JP2000324233A - Speakerphone set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration in speech quality of a speakerphone set and the occurrence of echoes and howling, using set with a simple configuration. SOLUTION: Two omnidirectional microphone units 12, 13 are provided to a telephone set main body, and they are placed at an equal distance (d) from a speaker unit 11 and pick up a loudspeaking sound of a received signal 16 in the same phase. Then a difference calculation means 14 receives output signals from the two microphone units 12, 13, to cancel a voice of a remote end talker through the difference processing. Furthermore, a frequency correction means 15 receives a voice signal from a near end talker obtained from the difference calculation means 14 to correct the voice signal according to a predetermined frequency characteristic, thereby suppressing deterioration in the voice quality of the near end talker. Thus, echoes and howlings due to the voice of the remote end talker can be suppressed, without the need for using a voice switch or a sound echo canceller requiring a complicated circuit configuration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loudspeaker equipped with a speaker for loudspeaking a reception signal from a communication partner and a microphone for picking up the utterance voice of the user.

[0002]

2. Description of the Related Art A loudspeaker equipped with a hands-free function for making a telephone call without a handset has become widespread in a home telephone, an in-vehicle telephone, a mobile telephone, and the like. In such a loudspeaker, the voice loudspeaked from the speaker is picked up by the microphone, causing echo or howling, which may cause a deterioration in the call quality. In order to suppress such echo and howling, a device such as a voice switch or an acoustic echo canceller may be used. However, there is a problem that adding these devices increases the circuit scale and the cost of the telephone. Therefore, there is a demand for an inexpensive device that suppresses echo and howling during loud speech.

A first conventional loudspeaker will be described with reference to FIG. This loudspeaker includes a speaker unit 101, a microphone unit 102, an echo suppressor 103, and a handset / loudspeaker switch 104. The speaker unit 101 is a speaker that amplifies a reception signal from a far-end speaker. The microphone unit 102 is a microphone that picks up the voice of the near-end speaker. The echo suppressor 103 suppresses the voice of the far end speaker based on the reception signal and the transmission signal, and outputs the voice of the near end speaker as the transmission signal. The handset / loudspeaker switch 104 is a switch for switching between a call using the handset (receiver) 105 or a loudspeaker call.

Normally, a telephone call is made using the receiver 105. However, by switching to a loudspeaker call with the handset / loudspeaker switch 104, a hands-free call can be made using the speaker unit 101 and the microphone unit 102. In the hands-free state, the receiver 105 is moved from above the speaker unit 101, so that the speaker unit 101 is not interrupted.

The loud sound from the speaker unit 101 propagates through the space and the telephone housing and goes around the microphone unit 102, so that a signal loop is formed between transmission and reception. In this case, echo and howling occur, and the call quality is greatly deteriorated. In order to prevent such echoes and howling, a voice switch and an acoustic echo canceller are provided as the echo suppressor 103. In the case of a voice switch, the microphone unit 102
Utterance of the near end speaker is detected based on the output signal of the near end speaker and the reception signal.
By outputting the output signal of No. 3 as a transmission signal, a loop between transmission and reception is cut off.

In the case of an acoustic echo canceller, an adaptive filter is provided, and a transfer function between the speaker unit 101 and the microphone unit 102 is adaptively obtained by a learning identification method or the like based on a reception signal and a transmission signal. Then, by convolving the obtained transfer function with the received signal and subtracting it from the output signal of the microphone unit 102, only the voice of the near end speaker is output from the output signal of the microphone unit 102.

A second conventional loudspeaker will be described with reference to FIG. This loudspeaker is disclosed in JP-A-3-117148.
It is described in the issue. The loudspeaker is provided with a speaker unit 111, microphone units 112 and 113, and a differential operation circuit 114. The speaker unit 111 is a speaker that amplifies a received voice. The microphone units 112 and 113 are microphones for sound collection arranged at an equal distance from the speaker unit 111. The differential operation circuit 114 outputs the output signal of the microphone unit 112 and the microphone unit 11
3 is a circuit for outputting a difference from the output signal of the third embodiment.

