JP2000332690A - Sound transmission system using optical signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a receiver to freely select a volume in accordance with his taste and to realize a better reception environment by equipping two or more light receivers which receive an optical sound signal and generate a reception signal and a receiver having a sound reproducing means which reproduces sound by the reception signal from the light receiver. SOLUTION: In a modulation part 14, modulation is performed for transmitting an electric sound signal reproduced by a sound source part 11 as a light sound signal 15. The light sound signal 15 is received by plural receivers 19 which constitute a reception part 18. The receiver 19 preferably has a structure of a normal headphone which a receiver can wear. The recoader 19 has a sound reproducing means for reproducing the sound in accordance with this electric signal, after the light sound signal 15 received is converted into an electric signal by the light receiver formed from, for example, a photodiode or the like. This receiver 19, that is, a sound reproducing circuit for the headphone, can use a receiver of a cordless headphone system which is normally used and is on the market.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice transmission system that can be used in listening and testing foreign languages, for example, for transmitting foreign language voices to listeners. It relates to a voice transmission system for transmitting information from a teacher to each student.

[0002]

2. Description of the Related Art In a language education, when a foreign language is listened and tested, a listening and test system required for the implementation is a PA system (Public).
Address system) has been commonly used. The PA system is a system in which a sound is output from a loudspeaker disposed in a listening room or the like, that is, a speaker to perform listening or the like.

FIG. 9 schematically shows a conventional listening and testing system using the PA system. In the PA system, reference numeral 41 denotes an audio signal generation device, which converts audio information recorded on a tape, CD, MD, or the like (not shown) containing a listening problem into an electric audio signal. Reference numeral 42 denotes a listening room capable of accommodating about 50 to 200 test takers. In the case of a large-scale examination such as a university entrance examination center examination, test takers take the listening test while being distributed and housed in about 50 such listening rooms. The electric audio signal 43 including the test question is transmitted from the audio signal generation device 41 to each listening room 42 via the wiring 44. In each listening room 42, for example, as shown in FIG. 9, four speakers 45 installed at four corners are used to simultaneously reproduce and broadcast the transmitted audio signal as audio.

[0004] However, listening and testing using the PA method have already been carried out at the University of Tokyo and the like, but the following problems have been pointed out. 1) Installation work of sound absorbing walls, soundproof walls, speakers and the like is required, so that a large amount of equipment and construction costs are required. 2) Due to the interference between a plurality of speakers installed in each listening room and the difference in sound pressure depending on the distance between the speakers and each examinee, there are places where it is difficult to hear depending on the positional relationship between the speakers and the examinees. 3) There is a case where the sound cannot be heard due to external noise such as a passing sound of a car, a train, a jet or the like.

[0005] 4) In some cases, it is difficult to hear due to internal noise such as a cough of the examinee and the squeaking noise of a desk or chair.

[0006] Among these problems, as a solution to the problem 2), for example, measures have been taken not to use the problematic seat from next time. 3)
As a solution to the above problem, improvements were made to further increase the sound absorbing wall, the sound insulating wall, etc. by investing in equipment and increase the effect thereof. However, these measures have not led to a fundamental solution. In particular, no solution has been implemented for the problem 4).

Unlike these countermeasures, a system in which each examinee uses headphones individually without using a speaker is considered. As a result of studying this headphone system, the above problems of the PA system 2). 3). 4)
Has been found to be easily resolved.

However, it is not a sufficient solution to the problem 1). In the conventional speaker system, the number of speakers per room can be, for example, about 4
In the headphone system, headphones are required for the number of examinees. It has been found that the electric wiring required for this is enormous, the equipment cost is large, and the implementation is impractical. Moreover, since such wiring equipment is permanent, the layout of the listening room 42 may be changed or the listening room 42 may be used for other purposes.
Is difficult to use.

However, the above-mentioned wiring problem can be solved by using a cordless headphone because most of the wiring is unnecessary. However, it has been found that when cordless headphones are used, the reliability of reception, such as securing a receivable area, becomes a new problem. Also,
The sound of the headphones can be confirmed only by the wearer of the headphones, which is usually the examinee. This is a serious problem in language education, as it may cause a candidate to make a “false report” called “device failure” when he does not understand the answer to a test question.

