JPH0418899A - Echo preventing device - Google Patents

Abstract

PURPOSE:To prevent an echo without stopping a sound signal from the other party by providing two systems of sound signal transmission lines from a studio to each schoolroom, one system of the sound signal transmission line from each schoolroom to the studio, and one system of a control signal transmission line from the studio to each schoolroom. CONSTITUTION:The sound signal by the microphone 3 of the studio and the sound signal obtained by synthesizing the sound signal and the sound signal transmitted from the schoolroom to the studio are transmitted by using the sound signal transmission line 16 from the studio to the schoolroom, and simultaneously, only the sound signal by the microphone 3 of the studio is transmitted by using the sound signal transmission line 17 other than the sound signal transmission line 16. At the schoolroom, two systems of the sound signals are selected by remote operation using the sound signal selecting device 12 of the studio. Thus, the echo can be suppressed without stopping the sound signal from the other party.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a distance learning system consisting of a studio and multiple classrooms, and a method for transmitting questions and answers between the studio and the classrooms to all classrooms. This invention relates to an echo prevention device that prevents a questioner's voice from returning to the classroom as an echo.

[Conventional technology]

Conventional echo prevention devices include: 1) In a form where the audio signal transmitted from the caller side to the other party is reproduced by a speaker, etc., the echo prevention device acoustically couples the speaker and microphone in the other party's room. If the audio signal sent from the caller side is transmitted to the caller side as an echo, the other party can reduce the playback volume of the speaker, increase the directivity of the microphone, suppress the echoes in the room, etc. A method that creates an environment in which the audio signal sent to the microphone is re-input into the microphone.

2) While transmitting audio signals to the other party, a device (or an electric circuit) is installed on the speaker's side to stop the reproduction of the audio signal from the other party that is being transmitted to the speaker. Method of stopping.

3) Generate a signal on the sender's side that has the opposite phase to the audio signal being sent to the other party, and combine the audio signal transmitted from the other party with this anti-phase signal to cancel out the echo. Device(
A method of suppressing echoes by installing an electrical circuit (or electric circuit).

etc.

[Problem to be solved by the invention]

Conventional echo prevention devices are configured as described above, so in the device 1), the environment at the other end of the caller is restricted, so there is no flexibility in adding or moving microphones, etc.
With the device that stops echoes (2), while the audio signal is being sent to the other party, you will not be able to hear the echo and the voice signal from the other party at the same time, and with the device that suppresses echoes (3), the voice signal between the sender and the other party will not be heard at the same time. Depending on the propagation time in the transmission path between
Since it is necessary to control the delay time for synthesizing anti-phase signals for canceling echo signals, there are problems such as the device (or electric circuit) becoming complicated and expensive.

This invention was made in order to solve the above-mentioned problems, and it is possible to prevent echoes from occurring without stopping the audio signal from the other party to the sender's side, and also to avoid complicating the device configuration. The purpose is to realize an echo prevention device without any noise.

[Means for Solving the Problems] The echo prevention device according to the present invention has two audio signal transmission lines between one studio and a plurality of classrooms, one from the studio to each classroom, and one from each classroom. One audio signal transmission line to the studio and one control signal transmission line from the studio to each classroom are provided, and an audio signal selection device is installed from the studio to the classroom via the control signal transmission line. It is equipped with a remote control device that remotely controls the.

[Function] The echo prevention device of the present invention transmits an audio signal from a studio microphone and an audio signal obtained by synthesizing this audio signal with an audio signal transmitted from the classroom to the studio. At the same time, only the audio signal from the microphone in the studio is transmitted using a separate audio signal transmission path from the above audio signal transmission path, and in the classroom, the audio signals of two systems are transmitted as the studio audio signal. By making the selection by remote control using the selection device, the audio signal from the other party is not interrupted.
To easily and inexpensively obtain an echo prevention device capable of suppressing echoes and having a high echo prevention effect.

[Embodiment 1] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1st
In the figure, 1 is the studio side and 2 is the classroom side. On the studio side, there is a microphone 3, an audio signal synthesizer 4 connected to the microphone 3, an audio signal distributor 5 connected to the audio signal synthesizer 4, an audio signal distributor 6 connected to the microphone 3, and an audio A sound-car signal splitter 8 connected to a signal synthesizer 7, a speaker 9 connected to this audio signal splitter 8, a remote side connected to a remote control device 10 (
A sum signal distribution device 11 is provided.

Further, the classroom side 2 is provided with a speaker 13 connected to an audio signal selection device 12 and a microphone 15 connected to an audio signal synthesizer 14.

