 from the plurality of pseudo echo paths stored in FIG.

The pseudo echo storage circuit 35 generally stores a pseudo echo path that simulates the echo path in a large concert hall or a small hall. By using the sound field simulator 33, a pseudo sound is added to an input signal of music or the like from an external device, so that the user can feel as if he or she is listening to music in a concert hall in a room. You can

[0012]

However, in the above-mentioned conventional acoustic echo canceller, there is a problem that in order to completely eliminate the reverberation characteristic in the room, the scale of hardware becomes large and the cost increases accordingly. . Further, there is a problem that it can be used only for the purpose of conversational communication.

The present invention has been made in view of the above points, and in the case of solving the problems of the above-mentioned conventional acoustic echo canceller, suppressing the cost, canceling echoes during a loud call, and listening to music. An object of the present invention is to provide an acoustic echo canceller having a sound field simulator capable of adding reverberation and a sound field simulator / acoustic echo canceller switching method.

A further object of the present invention is to provide an acoustic echo canceller and a sound field simulator / acoustic echo canceller switching method having a sound field simulator in which a pseudo echo convolution circuit can be shared by the acoustic echo canceller and the sound field simulator. Is.

[0015]

FIG. 1 is a block diagram showing the principle of the present invention.

According to the present invention, the pseudo echo signal generating means 32 for generating one pseudo echo signal by receiving the echo signal after being sent to the echo path and the echo signal after the echo signal has passed through the echo path.
0, switching means 310 for switching to either the acoustic echo canceller 100 or the sound field simulator 200 depending on the purpose of use, and obtained from the pseudo echo signal generating means 320 when the switching means 310 switches to the acoustic echo canceller 100. The acoustic echo canceller 100 that eliminates the pseudo echo signal by subtracting the generated pseudo echo signal from the echo signal, and the pseudo echo signal generated by the pseudo echo signal generation means 320 when switched to the sound field simulator 200 by the switching means 310. The sound field simulator 200 for adding a signal.

Further, according to the present invention, the pseudo echo path storage means for storing a plurality of pseudo echo signal generation means 320, and any one pseudo echo signal generation means 32 from the pseudo echo path storage means.
And a pseudo echo path selecting means for selecting 0.

Further, the present invention provides an acoustic echo canceller 100 and a acoustic field simulator 200 in an acoustic signal processing system having an acoustic echo canceller for canceling an echo signal output from an echo path and a sound field simulator for obtaining a pseudo echo signal. In order to be shared by a single echo reverberation circuit 320, the signal transmitted to the echo path and the echo signal after the echo signal has passed through the echo path are input to generate a pseudo echo signal.
If either the acoustic echo canceller 100 or the sound field simulator 200 is selected and the acoustic echo canceller 100 is selected, the echo signal is erased by the pseudo echo signal using the pseudo echo circuit 320, When the field simulator 200 is selected, the pseudo echo signal obtained from the pseudo echo circuit 320 is added to the input signal.

Further, according to the present invention, when a sound field simulator is selected, an arbitrary pseudo echo circuit is selected from a plurality of pseudo echo circuits 320 stored for each size of the pseudo echo signal, and the selected pseudo echo circuit is selected. The pseudo echo signal obtained from the circuit 320 is added to the input signal.

[0020]

The present invention is completely separate from an acoustic echo canceller used in the field of communication and a sound field simulator used in a stereo reproduction device and the like. Focusing on having a common element technology that performs convolution calculation of (sound field impulse response), by connecting and using them, an acoustic echo canceller that eliminates or suppresses echo signals and adding a sense of realism It is possible to realize multiple functions with a single device by using a sound field simulator.

[0021]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 2 shows the configuration of an acoustic echo canceller having a sound field simulator according to an embodiment of the present invention. In the figure, the same components as those in FIGS. 5 and 6 are designated by the same reference numerals.

An acoustic echo canceller 210 having a sound field simulator comprises an acoustic echo canceller mode / sound field simulator mode selection circuit 41, a changeover switch 42,
43, contact points 44, 45, 46, 47, input end 48, output end 49, input line 50, output line 51, external device output end 52, and echo path estimation circuit 23 which is the configuration of the conventional acoustic echo canceller 21. , Pseudo echo path convolution circuit 2
2, a subtractor 24, a pseudo echo path storage circuit 35, which is a configuration of the conventional sound field simulator 33, a pseudo echo path selection circuit 3
6 and an acoustic echo canceller mode / sound field simulator mode selection circuit 41.

FIG. 4 is a flow chart for explaining the operation of the embodiment of the present invention.

First, when used as a loudspeaker, the acoustic echo canceller mode / sound field simulator mode selection circuit 41 selects the acoustic echo canceller mode. As for the selection method, the user can freely select various selection modes such as pressing a button or the like (steps 101 and 102). When the acoustic echo canceller mode is selected, the input terminal 48 is connected to the input line 50 (step 103). The output terminal 49 is connected to the output line 51 (step 104). Further, the switch 42 falls to the contact 44 side, and the switch 43 falls to the contact 47 side (step 105). The echo path estimation circuit 23 is activated by the activation signal a and estimates the response impulse of the echo path between the speaker 4 and the microphone 3. Echo path estimation circuit 2
3 is a pseudo echo signal y ^ output from the pseudo echo path convolution circuit 22 from the output z (n) from the microphone 3.
The value e (n) obtained by subtracting (n) is estimated to be the minimum power, and the estimated value h ^ (n) is calculated as the pseudo echo path convolution circuit 2
2 is input (step 105). The pseudo echo path convolution circuit 22 outputs the estimated value h ^ (n) from the echo path estimation circuit 23.
Input, the estimated value h ^ (n) and the input signal x (n)
And outputs the pseudo echo signal y ^ (n) to the subtractor 24. The subtractor 24 subtracts the pseudo echo signal y ^ (n) from the echo signal z (n) from the microphone 3.