[0008] The reception signal loudspeaked from the speaker unit 111 is supplied to a microphone unit 112 for the speaker unit 111 and a microphone unit 113.
Are equal, the microphone units 112,
The sound is picked up at 113 by the same phase. When the respective output signals are differentiated by the differential operation circuit 114, the difference value is theoretically 0.
Thus, the wraparound of the voice of the far-end speaker can be suppressed. On the other hand, since the distance between the microphone unit 112 and the microphone unit 113 with respect to the utterance position of the near end speaker is different from each other, the microphone units 112 and 1 are different.
The voice of the near end speaker picked up at 13 is
Even if the difference is made by 4, the amount of attenuation due to the difference is small compared to the loudspeaker sound of the speaker unit 111.

[0009]

In the first conventional loudspeaker, the echo or howling caused by the wraparound of the reception signal from the speaker unit 101 to the microphone unit 102 is reduced by echo suppression means such as a voice switch and an acoustic echo canceller. I try to prevent it. When the voice switch is used, if the voice level of the near-end speaker is low, the voice switch may malfunction and a part of the voice of the near-end speaker may be interrupted. In this case, there is a disadvantage that the quality of the call is reduced. When an acoustic echo canceller is used, the voice of the near-end speaker does not drop out like a voice switch, but the circuit configuration becomes complicated to obtain a sufficient echo suppression effect, and the loudspeaker becomes expensive. There was a disadvantage of becoming.

In the second conventional loudspeaker, although the complexity of the circuit configuration for suppressing howling, which is a problem of the first conventional example, is improved, the loudspeaker of the first conventional example is improved. Also, there is a problem that the voice quality of the call of the near end speaker is deteriorated. FIG. 12 shows, as an example, the frequency characteristic of the output signal of the differential operation circuit 114 in the direction D1 of FIG. Here, the microphone unit 11
The interval between 2,113 was 20 cm. Since the phase difference between the signals picked up by the microphone unit 112 and the microphone unit 113 is small in the low frequency range, the difference value is greatly attenuated. In the high frequency range, the two microphone units cancel each other out at a frequency at which the interval between the two microphone units is an integral multiple of a half wavelength of the sound wave, and the output value is greatly attenuated at that frequency. Therefore, compared with the case where the sound is picked up by the omnidirectional microphone of the first conventional example, there is a shortage of bass and a partial lack of high frequencies, which causes a problem of deteriorating the speech voice quality.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and solves the drawbacks of the echo suppression means such as a voice switch and an acoustic echo canceller, and provides a near end speaker's voice quality. Without causing a decline
It is an object of the present invention to realize a loudspeaker capable of suppressing echo and howling.

[0012]

In order to solve such a problem, the invention of claim 1 of the present application receives a voice of a far-end speaker as a reception signal and transmits a voice of a near-end speaker. A loudspeaker for transmitting a signal to the far-end speaker as a signal, comprising: a speaker unit for loudspeaking the received signal; and a speaker unit provided at an equal distance from the speaker unit and at a different distance from the near-end speaker. First and second microphone units for picking up the voice of the end speaker, difference calculating means for calculating and outputting a difference value between output signals of the first and second microphone units, and Frequency correction means for correcting the output signal with a predetermined frequency characteristic.

According to such a configuration, two omnidirectional microphone units are arranged at the same distance from the speaker unit, and the loudspeaker is picked up in phase. By subtracting the output signals of these two microphone units, the voice of the far-end speaker is canceled, and the frequency characteristics of the output signal are corrected with predetermined frequency characteristics, thereby deteriorating the voice quality of the call voice. Can be reduced.

According to a second aspect of the present invention, there is provided a loudspeaker telephone for receiving a voice of a far-end speaker as a reception signal and transmitting a voice of a near-end speaker as a transmission signal to the far-end speaker, A speaker unit that amplifies the reception signal and a first unit that is provided at an equal distance from the speaker unit and at a different distance from the near-end speaker, and that captures the voice of the near-end speaker.
And a second microphone unit; a near-end speaker voice detecting means for detecting presence / absence of a near-end speaker's voice based on the received signal and an output signal of the first or second microphone unit; If the voice of the near-end speaker is detected by the speaker voice detecting means, the output signal of the first or second microphone unit is output as it is, otherwise, the first and second microphone units are output. Difference calculating means for calculating and outputting a difference value of the output signal of the microphone unit,
It is characterized by having.