The audio signal distributor 56 on the studio side 1 and the audio signal selection device 12 on the classroom side 2 are connected by two audio signal transmission lines 16 and 17 from the studio to the classroom. The synthesizer 7 and the audio signal synthesizer 14 on the classroom side 2 are connected by one audio signal transmission path 18 from the classroom to the studio, and the audio signal between the remote control signal distribution device 11 on the studio side l and the audio signal on the classroom side 2 is connected. Between the selection devices 12
They are connected via a system control signal transmission line 19.

Next, the operation of the above embodiment will be explained. In the distance education format, during a lecture, the audio signal from the microphone 3 is sent to the speakers 13 in all classrooms, but during a question-and-answer session, the question audio from the microphone 15 and the answer audio from the microphone 3 are transmitted to all the speakers 13 in all classrooms. It is necessary to send it to the speaker 13 in the classroom, but in the classroom where the questioner is present, the question voice will be heard as an echo, and depending on the acoustic conditions, it will become a ringing sound, so it is necessary to send only the answer voice to the speaker 13. There is.

Therefore, the answer voice from the microphone 3 is transmitted from the voice signal distributor 6 to the voice signal transmission line 17 to all the classrooms, and at the same time from the microphone 15 in the classroom to the voice signal synthesizer 14 and the voice signal transmission line 18. , audio signal synthesizer 7
, the question voice obtained via the voice signal distributor 8 and the response voice from the microphone 3 are synthesized by the voice signal synthesizer 4, and then transmitted to all classrooms via the voice signal divider 5 and the voice signal transmission line 16. At the same time, the remote control device 10 operates the audio signal selection device 12 via the remote control signal distribution device 11 and the control signal transmission path 19, and the classroom where the questioner is located is transmitted from the audio signal transmission path 17. The answer audio signal is sent to the speaker 13, and for other classrooms, a composite signal of the question audio and answer audio from the audio signal transmission line 16 is sent to the speaker 9, thereby eliminating echoes and ringing in the classroom where the questioner is present. Prevents noise and enables listening to question-and-answer situations in other classrooms.

In the above embodiment, the remote control device 10 operates the audio signal selection device 12 via the remote control signal distribution device 11 to select the audio signal from either the audio signal transmission path 16 or the audio signal transmission path 17 to the speaker. 13, the output of the audio signal synthesizer 14 and the audio signal transmission line 18 are additionally connected to the audio signal selection device 12, and the audio signal is transmitted from the remote control device 10 and the remote control signal distribution bag [11]. When operating the selection device 12 to send the audio signal from the audio signal transmission path 16 to the speaker 13, the audio signal from the audio signal synthesizer 14 is not sent to the audio signal transmission path 18, and the audio signal is When the audio signal from the transmission path 17 is sent to the speaker 13, the audio signal from the audio signal synthesizer 14 may be linked to be sent to the audio signal transmission path 18.

〔Effect of the invention〕

As described above, according to the present invention, an audio signal from a microphone in the studio and an audio signal obtained by combining this audio signal with an audio signal transmitted from the classroom to the studio are transmitted through the audio transmission path from the studio to the classroom. At the same time, only the audio signal from the microphone in the studio is transmitted using an audio transmission path different from the audio transmission path mentioned above, and in the classroom, the two types of audio signals transmitted above are transmitted from the studio. Since the selection is made using a remote control signal, it is possible to obtain an echo prevention device with a simple and inexpensive device configuration that is highly effective in preventing echoes and can suppress echoes without stopping the audio signal from the other party. .

[Brief explanation of the drawing]

The drawing is a block diagram showing an echo prevention device according to an embodiment of the present invention. 1 is the studio side, 2 is the classroom side, 3 and 15 are microphones, 9.13 are speakers, 4, 7.14 are audio signal synthesizers, 5 and 6.8 are audio signal distributors, and 12 is an audio signal selection device , 10 is a remote control device, 11 is a remote control 11 signal distribution device, 16.17 is an audio signal transmission path from the studio to the classroom, 18 is an audio signal transmission path from the classroom to the studio,
19 is a remote control signal transmission line. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] a studio in which a microphone and a speaker are installed; a plurality of classrooms in which a plurality of microphones and speakers are installed; a first audio signal transmission path for transmitting an audio signal to the microphone in the classroom to the studio; and the studio. a second audio signal transmission line for transmitting an audio signal to the microphone in the classroom to the classroom; a third audio signal transmission path to be transmitted to the classroom; and a third audio signal transmission path for transmitting the audio signal to the classroom; an audio signal selection device provided in the studio; and a control signal transmission path for transmitting a remote control signal from a remote control device provided in the studio to the audio signal selection device to remotely control the audio signal selection device. Anti-echo device.