JP3740313B2 - Loudspeaker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a loudspeaker communication device, and more particularly to a technique capable of realizing loudspeaker voice communication with good sound quality without causing echo.
[0002]
[Prior art]
As a conventional technique, for example, as described in Japanese Patent Application No. 1-252073, two omnidirectional microphones for loudspeaking calls and output signals of the two omnidirectional microphones are used. A differential arithmetic circuit for outputting a difference, a loudspeaker speaker, and a telephone case, the speaker case being provided with the speaker, and equidistant from the acoustic center of the sound hole of the speaker (L1 = L2 ), The two omnidirectional microphones are installed. With this configuration, the differential arithmetic circuit outputs the difference between the output signals of the two omnidirectional microphones as a transmission signal. Since they cancel each other out, there is a loudspeaker that prevents howling even if the voice switch or echo canceller is simplified.
[0003]
[Problems to be solved by the invention]
However, in the prior art, a blind spot occurs in the microphone sensitivity in the plane direction passing through the midpoint of the line connecting the two microphones. For example, there is a problem that the voice of the speaker cannot be recorded well when the direction of the speaker becomes a blind spot of microphone sensitivity.
[0004]
An object of the present invention is to provide a technique capable of realizing loudspeaker communication with good sound quality without causing echo.
[0005]
Another object of the present invention is to provide a technique capable of successfully recording a voice even when a speaker is in any direction and at the same time suppressing a reverberation caused by recording and transmitting the attended voice again. is there.
[0006]
The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.
[0007]
[Means for Solving the Problems]
Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.
[0008]
A loudspeaker unit for reproducing audio transmitted from a remote location using a communication line, and sound pickup means of N to record the sound around the own (N is an integer of 3 or more), by the respective sound collecting means Phase shifting means for changing the phase of the recorded audio signal, addition means for adding the audio signal whose phase has changed by each phase shifting means, and transmitting the audio signal added by the adding means to the remote location A voice communication device comprising means for outputting to a communication line for
The sound collecting means are arranged at equal angular intervals on a circumference centered on the loudspeaker means , and the phase shift amount in each phase shift means is constant over all frequencies, and between the adjacent phase shift means The amount of phase shift in is different by 360 / N degrees in the arrangement order .
[0010]
Hereinafter, the present invention will be described in detail together with embodiments (examples) with reference to the drawings.
[0011]
In all the drawings for explaining the embodiments, parts having the same functions are given the same reference numerals, and repeated explanation thereof is omitted.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram showing a schematic configuration of a loudspeaker device according to an embodiment of the present invention.
As shown in FIG. 1, the loudspeaker apparatus according to the present embodiment includes a speaker (speech means) 2 for reproducing voice transmitted from a remote place using a communication line 1 and four pieces of voices surrounding the user. Microphones 3 to 6 (three or more sound collecting means), two phase shifters (phase shifting means) 7A and 7B for changing the phase of the audio signal recorded by each of the microphones 3 to 6, and the phase Inverters 8A and 8B, an adder (adding means) 9 for adding the audio signals whose phases are changed by the phase shifters 7A and 7B and the phase inverters 8A and 8B, and the audio signal added by the adder 9 For outputting to the communication line 1 for transmitting to the remote location.
[0013]
The microphones 3 to 6 are arranged on the circumference around the speaker 2 at equal angular intervals, and the phase shift amounts in the phase shifters 7A and 7B and the phase inverters 8A and 8B are over all frequencies. The phase shift amount between the adjacent phase shifters 7A and 7B and the phase inverters 8A and 8B differs by 360 / N degrees (N is an integer of 3 or more) in the arrangement order.
[0014]
With this configuration, the received signals are simultaneously recorded by the microphones 3 to 6 and each phase is shifted by 360 / N degrees (N is an integer of 3 or more). Since the distance between the speaker 2 and each of the microphones 3 to 6 is equal, the sound output from the speaker 2 is collected at the same level and the same phase. Therefore, when the phase-shifted signals are added, they cancel each other.
