JPH08335976A - Loudspeaking device - Google Patents

Abstract

PURPOSE: To provide a loudspeaking speech device in which the attenuation in a transmission signal and a reception signal is properly and easily set in cross reference with a line coupling in the line connection state and the acoustic coupling based on an installation environment or the operating state so as to attain stable speech without losing natural speech performance. CONSTITUTION: A signal (e.g. white noise) to measure a coupling amount from a signal generator 33 to a transmission signal path 9 and from a signal generator 31 to a reception signal path 15 is outputted by an instruction of a control section 21, and an acoustic coupling measurement device 35 and a line coupling measurement device 37 calculate the acoustic coupling amount and the line coupling amount respectively based on a detection level difference of the signal between the receiver side and the transmitter side. Based on the result of calculation, the control section 21 sets the sum of attenuation of a transmission signal variable attenuator 13 and a reception signal variable attenuator 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice communication device such as a hands-free communication device or a telephone conference system. The present invention relates to a voice communication device.

[0002]

2. Description of the Related Art When making a loudspeaker call using a speaker and a microphone in a loudspeaker, a signal is input to a circuit from a loop gain and a line in the loudspeaker to prevent howling. It is necessary to reduce the amount of returns that represents the ratio of. Therefore, depending on the levels of the transmission signal and the reception signal, the transmission signal is provided in the transmission signal path through which the transmission signal is transmitted to the telephone line and the reception signal path through which the reception signal is transmitted through the speaker. A hands-free circuit that complementarily controls the attenuation of the variable attenuator and the received signal variable attenuator is used. 2 and 3 show an example of a conventional hands-free circuit. FIG. 2 is a block diagram of a hands-free circuit proposed in Japanese Patent Publication No. 4-50786. In the figure, a voice signal transmitted by a near-end speaker is input to the microphone 102 of the telephone 101. The voice signal input to the microphone 102 is amplified by the microphone amplifier 103, and is transmitted to the transmission signal variable attenuator 10
5, it passes through the amplifier 107, and is output from the output terminal 109 to the telephone line through the hybrid transformer. Further, the reception signal sent from the far-end speaker via the telephone line enters the telephone 101 from the input terminal 111 via the hybrid transformer, and the amplifier 113, the reception signal variable attenuator 115, and the speaker amplifier 117 are input. Is output by the speaker 119 and reaches the near-end speaker.

Here, the amount of attenuation of the transmission signal variable attenuator 105 and the amount of attenuation of the reception signal variable attenuator 115 are controlled by the control unit 120 based on the magnitude of the transmission signal and the reception signal. That is, the levels of the transmission signal and the reception signal are compared by the comparators 121 and 123. Further, the signal-to-noise detector 127 detects the presence or absence of voice in the transmitted signal, and the signal-to-noise detector 125 detects the presence or absence of voice in the received signal. Based on the output signals of the comparators 121 and 123 and the signal-to-noise detectors 125 and 127, the control unit 120 determines which of the transmission mode, the reception mode, and the high speed / slow idle mode should be performed, and the transmission mode is determined accordingly. The attenuation amount of the speech signal variable attenuator 105 and the attenuation amount of the reception signal variable attenuator 115 are determined. Attenuation amount of transmission signal variable attenuator 105 and reception signal variable attenuator 11
The attenuation amount of 5 is controlled complementarily, that is, while maintaining the complementary relationship so that the sum of the attenuation amounts of both is constant. In both the comparators 121 and 123, the transmission signal level is higher than the reception signal level, and the signal-to-noise detector 1
When the voice is detected by 27, the transmission mode is set, the attenuation amount of the transmission signal variable attenuator 105 is set to the minimum, and the attenuation amount of the reception signal variable attenuator 115 is set to the maximum. In addition, in both the comparators 121 and 123, the reception signal level is higher than the transmission signal level, and the signal-to-noise detector 1
When voice is detected by 25, the reception mode is set, and the attenuation amount of the transmission signal variable attenuator 105 is set to the maximum and the attenuation amount of the reception signal variable attenuator 115 is set to the minimum. When voice is not detected in both the transmission signal and the reception signal, the slow idle mode, the comparison results of the transmission and reception signal levels in the comparators 121 and 123 do not match, and the signal-to-noise detectors 125 and 127 detect When at least one of the voices is detected, the high speed idle mode is set, and the transmission signal variable attenuator 105 and the reception signal variable attenuator 1
Both attenuations of 15 are placed at an intermediate level. In any mode, by maintaining the sum of the attenuation amount of the transmission signal variable attenuator 105 and the attenuation amount of the reception signal variable attenuator 115 at a predetermined constant value, it is possible to make a stable call without howling. .