At present, products using cordless headphones are commercially available as home acoustic products. However, these devices are developed for individuals to listen to music, and use one transmitter and one or two or three receivers. Further, these commercially available cordless headphone systems do not have a reception level indicator described later.

[0011]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of improving the above-mentioned problems of the conventional PA system. However, a problem that arises when a cordless headphone system is employed for this purpose. It is intended to solve the problem.

When a cordless headphone system capable of solving the above-mentioned problems 1) to 4) of the conventional PA system is introduced into a listening system for language education, the following problem newly occurs. Therefore, an object of the present invention is to solve the problem that the receivable area is likely to be unstable, and the problem that the operation state of each receiver cannot be confirmed by a third party, a test supervisor. Things.

[0013] In other words, the headphones as the receiver are:
The voice signal from the transmitter can always be received stably without becoming unreceivable, and the operation state of the receiver can always be checked by a third party such as a test supervisor. The purpose of the present invention is to provide a system that has the effect of preventing the "declaration of a person".

[0014]

SUMMARY OF THE INVENTION Since the voice transmission system according to the present invention is put to practical use in a special environment, for example, used in language education and tests for students and test takers, the reliability of the device is particularly high. Therefore, the system is arranged so that each of the receivers such as headphones has two or more light receiving units and can always receive the optical sound signal from a plurality of signal sources, that is, light emitting units (radiators). This is a system related to a transceiver.

Further, for example, despite the normal operation, the false report of the receiver such as the failure of the receiving device is suppressed, and the third party instructor and test supervisor always receive the false report. For the purpose of confirming the state, a reception indicator that blinks, for example, in accordance with the reception signal is installed at a position that is invisible to the recipient and that is easy for the instructor and the test supervisor to confirm.

That is, the sound transmission system of the present invention comprises a sound source section for generating an electric sound signal, a branch section for branching the electric sound signal, and an optical sound signal corresponding to the split electric sound signal. A plurality of light-emitting portions that are arranged apart from each other to radiate, two or more light receivers that receive the optical sound signal and generate a reception signal, and reproduce sound by a reception signal from the two or more light receivers And a receiver having a sound reproducing means.

Further, the receiver may be provided with a reception state confirming means, and the plurality of light-emitting units may be arranged so that the receiver can always receive an optical sound signal from at least two or more light-emitting units. The reception status confirmation means disposed may be a reception indicator which lights up in response to a reception signal.

Further, the reception indicator can be arranged outside the field of view of the user of the receiver, the receiver can be formed in a headphone format, and the sound reproducing means controls the volume of the sound. The light emitting unit can be provided with a phase correction circuit. In addition, a sound transmission system in which the electric sound signal generated by the sound source unit is transmitted to the light emitting unit via the Internet can be provided.

Also, the sound transmission system of the present invention includes a sound source section for generating an electric sound signal, a modulating section connected to the sound source section for modulating the electric sound signal, and converting the modulated signal into a plurality of modulated signals. A transmitting unit including a branching unit for branching, and a plurality of light emitting units arranged at a plurality of positions for emitting an optical audio signal by each of the modulated signals connected to the branching unit, and emitted from the light emitting unit; A receiver for receiving the received optical audio signal, audio reproducing means connected to the optical receiver for reproducing the received optical audio signal into audio, and a receiving state confirming means for externally confirming a receiving state. And a receiving unit including a plurality of devices.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration example of a listening and testing system for language education using cordless headphones according to an embodiment of the present invention.

As a method of transmitting the electric audio signal 12 to each receiver, generally, two types, that is, wired and wireless are well known. In the present embodiment, when a large number of recipients are listening at the same time, if a wired method is employed, a great deal of cost will be required for wiring work and removal work, so a wireless method is employed. In the wireless system, the FM radio system and the infrared light system are currently the mainstream, but the FM radio system, which is a wireless system, is generally known to be susceptible to noise. On the other hand, unless the output is appropriately adjusted. However, the radio wave is too strong, and the signal may unexpectedly reach a wide range and may be received outside the listening room. This is, like this system,
When used for language education, it is a problem because "leakage of test questions", "interference with adjacent rooms", and "intentional test interference" can occur.