[0015]
On the other hand, the voice of the speaker is picked up by the microphone in the following state (1) or (2).
(1) Sound is picked up at the highest level by a single microphone.
(2) Sound is picked up in the same phase and at the same level by two adjacent microphones.
[0016]
The case (1) is a phenomenon that occurs when speaking in front of a single microphone, and the case (2) is a case where speaking is performed at an equal distance from an adjacent microphone.
[0017]
With regard to (1), the sound picked up at the highest level is dominant, and even if it is added to the signal after the phase shift, it becomes a transmission signal to the other party without being canceled out.
[0018]
Regarding (2) above, let A and B be the sounds collected at the same phase and level by adjacent microphones, respectively. If the collected sound is a sine wave for the sake of simplicity, A and B of adjacent microphone outputs are expressed by the following equation (1).
[0019]
[Expression 1]
A = sin (ωt)
B = sin (ωt)
Assuming that the number N of microphones is N = 4, the output signals A ′ and B ′ of each phase shift for each microphone are expressed by the following equation (2).
[0020]
[Expression 2]
A '= sin (ωt + π / 2)
B ′ = sin (ωt + π)
The sum of output signals from each phase shifter corresponding to each adjacent micro-hoshi is dominant in the transmission signal to the other party. The transmission signal C to the other party is expressed by the equation (3), and the transmission signal C does not become zero.
[0021]
[Equation 3]
C = A '+ B'
= Sin (ωt + π / 2) + sin (ωt + π)
= Sin (ωt) cos (π / 2) + cos (ωt) sin (π / 2)
+ Sin (ωt) cos (π) + cos (ωt) sin (π)
= Cos (ωt) −sin (ωt)
≠ 0
For example, when N = 4, the phase shift amount in each channel is set to 0 degrees, 90 degrees, 180 degrees, and 270 degrees in the arrangement order (clockwise).
[0022]
FIG. 2 and FIG. 3 are diagrams showing computer simulations for main call sizes 500 Hz, 1000 Hz, 2000 Hz, and 3000 Hz depending on an angle in the loudspeaker apparatus according to the present embodiment. 2 is a diagram showing a computer simulation when the conventional configuration shown in FIG. 4 is used, and FIG. 3 is a diagram showing a computer simulation when the configuration of the present embodiment shown in FIG. 1 is used.
[0023]
In FIG. 2, the output with respect to the incident sound from 0 degrees, 90 degrees, 180 degrees, and 270 degrees is 0 degrees.
[0024]
On the other hand, in FIG. 3, the incidence from each angle does not become zero, the zeros at each frequency do not overlap, and it can be seen that the main call voice quality is improved. In particular, improvements at low frequencies of 500 Hz and 1000 Hz have been obtained.
[0025]
The present invention has been specifically described above based on the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. .
[0026]
【The invention's effect】
As described above, according to the present invention, since the received voice is canceled and the voice is transmitted while leaving the voice of the speaker, it is possible to realize the loud voice communication with good sound quality without causing echo.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a loudspeaker device according to an embodiment of the present invention.
FIG. 2 is a diagram showing a computer simulation with respect to 500, 1000, 2000, and 3000 Hz of the size of the main call to the other party according to the angle in the conventional loudspeaker device shown in FIG. 4 when a phase shifter is not used.
FIG. 3 is a diagram showing a computer simulation with respect to 500 Hz, 1000 Hz, 2000 Hz, and 3000 Hz of the size of the main call to the other party according to the angle in the loudspeaker device when the phase shifter of the present embodiment is used.
FIG. 4 is a block diagram showing a schematic configuration of a conventional loudspeaker.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Communication line, 2 ... Speaker, 3-6 ... Microphone, 7A, 7B ... Phase shifter, 8A, 8B ... Phase inverter, 9 ... Adder.

Claims (1)

Recorded by a loudspeaker that reproduces sound transmitted from a remote location using a communication line, N (N is an integer greater than or equal to 3) sound collecting means for recording surrounding sounds, and each sound collecting means A phase-shifting means for changing the phase of the audio signal, an adding means for adding the audio signal whose phase has been changed by each phase-shifting means, and a voice signal added by the adding means for transmitting to the remote location. A voice communication device comprising means for outputting to a communication line of
The sound collecting means are arranged at equal angular intervals on a circumference centered on the loudspeaker means , and the phase shift amount in each phase shift means is constant over all frequencies, and between the adjacent phase shift means The loudspeaker apparatus is characterized in that the amount of phase shift differs by 360 / N degrees (N is an integer of 3 or more) in the arrangement order .

Images