Further, FIG. 3 shows US Pat. No. Three
It is a structural example of the conventional hands-free circuit proposed by 952166. In the same figure, the voice signal transmitted by the near-end speaker is input to the microphone 203 of the telephone 201.
The voice signal input to the microphone 203 is amplified by the microphone amplifier 205, passes through the transmission signal variable attenuator 207, and is output from the output terminal 209 to the telephone line via the hybrid transformer. Further, the reception signal transmitted from the telephone on the far-end talker side via the telephone line is transmitted from the input terminal 211 to the telephone 20 via the hybrid transformer.
1, it passes through the reception signal variable attenuator 213 and the speaker amplifier 215, is output from the speaker 217, and reaches the near-end speaker. Here, the attenuation amount of the transmission signal variable attenuator 207 and the attenuation amount of the reception signal variable attenuator 213 are complementarily controlled by the magnitudes of the transmission signal and the reception signal as in the prior art example of FIG. During the call, call voice is used to measure the amount of acoustic coupling and line coupling. That is, during the transmission of speech from the near-end speaker, the line coupling amount is measured by detecting the voice signal level in the reception signal path with respect to the voice signal level in the transmission signal path, and is set first. If it is smaller than the line coupling amount, the attenuation amount of the reception signal variable attenuator 213 is changed to be smaller by the difference. Also, while the far-end speaker is speaking, the amount of acoustic coupling is measured by detecting the voice signal level in the transmission signal path with respect to the voice signal level in the reception signal path, and the acoustic level set first If it is smaller than the coupling amount, the attenuation amount of the transmission signal variable attenuator 207 is changed to be smaller by the difference. By continuously performing this operation during a call, the attenuation amounts of the transmission signal variable attenuator 207 and the reception signal variable attenuator 213 can be adjusted appropriately in accordance with the state in which the voice communication device is placed. It is possible to prevent the howling margin from unnecessarily increasing in the hands-free circuit, reduce the change amount of the attenuation amount of the transmission signal variable attenuator 207 and the reception signal variable attenuator 213 as much as possible, and perform the phase-direction simultaneous call. It is possible to improve the property.

[0005]

By the way, the line coupling amount changes depending on the line to which the voice communication device is connected.
In addition, the acoustic coupling amount may change depending on the environment in which the speaker and the microphone are installed and the situation of use. for that reason,
In the former cases of the above two conventional examples, the line coupling amount and the acoustic coupling amount used when determining the sum of the attenuation amount of the transmission signal variable attenuator and the attenuation amount of the reception signal variable attenuator are Since it is necessary to assume in advance a state in which each coupling amount is close to the maximum, the sum of the attenuation amount of the transmitting signal variable attenuator and the attenuation amount of the receiving signal variable attenuator is determined to be larger than necessary. There are many. In this way, if the sum of the attenuation of the transmission signal variable attenuator and the attenuation of the reception signal variable attenuator is set larger than necessary, the change in the attenuation of the variable attenuator when switching between transmission and reception Becomes larger, leading to disconnection at the beginning and ending of the ending, and even if one tries to talk while the other is talking, the amount of attenuation of the received signal variable attenuator inserted in the received signal path is large. Therefore, the other voice is hardly or not heard by the one voice.
That is, the two-way simultaneous callability is low and the naturalness of the call is impaired. Also, in the latter case of the above-mentioned conventional example, the acoustic coupling amount and the line coupling amount are constantly measured during a call, and the attenuation amount of the transmitting or receiving signal variable attenuator is changed in accordance with the measurement, thereby making a call. The attenuation of the variable transmitter / receiver signal attenuator is adjusted to the optimum state when the loudspeaker is placed. However, the acoustic coupling amount and the line coupling amount are constantly measured during the call, and In addition, in order to adjust the attenuation amount of the transmission signal variable attenuator or the reception signal variable attenuator, the circuit configuration becomes complicated and the amount of calculation processing increases, which increases the cost of the device. Moreover, when the amount of acoustic coupling changes due to the movement of the near-end speaker during reception, etc., the amount of attenuation given to the transmitted signal changes accordingly, especially when the ambient noise of the near-end speaker is large. However, the noise level heard by the far-end speaker from the handset may fluctuate, giving an unstable and unnatural call feeling. The present invention has been conceived in view of the above circumstances, and the attenuation amount of the transmission signal and the reception signal is made to correspond to the line coupling amount depending on the connection state with the line and the acoustic coupling amount depending on the installation environment and the usage situation. It is an object of the present invention to provide a loudspeaker communication device capable of properly and easily setting a call and making a stable call without impairing the naturalness.

