JPH05227589

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DESCRIPTION JPH05227589
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
audio signal processing apparatus for extracting an audio signal having a specific directivity from
a plurality of audio signals.
[0002]
2. Description of the Related Art Generally, in sound collection of sounds, it is required to collect
sound of only a target sound source. For this reason, it is necessary to provide a directional
microphone that picks up only the intended audio source without capturing unnecessary audio
sources. Hereinafter, a conventional example will be described with reference to FIG.
[0003]
FIG. 2 is a diagram showing an audio signal processing system according to a conventional
embodiment. In the figure, 3a to 3n are a plurality of directional voice sources. Further, 4 is a
microphone, and has directivity such that an audio signal in a specific direction is received.
[0004]
In the reception of the extracted voice signal of the conventional directivity, for example, the
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voice source 3b, the microphone 4 structurally oriented is directed to the voice source 3b, and
only the voice signal from the voice source 3b is Was extracted.
[0005]
Therefore, although it is necessary to use a directional microphone to collect only the target
audio signal, the directional microphone is structurally large, and the microphone must be used
for sound collection. There is a problem that an operation directed to the source is required.
[0006]
The present invention aims to use a structurally small microphone and to collect only the desired
audio source without directing the microphone to the audio source for sound collection.
[0007]
SUMMARY OF THE INVENTION In order to achieve the above object, according to the present
invention, a plurality of nondirectional microphones 4-1 to 4-n disposed at different places with
respect to an audio source 3 and the microphones 4 are provided. A delay correction unit 1
comprising a plurality of delay control units 1a to 1n for correcting the delay amount of each
audio signal provided every -1 to 4-n and making the phases of the audio signals output the same
A plurality of audio signals output from the delay unit 1 are correlated, and a correlation unit 2 is
provided to extract only a specific directional audio signal.
[0008]
According to the present invention, as shown in FIG. 1, an audio source 3 at a position where
sound collection is desired and microphones 4-1 located at a plurality of observation points at
positions separated by distances L1. Each propagation time T1, T2,... Tn until reaching the
microphone 4-n is calculated, and the delay amount of the audio signal of each of the
microphones 4-1 to 4-n is provided in the delay correction unit 1 The corrections are made by
the control unit 1a to the delay control unit 1n so that the delay amounts of the respective
corrected audio signals input to the correlation unit 2 become the same.
[0009]
Therefore, it is possible to extract only the audio signal from the audio source 3 at the target
position by correlating the corrected audio signal in the correlation unit 2.
[0010]
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DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will be described below
with reference to FIG.
FIG. 1 is a diagram showing an audio signal processing system according to an embodiment of
the present invention.
In addition, the case where a certain predetermined ¦ prescribed audio ¦ voice signal is received
by four points is shown as an example.
[0011]
In the figure, reference numeral 1 denotes a delay correction unit, which includes a plurality of
delay control units 1a to 1d that perform correction and operation so that the plurality of
received first to n-th audio signals have the same phase. For example, a delay line, a charge
coupled device (CCD), or the like is used to give a delay to an audio signal.
[0012]
Reference numeral 2 denotes a correlation unit, which correlates a plurality of audio signals
whose delay amounts are controlled, and extracts a target audio signal.
3 is an audio source having directivity.
Also, 4-1 to 4-4 are nondirectional microphones provided at the observation points of the
distance L1 to L4 or the propagation time T1 to the propagation time T4 from the voice source 3,
and voices are generated at four distant places. Are received and converted into an electrical
voice signal.
[0013]
Here, the delay amount tA to the delay amount tD of the delay control unit 1a to the delay
control unit 1d are the propagation of the positions of the four microphones 4-1 to 4-4 and the
distances L1 to L4 of the audio source 3 to be recorded The time T1 to the propagation time T4
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are calculated, and the phases of the audio signals at the output terminals of the delay control
unit 1a to the delay control unit 1d are set to be the same phase.
[0014]
In the figure, voices transmitted from the voice source 3 are received at propagation time T1 to
propagation time T4 at microphones 4-1 to 4-4 provided at observation points separated by
distances L1 to L4, and the first audio signal is generated. To be converted into a fourth audio
signal.
[0015]
The first to fourth audio signals are input to the delay correction unit 1 and corrected by the
delay control units 1a to 1d so that the relationship of T1 + tA = T2 + tB = T3 + tC = T4 + tD is
satisfied.・ Operation is performed.
Then, the phase-controlled voice signal is added to the correlation unit 2 to form a synergetic
effect, and only the voice of the voice source 3 in the specific direction is extracted and received.
[0016]
In the above embodiment, although the delay amount tA of the delay control unit 1a to the delay
amount td of the delay control unit 1d are fixed values and voices of fixed positions are recorded,
the delay control unit 1a to the delay control unit The amount of delay may be arbitrarily
changed by external control for 1 d so that voice at any position can be recorded.
[0017]
As apparent from the above description, according to the present invention, only a specific audio
signal is extracted by controlling the delay amount of the audio signal from a plurality of
microphones separated by a space. Therefore, it is possible to collect an audio signal of only a
target audio source without using a structurally small non-directional microphone and directing
the microphone to the audio source for sound collection, The effect of contributing greatly to the
performance improvement is exerted.
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