According to such a configuration, two omnidirectional microphone units are arranged at the same distance from the speaker unit, and the loudspeaker is picked up in phase. When only the far-end speaker speaks, the output signals of the two microphone units are subtracted to cancel the voice of the far-end speaker. When the near-end speaker speaks, the subtraction is stopped, and only the signal of one of the microphone units is output. In this way, echo generation of the voice of the far end speaker is prevented, and howling is suppressed. Further, since the signal of one of the microphone units is always output as the transmission signal, the voice of the near-end speaker is not lost, and a smooth call can be performed.

According to a third aspect of the present invention, there is provided a loudspeaker telephone for receiving a voice of a far-end speaker as a reception signal and transmitting a voice of a near-end speaker as a transmission signal to the far-end speaker, First and second microphone units that are provided at different distances from the near-end speaker and that pick up the voice of the near-end speaker, the reception signal and the output of the first or second microphone unit A near-end speaker voice detecting means for detecting the presence or absence of a near-end speaker voice from the signal, and the first end when the near-end speaker voice detecting means detects the near-end speaker voice. Or a difference calculating means for outputting the output signal of the second microphone unit as it is, and otherwise calculating and outputting a difference value between the output signals of the first and second microphone units; Near-end speaker's voice is detected by speaker's voice detection means The in when the reception signal phase inversion to the output, a phase inversion means for outputting as the reception signal in other cases, the first and second
A line segment connecting the microphone unit to the axis of symmetry, provided on one of the perpendiculars of the line segment across the axis of symmetry,
A first speaker unit for amplifying the reception signal;
A second line is provided on the other side of the perpendicular line of the line segment with the line segment connecting the first and second microphone units as a symmetric axis, and the output signal of the phase inversion means is amplified. And a speaker unit.

According to such a configuration, two speaker units and two microphone units are arranged at equal intervals from each speaker unit, so that two speaker units are provided for each microphone unit. The sound louder from is collected in phase. When only the far-end speaker speaks, the far-end speaker's voice is louder from both speaker units in the same phase and the output signals of the two microphone units are differentiated. Turn off. When the near-end speaker speaks, the far-end speaker voice whose phase is inverted from one of the speaker units is amplified, and only the signal from the one microphone unit is output. In this way, the sound of the far-end speaker loudspeaked from the two speaker units is canceled at the sound collection point of the microphone unit that picks up the sound of the near-end speaker.
For this reason, at the time of the double talk in which the far-end speaker and the near-end speaker speak simultaneously, only the near-end speaker's voice can be output as the transmission voice, and a smooth call can be performed by the further echo suppression effect. it can.

The invention of claim 4 of the present application is directed to claim 2 or 3
In the loudspeaker of the above, the near-end speaker voice detection means,
First level calculating means for calculating a short-time average level of the output signal of the first microphone unit, second level calculating means for calculating a short-time average level of the reception signal, and the first level calculation Division means for dividing the output value of the means by the output value of the second level calculation means, and comparing the division result of the division means with a predetermined threshold to determine the magnitude thereof, and when the division result is large. And a threshold discriminating means for judging that the voice of the near end speaker is present, and judging that there is no voice of the near end speaker when the comparison result is small.

According to this configuration, the short-time average level of the signal picked up by one of the microphone units is divided by the short-time average level of the received signal, and if the division result is larger than a predetermined threshold value, The control signal is output as the utterance state of the near end speaker, and otherwise as the non-speech state. This makes it possible to detect the utterance of the near end speaker with a simple configuration.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A loudspeaker according to each embodiment of the present invention will be described below with reference to FIGS. In the following embodiment, since the description is for the loudspeaker call state, the handset / loudspeaker switch provided in the telephone is omitted, and only the loudspeaker call state will be described.

(Embodiment 1) FIG. 1 is a configuration diagram of a main part of a loudspeaker according to Embodiment 1 of the present invention. This loudspeaker includes a speaker unit 11, microphone units 12 and 13, difference calculating means 14, frequency correcting means 1
5 is included. The speaker unit 11 is a speaker that loudspeaks the reception signal 16. The microphone units 12 and 13 are arranged at an equal distance d from the speaker unit 11, and output sound of the speaker unit 11
This is a microphone that picks up the voice of the near end speaker. The difference calculator 14 is a circuit that outputs a difference value between the output signal of the microphone unit 12 and the output signal of the microphone unit 13. The frequency correction means 15 is a circuit for correcting the output signal of the difference calculation means 14 with a predetermined frequency characteristic. Thus, the transmission signal 17 is transmitted from the frequency correction means 15 to the far end speaker.