[0006]

In order to solve the above-mentioned problems, the present invention outputs a transmission signal input from a microphone to a line section via a transmission signal path and is input from the line section. A voice communication device for outputting a received voice signal to a speaker via a voice signal path, wherein a voice signal variable attenuator for attenuating the voice signal input from the microphone to the voice signal path, and the line section A reception signal variable attenuator for attenuating the reception signal input to the reception signal path, and a control means for controlling the transmission signal variable attenuator and the reception signal variable attenuator while maintaining a complementary relationship between them. In a loudspeaker communication apparatus including: a line coupling amount measuring means for measuring a line coupling amount from the transmission signal path to the reception signal path through the line section, and a speaker to a microphone. Based on the measurement output of the line coupling amount measuring means and the measurement output of the acoustic coupling amount measuring means, and the attenuation amount of the transmission signal variable attenuator and the acoustic coupling amount measuring means. A voice communication device comprising a gain setting means for setting a sum with an attenuation amount of a reception signal variable attenuator and sending the set value to the control means when a call is not started. It The voice communication device includes a first signal generator connected to the reception signal path, and the acoustic coupling amount measuring means outputs the signal output from the first signal generator into the reception signal path. The difference between the signal level detected in the reception signal path and the signal level detected in the transmission signal path is calculated, and the acoustic coupling amount is measured based on the result.

Also, the voice communication device includes a second signal generator connected to the transmission signal path, and the line coupling amount measuring means is provided in the transmission signal path from the second signal generator. A configuration for calculating the difference between the signal level detected in the transmission signal path and the signal level detected in the reception signal path of the output signal, and measuring the line coupling amount based on the result. It is possible to In this case, the signals generated from the first and second signal generators can be configured as signals including frequency components necessary for the call transmission band. Also, the signals generated from the first and second signal generators can be configured as band noise. Further, the signals generated from the first and second signal generators can be composed of white noise. Furthermore, the signals generated from the first and second signal generators can be composed of pure tones.

[0008]

In the loudspeaker communication apparatus of the present invention, the line coupling amount and the acoustic coupling amount are automatically measured by outputting a signal from the signal generator into the transmission signal path and the reception signal path. Since the sum of the attenuation amount of the transmission signal variable attenuator and the attenuation amount of the reception signal variable attenuator is set using the line coupling amount and the acoustic coupling amount measured in the actual use environment, the desired howling margin is set. The amount of attenuation can be set according to the environment of use, and the sum of the amounts of attenuation of the transmission variable attenuator or the reception variable attenuator will not be set unnecessarily large. Therefore, the change in the attenuation amount when switching between transmitting and receiving becomes relatively small, leading to disconnection
Sufficient tail disconnection does not occur and natural conversations can be made. In addition, the measurement of the amount of acoustic coupling and the amount of line coupling and the setting of the sum of the amounts of attenuation of the variable transmission attenuator and the variable reception attenuator corresponding to the measurement are performed at a suitable timing when the call is not started. There is no need to perform complicated processing such as constantly measuring the acoustic coupling amount and the line coupling amount and changing the attenuation amount during a call accordingly, and the line configuration can be simplified and the calculation processing amount can be reduced. ， It is possible to reduce the assembly cost of the device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of a speakerphone (hands-free phone) according to an embodiment of the present invention. In the figure, a speakerphone 1 includes a microphone 2 for inputting a transmitted voice and a speaker 3 for outputting a received voice. Each of the microphone 2 and the speaker 3 is connected to a telephone line (illustrated by a broken line) via a hybrid transformer 5. A microphone amplifier 1 is provided in a transmission signal path 9 connecting the microphone 2 and the hybrid transformer 5.
1 and a transmission signal variable attenuator 13 are provided, and a speaker 3
A speaker amplifier 17 and a reception signal variable attenuator 19 are provided in a reception signal path 15 connecting the hybrid transformer 5 and the hybrid transformer 5. The speakerphone 1 further includes a control unit 21 in order to prevent howling in a loud call.
Speech-to-noise detectors 23 and 25 on the transmitting and receiving sides,
Level comparators 27 and 29, signal generators 31 and 33,
An acoustic coupling amount measuring instrument 35 and a line coupling amount measuring instrument 37 are provided.