Therefore, the present embodiment employs an infrared light system. This uses infrared light for communication means, is generally resistant to noise, and the reachable range of a signal is limited only to a room, so the above-described problem does not occur. In addition,
The invention is not limited to the use of infrared light, but it is also possible to use light of other wavelengths, for example yellow if necessary.

Reference numeral 11 denotes a sound source section for generating an electric audio signal 12, for example, a commonly used tape, CD, MD, or the like.
An electric audio signal 12 is generated from audio information recorded on a tape, CD, MD or the like using a deck or the like. Sound source section 11
Is connected to the modulation unit 14 of the transmission unit 13.

The modulation section 14 is a section that performs modulation for transmitting the electric audio signal 12 reproduced by the sound source section 11 as an optical audio signal 15. For example, it is modulated to a carrier of 2.3 MHz. The modulator 14 is connected to the amplifier / branch 15. The circuit configuration of the modulation unit 14 is generally known to those skilled in the art, and in the present embodiment, the modulation unit of a cordless headphone system that is usually commercially used is used. Cordless headphone systems using infrared light emitting diodes which are currently commercially available and used have a common standard, and these circuits can be used.

The modulating unit 14 is connected to the amplifying / branching unit 17. The amplifying / branching unit 17 is a part that amplifies and branches the modulated electric audio signal. In the present embodiment shown in FIG. 1, since four light emitting units 16 are provided, the modulated electric audio signal is divided into four parts. Amplification / branching unit 1
7 is connected to the light emitting unit 16.

FIG. 2 shows a circuit example of a transmission unit (transmitter) in the amplification / branching unit 17. In this embodiment, two channels are provided for left and right. In the figure, reference numeral 31 denotes a left channel input (2.3 MHz) and a right channel input (2.8 MHz) of the transmission unit, and 32 denotes a frequency modulation IC. The electronic circuit on the right side of FIG. 2 connected to the output of the frequency modulation IC 32 is generally called a buffer amplifier, and is a normal amplifier for amplifying a frequency modulation signal. Reference numeral 33 denotes an output terminal of the transmission unit, which has two terminal outputs. The signal from this output terminal is divided into four, for example, as shown in FIG. The number of divisions is appropriately determined by the size and shape of the listening room, and is 4
Although not limited to division, in a normal single listening room, four divisions is optimal.

Dividing circuit of amplification / branching unit 17 (not shown)
In, the frequency-modulated and amplified signal is divided for distribution to the inputs of the four light emitting units (radiators) 16. When the driving capability of the output terminal 33 of the transmitting unit shown in FIG. 2 has only one light emitting portion, this is further divided into four after being amplified to the driving capability of four units.

As a method of connecting the transmitting unit and the light emitting unit (radiator) 16 to form a branching unit, two types of connection systems can be roughly classified. The first is a serial connection method, which is a method of connecting a transmitting section, a light emitting section 1, a light emitting section 2, a light emitting section 3, and a light emitting section 4.

The second is a parallel connection system. This is how to connect.

The feature of the first serial connection is that the number of units can be increased because the connection is made sequentially, and the wiring is simple. The transmitting unit and the light emitting unit are wired with a coaxial cable or the like. In this case, the electric signal has a time delay in proportion to the length of the distribution cable. When a plurality of light emitting units are installed in one listening room, if there is a time difference between the radiator signals (optical audio signals), they interfere with each other, and as a result, there are places where there is no signal or where the signal level is extremely low. The possibility exists. In such a case, a phase correction circuit is provided in the light emitting unit. A commonly used correction circuit can be used as the phase correction circuit.

On the other hand, in the parallel connection, the phase correction circuit becomes unnecessary by making the lengths of the cables all the same. In this case, a branch circuit is required, and the light emitting unit can be connected only to the branch circuit.

The branching portion of the embodiment shown in FIG. 1 shows a case of parallel connection, and therefore requires an amplifying / branching circuit 17. Since the branch circuit is not a special circuit configuration, no particular description is required.