The frequency correction means 15 is constituted by, for example, a low-pass filter, and multiplies an input signal by a predetermined frequency characteristic and outputs the result. Receive signal 16 of far end speaker
Is amplified in our sound field by the speaker unit 11, but the speaker unit 11 and the microphone unit 1
Since the distance d to the microphone units 2 and 13 is equal, the microphone units 12 and 13 collect the sound in phase, and
When the difference value between these signals is calculated, it becomes 0 theoretically. For this reason, it is possible to suppress the voice of the far end speaker output from the microphone units 12 and 13 from being mixed into the transmission signal 17.

On the other hand, the uttered voice of the near-end speaker is picked up by the microphone units 12 and 13. However, since the distance between the uttered position and the microphone units 12 and 13 is different, the microphone units 12 and 13 normally use the voices. Even if the sound signal of the collected near-end speaker is differentiated by the difference calculating means 14, the attenuation is small compared to the case of the sound of the far-end speaker. Therefore, the output of the difference calculation means 14 can be used as the transmission signal 17.

FIG. 2 shows that the sound source is the microphone unit 1
When the angle θ from the straight line connecting 2, 13 is changed,
5 shows a change in the output level of the difference calculation means 14. Here, the level ratio when the interval L between the microphone units 12 and 13 is 20 cm and θ = 0 ° is shown as a reference is shown. As shown, two microphone units 12,
13 and the difference calculation means 14, bidirectionality is formed, and the sensitivity is greatly attenuated in the 90 ° direction, that is, in the left and right directions where the speaker unit 11 is located.

On the other hand, due to phase interference, the frequency characteristics of the near end speaker for the collected voice in the difference calculating means 14 are shown in FIG.
As a result, the sound quality is deteriorated as compared with the case where the sound is received by the non-directional microphone alone. In particular, when transmitting voice, important voice information is included in a band of 1 kHz or less, and if there is attenuation in a low frequency band as shown in FIG. Therefore, the frequency correction characteristic as shown in FIG. 3 is set in the frequency correction means 15, and the frequency characteristic of the output signal of the difference calculation means 14 is corrected so as to increase the gain on the low frequency side. FIG. 4 shows the frequency characteristics after correction, and the frequency characteristics of the low-frequency component of the near-end speaker's voice suppressed by the phase interference could be improved. Since the frequency characteristics in FIG. 12 are determined by the distance L between the microphone units 12 and 13, a correction frequency characteristic corresponding to the distance is set in the frequency correction unit 15.

(Embodiment 2) Next, a loudspeaker according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 5 is an explanatory diagram showing a main part configuration of the loudspeaker according to the present embodiment. This loudspeaker includes a speaker unit 51, microphone units 52 and 53, a near-end speaker voice detecting unit 54, and a difference calculating unit 55. The speaker unit 51 is a speaker that amplifies the reception signal 56. Microphone unit 52,
Reference numeral 53 denotes an omnidirectional microphone that is arranged at an equal distance d from the speaker unit 51 and that collects output sound from the speaker unit 51 and voice of a near-end speaker.

The near-end speaker's voice detecting means 54 receives a received signal 56
And the output signal of the microphone unit 52, and detects whether or not the near-end speaker is speaking, and supplies the detection result to the difference calculating means 55. Difference calculation means 5
Reference numeral 5 denotes an input of the voice signal collected by the microphone units 52 and 53, and when the near-end speaker voice detection means 54 detects the utterance of the near-end speaker, the signal of the microphone unit 52 or the microphone unit 53 is input. Is output as the transmission signal 57 as it is, and in other cases, the difference value between the output signals of the microphone units 52 and 53 is calculated and output.