By the combination of the voice-to-noise detectors 23 and 25, the level comparators 27 and 29, and the control unit 21, "a transmission signal variable attenuator for attenuating a transmission signal input from a microphone and a telephone line are used. A reception signal variable attenuator for attenuating an input reception signal, and a control means for complementarily controlling the attenuation amounts of the transmission signal variable attenuator and the reception signal variable attenuator, that is, a conventionally known "echo suppressor". "Is configured. Speech side noise-to-noise detector 23
Is the signal at the point A on the transmission signal path, and the voice-to-noise detector 25 indicates that the signal at the point C on the reception signal path is only background noise (sound signal whose magnitude changes only slowly) or voice ( It is determined whether or not a sound signal whose magnitude changes rapidly is included. The level comparators 27 and 29 detect which of the signal on the transmitting side and the signal on the receiving side is larger. The control unit 21 performs stable echo suppressor control with few malfunctions by determining from the signals transmitted from these four devices whether the transmission state or the reception state. In addition,
Other methods of controlling the echo suppressor include, for example, 1) two points such as point A and point C, point A and point D ', point B'and point D'or point B'and point C in FIG. Two-point detection method for judging whether the signal is transmitted or received only by comparing the levels of the signals of 2) In addition to the level comparison between the two points shown in 1) above, the point A
Alternatively, a three-point detection method for detecting the voice of the signal at the point C can be considered. In either method, the level comparator and voice-to-noise detector as in this embodiment are used. The specific operation of the speakerphone 1 configured as described above is as follows.

(1) Acoustic coupling amount measuring device 35 and line coupling measuring device 37 at the time of initial setting (when power is turned on or line is connected)
The acoustic coupling GAC and line coupling GST are automatically measured by. Based on this measured value, the control unit 21 recognizes the acoustic environment and the line environment in which the telephone is installed, and the maximum value of the attenuation amount allowed for the attenuators 13 and 19 from the requirement of howling margin, The sum of the minimum values is set. Further, the minimum value of the attenuation amount is determined by the requirements of the reception gain from the line to the speaker 3 and the transmission gain from the microphone 2 to the line. The maximum value and the minimum value of this attenuation amount are determined based on "a method for determining the sum of the attenuation amount in the transmission signal variable attenuator 13 and the attenuation amount in the reception signal variable attenuator 19" which will be described later. , It is decided as described below according to the call state such as the listening mode. In this embodiment, each attenuation amount is determined on the basis of a complementary relationship that keeps the "sum" of the above attenuation amounts constant, but the complementary relation is only the above "case where the two sums are constant". Otherwise, control is performed so that the sum of both attenuations does not exceed a certain value.
For example, in the transmission state, the attenuation amount of the transmission signal variable attenuator 13 is maximized, the attenuation amount of the reception signal variable attenuator is minimized, and the attenuation amount of the transmission signal variable attenuator 13 is minimized in the reception state. ， Maximize the attenuation of the reception signal variable attenuator,
In other states (such as when both callers are silent), the amount of attenuation of both variable attenuators may be maximized. (2) When a call is started, the control unit 21 distinguishes between the transmitting state, the receiving state, and the silent state based on the detection values of the comparators 27 and 29.

