JPH06178382

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DESCRIPTION JPH06178382
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
microphone apparatus for a video camera, and more particularly to a wind noise reduction
function.
[0002]
2. Description of the Related Art A unidirectional microphone is used as a microphone device for
a video camera in order to clearly pick up the sound emitted from a target object. Video cameras
are frequently used outdoors, but when sound is collected while the wind is blowing, wind noise
is generated and the sound collection SN ratio is significantly reduced. In the case of directional
microphones, in particular, they are more susceptible to wind than nondirectional microphones.
However, since the power of wind noise usually concentrates on the low frequency, it is possible
to prevent a drop in the sound pickup SN ratio by removing the low band signal when the wind
noise occurs.
[0003]
FIG. 2 shows an example of the configuration of a conventional video camera microphone device
having a wind noise reduction function. In FIG. 2, 21 is a unidirectional microphone, 22 is a high
pass filter (HPF), 23 is wind noise detection means, and 24 is a changeover switch. In the
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example shown in FIG. 2, according to the determination result of the wind noise detection
means 23, the switch 24 is at the dotted line position and the output of the unidirectional
microphone 21 is output as it is when there is no wind. And a high pass filter 22 is used to
output a signal from which the low frequency component of the output of the unidirectional
microphone 21 has been removed. Therefore, wind noise can be reduced automatically without
the photographer being aware.
[0004]
However, in the configuration as shown in FIG. 2, when the low frequency component is cut, the
sound quality of the sound which is originally intended to be picked up is also changed, which
causes a sense of discomfort at the time of reproduction. In addition, if the cutoff frequency of
the high-pass filter is lowered to such an extent that the sense of incongruity does not occur, the
wind noise reduction effect is also reduced.
[0005]
The microphone device for a video camera according to the present invention solves the abovementioned problems, maintains a high sound collection SN ratio even in a windy state, and is for
a video camera without causing discomfort in the sound quality of the collected sound. It is an
object to provide a microphone device.
[0006]
[Means for Solving the Problems] In order to achieve the above object, the microphone device for
video camera of the present invention uses two non-directional microphones, and a signal to be
collected is set in a low frequency range according to its frequency. Primary sound pressure
gradient type that is divided into high frequency band, low frequency band signal is added the
output of two omnidirectional microphones, high frequency band signal is composed of two
omnidirectional microphones and delay device It picks up sound in a single direction.
[0007]
In general, by making the low frequency region nondirectional, the influence of the wind can be
reduced more than in the case of a directional microphone, but according to the present
invention, two nondirectional characteristics in the low frequency region Since the outputs of the
microphones are added, the influence of the wind can be reduced more than in the case of one
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nondirectional microphone.
Further, in a high frequency range, it operates as a primary sound pressure gradient type
unidirectional microphone, and can pick up a sound from a desired sound source with a high
sound collection SN ratio.
[0008]
Examples of the present invention will be described in detail below.
[0009]
FIG. 1 is a diagram showing the configuration of a video camera microphone device according to
an embodiment of the present invention.
In FIG. 1, 1 and 2 are both nondirectional microphones, 3 and 4 are high pass filters (HPF), 5 is a
delay device, 6 is a subtractor, 7 and 8 are low pass filters (LPF), and 9 and 11 are adders. , 10 is
an attenuator (ATT).
[0010]
This arranges all the nondirectional microphones 1 and 2 at appropriate intervals.
The high pass filters 3 and 4 respectively remove low frequency components of the outputs of
the nondirectional microphones 1 and 2, and the subtractor 6 is a high pass filter 4 delayed by
the delay unit 5 by the output of the high pass filter 3. Subtract the output of The low pass filters
7 and 8 remove high frequency components of the nondirectional microphones 1 and 2
respectively, and the adder 9 adds the outputs of the low pass filters 7 and 8. The attenuator 10
attenuates the output of the adder 9, and the adder 11 adds the outputs of the attenuator 10 and
the subtractor 6. The cutoff frequencies of the high pass filters 3 and 4 are made equal, and
similarly the cutoff frequencies of the low pass filters 7 and 8 are made equal, and the gain of the
attenuator 10 is set to -6 dB.
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[0011]
The microphone device for a video camera according to the present embodiment can reduce the
influence of the wind by adding the outputs of the two nondirectional microphones 1 and 2 in
the low frequency range by the adder 9 according to the above-described configuration. At the
same time, it operates as a primary sound pressure gradient type unidirectional microphone
composed of two nondirectional microphones 1 and 2 and a delay device 5 in a high frequency
range, and a high sound collection SN from a desired sound source. It can be picked up by ratio.
[0012]
As described above, the microphone device for a video camera according to the present invention
divides the signal to be picked up into the low frequency region and the high frequency region
according to the frequency, and the low frequency signal is 2 The outputs of the two
omnidirectional microphones are added, and the high frequency range signal outputs a signal
picked up with the primary sound pressure gradient type unidirectionality, compared with the
conventional microphone for video camera. The influence of the wind can be reduced without
losing the sound quality, and a high sound collection SN ratio can be realized.
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