Here, when the output signal from the microphone 3 does not include the transmission signal s (n), the error signal e (n) is given by e (n) = z (n) -y ^ (n). ).

The echo path estimation circuit 23 uses the above error e.
The echo signal y (n) is eliminated by accurately estimating the response impulse so that (n) is eliminated (step 106).

When the output signal from the microphone 3 includes the transmission signal s (n), adaptive estimation is not performed.

Next, when using as a sound field simulator, the sound field simulator mode is selected in the acoustic echo canceller mode / sound field simulator mode selection circuit 41. Regarding the selection method at this time, the user can freely select various selection modes such as pressing a button or the like (steps 101 and 201). When the sound field simulator mode is selected, the pseudo echo path selection circuit 36 selects a pseudo echo path, and based on the selection result, the pseudo echo path convolution circuits stored in the pseudo echo path storage circuit 35. Select one arbitrary pseudo echo path convolution circuit from The input end 48 is connected to the external device output end 52 (step 202), the switch 42 is tilted to the contact 45 side, and the switch 43 is tilted to the contact 46 side (step 203). As a result, a reproduction device such as a CD can be connected as an external device connected to the external device output terminal 52, and the signal x (n) output from the external device is input to the pseudo echo path convolution circuit 22. It As a result, a pseudo echo is added to the input signal x (n) by using the selected pseudo echo path convolution circuit 22 (step 20).
4), send to speaker 4 and play back (step 20)
5).

In the above embodiment, in the sound field simulator, a plurality of pseudo echo paths are stored in the pseudo echo path storage circuit 35 so that a desired echo path can be selected. However, the present invention is not limited to this example. Alternatively, a single pseudo echo path may be fixedly set and used.

Further, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the scope of the claims.

[0032]

As described above, according to the present invention, by sharing the pseudo echo path with the acoustic echo canceller and the sound field simulator, both devices can be accommodated in the same hardware, and the pseudo echo path convolution is performed. Since the circuit can be shared by the acoustic echo canceller and the sound field simulator, the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a configuration diagram of an acoustic echo canceller having a sound field simulator according to an embodiment of the present invention.

FIG. 3 is a flowchart for explaining the operation of the embodiment of the present invention.

FIG. 4 is a conceptual diagram of a conventional loudspeaker communication system.

FIG. 5 is a configuration diagram of a conventional acoustic echo canceller.

FIG. 6 is a configuration diagram of a conventional sound field simulator.

[Explanation of symbols]

1, 3 Microphones 2, 4 Speakers 5, 6, 7, 8 Amplifier 9 Transmission line 10 Sender 11 Receiver 12 Exchange 21 Acoustic echo canceller 22 Pseudo echo convolution circuit 23 Echo path estimation circuit 24 Subtractor 33 Sound field simulator 35 Pseudo echo path memory circuit 36 Pseudo echo path selection circuit 41 Acoustic echo canceller mode / sound field simulator mode selection circuit 42, 43 Switch 44, 45, 46, 47 Contact 48 Input end 49 Output end 50 Input line 51 Output line 52 External device Output terminal 100 Acoustic echo canceller 200 Sound field simulator 210 Acoustic echo canceller having a sound field simulator 300 Acoustic echo canceller having a sound field simulator 310 Switching means 320 Pseudo echo signal generation means

Claims (4)

[Claims] 1. A pseudo echo signal generating means for generating a single pseudo echo signal, the echo signal being sent to the echo path and the echo signal after the echo signal having passed through the echo path is input, and a pseudo echo signal generating means according to a purpose of use. Switching means for switching between the acoustic echo canceller and the sound field simulator, and when the switching means switches to the acoustic echo canceller, the pseudo echo signal obtained from the pseudo echo signal generating means is subtracted from the echo signal. An acoustic echo canceller that eliminates the pseudo echo signal, and a sound field simulator that adds the pseudo echo signal generated by the pseudo echo signal generating means to the input signal when switched to the sound field simulator by the switching means. An acoustic echo canceller having a sound field simulator having: 2. A pseudo echo path storage means for storing a plurality of pseudo echo signal generation means, and a pseudo echo path selection means for selecting any one pseudo echo signal generation means from the pseudo echo path storage means. An acoustic echo canceller having the sound field simulator according to claim 1. 3. An acoustic signal processing system having an acoustic echo canceller for canceling an echo signal output from an echo path and a sound field simulator for obtaining a pseudo echo signal, for sharing between the acoustic echo canceller and the sound field simulator. To the echo path, and the echo signal after the echo signal after the echo signal has passed through the echo path is input, and one pseudo echo circuit for generating a pseudo echo signal is provided, and the acoustic echo canceller or the sound echo If any of the field simulators is selected and the acoustic echo canceller is selected, then the echo signal is canceled by the pseudo echo circuit using the pseudo echo circuit, and if the sound field simulator is selected, A sound field simulator / acoustic echo canceller switching method characterized in that the pseudo echo signal obtained from the pseudo echo circuit is added to an input signal. 4. When the sound field simulator is selected, an arbitrary pseudo echo circuit is selected from a plurality of pseudo echo circuits stored according to the size of the pseudo echo signal, and the pseudo echo circuit is obtained from the selected pseudo echo circuit. The sound field simulator / acoustic echo canceller according to claim 3, wherein the pseudo echo signal is added to the input signal.