If it is in the transmitting state, the control unit 21
The transmission attenuator 13 is controlled to the minimum attenuation, and the reception attenuator 1
9 is controlled to the maximum attenuation amount. In this embodiment, the minimum attenuation amount of the transmission attenuator 13 and the maximum attenuation amount of the reception attenuator 19 are maintained in a complementary relationship such that the sum thereof becomes a predetermined constant value. If it is in the receiving state, the control unit 21 controls the transmitting attenuator 1
3 is controlled to the maximum attenuation amount, and the reception attenuator 19 is controlled to the minimum attenuation amount. Also at this time, the maximum attenuation amount of the transmission attenuator 13 and the minimum attenuation amount of the reception attenuator 19 are controlled so that the sum thereof becomes a predetermined constant value. In the silent state, the previous state of each attenuation is maintained. Although two comparators are provided in the present embodiment, when a digital circuit is used, the attenuation amounts of the transmitting / receiving attenuators 13 and 19 are known in advance, so the transmitting attenuator 13 and the receiving attenuator 19 are used.
There may be only one comparator that compares each input of the. Also, although the attenuation amounts of the attenuators 13 and 19 were set at the time of initial setting, if the external volume of the speaker amplifier may be changed during use, the attenuation amount will be reset in response to the volume change. It may be set.

As described above, "contents of complementary control" are important in "complementarily controlling the attenuation amounts of the transmission signal variable attenuator and the reception signal variable attenuator". For example, when maintaining the complementary relationship such that the sum of the attenuation amounts of the transmission signal variable attenuator and the reception signal variable attenuator becomes constant as described above, what value should the sum be set to? Is important, and how to determine a value that is necessary and sufficient for the actual situation, that is, set so that the disadvantage due to the unnaturalness of the call can be avoided at all. The echo suppressor type hands-free circuit without the following functions, which is a feature of this embodiment, is designed on the safe side so that howling does not occur in consideration of variations in the environment in which a telephone or the like is placed. Two variable attenuators 1
The sum of the attenuation amounts of 3 and 19 becomes larger than necessary,
There is a high risk that tail-cuts will occur more easily, the two-way simultaneous talkability will deteriorate, and calls will become unnatural. Therefore, in this embodiment, the sum of the attenuation amounts of the transmission signal variable attenuator 13 and the reception signal variable attenuator 19 is appropriately determined according to the environment in which the speakerphone 1 is placed, so that the minimum necessary amount is obtained. Unnaturalness (if conditions are good, it is also possible to realize a call that does not feel totally unnatural), it enables more natural calls.

Next, a method for calculating the sum of the attenuation amounts of the transmission signal variable attenuator 13 and the reception signal variable attenuator 19 will be described. When the speakerphone 1 is powered on and connected to the telephone line, the signal generator 33 causes a signal for measuring the line coupling amount according to a command from the control unit 21.
For example, white noise is transmitted to the midpoint B of the transmission signal path 9. This signal is sent to the telephone line through the hybrid transformer 5 and also enters the reception signal path 15 as a side tone by line coupling. The line coupling amount is obtained by the line coupling amount measuring device 37 from the difference between the level of the signal transmitted in the transmission signal path 9 and the level of the signal detected in the reception signal route 15. Similarly, in response to a command from the control unit 21, the signal generator 31 transmits a signal for measuring the acoustic coupling amount, for example, white noise to the point D in the reception signal path 15. The signal is radiated as sound from the speaker 3, a part of which is incident on the microphone 2 and is transmitted to the transmission signal path 9. The acoustic coupling amount is determined by the acoustic coupling amount measuring device 35 from the level of the signal transmitted in the reception signal path 15 and the level of the signal detected in the transmission signal path 9. The control unit 21 uses the measured outputs from the acoustic coupling amount measuring device 35 and the line coupling amount measuring device 37 and the known gains of all parts in the hands-free circuit to attenuate the transmission signal variable attenuator 13 and receive the received signal. The sum with the signal variable attenuator 19 is determined.

In this case, the gain GMA (known) of the micro-amplifier 2 of the hands-free circuit, the line coupling amount GST (unknown), the gain GSA (known) of the speaker amplifier 17, the acoustic coupling amount GAC (unknown), and the transmission signal path. Other gains GT (known) existing therein, gain GHT (known) given to the transmission signal by the hybrid transformer 5, gain GHR (known) given to the reception signal by the hybrid transformer 5 and return amount RL to the line (known) , Other gain GR (known) existing in the reception signal path and desired howling margin HM
There is (known). Using these values, the attenuation amount GTX (dB) of the transmission signal variable attenuator 13 and the reception signal variable attenuator 1
The sum G of 9 and the attenuation amount GRX (dB) is determined so as to satisfy G = GTX + GRX> HM + GMA + GT + GST + GR + GSA + GAC G = GTX + GRX> -RL + GHR + GR + GSA + GAC + GMA + GT + GHT. (However, howling allowance H
In the gain setting, the M and the return amount RL are first determined in accordance with the requirement that the howling margin HM be 6 dB and the return amount RL be −2 dB, and are treated as known values.

