JP2003046636A - Handset device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a transmission / reception device provided with a function capable of easily and effectively eliminating the difficulty of listening to a received voice caused by an echo signal. SOLUTION: Means for extracting a part of a transmission signal transmitted from a transmitter 1 to a digital communication line 4 as a side tone having a volume of -15 dB to -20 dB with respect to the volume of the transmission signal, for example. (Variable gain amplifier 6) and means (adder 7) for adding this side tone to the signal received by the receiver 2 and masking the echo signal of the transmission signal via the digital communication line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitter / receiver device capable of simplifying and effectively eliminating the uncomfortableness of a received voice caused by an echo signal (echo) during a call through a digital communication line. .

[0002]

Related Background Art Recently, various kinds of information transmission using digital communication lines have been popular, and telephone calls have also been made using the digital communication lines. However, when talking over a digital communication line, it cannot be denied that the echo (echo) of the transmitted voice (transmitted signal) due to the digital communication line occurs. The echo of this transmitted voice is
This is a phenomenon in which the transmitted voice transmitted from the transmitter returns to the receiver on the transmitting side after a certain period of time, which causes a problem that the received voice by the receiver becomes difficult to hear.

[0003]

Therefore, in the prior art, a pseudo echo signal is generated on the transmitting side in order to cancel the echo, and the pseudo echo signal is subtracted from the received signal received by the receiver. The echo signal from the digital communication line is canceled. However, the delay time of the echo signal changes depending on the route length of the digital communication line, and therefore it is necessary to generate a pseudo echo signal according to the delay time.

Therefore, conventionally, a pseudo echo signal is generated while adjusting the delay time exclusively using a transversal filter or the like. However, this type of echo signal canceller (echo canceller) has a complicated structure and is very expensive. In particular, an echo canceller integrated into an integrated circuit has various problems in that it can be incorporated in a digital cordless phone or the like, because the delay time that can be handled is limited.

The present invention has been made in view of the above circumstances, and an object thereof is to easily and effectively eliminate the uncomfortableness of a received voice caused by an echo signal of a transmitted voice. It is to provide a handset device having a function capable of performing.

[0006]

In order to achieve the above-mentioned object, the present invention relates to a transmitter / receiver device comprising a transmitter and a receiver for communicating with a communication partner via a digital communication line,
Particularly, a part of the transmission signal transmitted from the transmitter to the digital network is, for example, −15d with respect to the volume of the transmission signal.
Means for extracting as a sidetone having a sound volume of B to -20 dB, and means for adding the sidetone to a signal received by the receiver to mask an echo signal of the transmission signal through the digital communication line. It is characterized by having.

That is, the present invention was made by paying attention to the fact that a part of the voice uttered by a human being is transmitted from the cheek bone to the eardrum through the ear bone, but there is almost no discomfort. A part of the voice signal sent from the device is extracted as its sidetone, and this sidetone is added to the signal received by the handset to mask the echo signal of the transmission signal via the digital communication line. It is characterized by eliminating the difficulty in listening to the received voice due to the echo signal.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A transmitting / receiving device according to an embodiment of the present invention will be described below. FIG. 1 is a schematic configuration diagram of a main part of a transmitter / receiver device according to the present invention. Reference numeral 1 is a transmitter, and 2 is a receiver paired with the transmitter 1. The voice signal input from the transmitter 1 is transmitted and output to the digital communication line 4 via the transmission amplifier 3, and the reception signal received from the digital communication line 4 is received via the reception amplifier 5 in the receiver. It is given to No. 2 and is output as voice. The handset device including the handset 1 and the handset 2 is used to make a voice call with the handset device of the same configuration at the other end of the call via the digital communication line 4.

Basically, in the transmitter / receiver device including the transmitter 1 and the receiver 2 described above, the feature of the present invention lies in that the transmitter 1 is connected via the transmitter amplifier 3 A part of the transmission signal transmitted and output to the digital communication line 4 is extracted as a side tone of the transmission signal via the gain variable type amplifier 6, and the side tone is added to the side line of the reception side. It is configured to add to the received signal using the device 7.

