JPH0220193B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to an audio teleconferencing system having teleconferencing devices facing each other, and in which the indoor noise of at least one conference room is large and the difference in indoor noise between both conference rooms is large. This invention relates to a method for preventing speech-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial-initial truncation.

(b) Background of the technology An audio teleconferencing system connects remote conference rooms through communication lines, and each conference room is equipped with an audio teleconferencing device with a microphone and a speaker to listen to the speaker's sound from the microphone in one of the conference rooms. A conference is held between people in a remote conference room who listen through the speaker in the other conference room.

(c) Prior Art and Problems Figure 1 is a block diagram of a conventional audio teleconferencing device.

In the figure, 1 and 2 are microphones, 3 is a microphone coupling amplifier, 4 and 6 are automatic loss adjusters, 5 and 7 are amplifiers, 8 and 9 are speakers, 10 and 12 are rectifiers, 1
1 indicates a voltage comparator.

The audio signals from microphones 1 and 2 are amplified by a microphone coupling amplifier 3, passed through an automatic loss adjuster 4, amplified by an amplifier 5, and sent to the other party via a transmission line. After passing through an automatic loss adjuster 6, the signal is amplified by an amplifier 7 and outputted from speakers 8 and 9. In this case, it is necessary to prevent howling caused by the sounds from the speakers 8 and 9 entering the microphones 1 and 2 of the local station. For this purpose, the output level of the microphone coupling circuit 3 and the reception level from the other party are rectified by rectifiers 10 and 12 to create a DC voltage v ₁ v ₂
is calculated and input to the voltage comparator 11, and the DC voltage v ₁ and
When v ₂ are equal (when there is no sound), automatic loss adjusters 4 and 6
When the DC voltage v ₁ is larger than v ₂ (during transmission), the loss of the automatic loss adjuster 6 is increased, and the loss of the automatic loss adjuster 4 is kept small. When the DC voltage v ₂ is greater than v ₁ (when receiving a call), the loss of the automatic loss adjuster 4 is increased, and the loss of the automatic loss adjuster 6 is kept small. In this way, the loss of one automatic loss adjuster is increased to prevent howling and to enable two-way communication. However, some conference rooms have large indoor noise, and this varies depending on the environment. For example, to explain the case where the indoor noise in one of the conference rooms is loud, in conference room A where the indoor noise is loud, the DC voltage v ₁ when there is no call is
In conference room B, where the indoor noise on the other side is low, the DC voltage v ₂ is higher than v ₂ due to the noise from conference room A.
becomes larger than v ₁ . Therefore, the loss of the automatic loss adjuster 6 in the conference room A where the indoor noise is large and the automatic loss adjuster 4 in the conference room B where the indoor noise is low becomes large. Therefore, when a call is transmitted from conference room B, there is an automatic loss in conference room B until the DC voltage v ₁ of conference room B becomes greater than v ₂ and until the DC voltage v ₂ of conference room A becomes greater than v ₁ . Adjuster 4 and automatic loss adjuster 6 in conference room A
The loss is large and the beginning of the speech is cut off. Also conference room B
While the outgoing voice disappears, the loss in the automatic loss adjuster 4 increases when the DC voltage in conference room B becomes smaller than _v2 due to the noise from conference room A.
Furthermore, in the conference room A, when the DC voltage due to noise becomes smaller than v ₁ , the loss of the automatic loss adjuster 6 becomes large and the end of the word is cut off. As described above, even if the indoor noise levels in both conference rooms are large and there is a difference in the indoor noise levels, truncations at the beginning and end of speech will similarly occur. Conventional audio teleconferencing devices have such drawbacks.

(d) Object of the Invention In view of the above-mentioned drawbacks, the object of the present invention is to provide a method for preventing syllable-initial-end truncation when the indoor noise in at least one conference room is large and there is a difference in indoor noise between the two conference rooms. It is provided by.

(e) Structure of the Invention In order to achieve the above object, the present invention inputs the output from the microphone to the first input of the voltage comparator via the first rectifier, and also performs the first automatic loss adjustment. and input the received input from the opposite audio teleconferencing device to the second input of the voltage comparator via the second rectifier. is transmitted to the speaker via an automatic loss adjuster, and the voltage comparator reduces the loss of the first and second automatic loss adjusters when the voltages to the first and second inputs are equal. and when the voltage to the first input is higher than the voltage to the second input, the loss of the first automatic loss adjuster is decreased and the loss of the second automatic loss adjuster is increased. When the voltage to the second input is higher than the voltage to the first input, the loss of the first automatic loss adjuster is increased and the loss of the second automatic loss adjuster is decreased. In an audio teleconferencing device that controls the input of the first rectifier or the second rectifier,
High frequency noise outside the audible frequency is always applied at a level where the output voltage of the first rectifier and the output voltage of the second rectifier are equal when there is no call.