For example, when used in a normal test room or the like,
Four light emitting units are installed in the four corners of the room to provide quadruple security,
As a wiring method, it is preferable to connect these four light emitting units in parallel. If a large number of light emitting units need to be arranged in a large test room, connect the light emitting units in series to prevent the total extension distance of the wiring from becoming long, and if necessary, correct the phase for each light emitting unit. It is good to install a circuit.

FIG. 3 shows a circuit example of the light emitting section 16. The signals divided into four by the amplifying / branching unit 17 are respectively input to the input terminals 34 of the light emitting unit 16. As shown in FIG. 3, the light emitting section 16 includes an input terminal 34 and the infrared light emitting diode 3.
5, a driving circuit generally called a driver is provided.

In the embodiment shown in FIG.
4 × 8 50 nm infrared light emitting diodes 35 are arranged in an array. Each of the used infrared light emitting diodes can secure a receiving distance of about 5 m and a spread of about 90 ° as a receiving area.

In the present embodiment, a circuit of a light emitting section of a cordless headphone system which is usually commercially available can be used. In this case, it is desirable to adjust the receivable distance of the infrared light emitting diode according to the size of the listening room.

FIGS. 4 and 5 show examples of the arrangement of the light emitting units 16 in the listening room 20. FIG. 4 is an elevation view and FIG. 5 is a plan view. As shown in FIG. 5, four light emitting units 16 are installed near the ceiling of the wall at the four corners of the listening room 20 to increase the reliability of reception. Then, as shown in FIGS. 4 and 5, each light emitting unit 16 is installed so as to emit light in a diagonal direction toward the floor, that is, obliquely downward.

The optical audio signal 15 is received by a plurality of receivers 19 constituting a receiver 18 as shown in FIG.

As shown in FIG. 6, it is desirable that the receiver 19 has a structure of ordinary headphones that can be worn by a receiver. The receiver 19 receives the received optical audio signal 15
Is converted into an electric signal by a photodetector 23 formed of, for example, a photodiode or the like, and thereafter, there is provided a sound reproducing means for reproducing a sound in accordance with the electric signal. Receiver 1 of the present embodiment
The sound reproducing circuit of the headphone 9 does not need to be special, and a well-known sound reproducing circuit used for headphones which are receivers of a cordless headphone system which is usually used and commercially available can be used.

The headphone of the present embodiment is different from a normal cordless headphone in that it has a plurality of light receivers 23 and an indicator 21 for confirming a reception state.
It is a point which has. As shown in FIG. 6, the indicator 21 is made of, for example, a red light emitting diode, and can be installed near the center of the headset 22 of the headphone 19, that is, at the top of the head. The indicator 21 is used not only as a confirmation means for confirming the reception level, but also as an ON / OFF indicator of the power of the receiver 19 if necessary, for example, by using a plurality of light emitting diodes. Can be. The means for confirming the reception status using the indicator 21 is configured so that the reception of each receiver 19 can be visually performed by a third party other than the recipient. For example, as an example,
A drive circuit for driving the red light emitting diode may be provided in accordance with the electric signal output from the light receiver 23 (not shown).

A plurality of display units may be provided as the indicator 21. For example, two light emitting diodes of red and green are arranged, and when power is supplied to the headphones, one of the light emitting diodes (for example, red) is turned on. When a sound signal can be normally received and reproduced as sound, the other light emitting diode is emitted. For example, a diode (for example, green) lights up. And
If a failure occurs during reception, one of the light-emitting diodes (red) is turned on again, so that the occurrence of a failure in each of the headphones can be indicated by re-lighting of the one light-emitting diode (red). .

In order to improve the reliability of receiving the optical audio signal,
It is particularly desirable that the headphones include a plurality of light receivers 23. By arranging the light receiving surfaces of the plurality of light receivers 23 so that the directions of the light receiving surfaces are different from each other, it is possible to efficiently receive optical audio signals from different light emitting units 16 in the listening room 20. In FIG. 6, a pair of light receivers 23 are arranged in opposite directions, and it is possible to efficiently and efficiently receive each optical sound signal from the light emitting units 16 arranged at the four corners of the listening room 20. .