Incidentally, the sidetone extracted through the amplifier 6 is obtained as a signal having a volume of about -15 dB to -20 dB with respect to the volume of the transmission signal output from the transmission amplifier 3. For example, -20 dB when the delay time of the echo signal in the digital communication line 4 is as short as 40 msec.
The side volume is reduced to about 15 msec, and when the delay time is as long as about 60 msec, the side volume is set to about -15 dB. Regarding the volume of the sidetone, there is an auditory difference in the masking effect on the echo signal, so the level (volume) can be adjusted arbitrarily within a predetermined range while checking the masking effect, for example. It has become.

Thus, according to the transmitting / receiving device configured to generate the sidetone of the transmitted voice and forcibly add the sidetone to the received voice, the transmitted voice A ( A solid line), its reverberation signal B (broken line), and a sidetone C (dashed line) generated from the transmitted voice A are schematically shown, and a sidetone C of a certain volume is added to the received voice. For example, the echo signal B in the received voice can be masked by the sidetone C. Especially the beginning of the echo signal B, which is offensive to the ear,
It is possible to effectively mask with the ending of the sidetone C, eliminate the discomfort caused by the echo signal B, simplify the listening difficulty of the received voice, and effectively reduce it.

FIG. 3 shows the effect of masking an echo signal by a side tone by a plurality of persons using the transmitter / receiver device configured as described above and assuming a digital communication line 5 having echo delay times of 40 msec, 50 msec and 60 msec. Shows the experimental results confirmed in. Then, while changing the side volume that is added to the received voice, the side volume when the echo signal interferes and makes it difficult to hear the received voice, the range of the side volume at which the received voice can be heard comfortably, and the sidetone is noisy This is a calculation of the side volume when the voice becomes difficult to hear.

As shown in the results of this experiment, although there are some individual differences in the hearing sensation of a plurality of people, the echo delay time is 40%.
It has been confirmed that a practically sufficient masking effect is obtained at a side volume of about -20 dB to -16 dB on average for m seconds. Similarly, when the echo delay time is 50 msec, the average sound volume is about -17 dB to -14 dB, and when the echo delay time is 60 msec, the average sound level is -13 dB.
It was confirmed that a practically sufficient masking effect can be achieved with a side volume of about dB to -12 dB.

Further, according to the transmitter / receiver device configured as described above, the variable gain type amplifier 6 for generating the side tone,
Since it suffices to newly incorporate an adder 7 for adding sidetone to the received voice, the configuration is far simpler than the case of incorporating an echo signal canceling device (echo canceller) using a transversal filter or the like. And the cost is very low. Therefore, it has great practical advantages such as being very suitable for being incorporated in a device such as a digital cordless phone.

The present invention is not limited to the above embodiment. For example, the side volume can be changed not only continuously but also stepwise in several stages. It is also possible to add the above-mentioned masking function by the side tone to the transmitting / receiving device incorporating the echo signal canceling device (echo canceller). In this case, it works effectively when the setting range of the echo delay time in the echo canceller is less than the actual delay time in the digital communication circuit 4. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

[0016]

As described above, according to the present invention, the echo signal is masked by using the sidetone of the transmitted voice.
It is possible to simply and effectively eliminate the unpleasantness of the received voice caused by the echo signal, and it is possible to achieve a great practical effect such that the configuration is simple and can be realized at low cost.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a main part of a handset device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram for explaining a masking effect of an echo signal by a side sound.

FIG. 3 is a diagram showing an experimental result for confirming a masking effect of an echo signal by a side sound.

[Explanation of symbols]

1 transmitter 2 handset 4 digital transmission lines 6 Variable gain amplifier (side tone generating means) 7 adder

Claims (2)

[Claims] 1. A transmitter / receiver device comprising a transmitter and a receiver for communicating with a communication partner via a digital communication line, wherein the transmitter signal is transmitted from the transmitter to the digital communication line. Means for extracting a part of the side sound as a side sound and means for adding the side sound to the signal received by the receiver to mask the echo signal of the transmission signal through the digital communication line. Characteristic transmitting / receiving device. 2. The sidetone is − with respect to the volume of the transmission signal.
The handset device according to claim 1, which is extracted as a sound volume of 15 dB to -20 dB.