GS obtained by measurement on the right side of the above equation
By substituting T and GAC, it is possible to obtain an appropriate sum of the attenuation amount GTX in the transmission signal path and the attenuation amount GRX in the reception signal path. In this embodiment, as described above, the maximum and minimum attenuation amounts of GTX and GRX are determined on the basis of this sum and the requirements for the reception gain and the transmission gain, and the transmission amount is determined according to the transmission or reception mode. Speech signal variable attenuator 1
3 attenuation amount GTX and reception signal variable attenuator 19 attenuation amount G
It controls RX. In the present invention, as described above, the sum GTX + GRX of the attenuation amount of the transmission signal variable attenuator 13 and the attenuation amount of the reception signal variable attenuator 19 is the line coupling amount and the acoustic level measured in the actual use environment of the device. Since it is determined from the coupling amount and the desired howling margin and return amount, the change in the attenuation amount of the transmitting or receiving variable attenuator does not increase more than necessary.
A natural call with little tail cut can be realized. The details of the method of measuring the line coupling amount and the acoustic coupling amount are as follows. In this embodiment, specifically, the line / acoustic coupling amount is calculated from the ratio of "signal magnitude" at two points in the circuit.

(1) At the time of line coupling measurement A signal is sent to point B in the circuit, the "signal magnitude" at points B and C is obtained, and (signal magnitude at point C) / (point B) Signal magnitude at) = R '. Assuming that the attenuation amounts of the paths from the point B to the hybrid transformer 5 and from the hybrid transformer 5 to the point C are negligible, the line coupling amount R is the above-mentioned attenuation rate R'in the circuit in the hybrid transformer 5, that is, the line portion. Is synonymous with. The level of line coupling is 20 log ₁₀ R '(unit: dB)
Therefore, if the level display is used, the line coupling amount R
= (Signal level at point C)-(Signal level at point B) (2) At the time of acoustic coupling measurement The signal is sent to point D in the circuit, the “signal magnitude” at points D and A is obtained, and the speaker amplifier 17 → acoustic space from speaker 3 to microphone 2 → microphone amplifier 11 The attenuation rate r'in the path of (the signal magnitude at point A) / (the signal magnitude at point D)
= R '. The acoustic coupling amount r is the attenuation rate in the acoustic space from the speaker 3 to the microphone 2. The level of acoustic coupling is 20 log ₁₀ r '(unit d
Therefore, using the level display, the acoustic coupling amount r = (signal level at point A)-(signal level at point D)-(amplification factor level of speaker amplifier)-(microphone amplifier level) It can be measured by the amplification factor level).

The above-mentioned automatic measurement of the line coupling amount and the acoustic coupling amount and the transmission signal variable attenuator 13 to be subsequently performed.
The sum of the amount of attenuation and the amount of attenuation of the reception signal variable attenuator 19 is determined when the power is turned on. In the present embodiment, in order to recognize such a state, the control unit 21 controls the points A and C.
(See FIG. 1) Detect and judge. In addition, as the timing, in addition to this, for example, when the user presses the initial setting button to instruct, the power is on, and the call is not yet performed, that is, It may be any time as long as the voice signal by the conversation of the speaker is not transmitted to either the transmission signal path 9 or the reception signal path 15.

As a method of measuring the magnitude of a signal in the above method, for example, the following means can be considered. 1) RMS value at a certain time interval (for example, 100 ms) 2) Output value when a signal is input to a certain number of filters Noise and a signal with large fluctuation such as voice signal are used. Such processing is effective. Regarding the timing of measurement, a) Measure at the same timing at the two points to be observed. b) Considering the time delay propagating in the circuit or in space a) has the advantage of simple processing, and b) has the advantage of being able to measure the coupling amount more accurately, although the processing is complicated. However, the receiving signal path 1 by line coupling
The delay time of the signal entering 5 is extremely small and constant, but the delay time of the signal entering the transmission signal path 9 due to acoustic coupling always fluctuates depending on the surrounding conditions such as a person approaching, so it is accurate. In order to perform b), it is necessary to constantly detect the delay time. However, when considering the application of such time detection to an actual speakerphone configuration, it is difficult to realize it when using noise or pure tones, and when using a voice signal, use the peak of the signal as a landmark. It is important to keep in mind that it is necessary to provide extremely fine and complicated circuits such as.