That is, if the noise in the room where the microphone of one audio remote conference device is located is large and the noise in the room where the microphone of the other audio remote conference device is located is low,
High frequency noise outside the audible frequency range is constantly applied to the input of the second rectifier of one audio teleconferencing device at a level where the output voltage of the first rectifier is equal to the output voltage of the second rectifier when there is no call. This eliminates the influence on the timing of loss increase in the first and second automatic loss adjusters due to large room noise on one side, at the start of a call and at the end of a call, and at the end of a call. It is possible to prevent word endings from being cut off.

(f) Embodiment of the invention An embodiment of the invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of an audio teleconferencing device according to an embodiment of the present invention.

Components in the figure that have the same functions as those in FIG. 1 are indicated by the same symbols. Reference numeral 13 indicates a noise generator that sends out high frequency noise outside the audio frequency range. First, it is assumed that the indoor noise in conference room A is loud and the indoor noise in conference room B is low. In this case, when there is no call, in the audio teleconferencing device in conference room A, the DC voltage v ₁ of the output of the rectifier 10 on the transmitting side and the DC voltage v 2 of the output of the rectifier 12 on the receiving side due to indoor noise on the transmitting side _.
In addition, in the audio teleconferencing device in conference room B, the DC voltage v ₂ of the output of the rectifier 12 due to indoor noise from conference room A on the receiving side is equal to the DC voltage v 1 of the output of the rectifier ₁₀ on the transmitting side. High frequency noise outside the audible frequency is applied from the noise generator 13 to the input side of the rectifier 12 in conference room A and to the input side of the rectifier 10 in conference room B so that If this is done, the loss of the automatic loss adjusters 4 and 6 of each audio teleconference device will be small when there is no call, so no cutting off will occur at the beginning of the conversation. Furthermore, the losses of the automatic loss adjuster 4 on the transmitting side and the automatic loss adjuster 6 on the receiving side do not increase until the voice during the call disappears, so no end-of-word truncations occur. Since the high frequency noise from the noise generator 13 is outside the audible frequency, it does not interfere with conversation, and since the frequency is insensitive to the microphones 1 and 2, it does not cause howling.

(g) Effects of the Invention As explained in detail above, according to the present invention, there is an effect that it is possible to prevent speech-initial and ending-word cutting when the indoor noise in at least one of the conference rooms is large and there is a difference in the indoor noise between the two conference rooms. .

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional audio teleconferencing device, and FIG. 2 is a block diagram of an audio teleconferencing device according to an embodiment of the present invention. In the figure, 1 and 2 are microphones, 3 is a microphone coupling amplifier, 4 and 6 are automatic loss adjusters, 5 and 7 are amplifiers, 8 and 9 are speakers, 10 and 12 are rectifiers, 1
1 is a voltage comparator, and 13 is a noise generator.

Claims (1)

[Claims] 1. The output from the microphone is input to the first input of the voltage comparator via the first rectifier, and is also input to the opposing audio teleconferencing device via the first automatic loss adjuster. and inputting the received input from the opposite audio teleconferencing device to the second input of the voltage comparator via the second rectifier, and transmitting it to the speaker via the second automatic loss adjuster. , the voltage comparator controls the losses of the first and second automatic loss adjusters to be small when the voltages to the first and second inputs are equal, and the voltage to the first input is is larger than the voltage to the second input, the loss of the first automatic loss adjuster is controlled to be small and the loss of the second automatic loss adjuster is large, and the voltage to the second input is controlled to be small. In an audio teleconferencing device that controls the loss of the first automatic loss adjuster to be large and the loss of the second automatic loss adjuster to be small when the voltage is higher than the voltage to the first input, at the input of the first rectifier or the second rectifier;
A method for preventing speech cutting at the beginning and end of a speech, characterized in that high frequency noise outside the audible frequency is always applied at a level where the output voltage of the first rectifier and the output voltage of the second rectifier are equal when there is no call.