When the near end speaker is not speaking, the difference value of the microphone units 52 and 53 is output by the difference calculation means 55, so that the microphone units 52 and 53 and the difference calculation means 55 are provided as in the first embodiment. As a result, the directivity as shown in FIG. 2 is formed, and the voice of the far-end speaker loudspeaked from the speaker unit 51 is greatly attenuated.
7 can be suppressed.

On the other hand, when the near-end speaker is speaking, the near-end speaker voice detecting means 54 detects the utterance of the near-end speaker,
The difference operation of the difference calculation means 55 is stopped, and the output signal of the microphone unit 52 or 53 is directly used as the transmission signal 57.
Output as In this case, it is possible to suppress the deterioration of the frequency characteristics of the low-frequency portion of the near-end speaker voice due to the phase interference as shown in FIG.

FIG. 6 is an explanatory diagram showing an example of the arrangement of speaker units and microphone units when the loudspeakers according to the first and second embodiments are applied to an in-vehicle loudspeaker. FIG. 6 shows an example in which the speaker unit 62 is incorporated in the center of the handle 61 or the center of the instrument panel, and the microphone units 63 and 64 are incorporated in the arm of the handle 61 or the left and right portions of the instrument panel. The speaker unit 62 and the microphone units 63 and 64 are arranged so that the distance between them is equal. By arranging the speaker unit and the microphone in the in-vehicle loudspeaker in this manner, the same effect as in the first and second embodiments can be realized, and the driver's hand during the call is released from the telephone. Contribute to safe driving.

(Embodiment 3) Next, a loudspeaker according to Embodiment 3 of the present invention will be described with reference to FIG.
FIG. 7 is an explanatory diagram showing a main configuration of the loudspeaker according to the present embodiment. This loudspeaker includes speaker units 71 and 72, microphone units 73 and 74, near-end speaker voice detection means 75, difference calculation means 76, and phase inversion means 77. The speaker unit 71 is a speaker that amplifies a received signal. The speaker unit 72 is a speaker for increasing the output sound of the phase inversion means 77. The microphone units 73 and 74 are arranged at an equal distance d from the speaker units 71 and 72, and are omnidirectional microphones that collect the output sound from the speaker units 71 and 72 and the voice of the near-end speaker.

The first microphone unit 73 and the second microphone unit 73
Microphone unit 74 is provided at a different distance from the near-end speaker. The first speaker unit 71 has a line connecting the first and second microphone units 73 and 74 as a symmetric axis, and is provided on one of the perpendiculars of the line with the symmetric axis interposed therebetween. The second speaker unit 72 sets a line connecting the first and second microphone units 73 and 74 as a symmetric axis,
It is provided on the other side of the perpendicular to the line segment with the symmetry axis interposed.

The near-end speaker voice detecting means 75 is a voice detecting means for detecting the utterance of the near-end speaker from the received signal and the output signal of the microphone unit 73. The difference calculating means 76 outputs the output signal of the microphone unit 73 or 74 as it is when the near-end speaker's speech is detected by the near-end speaker voice detecting means 75, and otherwise outputs the signals of the microphone units 73 and 74. This is a circuit that calculates and outputs a difference value.
The phase inversion means 77 is a circuit for inverting the phase when the near-end speaker's speech detection means 75 detects the speech of the near-end speaker, and otherwise outputting the input signal as it is.

When the near end speaker is not speaking, the phase inversion means 77 converts the received signal into the speaker unit 7 as it is.
2 is output to the speaker unit 7
The sound is amplified in the same phase from 1,72. Also, the difference calculation means 7
6 calculates the difference between the output signals of the microphone units 73 and 74. Therefore, similar to the first and second embodiments, the directivity shown in FIG. 2 is formed, and the mixing of the reception signal into the transmission signal is suppressed. Can be.

On the other hand, when the near end speaker is speaking, the phase inversion means 77 inverts the phase of the received signal by 180 ° and outputs the inverted signal. Since the microphone units 73 and 74 have the same distance from the speaker units 71 and 72, respectively, at the sound receiving points of the microphone units 73 and 74, the in-phase received signal loudspeaked from the speaker unit 71 and the loudspeaker from the speaker unit 72. The received speech signals of the reverse transmission cancel each other out, and become theoretically 0. On the other hand, the distance between the receiving point of the speaker and the speaker units 71 and 72 is usually different, and the microphone units 73 and 72 are different.
There is little attenuation for the amount of attenuation at 74. At this time, the difference calculating means 76 is provided by the microphone unit 7.
Since the output of No. 3 or 74 is output as a transmission signal as it is, it is possible to suppress the deterioration of the frequency characteristic of the near-end talker voice due to the phase interference as shown in FIG.