In addition to the white noise described above, the signal used for measuring the amount of coupling may be, for example, a signal containing a frequency component necessary for a speech transmission band, band noise, or a pure tone (the advantages of each will be described later). ). The embodiments of the present invention have been described above. The characteristic points of the configuration of the above embodiment will be described below. The line coupling amount measuring device 37 constitutes a line coupling amount measuring means for measuring the line coupling amount from the transmission signal path to the reception signal route via the line portion, and the acoustic coupling amount measuring device 35 includes: An acoustic coupling amount measuring means for measuring the acoustic coupling amount from the speaker to the microphone in the environment where the speaker and the microphone are installed is configured. Based on the measurement output of the line coupling amount measuring means and the measurement output of the acoustic coupling amount measuring means, the control section 21 causes the attenuation amount of the transmission signal variable attenuator and the attenuation amount of the reception signal variable attenuator. And a gain setting means for setting the sum of the above and sending the set value to the control means when the call is not started.

[0021]

As described above, according to the voice communication device of the present invention, the line coupling amount and the acoustic coupling amount are generated by outputting the signal from the signal generator into the transmission signal path and the reception signal path. Is automatically measured, and the sum of the attenuation of the transmission signal variable attenuator and the attenuation of the reception signal variable attenuator is calculated using the line coupling and acoustic coupling measured in the actual environment of use of the loudspeaker. Is set, the amount of attenuation can be set according to the usage environment to obtain the desired howling margin, and the sum of the amounts of attenuation of the variable transmission attenuator or the variable reception attenuator is set larger than necessary. Never. Therefore, the change in the attenuation amount at the time of switching between transmitting and receiving is relatively small, and head disconnection and tail disconnection are less likely to occur, and natural communication can be performed. In addition, the measurement of the amount of acoustic coupling and the amount of line coupling and the setting of the sum of the amounts of attenuation of the variable transmission attenuator and the variable reception attenuator corresponding to the measurement are performed at a suitable timing when the call is not started. There is no need to perform complicated processing such as constantly measuring the acoustic coupling amount and the line coupling amount and changing the attenuation amount during a call accordingly, and the line configuration can be simplified and the calculation processing amount can be reduced. ， It is possible to reduce the assembly cost of the device. Then, by setting the types of signals generated from the signal generator as follows, a unique effect is achieved for each. For example, if the signal contains the frequency components required for the telephone transmission band, the following advantages are obtained. Originally, it is possible that acoustic coupling can occur over the telephone line,
In addition, it is around the frequency that is output by the speaker and can be received by the microphone, which is set according to the transmission frequency band of the telephone, and the received signal arrives via the telephone line is transmitted by the telephone. Since it is a frequency component that is generated, it is necessary to measure the acoustic coupling in the signal of such a frequency component. For example, by using a signal containing frequency components that are basically transmitted by telephone, such as telephone ringing tone, ringing confirmation tone, synthetic voice (guidance sound such as "starting a voice call", etc.) Accurate measurement is possible.

Further, for example, the use of band noise for measurement has the following advantages. For example, if the loudspeaker is expected to be used in an environment with large background noise,
Frequency band where S / N ratio (signal to noise ratio) is expected to be large (generally, environmental noise such as fan noise of an air conditioner has a large low frequency component, and voice has a large frequency component around 1 KHz to 3 KHz. The S / N ratio is small in the low frequency range and often increases around 1 KHz to 3 KHz).
It is possible to reduce the magnitude of the generated signal by using (kHz or 2 kHz). That is, the sound emitted from the speaker on the near-end speaker side can be reduced during the acoustic coupling measurement, and the sound emitted from the receiver of the far-end speaker can be reduced during the line coupling measurement. Also, by using white noise for the measurement, the configuration of the signal generator can be simplified, and since the white noise contains all the frequency components necessary for measuring the line coupling and acoustic coupling, It is possible to properly perform the above-described control of the attenuation amount without impairing the accuracy of. Also, by using pure tones for measurement, the configuration of the signal generator can be made much simpler than the above signals. In particular, when an LSI is used in a line section, for example, a hybrid transformer (2-wire to 4-wire converter), the amount of line coupling is almost constant regardless of frequency, so that a pure tone (single frequency A value that is sufficiently accurate for practical use can be obtained with the amount of line coupling measured using (sine wave). As described above, it is possible to properly and easily set the attenuation amount of the transmission signal and the reception signal according to the amount of line coupling depending on the connection state with the line and the amount of acoustic coupling depending on the installation environment and usage conditions, which impairs naturalness. It is possible to provide a loudspeaker communication device capable of making a stable call without a call.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a speakerphone according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a conventional hands-free circuit.