The headphones 19 according to the present embodiment have a volume control knob 24. The volume control knob 24 may be any device that can adjust the current output from a sound reproducing circuit (not shown), for example, in conjunction with a variable resistor or the like. This is for adjusting so that sound reproduced at a predetermined level can be obtained even when the intensity of the optical sound signal differs depending on the receiving position in the listening room 20.

Although the embodiment of the present invention has been described above, the embodiment described here is merely an example, and the embodiment of the present system can be variously modified. The present invention can be used not only for listening and testing in a foreign language, but also for, for example, an audio transmission system for transmitting an educational program or the like from a teacher to a student.

The operation when this system is introduced into, for example, the listening and testing of university language education will be described below.

A) Effect of Adopting Headphone System (1) By employing the headphone system, most of the noise generated outside or inside the listening room 20 can be cut off by the pad 29, and these noises are almost ignored. can do. As a result, there is no need to use a dedicated listening room.

(2) Since the optical sound signals from the plurality of light emitting units are received by the plurality of light receivers and the sound is reproduced, the receiving state (sound pressure and sound quality) depending on the location in the listening room 20
Differences are reduced. Therefore, the test can be performed in an equal environment.

(3) The volume can be adjusted by each receiver. For this reason, for example, consideration for a hearing-impaired person is easy.

(4) By using a multi-channel transceiver, listening and testing of a plurality of languages can be performed at one test site.

B) Effect of Adopting Cordless System Almost no wiring is required for each receiver.

C) Operation of a plurality of light emitting units installed at a plurality of places in a room The total amount of light from each light emitting unit depends on the position of the receiver in the listening room 20 and the movement of the receiver's own head and the like. There is no large fluctuation. For this reason, instability of the reception area due to cordlessness is eliminated, and a stable reception area can always be secured.

D) Effect of installing the reception indicator near the headset apex of the headphone, for example, the examiner can easily confirm the reception state of the headphone. For this reason, it is possible to suppress the receiver's “false declaration”.

A major difference between the conventional PA system and the headphone system is that the speaker is replaced by a headphone. Speakers are common equipment in the listening room (listening to everyone), while headphones are equipment for each individual. Since it is a facility for each individual, the volume can be freely adjusted, and it can be said that the system is gentle to listeners, for example, examinees. In addition, noise (internal / external) due to use in headphone
No countermeasures are required, but as a result, equipment is required for headphone installation.

In the present invention, this is made cordless, and wiring equipment is reduced. In this case, "false declaration"
This problem has been overcome by installing an indicator. In addition, as a result of employing cordless headphone for optical communication, there is a possibility that signals may interfere with each other and a shadow may occur, and if a shadow occurs, a reception failure always occurs. For example, in a listening test of an entrance examination, a reception failure is fatal. To solve this,
A plurality of light-emitting units (four in FIG. 1) were installed to create a system that does not create shadows in any case. In this case, since the time delay of the signal becomes a problem, this problem can be solved by adopting a parallel connection system in which the length of the cable is the same for each test room.

An embodiment in which the voice transmission system of the present invention is used for a listening test will be described. FIG. 7 shows a schematic diagram of an indicator for confirming the test execution status of each test room. A control room indicator 52 including an indicator lamp 57 is installed in the control room 51 in order to confirm the test execution state of each of the test rooms 53 to 56 in the control room 51 where the sound source is placed. The control room indicator 52 is used to control the control room 5 for reproducing the test questions.
In 1, the system is installed to confirm that the sound transmission system of each test room is operating normally.

In the control room 51, each test room 53-
Indicator lights 57 corresponding to the number of the test chambers are provided corresponding to the number of the test chambers, and the indicator switch 58 is automatically switched, for example, when some abnormality occurs in each test chamber, for example, red, and when the normal, green, for example, green. Is displayed.
In addition, the detection of this abnormality is not always automatic, and each test room 53
The ~ 56 test coaches can manually operate the indicator switch 58.

The flow from the start of the test will be briefly described below. a) Before the start of the test: In all the test rooms 53 to 56, the indicator switch 58 in the test room is set to off (during preparation or abnormal) until the preparation for the test is completed for all the examinees. At this time, all indications of the control room indicator 52 are red.