(Embodiment 4) An embodiment of the near-end speaker detecting means used in Embodiments 2 and 3 will be described as a loudspeaker according to Embodiment 4 of the present invention. FIG. 8 is a configuration diagram of the near-end speaker voice detecting means. The near-end speaker voice detecting means includes a first level calculating means 81, a second level calculating means 82, a dividing means 83, and a threshold value determining means 84.
It consists of. The first level calculating means 81 is a level calculating means for calculating a short-time level of the output signal of the microphone unit. The second level calculating means 82 is a level calculating means for calculating a short-time level of the received signal from the far end speaker. The dividing means 83 is the first level calculating means 8
1 is a circuit that divides the output of 1 by the output of the second level calculation means 82. The threshold value discriminating means 84 is a circuit for comparing the output of the dividing means 83 with a predetermined threshold value and discriminating the magnitude.

FIG. 9 shows an example of an output signal of the dividing means 83 during a call. The state where the near end speaker is not speaking, that is, time t
From 1 to t2, since the transfer characteristic between the speaker unit and the microphone unit is steady, the microphone output approximates the received signal, and the dividing means 84 divides the short-time level of the microphone output by the short-time level of the received signal. Is almost constant. On the other hand, when the near-end speaker speaks, the near-end speaker's voice is greatly mixed in the microphone output, and the output of the dividing means 84 increases as shown in the near-end speaker's speech section from time t2 to t3. Therefore, the output of the dividing means 84 in a state where no near-end speaker is generated is measured in advance, and the threshold value is appropriately set. Can be detected.

[0038]

As described above, according to the loudspeaker of the first aspect, two microphone units are arranged at equal intervals from the loudspeaker unit, and the output signals of these microphone units are determined in advance after the difference. By using the frequency correction characteristics, the received signal is prevented from being mixed into the transmitted signal, and echo and howling can be suppressed with a simple configuration without using complicated echo suppression means such as a voice switch or acoustic echo canceller. can do. In addition, by the difference output of the two microphone units, it is possible to suppress the deterioration of the near-end talker voice due to the phase interference,
A smooth call can be made.

Further, according to the loudspeaker of the second aspect, two microphone units are arranged at equal intervals from the loudspeaker unit for loudspeaker, and the difference is made only when the near-end speaker is not speaking. Echo and howling can be suppressed with a simple configuration when the near end speaker is not speaking without causing deterioration of the near end speaker's voice when the end speaker is speaking.

According to the third aspect of the present invention, the two loudspeaker units and the microphone units are arranged at equal intervals from each of the loudspeaker units, and when the near end speaker is not speaking, The received signal is loudspeaked in phase from the two speaker units, and the output of the two microphone units is differentiated, thereby preventing the received signal from being mixed into the transmitted signal. When the near-end speaker is speaking, the receiving signal of the opposite phase is loudspeaked from one of the speakers, and the receiving signals are canceled at the sound pickup points of the two microphone units, so that the near-end talking is performed. Even when a speaker speaks, echo and howling can be suppressed with a simple configuration without causing deterioration of the near-end speaker's voice.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of a loudspeaker according to Embodiment 1 of the present invention.

FIG. 2 is a directional characteristic diagram when the outputs of two microphone units are differentiated.

FIG. 3 is a frequency characteristic diagram of a frequency correction unit used in the loudspeaker according to the first embodiment;

FIG. 4 is a sound pickup frequency characteristic diagram after correction by a frequency correction unit in the loudspeaker according to the first embodiment;

FIG. 5 is a main part configuration diagram of a loudspeaker according to Embodiment 2 of the present invention.

FIG. 6 is an explanatory diagram showing an arrangement example of a microphone unit and a speaker unit in a vehicle-mounted loudspeaker according to the first and second embodiments.

FIG. 7 is a main part configuration diagram of a loudspeaker according to Embodiment 3 of the present invention.