FIG. 3 is a circuit diagram showing a configuration of a conventional hands-free circuit.

[Explanation of symbols]

 1 ... Speakerphone 2 ... Microphone 3 ... Speaker 5 ... Hybrid transformer (line interface part) 9 ... Sending signal path 11 ... Microphone amplifier 13 ... Sending signal attenuator 15 ... Reception signal path 17 ... Speaker amplifier 19 ... Receiving signal variable Attenuator 21 ... Control unit 23 ... Speech side noise-to-noise detector 25 ... Reception side speech-to-noise detector 27, 29 ... Level comparator 31, 33 ... Signal generator 35 ... Acoustic coupling amount measuring device 37 ... Line coupling Measuring instrument

Front page continued (72) Inventor Toru Sakata 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Inside Kobe Steel Co., Ltd., Kobe Steel, Ltd. (72) Toshiaki Shimoda 1-chome, Takatsuka-dai, Nishi-ku, Kobe-shi, Hyogo No. 5-5 Kobe Steel Co., Ltd. Kobe Research Laboratory (72) Inventor Hideo Utsuno 1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Kobe Steel Works Kobe Research Laboratory

Claims (7)

[Claims] 1. A loudspeaker communication device for transmitting a transmission signal input from a microphone to a line section via a transmission signal path and outputting a reception signal output from the line section to a speaker via a reception signal path. And a transmission signal variable attenuator that attenuates the transmission signal input from the microphone to the transmission signal path, and a reception signal variable attenuator that attenuates the reception signal input from the line unit to the reception signal path. And a control means for controlling the transmission signal variable attenuator and the reception signal variable attenuator while maintaining a complementary relationship between the two, in a loudspeaker communication device, the line section is connected from the transmission signal path. A line coupling amount measuring means for measuring the line coupling amount through the reception signal path, and a sound from the speaker to the microphone in the environment where the speaker and the microphone are installed. Acoustic coupling amount measuring means for measuring the amount of acoustic coupling, attenuation amount of the transmission signal variable attenuator and the receiving voice based on the measurement output of the line coupling amount measuring means and the measurement output of the acoustic coupling amount measuring means. A loudspeaker communication device, comprising: a gain setting means for setting a sum with an attenuation amount of a signal variable attenuator and sending the set value to the control means when a call is not started. 2. The voice communication device includes a first signal generator connected to the reception signal path, and the acoustic coupling amount measuring means is provided in the reception signal path from the first signal generator. 2. The acoustic coupling amount is measured based on the difference between the signal level detected in the transmission signal path and the signal level detected in the transmission signal path of the output signal, and the difference between the signal levels detected in the transmission signal path and the signal level. The voice call device described. 3. The voice communication device includes a second signal generator connected to the transmission signal path, and the line coupling amount measuring means is provided in the transmission signal path from the second signal generator. 6. A line coupling amount is measured based on a result of calculating a difference between a signal level detected in the transmission signal path and a signal level detected in the reception signal path of a signal output to the reception signal path. The voice call device described in 1. 4. The voice communication device according to claim 2, wherein the signals generated from the first and second signal generators are signals containing a frequency component necessary for a communication transmission band. 5. The loudspeaker communication apparatus according to claim 2, wherein the signals generated by the first and second signal generators are band noise. 6. The loudspeaker communication apparatus according to claim 2, wherein the signals generated from the first and second signal generators are white noise. 7. The loudspeaker communication apparatus according to claim 2, wherein the signals generated from the first and second signal generators are pure tones.