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JP2007081560

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DESCRIPTION JP2007081560
A noise reduction apparatus, a noise reduction method, and a noise reduction program in which
wind noise is strongly minimized by selecting a minimum (minimizing) signal from a plurality of
microphones appropriately and recombining as appropriate. The electronic device pickup device
is obtained. SOLUTION: A plurality of first level detection means 66 for detecting signal levels in
a predetermined period of a plurality of band extraction signals by calculating an arithmetic
mean of extraction signals obtained by extracting a plurality of predetermined bands from a
plurality of audio signals 68, second level detection means 67 for detecting the signal level in a
predetermined period of the signal obtained by calculating the addition average, and a plurality
of first level detection means 66, 68 and second level detection means 67 The signal selected by
the selection means is band-limited for the signal having the lowest level value as the level value
at predetermined intervals, and the band-limited signal and the band signals other than the
plurality of extraction bands are provided for each audio channel. Band synthesis is performed to
obtain an output signal of each voice channel. [Selected figure] Figure 2
Noise reduction device and noise reduction method, noise reduction program and sound
collection device for electronic device
[0001]
The present invention relates to a noise reduction device and a noise reduction method capable
of reducing noise generated by the wind of a microphone as an electric circuit, and a noise
reduction program and a sound collection device for the electronic device, in particular, a
plurality of microphone signals at predetermined intervals. The present invention relates to a
noise reduction device and a noise reduction method, a noise reduction program, and a sound
collection device for the electronic device, which is appropriately minimized and selectively
recombined.
04-05-2019
1
[0002]
Conventionally, in a large-sized video camera for broadcasting or business use, in order to
prevent wind noise in outdoor sound collection, a windscreen device called a jammer is often
attached to the microphone, or the microphone is often covered with urethane. In built-in
microphones in audio pickup devices for portable electronic devices such as cameras, in most
cases, windshield measures for the electric circuit configuration have been taken instead of the
above-mentioned mechanical windshield devices for miniaturization. .
Heretofore, the following methods have been implemented as windshield measures for such an
electric circuit configuration. 1. The directional characteristics (sound field characteristics,
independence) of each audio signal are controlled to be monaural. 2. Attenuates the level of
the frequency band containing many wind noise components. 3. Change sound field
generation operation processing to make it omnidirectional. And, these measures are often
implemented alone or in combination.
[0003]
For example, according to Patent Document 1, the first and second low-frequency components
including the wind component are subjected to the measures of both the first and second terms,
and the second low-frequency component further includes more wind noise components. A
sound collection device is disclosed that automatically controls its characteristics with a signal
that has been detected. FIG. 13 shows a general system diagram of a left / right (hereinafter
referred to as L / R) two-channel automatic wind noise reduction circuit of a sound collection
device disclosed in Patent Document 1. As shown in FIG. Further, a schematic diagram of the
system is shown in a broken line portion of FIG. In FIG. 13, a right audio signal (hereinafter
referred to as Rch) and a left audio signal (hereinafter referred to as Lch) including wind noise
signals input from R microphone 1 and L microphone 2 are respectively amplifiers (hereinafter
referred to as AMP) The analog voice signal and the wind noise signal are converted digitally by
analog-digital converters (hereinafter referred to as ADC) 5 and 6 through 3 and 4, respectively,
and as digital data, the Rch side is a delay unit (hereinafter referred to as DL) 7 And the Lch side
is input to the DL8 and the plus terminal of the adder 9, and the adder 9 calculates the difference
signal component (L−R) of the both and a low pass filter (hereinafter referred to as It is input to
LPF) 10 and 21.
04-05-2019
2
[0004]
Here, FIG. 14 shows an example of the frequency characteristic of a wind noise signal in a
general video camera. The wind noise signal increases in level with 1 / F characteristics (F is
frequency) as it goes from about 1 kHz to the lower frequency side, but the characteristics of the
microphone used and the coupling capacitor connected to the analog circuit of the input stage
The peak has a peak at about 100 to 200 Hz because the level decreases at extremely low
frequency due to the influence of. Furthermore, since the characteristics of the wind noise signal
are caused by the vortex-like (called Karman's vortex) air flow generated in the vicinity of the
microphone, the wind noise signals from the plurality of microphones are not correlated with the
voice signal. Approximate to a random signal. As described above, since the wind noise signal has
no correlation between L / R channels, a large amount of wind noise component is extracted in
the difference signal component (LR). Then, when only the extremely low frequency component
is passed through the LPF 21, only the wind noise signal containing almost no audio signal is
extracted (wind noise extraction means 33 shown by a broken line in FIG. 13). Further, the
output of the LPF 21 is amplified by the AMP 22 and the level of the wind noise signal is
detected by the detector (hereinafter referred to as DET) (detection means 34 indicated by a
broken line in FIG. 13). Furthermore, the control coefficient to be supplied to the next stage is
shaped by the MAKECOEF (control coefficient generator) 24 to obtain a wind noise level
detection signal having an attack / recovery time constant (a control value indicated by a broken
line in FIG. 13). Generation means 35).
[0005]
Further, in the above-described LPF 10, most of the wind noise signal can be extracted by
passing the low-pass wind noise band shown in FIG. 14, and this signal is level-controlled by the
wind noise level detection signal by the level variable unit 11. However, at this time, the level
changer 11 is controlled so that the wind noise is large, that is, the output becomes large when
the level of the wind noise level detection signal is large, and conversely, when there is no wind
noise, the wind noise level detection signal Control the output level to zero. Then, the output of
the level changer 11 is added by the adder 12 to the signal passed through DL7, and the adder
13 is subtracted from the signal passed through DL8 (first control means 31 shown by a broken
line in FIG. 13). .
[0006]
04-05-2019
3
Here, the meaning of this operation will be described. First, Lch voice signal is Ls, wind noise
signal is Lw, Rch voice signal is Rs, wind noise signal is Rw, and when wind noise is maximum,
the output / input ratio of the level changer 11 is 0.5. When setting to double, the output Ra of
the adder 12 and the output La of the adder 13 are expressed by the following equations (1) and
(2) respectively.
[0007]
[Equation 1] Ra = (Rs + Rw) + 0.5 (Lw-Rw) = Rs + 0.5 (Lw + Rw) (1) La = (Ls + Lw)-0.5 (Lw-Rw) =
Ls + 0.5 (Lw + Rw) ) ... (2)
[0008]
That is, when the wind noise signals Rw and Lw are large, both of the wind noise signals are (Lw
+ Rw) components and become monaural signals, and when the wind noise signals Rw and Lw
are zero, the respective audio signals Rs and Ls are output.
The wind noise signal can be greatly reduced by the addition because there is no correlation
between the channels compared to the voice signal. Also, since DL7 and DL8 compensate for the
delay due to the LPF 10 on the main line side, the signal timing in the adder 12 and the adder 13
are matched to further improve the reduction effect. Further, the outputs of the adders 12 and
13 are input to DL 15 and DL 16 respectively, and are also input to the adder 14 to be added to
each other, and the output is input to the LPF 17. The LPF 17 is set to a band for extracting a
wind noise band as in the LPF 10.
[0009]
The output of the LPF 17 is level controlled by the above-mentioned wind noise level detection
signal in the level variable unit 18, and is controlled so that the output is large when the wind
noise is large, that is, the level of the wind noise level detection signal is large. Conversely, when
there is no wind noise, the level of the wind noise level detection signal is controlled to be zero
and the output to be zero. The output of the level changer 18 is subtracted from the signal
passed through the DL 15 in the adder 19, and the adder 20 is subtracted from the signal passed
through the DL 16 (second control means 32 in FIG. 13).
04-05-2019
4
[0010]
Here, the meaning of this operation will be described. First, when the wind noise is at a
maximum, if the output / input ratio of the level variable device 18 is set to 0.5, the output Rb of
the adder 19 and the output of the adder 20 Lb is respectively expressed by the following
equations (3) and (4).
[0011]
[Equation 2] Rb = Rs + 0.5 (Lw + Rw)-0.5 (Lw + Rw) = Rs (3) Lb = Ls + 0.5 (Lw + Rw)-0.5 (Lw +
Rw) = Ls (4)
[0012]
Accordingly, the wind noise signals Rw and Lw are canceled to obtain only the audio signals Rs
and Ls.
Further, the above-described DL15 and DL16 compensate for the delay due to the LPF 17 on the
main line side, and the signal timing of the adder 19 and the adder 20 is matched to further
improve the reduction effect. Therefore, the output signals of the adder 19 and the adder 20
become an audio signal with a reduced wind noise signal, and if it is a video camera, it is input to
recording system signal processing and recorded on a recording medium such as a tape together
with a separately prepared video signal. Be done.
[0013]
Further, in the microphone device and the processing device of the reproduction sound signal
disclosed in Patent Document 2, and the wind and sound reduction device of the sound signal,
the minimum clip level of the detection signal from the detection means of the sound collection
device disclosed in Patent Document 1 The L / Rch circuit in the front stage circuit of the wind
noise reduction circuit that reduces the wind noise included in each of the L / Rch audio signals
based on the plurality of audio signals from the plurality of microphones by providing Of the
characteristics of the microphone, the shape of the microphone used at the time of sound
collection, the shape of the windshield device (sponge, wire mesh etc.) around the installation, the
mounting method, the difference between the microphones, etc. Non-wind noise other than wind
noise due to conversion of L / Rch to audio signal by stereo processing circuit of audio signal
04-05-2019
5
Seki even component amount is increased, the audio signal of L / Rch, the microphone that can
be reduced by reliably signal the wind noise is disclosed.
[0014]
Further, Patent Document 3 detects the simultaneousness of 1 / f fluctuation of a wind
component in a signal collected by a microphone of one channel, and automatically attenuates
the low range level using the above two terms. A wind noise reduction method and a wind noise
reduction device therefor are disclosed.
Furthermore, according to Patent Document 4, in stereo sound field generation processing, a
band containing a large amount of wind noise components and a band other than that are
separated, and at the time of wind noise detection, a stereo sound field of a band containing a
large amount of wind components A sound collecting device and a stereo operation method for
changing the generation process are disclosed (the above three items). Patent Document 4 also
discloses an automatic wind noise reduction device and an automatic wind noise reduction
method that perform automatic wind noise reduction processing corresponding to multi-channel
sound field generation processing collected from microphones of three or more channels
(described above. Section 1 and 2).
[0015]
Furthermore, Patent Document 5 discloses an audio processing circuit device capable of
attenuating only an extra wind noise component without removing the low frequency component
of the voice to be picked up. FIG. 15 shows the audio processing circuit device disclosed in Patent
Document 5. In FIG. 15, the Rch microphone 201 and the Lch microphone 202 transmit Rch and
Lch audio signals Rs centered on the right and left. , Ls and wind noise signals Lw, Rw are input.
[0016]
The Rch is connected to an analog delay circuit 205 that passes the low band of the LPF
configuration via the AMP 203, and the Lch of the left audio signal is connected to the analog
delay circuit 206 via the AMP 204. The output of the AMP 203 and the output of the delay
circuit 206 are connected to the subtraction circuit 207 to perform subtraction processing.
04-05-2019
6
Further, the output of the AMP 204 and the output of the delay circuit 205 are connected to the
subtraction circuit 208 to perform subtraction processing. At this time, it is ideal that only the
right audio signal is input to the right microphone 201 and only the left audio signal is input to
the left microphone 202. However, the performance of the left and right microphones 202 and
201 is desirable. The sound signals from the opposite sides are also mixed and picked up. In
particular, when the directivity of the microphone to be used is nondirectional, there is almost no
difference and there is no sense of stereo, so in the voice processing apparatus 200 of this
configuration, the voice collected by the two left and right microphones 202 and 201 By using
the phase difference of the signals, respectively delaying the audio signals output from the
microphones of each other and subtracting it from the audio signal of the other party, the signal
components mixed and collected are attenuated, and the channel separation is improved. There
is.
[0017]
Now, assuming that the wind noise component Rw is mixed with the Rch audio signal Rs of the
right microphone 201 and the wind noise component Lw with the left audio signal Ls of Lch of
the left microphone 202, the audio signal input to the right microphone 201 is Rs + Rw. Although
this is amplified by the AMP 203, it does not change as a signal component, so the output of the
AMP 203 is the same, Rs + Rw, and the audio signal input to the left microphone 202 is Ls + Lw,
which is amplified by the AMP 204, but as a signal component Since there is no change, the
output of AMP 204 is the same, Ls + Lw. These signals are input to the subtractors 207 and 208
and the delay circuits 205 and 206 as they are.
[0018]
Here, considering the case where the delay circuit 205 and the LPF as the delay circuit 206 are
used, the right signal Rs of the audio signal Rs + Rw which is an input signal of the delay circuit
205 is a right audio low band component RsL and a right audio high band component It can be
divided into RsH. That is, the output of the delay circuit 205 is (RsL + RsH) + Rw, and similarly
the output of Ls + Lw which is the input signal of the delay circuit 206 can be expressed as (LsL
+ LsH) + Lw, but the delay circuits 205 and 206 are LPFs. The outputs of the circuits 205 and
206 pass through the low frequency component of the voice without being attenuated, but the
higher frequency components are attenuated. As a result, when the delayed RsL and LsL are LR
and LL, and the high frequency components with attenuated RsH and LsH are HR and HL, the
outputs are LR + HR + WR and LL + HL + WL.
