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DESCRIPTION JPH02214400

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DESCRIPTION JPH02214400
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
microphone device suitable for use in outdoor recording and the like. SUMMARY OF THE
INVENTION The present invention relates to a microphone device suitable for use outdoors for
recording, etc., comprising a microphone for converting sound into an electric signal, and an
electric signal supplied from the microphone and having a predetermined frequency or higher. A
high pass filter that passes through, a low pass filter that supplies an electrical signal from the
microphone, and a low pass filter that passes a signal below a predetermined frequency, and an
output signal of the low pass filter, the output signal level according to the level of the output
signal And an adder circuit for adding the output signal of the high-pass filter and the output
signal of the automatic level control circuit, and automatically deriving the output signal from the
adder circuit. The wind noise can be well removed. 2. Description of the Related Art In general,
wind noise is always a problem when using a microphone outdoors for recording and the like.
Although a large windscreen is provided as a measure against this wind noise, this windscreen
alone is usually insufficient. Further, as disclosed in JP-A-57-15597 and JP-B-62-24999, it has
also been proposed to combine the high-pass filter and the low-pass filter to remove this wind
noise. The combination of the filter and the low pass filter failed to remove this wind noise well.
In the prior art, therefore, the frequency characteristics of the low frequency band, which is the
main component of wind noise, are attenuated in several stages, for example, in four stages by
using an external changeover switch as shown in FIG. That is, in FIG. 4, (1) shows a microphone
for converting sound into an electric signal, and the electric signal from this microphone (1) is
transmitted to the external changeover switch (3) through the preamplifying circuit (2). Three
low-pass cut filters (4) configured to be supplied to the first fixed contact (3,) and configured
such that the output signal of this pre-amplification circuit (2) is different in low-pass attenuation
in three steps To supply the second fixed contact (3z), the third fixed contact (3,) and the fourth
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fixed contact (34) of the external changeover switch (3) through (5) and (6) respectively Do. In
this case, the magnitude of low-pass attenuation is set as low-pass cut filter (4) <low-pass cut
filter (5) <low-pass cut filter (6). An audio signal is derived from the movable contact (3a) of the
external changeover switch (3).
(7) is an audio signal output terminal. In such a conventional microphone device as shown in FIG.
4, when the operator monitors the sound of the movable contact (3a) of the external changeover
switch (3) and the wind noise is large, the lower one of the lower attenuation is desired.
Switching connection to the fixed contact (the fourth fixed contact (34) side), and switching
connection to the desired fixed contact (the first fixed contact (31) side) of the lower low range
attenuation when there is no wind noise And a good sound signal with little wind noise at the
sound signal output terminal (7). However, in the microphone device as shown in FIG. 4, since
the human monitors the sound, the movable contact (3a) of the external changeover switch (3) is
changed according to the wind noise. There was an inconvenience that it was troublesome to
switch one by one. An object of the present invention is to make it possible to automatically
remove wind noise in view of such points. [Means for Solving the Problems] The microphone
device of the present invention is, for example, a microphone (1) for converting sound into an
electric signal as shown in FIG. 1, and an electric signal from this microphone (1) is supplied. And
an electrical signal from the microphone (1), and a low pass filter (9) passing a signal below a
predetermined frequency, and an output signal of the low pass filter (9) The automatic level
control circuit (10) supplied and whose output signal level is controlled according to the level of
the output signal, and the output signal of the high pass filter (8) and the output signal of the
automatic level control circuit (10) are added And an adder circuit (11) to derive an output signal
from the adder circuit (11). [Operation] According to the present invention, since the level
control circuit (10) automatically controls the level of low frequency components from the low
pass filter (9) according to the level of wind noise, the wind noise can be automatically generated.
It can be removed. An embodiment of the microphone device of the present invention will be
described below with reference to FIG. In FIG. 1, parts corresponding to FIG. 4 are given the same
reference numerals, and the detailed description thereof will be omitted. In this example, the
voice signal obtained by converting the voice from the microphone (1) into an electric signal is
supplied to the high pass filter (8) and the low pass filter (9) through the preamplifying circuit
(2). If this high pass filter (8) is shown as a curve F L I in FIG. 2 (in this example, a signal having a
frequency of 1507 or more is allowed to pass and this low pass filter (9) is a curve shown in FIG.
FL.
In this example, a low frequency signal including a main component of wind noise of 150 Hz or
less is passed as shown as. The output signal of the high pass filter (8) is supplied to one input
terminal of the addition circuit (11), and the output signal of the low pass filter (9) is added via
the automatic level control circuit (10) Supply to the other input terminal of In this case, the
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automatic level control circuit (10) supplies the output signal of the low pass filter (9) to the
input side of the variable gain amplification circuit (10a), and the output signal of the variable
gain amplification circuit (10a) is added to the addition circuit (11) And the output signal of the
variable gain amplification circuit (loa) to the level detection circuit (10b), and the variable gain
amplification circuit according to the detection level of the level detection circuit (10b). It is
configured to reduce the gain of (10a). That is, this automatic level control circuit (10) does not
attenuate the level when there is no wind noise (the output level is as shown by a broken line in
FIG. 3, for example). For example, as shown in FIG. 3 solid line and-dot-and-dash line. An audio
signal output terminal (7) is derived from the output side of the addition circuit (11). Since this
example is configured as described above, the frequency is attenuated according to the
magnitude of the signal that has passed through the low pass filter (9), that is, the magnitude of
wind noise, so the frequency on the output side of the adding circuit (11) As shown in FIG. 3, in
response characteristics, an audio signal in which low frequency components are attenuated
according to the magnitude of wind noise is obtained, and the wind noise can be automatically
removed. In this case, since the cutoff frequencies of the low pass filter (9) and the high pass
filter (8) are set low, for example, to 1507, the influence on the sound quality is extremely small.
As described above, according to the present embodiment, wind noise can be automatically and
favorably removed, and when a voice signal from the microphone (1) is recorded as in the prior
art, a person monitors the voice according to the magnitude of the wind noise. Thus, there is a
benefit that there is no need to switch the external changeover switch (3). Needless to say, the
present invention is not limited to the above-described embodiment, and various other
configurations can be taken without departing from the scope of the present invention.
According to the present invention, there is an advantage that wind noise can be well removed
automatically.
[0002]
Brief description of the drawings
[0003]
1 is a block diagram showing one embodiment of the microphone device of the present
invention, FIG. 2 and FIG. 3 are diagrams for respectively explaining the present invention, and
FIG. 4 is a configuration diagram showing an example of a conventional microphone device. is
there.
(1) is a microphone, (2) is a preamplifier circuit, (7) is an audio signal output terminal, (8) is a
high pass filter, (9) is a low pass filter, (10) is an automatic level control circuit, (11) Is an adder
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circuit.
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