B) At the start of the test: Each test room 53 to 56
Then, after confirming that the students are ready, the proctor turns on the indicator switch in the test room (ready or normal)
And In the control room 51, it is confirmed that all the indicators 57 of the control room indicator 52 have turned green, and the reproduction of the test questions is started to start the test.

C) During the test: In each of the test rooms 53 to 56, if an examinee reports an abnormality, or if the test supervisor finds a red color in the indicator 21 provided with headphones, the indicator in each test room is immediately used. The switch is turned off. In the control room 51, when red is found in the indicator lamp 57 of the control room indicator 52 after the start of the test, the sound reproduction is immediately stopped, the test is temporarily stopped, and the test room in which the failure has occurred is contacted. Hit. After the elimination of the fault, all the control room indicators 52 turn green. After confirming that, the reproduction of the test questions is restarted. At this time, the test questions are slightly rewound if necessary.

A signal transmission method between the control room 51 and the test rooms 53 to 56 can be performed by the following method shown in FIG. For example, when a listening test is performed on a small scale such as using only one test room, the sound source 61 in the control room is used as shown in FIG.
The wiring between the radiator 64 and each test room is distributed using analog signals using a normal metal wiring 62, and the radiator 64 receives a signal via the transmitter 63 and outputs sound.

In the case of a medium scale, that is, when there are a plurality of test rooms in a school or the like, an optical fiber wiring 66 is used as shown in FIG. 8B, and an AD converter 65 and a DA converter are used. It is better to distribute by digital signal via 67. This is because the length of the wiring is expected to be very long, and as a result, noise countermeasures during that time are indispensable. It is well known that optical fiber wiring is generally superior to ordinary wiring for noise. When an optical fiber is used for the wiring, it is preferable to transmit the digital signal between the control room and the test room.

In the case of a large-scale test, for example, in which tests are performed simultaneously at many test sites installed in remote locations, it is practically impossible to lay a dedicated signal line, as shown in FIG. 8 (c). A method of distributing using the Internet line 70 via the transceivers 68 and 69, or distributing using the satellite communication line 72 by the transmitter 73, the communication satellite 71, and the receiver 74 as shown in FIG. Can be implemented.

As described above, as an advanced type of this system, the Internet (or intranet) can be used for communication wiring. This makes the scheme shown in FIG. 1 even larger, and FIG. 8 (c) and FIG. 8 (d)
And a system that can be received anywhere from one sound source (one control room) via the Internet line, communication satellite, or the like.

For example, assuming that the English listening test of the university entrance examination center is conducted in various places, the listening questions generated by the entrance examination center are distributed to the university's examination centers nationwide using the Internet or communication satellites. Candidates in different locations can listen to common questions under the same conditions.

[0065]

As described above, the sound transmission system according to the present invention has a unique configuration employing a headphone system, and therefore, a) the influence of external noise as compared with the conventional PA system using speakers. Can be almost ignored, b) the effect of internally generated noise can be almost ignored, c) there is no effect due to the location of the receiver, and d) the receiver can adjust the volume according to his / her preference. Can be freely selected, and there is an effect that a better reception environment can be realized.

Also, one of the problems expected as a result of employing headphones, the complexity of wiring due to the necessity of using a larger number of headphones as compared with the use of a conventional PA system speaker is as follows. The problem can be solved by adopting cordless headphones.

Also, for one of the problems expected by adopting headphones, for example, “false declaration” by the receiver, the reception indicator is set at a position invisible to the receiver, and the instructor and By installing the device at a position that is easy for the supervisor or the like to see, for example, at the position of the head of the receiver, it is possible to suppress “false declaration” or the like to the extent that there is no practical problem.

Further, with respect to the stability of reception, which is a problem expected due to the use of cordless headphones, it is necessary to ensure that each receiver can receive optical audio signals from a plurality of locations at the same time by a plurality of receivers. With this configuration, required reception stability can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a listening test system using cordless headphones according to the present invention.

FIG. 2 is a diagram illustrating a circuit example of a transmission unit according to the embodiment illustrated in FIG. 1;

FIG. 3 is a diagram illustrating a circuit example of a light emitting unit according to the embodiment shown in FIG. 1;

FIG. 4 is an elevation view showing the arrangement of the light emitting unit according to the present invention in a listening room.

FIG. 5 is a plan view showing an arrangement of a light emitting unit according to the present invention in a listening room.

FIG. 6 is a diagram showing an embodiment of a light receiver according to the present invention.

FIG. 7 is a schematic diagram of an indicator for confirming the test execution status of each test room in the present invention.

FIGS. 8A and 8B are diagrams showing a signal transmission method between a control room and each test room in the present invention, wherein FIG. 8A is a small-scale listening system, FIG. (D) is a case of a large-scale listening system.

FIG. 9 is a schematic diagram of a listening and test system using a conventional PA system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Sound source part 12 ... Electric audio signal 13 ... Transmission part 14 ... Modulation part 15 ... Optical audio signal 16 ... Light emitting part 17 ... Amplification / branching part 18 ... Receiving part 19 ... Receiver 20 ... Listening room 21 ... Indicator 22 ... Head Set part 23… Light receiver 24… Sound adjustment knob 25… Wall 26… Ceiling 27… Floor 28… Desk 29… Pad 31… Input 32… Modulator 33… Output 34… Input 35… Light emitting element 41… Sound signal generator 42 ... listening room 43 ... audio signal 44 ... wiring 45 ... speaker 51 ... control room 52 ... control room indicator 53, 54, 55, 56 ... test room 57 ... indicator light 58 ... switch 61 ... sound source 62 ... metal wiring 63 ... transmitter 64 … Radiator 65… A / D converter 6 ... optical fiber line 67 ... D-A converter 68, 69 ... transceiver 70 ... internet 71 ... communication satellite 72 ... satellite communication line 73 ... transmitter 74 ... Receiver

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H04R 1/10 104 // H04R 5/033 F term (reference) 2C028 AA03 BA05 BB06 BC01 CA09 CA11 CB13 DA07 5D005 BA00 5K002 AA01 AA03 BA14 EA03 FA03 GA02 9A001 BB04 CC05 EE04 HH15 JJ74 KK09

Claims (10)

[Claims] A sound source unit that generates an electric audio signal; a branch unit that branches the electric audio signal; and a light emitting unit that emits an optical audio signal corresponding to the split electric audio signal. A plurality of light emitting units, two or more light receivers for receiving the optical sound signal to generate a reception signal, and a sound reproduction unit for reproducing sound based on the reception signals from the two or more light receivers. And a voice transmission system. 2. The voice transmission system according to claim 1, wherein said receiver further comprises a reception state confirmation unit. 3. The audio transmission system according to claim 1, wherein the plurality of light emitting units are arranged such that the receiver can always receive an optical audio signal from at least two or more light emitting units. . 4. The voice transmission system according to claim 2, wherein said reception status confirmation means has a reception indicator which lights up in response to said reception signal. 5. The voice transmission system according to claim 4, wherein the reception indicator is disposed outside a field of view of a user of the receiver. 6. The audio transmission system according to claim 1, wherein the receiver is formed in a headphone format. 7. The sound reproducing means further comprising means for controlling the volume of the sound.
The voice transmission system according to claim 6. 8. The audio transmission system according to claim 1, wherein a phase correction circuit is provided in the light emitting unit. 9. The sound transmission according to claim 1, wherein the electric sound signal generated by the sound source unit is transmitted to the light emitting unit via the Internet. system. 10. A sound transmission system, comprising: a sound source section for generating an electric sound signal; a modulating section connected to the sound source section for modulating the electric sound signal; and converting the modulated signal into a plurality of modulated signals. A transmitting unit including a branching unit for branching, and a plurality of light emitting units arranged at a plurality of positions for emitting an optical audio signal by the respective modulated signals connected to the branching unit and radiated from the light emitting unit; A light receiver for receiving the received optical audio signal, audio reproducing means connected to the optical receiver for reproducing the received optical audio signal into audio, and a reception state confirmation means for externally confirming a reception state. And a receiving unit including a plurality of receivers.