FIG. 8 shows a loudspeaker according to a fourth embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a near-end speaker detection unit.

FIG. 9 is a waveform diagram illustrating an operation of a near-end speaker voice detecting unit according to the fourth embodiment.

FIG. 10 is a configuration diagram of a main part of a loudspeaker according to a first conventional example.

FIG. 11 is a configuration diagram of a main part of a loudspeaker according to a second conventional example.

FIG. 12 is a frequency characteristic diagram of a second conventional example of a loudspeaker.

[Explanation of symbols]

11, 51, 62, 71, 72 Speaker unit 12, 13, 52, 53, 63, 64, 73, 74 Microphone unit 14, 55, 76 Difference calculating means 15 Frequency correcting means 54, 75 Near-end speaker voice detecting means 77 phase inversion means 81, 82 level calculation means 83 division means 84 threshold value determination means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04R 27/00 H04R 27/00 A (72) Inventor Ryo Tagami 1006 Kazuma Kadoma, Kadoma, Osaka Matsushita Electric Industrial Incorporated (72) Inventor Satoru Ibaraki 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.F-term (reference) 5D017 AE22 AE29 BB04 5D020 AD01 CC04 5K027 AA16 BB03 DD07 DD10

Claims (4)

[Claims] 1. A loudspeaker for receiving a voice of a far-end speaker as a reception signal and transmitting a voice of a near-end speaker as a transmission signal to the far-end speaker, wherein the speaker loudspeaks the reception signal. A first and second microphone unit provided at equal distances from the speaker unit and at different distances when viewed from the near-end speaker, and picking up the voice of the near-end speaker; A difference calculation unit that calculates and outputs a difference value of an output signal of the second microphone unit; and a frequency correction unit that corrects an output signal of the difference calculation unit with a predetermined frequency characteristic. Characterized loudspeaker. 2. A loudspeaker for receiving a voice of a far-end speaker as a reception signal and transmitting a voice of a near-end speaker as a transmission signal to the far-end speaker, wherein the speaker loudspeaks the reception signal. A unit, first and second microphone units provided at equal distances from the speaker unit and at different distances when viewed from the near-end speaker, and picking up the voice of the near-end speaker; A near-end speaker voice detecting means for detecting presence / absence of near-end speaker voice based on an output signal of the first or second microphone unit; and a near-end speaker voice by the near-end speaker voice detecting means. Is detected, the output signal of the first or second microphone unit is output as it is, otherwise, the difference value between the output signals of the first and second microphone units is calculated. Output difference Loudspeaker telephone is characterized by comprising a calculation means. 3. A loudspeaker which receives a voice of a far-end speaker as a reception signal and transmits a voice of a near-end speaker as a transmission signal to the far-end speaker. A first and a second microphone unit provided at different distances for collecting voices of a near-end speaker; and a near-end talk based on the received signal and an output signal of the first or second microphone unit. Near-end speaker voice detecting means for detecting the presence or absence of a speaker's voice; and when the near-end speaker voice detecting means detects the voice of the near-end speaker, the first or second microphone unit A difference calculating means for outputting an output signal as it is, and otherwise calculating and outputting a difference value between the output signals of the first and second microphone units; When the speaker's voice is detected, A phase inverting means for inverting and outputting the phase of the speech signal, and otherwise outputting the received signal as it is, and a line connecting the first and second microphone units as a symmetric axis, A first speaker unit, which is provided on one of the perpendiculars of the line segment with the axis interposed therebetween, and connects the first speaker unit that loudspeaks the reception signal, and a line segment that connects the first and second microphone units, to a symmetric axis; A second speaker unit provided on the other side of the perpendicular to the line segment with an axis interposed therebetween, and loudspeaking the output signal of the phase inversion means. 4. The near-end speaker voice detection means, first level calculation means for calculating a short-time average level of an output signal of the first microphone unit, and calculation of a short-time average level of the reception signal A second level calculator, a divider that divides an output value of the first level calculator by an output value of the second level calculator, and compares a division result of the divider with a predetermined threshold. Threshold value discriminating means for judging the magnitude thereof, judging that there is a voice of the near end speaker when the division result is large, and judging that there is no voice of the near end speaker when the comparison result is small. The loudspeaker according to claim 2 or 3, wherein: