JP2001007671A - Telephone exchange - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means of a telephone exchange that conducts tone volume adjustment, in response to a background noise level in a lot. SOLUTION: When busy telephone sets 4, 6 are under an environment with a large background noise, a telephone exchange 8 fixedly or selectively connects subscriber circuits 3, 5, to which the telephone sets are connected, to a correction circuit 1 that automatically adjusts the tone volume by means of a switch circuit 2. The correction circuit 1 is provided with a noise detection circuit that detects a background noise level from a voice signal received from the subscriber circuits 3, 5, and an attenuator and an amplifier whose attenuation and amplification factor are controlled with a control signal outputted from the noise detection circuit, and automatically adjusts the input voice level and the output voice level, in response to the input side background noise level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephone exchange, and more particularly to a method for improving speech quality in an environment with a large background noise.

[0002]

2. Description of the Related Art When a telephone is used in an environment with high background noise, the level of reception or transmission becomes relatively low as the background noise level increases, so that it is difficult to hear the conversation from the other party.

Conventionally, in order to solve such a problem,
If the environment in which the telephone is used has relatively large background noise and it is difficult to hear the conversation from the other party, adjust the volume provided on the telephone to increase the speaker's voice, or Japanese Patent Laid-Open No. 4-40142 discloses a technology in which a level detecting means and a means for automatically adjusting the receiving sound volume according to the background noise level are provided so that a telephone call can always be made at an optimum receiving sound volume. Alternatively, it is described in JP-A-4-82331.

[0004]

According to the above prior art, the volume of a received voice is automatically adjusted in accordance with the background noise of the usage environment. However, for this purpose, there is a problem in that each terminal must be provided with a background noise level detecting means and a means for automatically adjusting the receiving sound volume according to the background noise level in each terminal.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide means for a telephone exchange to collectively adjust a volume according to a background noise level.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a telephone exchange detects the level of background noise contained in a voice signal to be switched, and adjusts the transmission and reception levels according to the detected background noise level. It is characterized by eliminating the difficulty of hearing due to background noise.

When a currently connected telephone connected to a telephone exchange is in an environment with a large background noise, the telephone exchange
A subscriber circuit to which the telephone is connected and a correction circuit for automatically adjusting the volume are fixedly or selectively connected by a switch circuit.

The correction circuit includes a noise detection circuit that detects a background noise level from a voice signal input from a subscriber circuit, and an attenuation whose attenuation and amplification are controlled by a control signal output from the noise detection circuit. And an amplifier for automatically adjusting the input audio level and the output audio level according to the input background noise level.

In this way, by connecting the subscriber circuit and the correction circuit fixedly or selectively by the switch circuit, it is difficult to hear the background telephone of the busy telephone connected via the telephone exchange due to the background noise. Can be resolved in the telephone exchange itself, so the telephone of each terminal
There is no need to provide automatic volume control means for adjusting the transmission and reception sound according to the background noise level.

[0010]

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, 8 is a telephone exchange, 1
Is a correction circuit newly provided according to the present invention, 2 is a switch circuit, 3 and 5 are subscriber circuits, 4 and 6 are telephone sets, 7
Represents a trunk circuit.

The subscriber circuits 3 and 5 are circuits for connecting a general telephone, a multifunctional telephone, a mobile telephone or a base station of a PHS. The telephones 4 and 6 are a general telephone, a multifunctional telephone, a mobile telephone or a PHS base station and terminals thereof connected according to the types of the subscriber circuits 3 and 5. The trunk circuit 7 is a circuit for connecting to another telephone exchange by analog signals or digital signals. The switch circuit 2 includes subscriber circuits 3 and 5, a trunk circuit 7
Are fixedly or selectively arbitrarily connected.

FIG. 2 is a schematic block diagram of the correction circuit 1 in FIG. 1. The attenuator 9 adjusts the transmission level, the amplifier 11 adjusts the reception level, and the level of the background noise included in the audio signal. It comprises a noise detection circuit 10 which detects and sends a signal corresponding to it to the attenuator 9 and the amplifier 11 as a level control signal.

The operation of this embodiment will be described below with reference to FIG.
This will be described with reference to FIGS. In the correction circuit 1 of FIG. 2, the side on which the audio signal is input to the noise detection circuit 10 is called the input side for convenience, and the opposite side is called the output side.

The noise detection circuit 10 detects the level of the background noise contained in the audio signal input from the input side, and outputs a control signal corresponding to the background noise level to the attenuator 9 and the amplifier 11.
Output to In general, the background noise has a small level fluctuation over time. For example, the noise detection circuit 10 may use a method of temporally integrating the input voice signal and detecting the integrated output as the background noise level. it can.

The form of the control signal output from the noise detection circuit 10 may be a method of outputting a signal proportional to the level of the detected background noise, or a level smaller than a preset threshold value or background noise level. For example, an appropriate control signal such as a method of outputting an OFF signal when the threshold value does not reach the high value and an ON signal when the threshold value is exceeded may be employed.

The attenuator 9 adjusts the level of the audio signal on the input side according to the control signal from the noise detection circuit 10 and outputs the signal to the output side. This improves the transmission level. Similarly, the amplifier 11 adjusts the level of the audio signal on the output side according to the control signal from the noise detection circuit 10 and outputs the signal to the input side. This improves the reception level.

In this method of adjusting the audio level, appropriate adjustment means such as continuous adjustment or stepwise adjustment can be adopted according to the form of the control signal output from the noise detection circuit 10.

In FIG. 1, a telephone exchange 8 forms a communication path by connecting a corresponding circuit according to a selection signal received from a subscriber's circuit 3, 5 or a trunk circuit 7 by a switch circuit 2. .

At this time, if the background noise of the telephone 4 is always large, or if it is known in advance that the background noise of the telephone 4 is large, the subscriber circuit 3 and the correction circuit 1
And the input side thereof is fixedly connected by a switch circuit 2. As a result, it is not necessary to increase the control processing of the switch circuit 2 for forming the communication path. In this state, when it is desired to form a communication path between the telephone 4 and the telephone 6, for example, the output side of the correction circuit 1 and the subscriber circuit 5 are connected by the switch circuit 2 so that the communication level is adjusted according to the background noise. Can be adjusted.

The volume control by the correction circuit 1 is as follows.
When the telephone 4 and the telephone 6 are in a talking state, only when the caller of the telephone 4 or the telephone 6 operates a predetermined push button of the telephone and transmits a PB signal (special number) to the telephone exchange 8. It may be made to be performed.

For example, when the telephone 4 and the telephone 6 are talking while the subscriber's circuit 3 and the subscriber's circuit 5 are connected by the switch circuit 2 and the background noise of the telephone 4 is large, it is difficult to hear. By receiving a special number for connection of the correction circuit from the telephone 4 or by receiving a special number for connection of the correction circuit from the telephone 6, the subscriber circuit 3 connected to the switch circuit 2 The subscriber circuit 5 is opened, the subscriber circuit 3 is connected to the input side of the correction circuit 1, and the subscriber circuit 5 is connected to the output side of the correction circuit 1 to form a communication path. As a result, the communication level is controlled according to the background noise.

In the above-described embodiment, the correction circuit is described as a circuit independent of the subscriber circuit and the trunk circuit. However, the correction circuit may be built in the subscriber circuit and the trunk circuit. In this case, connection by the switch circuit can be omitted.

In the above embodiment, the correction circuit 1 has the attenuator 9 connected from the input side to the output side, and the amplifier 11 connected from the output side to the input side. The devices or both may be amplifiers.

[0024]

According to the present invention, the telephone exchange is provided with a function of adjusting the communication level in accordance with the background noise, so that it becomes easy to hear even a telephone call from a telephone in an environment with a large background noise.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration example of a correction circuit according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Correction circuit 2 Switch circuit 3,5 Subscriber circuit 4,6 Telephone 7 Trunk circuit 8 Telephone exchange 9 Attenuator 10 Noise detection circuit 11 Amplifier

Claims (6)

[Claims] 1. A method for detecting a background noise level contained in an audio signal switched in a telephone exchange, and controlling a communication level of the switched audio signal in the telephone exchange according to the detected background noise level. A method for adjusting a call volume. 2. A subscriber circuit for connecting a base station of a general telephone, a multifunctional telephone or a mobile phone or a PHS, a trunk circuit for connecting to another telephone exchange, and a connection between the subscriber circuit and the trunk circuit. A telephone exchange having a switch circuit for selectively switching between subscriber circuits connected between the switch circuits or between a subscriber circuit and a trunk circuit according to background noise included in an audio signal switched by the switch circuit. A telephone exchange to which a correction circuit having a function of adjusting a call level is connected. 3. The telephone exchange according to claim 2, wherein the correction circuit is connected only when a connection instruction is received from a telephone during a call via the exchange. 4. A noise detection circuit for detecting a level of background noise contained in an audio signal inputted from an input side, and a correction circuit for an input side according to a control signal output from the noise detection circuit. A first audio level adjustment circuit that adjusts the level of the signal and outputs the signal to the output side; and adjusts the level of the audio signal on the output side according to a control signal output from the noise detection circuit and outputs the signal to the input side. 4. The telephone exchange according to claim 2, further comprising a second audio level adjusting circuit. 5. The telephone exchange according to claim 4, wherein said first audio level adjusting circuit is constituted by a variable attenuator, and said second audio level adjusting circuit is constituted by a variable gain amplifier. . 6. The telephone exchange according to claim 2, wherein the correction circuit is built in the subscriber circuit or the trunk circuit.