JP2590116B2 - Voice input / output device - Google Patents

Description

Description: Object of the Invention (Industrial application field) The present invention relates to a voice input / output device used for a remote conference system, a loudspeaker device, etc., and particularly to an audio input / output device for removing howling and echo. And a voice input / output device including the echo canceller.

(Prior Art) Conventionally, there is an audio input / output device having an echo canceller which can be applied to both a two-wire line and a four-wire line as shown in FIG.

As shown in FIG. 1, the audio input / output device includes a hybrid coil 1, an echo canceller 3, a subtractor 5, switches 7, 9, split filters 11, 13, coupling filters 15, 17,
High-frequency echo canceller 19, low-frequency echo canceller 21, subtractors 23 and 25, amplifiers 27 and 29, microphone 31,
It comprises a speaker 33.

The echo canceller 3 generates a pseudo echo signal of an echo generated on the line side. The subtracter 5 subtracts this pseudo echo signal from the signal sent from the hybrid coil 1. Switches 7 and 9 switch between a two-wire line connection mode and a four-wire line connection mode. That is, in the two-wire line connection mode, it is at the position shown by the solid line in the figure, and in the four-wire line connection mode, it is tilted to the position shown by the dotted line in the figure. The division filter 11 divides the band of the signal transmitted through the switch 7 into high-frequency components of 4 to 7 KHz and low-frequency components of 0 to 4 KHz. The coupling filter 15 couples the high frequency component and the low frequency component sent through the division filter 11. The amplifier 27 amplifies the signal sent through the coupling filter 15,
The speaker 33 outputs the amplified signal as sound. The high-frequency echo canceller 19 receives a high-frequency component of the signal divided into bands by the division filter 11, and generates a pseudo echo signal. The low-frequency echo canceller 21 receives the low-frequency signal from the division filter 11 and generates a pseudo echo signal. The microphone 31 converts the voice uttered by the speaker into an electric signal, and the amplifier 29 amplifies this signal. The division filter 13 divides the output signal of the amplifier 29 into bands, and divides the output signal into high-frequency components and low-frequency components. The subtractor 23 subtracts the pseudo echo signal output from the high-frequency echo canceller 19 from the high-frequency component output from the division filter 13. The subtracter 25 subtracts the pseudo echo signal output from the low-frequency echo canceller 21 from the low-frequency component output from the division filter. The combining filter 17 combines the high frequency components and the low frequency components sent from the subtracters 23 and 25.

In the above circuit, when a two-wire circuit is connected, 0 to 3.
Processes a narrow band signal of 4KHz.
7KHz wideband signal processing is performed.

 Next, the operation of the voice input / output device will be described.

First, when the four-wire line is connected, the switches 7 and 9 are at positions indicated by dotted lines. Thereby, 0 to be input from the terminal 35
The signal in the 7 KHz band is output as voice through the switch 7, the division filter 11, the coupling filter 15, the amplifier 27, and the speaker 33. At this time, pseudo echo signals are generated by the high-frequency echo canceller 19 and the low-frequency echo canceller 21 and input to the subtracters 23 and 25, respectively. The audio signal collected by the microphone 31 is input to the division filter 13 via the amplifier 29 and is divided into bands. A pseudo echo signal is subtracted from the high frequency component by a subtractor 23, and a pseudo echo signal is subtracted from a low frequency component by a subtracter 25. After the band is combined by the coupling filter 17, the signal is output from a terminal 37 via a switch 9. You.

On the other hand, when a two-wire line is connected, the switches 7 and 9 are at positions shown by solid lines. As a result, the audio signal collected by the microphone 31 is output to the amplifier 29, the divided filter 13, the subtractor 25,
The signal is output to the line side via the coupling filter 17, the switch 9, and the hybrid coil 1. At this time, the echo canceller 3 generates a pseudo echo signal of an echo generated on the line side from the signal sent from the switch 9. As a result, the signal on the line side sent from the terminal 39 is sent to the subtractor 5 via the hybrid coil 1, and the pseudo echo signal is subtracted by the subtracter 5. And a speaker via the switch 7, the division filter 11, the coupling filter 15, and the amplifier 27.
Output from 33 as audio. At this time, the split filter 11
The low-frequency component of the signal divided into bands is input to the echo canceller 21, and the echo canceller 21 generates a pseudo echo canceller. Then, the pseudo echo signal is subtracted by the subtractor 25 from the low frequency signal sent through the division filter 13. Therefore, the echo of the acoustic system between the speaker 33 and the microphone 31 is removed by the low-frequency echo canceller 21 and the subtracter 25.

However, in the above audio input / output device, 3.4K
Since the high frequency echo canceller 19 is not used in the 2-wire line connection mode in the Hz band, and the echo canceller 3 is not used in the 4-wire line connection mode in the 7 KHz band, parts are not fully utilized. is there.

(Problems to be Solved by the Invention) As described above, in the above-described conventional voice input / output device, there is an unused echo canceller in any of the two-wire line connection mode and the four-wire line connection mode. As a result, there is a problem that parts are wasted, which results in an increase in the number of parts, an increase in cost, and an increase in the size of the apparatus.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a voice input / output device capable of reducing the number of components and reducing the size and cost of the device.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides an audio input / output device capable of selecting a first line or a second line as a connection line. A speaker that outputs a signal from one line or the second line, a microphone that inputs a signal to the first line or the second line, and a first band that goes from the speaker to the microphone. A first echo canceller for removing an echo, and first and second signals for selectively passing one of the signal in the first band or the signal in a second band higher than the first band. A second filter; a second echo canceller for removing an echo circulating from the signal passed through the first filter to the signal passed through the second filter; When but that is connected,
A signal from the second band is passed through the first and second filters, a signal from the first line is output to the speaker via the first filter, and a signal from the microphone is output. To the first line via the second filter, while passing the signal of the first band through the first and second filters when the second line is connected. In both cases, the signal from the second line is output to the speaker via the second filter, and the signal from the microphone is output to the second line via the first filter. Switching means for switching.

(Operation) When the switching means is connected to a four-wire line, one of the two echo cancellers functions as a high-frequency echo canceller, and the other functions as a low-frequency echo canceller. The components are input to the high-frequency echo canceller, the low-frequency components are input to the low-frequency echo canceller, and the outputs of these echo cancellers are subtracted from the signal input from the microphone. When the switching means is switched to the two-wire line connection mode, one of the two echo cancellers functions as an echo canceller for removing an echo generated on the line side, and the other echo canceller for removing an echo between the speaker and the microphone. Function as Therefore, in the present invention, only two echo cancellers need to be used, so that the number of components can be reduced and the size of the apparatus can be reduced.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a voice input / output device according to one embodiment of the present invention.

As shown in the figure, the audio input / output device includes a high-frequency acoustic echo canceller and side-sound echo canceller 51, a low-frequency acoustic echo canceller 53, analog-to-digital converters (AD converters) 55 and 57, digital Analog converter (DA
Converter) 59, 61, hybrid coil 63, amplifier 65, 6
7, a speaker 69, a microphone 71, and terminals 73, 75, 77.

The above high-frequency acoustic echo canceller and side-tone echo canceller unit 51 includes an echo canceller 79, switches 81, 83, and 8
5, 87, 88, digital filters 89, 91, 93, 95, down sampling circuits 97, 99, up sampling circuits 101, 103,
It comprises a subtractor 105.

The low-frequency acoustic echo canceller unit 53 includes an echo canceller 107, switches 109 and 111, a low-pass filter 113,
115, 117, 119, down sampling circuits 121, 123, up sampling circuits 125, 127, subtractor 129, adders 131, 132, A
It comprises a D converter 133 and a DA converter 135.

Each of the above switches is connected to the A side when the four-wire line is connected, and is connected to the B side when the two-wire line is connected.

The echo canceller 79 has a terminal when a 4-wire line is connected.
A pseudo echo for the high-frequency component is generated from the high-frequency component of the signal input via the link 73, and a pseudo echo signal generated on the line side when a two-wire line is connected is generated. Digital filters 89, 91, 93 and 95 are 4
The coefficient is set so as to be a high-pass filter in a band of up to 7 KHz, and when two wires are connected, switching is made so as to become a low-pass filter in a band of 0 to 3.4 KHz.

Further, the echo canceller 107 generates a pseudo echo signal of a signal in the 0 to 4 KHz band, and removes the echo of the low frequency signal in cooperation with the subtractor 129. Down sampling circuit 97, 99, 12
1, 123 converts a 16 KHz signal into an 8 KHz sample signal. The up-sampling circuits 101, 103, 125, and 127 convert an 8 KHz signal to 16 KHz.

Next, the operation of the thus configured audio input / output device will be described.

First, when a 4-wire line is connected, all switches are connected to the A side, and the digital filters 89, 91, 93, and 95 are switched so as to be high-pass filters in the 4 to 7 KHz band.

The signal input from the terminal 55 is converted by the AD converter 55 to 16
It is sampled at KHz and input to the switches 81 and 109.
At this time, since the digital filter 89 is a 4-7 KHz high-pass filter, the signal input through the switch 81 is band-limited to a 4-7 KHz signal, and is converted into an 8 KHz sample signal by the down-sampling circuit 97. The signal is input to the echo canceller 79 and the up-sampling circuit 101.

At that time, the echo canceller 79 generates a pseudo echo signal from this signal.

The signal converted to a 16 KHz sample signal by the up-sampling circuit 101 is converted into a 4K signal by the digital filter 91.
The band is limited to a band of about 7 KHz and input to the adder 132 via the switches 83 and 111.

On the other hand, the signal input from the terminal 73 and input to the switch 109 is band-limited to 0 to 4 KHz by the low-pass filter 113, converted to an 8 KHz sample signal by the down-sampling circuit 121, and input to the echo canceller 107 and the up-sampling circuit 125. You.

At that time, the echo canceller 107 generates a pseudo echo signal from this signal.

The signal converted to 16 KHz by the up-sampling circuit 125 is input to the adder 132 after being band-limited to 0 to 4 KHz by the low-pass filter 115.

Thus, the adder 132 adds the output signal of the digital filter 91 and the output signal of the low-pass filter 115, and
The signal is sent to the A converter 135, where it is converted into an analog signal, amplified by the amplifier 65, and output from the speaker 69 as sound.

On the other hand, the audio signal input from the microphone 71 is amplified by the amplifier 67, digitized by the AD converter 133, and input to the digital filter 93 via the low-pass filter 117 and the switch 87. At this time, the low-pass filter 11
The signal input to 7 is band-limited to 0 to 4 KHz, converted into an 8 KHz signal by the down-sampling circuit 123, and then the echo is removed by the subtractor 129, and the up-sampling circuit 1
The signal is again converted into a 16 KHz signal by 27, band-limited to 0 to 4 KHz by the low-pass filter 119, and input to the adder 131.

On the other hand, the signal input to the digital filter 93 via the switch 87 is band-limited to 4 to 8 KHz by the digital filter 93, converted into an 8 KHz signal by the down-sampling circuit 99, and the echo is removed by the subtracter 105. The signal is again converted to a 16 KHz signal by the up-sampling circuit 103, band-limited to 4 to 8 KHz by the digital filter 95, and input to the adder 131 via the switches 85 and 88.

Thus, the adder 131 adds the output signal of the low-pass filter 119 and the output signal of the digital filter 95, and
The signal is converted into an analog signal by the DA converter 59 and output from the terminal 77.

 Next, a description will be given of a case where a two-wire line is connected.

At this time, all the switches are connected to the B side, and the digital filters 89, 91, 93, and 95 are switched so as to be low-pass filters in the 0 to 4 KHz band.

The audio signal input from the microphone 71 is amplified by the amplifier 67, digitized by the AD converter 133, and input to the low-pass filter 117. The signal input to the low-pass filter 117 is band-limited to 0 to 4 KHz, converted into an 8 KHz signal by the down-sampling circuit 123, and then subtracted by a subtractor 129.
The echo is removed, the signal is again converted to a 16 KHz signal by the up-sampling circuit 127, the band is limited to 0 to 4 KHz by the low-pass filter 119, and input to the digital filter 89 via the adder 13 and the switch 81. At this time, since the digital filter 89 is a low-pass filter in the 0 to 4 KHz band, the signal input through the switch 81 is 0
The band is limited to a signal of about 4 KHz, converted to a sample signal of 8 KHz by the down-sampling circuit 97 and input to the echo canceller 79 and the sampling circuit 101.

At that time, the echo canceller 79 generates a pseudo echo signal from this signal.

The signal converted to a 16 KHz sample signal by the up-sampling circuit 101 is output from the digital filter 91 to 0 to 16 KHz.
The band is limited to the 4 KHz band and the DA converter 61 via the switch 83
And is converted into an analog signal and output to the line side via the hybrid coil 63.

On the other hand, the signal on the line side input via the hybrid circuit 63 is digitized by the AD converter 57 and input to the digital filter 93 via the switch 87. The signal input to the digital filter 93 is band-limited to 0 to 4 KHz and is converted to an 8 KHz signal by the down-sampling circuit 99, after which the echo is removed by the subtracter 105 and converted again to a 16 KHz signal by the up-sampling circuit 103. Switch band limited to 0 to 4KHz by digital filter 95
The signal is input to the low-pass filter 113 via 85 and 109.

This signal is band-limited to 0 to 4 KHz by the low-pass filter 113, converted to a 8 KHz sample signal by the down-sampling circuit 121, and input to the echo canceller 107 and the sampling circuit 125.

At that time, the echo canceller 107 generates a pseudo echo from this signal.

The signal converted to 16 KHz by the up-sampling circuit 125 is band-limited to 0 to 4 KHz by the low-pass filter 115, then converted to a DA converter 135 via an adder 132, and then converted to an analog signal. 65, speaker 69
Is output as voice.

Thus, according to the configuration of the present embodiment, the echo canceller
The 79 is used as a high-frequency echo canceller when connected to a 4-wire line, and is used as an echo canceller for a line when connected to a 2-wire line. No echo cancellers are used, ie the number of echo cancellers is reduced. As a result, the cost can be reduced and the device can be downsized.

[Effects of the Invention] As described above in detail, according to the present invention, the number of components can be reduced, and the size and cost of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a voice input / output device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a configuration of a conventional voice input / output device. 69 Speaker 71 Microphone 79, 107 Echo canceller 81, 83, 85, 87, 88, 109, 111 Switch

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masakazu Nishino 1-256, Take, Yokosuka-shi, Kanagawa Prefecture Within the Combined Communications Research Laboratories of Nippon Telegraph and Telephone Corporation (72) Inventor Shigenobu Minami 70 Yanagimachi, Saiwai-ku, Kawasaki-shi, Kanagawa Stock Inside the Toshiba Yanagimachi Plant (72) Inventor Takashi Saeki 3-3-1 Asahigaoka, Hino-shi, Tokyo Inside the Toshiba Hino Plant (72) Inventor Mitsunori Omokawa 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Address Toshiba Research Institute, Inc. (56) References JP-A-62-163424 (JP, A) JP-A-62-207032 (JP, A) JP-A-62-284530 (JP, A)

Claims (1)

(57) [Claims] 1. An audio input / output device capable of selecting a first line or a second line as a connection line, comprising: a speaker for outputting a signal from the first line or the second line; A microphone for inputting a signal to the second line or the second line; a first echo canceller for removing an echo in a first band from the speaker to the microphone; and a signal in the first band or the first band. First and second filters for selectively passing one of signals of a second band in a band higher than the first band; and a second filter based on a signal passed through the first filter. A second echo canceller that removes an echo wrapping around the signal that has passed through the first line, and when the first line is connected, the second filter is added to the first and second filters. Band signal, and outputs a signal from the first line to the speaker via the first filter, and a signal from the microphone via the second filter to the first signal. And when the second line is connected, the signal of the first band is passed through the first and second filters, and the signal from the second line is transmitted to the second line. Switching means for outputting to the speaker via the second filter and outputting the signal from the microphone to the second line via the first filter. I / O device.