04-05-2019
7
[0019]
Therefore, the input signal of the subtraction circuit 207 is RsL + RsH + Rw− (LL + HL + WL),
and the output signal a thereof is expressed by the following equation (5). [Equation 3] a = (RsLLL) + (RsH-HL) + (Rw-WL) (5)
[0020]
Since the first term and the second term of the above equation (5) are audio signals, they can be
treated as a synthesized signal of audio signals having a phase difference. On the other hand, the
wind noise component is generated by the structural elements of the microphones 201 and 202,
and since the vortex flow is the main component, the wind noises collected by the left and right
microphones 201 and 202 have no correlation with each other. It can not be treated as a
composite signal. Therefore, assuming that (RsL−LL) = RL ′ and (RsH−HL) = RH ′, the output
signal a of the equation (5) of the subtraction circuit 207 and the output signal b of the
subtraction circuit 208 have the following equation 4 6) and (7).
[0021]
[Equation 4] a = RL '+ RH' + (Rw-WL) (6) b = LL '+ LH' + (Lw-WR) (7)
[0022]
The output signal a is divided into the high frequency component and the low frequency
component in the LPF 210 and the HPF 209, and the output signal c of the LPF 210 outputs the
audio signal RL ′ + (Rw−WL) of the low frequency component of Rch, The output signal e of
the HPF 209 is RH '.
The output signal c of the LPF 210 is input to the fixed contact A of the switch 214 with the
adder 213. The output signal b is divided into the low frequency component and the high
frequency component by the LPF 211 and the HPF 212, and the output signal d of the LPF 211
outputs the audio signal LL ′ + (Lw-WR) of the low frequency component of Lch, and the output
signal f of the HPF 212 is The output signal d of the LPF 211 is input to the adder 213 and the
fixed contact D of the switch 214. The signal g is a synthesized voice signal of low frequency
04-05-2019
8
components of Rch and Lch which does not contain wind noise component and shows RL '+ (RwWL) + LL' + (Lw-WR) and the wind noise component is (Rw + Lw)-(WL + WR) It can be seen that
the remaining component, which is reduced due to lack of correlation, is the synthesized signal
RL '+ LL' of the low-pass component of the input speech signal. Also, from the output terminals E
and F connected to the fixed contacts A and B of the switch 214 and the movable contacts that
switch the fixed contacts C and D, a signal from the contact A or B or a signal from the contact D
or C Is selected and output. The signals j and k output from the switch 214 output terminals E
and F switch and select the signals c, g and d input from the respective fixed contacts in
accordance with the fixed contacts A, B, C and D of the switch 214. The data can be output from
the adders 215 and 216 to the output terminals 217 and 218.
[0023]
Therefore, when an instruction to cancel the reduction effect of the wind noise component is
given by operating the switch 214, the switch 214 connects the output terminal E to the contact
A, connects the output terminal F to the contact D, and When there is no noise reduction effect,
or when the switch 214 is operated to give an instruction to make the wind noise reduction
effect effective, the switch 214 connects the output terminal E to the contact B and the output
terminal F to the contact By connecting to C, the wind noise reduction effect is maximized. That
is, by the switching operation by the switch 214, the wind noise reduction effect can be switched
intermittently, and the wind noise reduction effect can be intermittently selected only when
necessary.
[0024]
The techniques disclosed in Patent Document 1 to Patent Document 4 described above are all
wind noise reduction processing using the countermeasure method described above. By the way,
with the spread of high definition television broadcasting in the future, high vision recording and
/ or reproduction will be easily performed even at home, and along with this, high quality sound
recording can be performed even in a small size in accordance with high definition of high vision.
A sound collection system is required. Further, according to the voice processing device disclosed
in Patent Document 5, the circuit for improving the stereo separation in the previous stage with
respect to the low-frequency component of the voice to be collected is also monauralized when
the wind noise is reduced. The range signal RL '+ LL' is a monaural signal). Patent No. 359 3860
Japanese Patent Application Laid-Open No. 2001-186585 Japanese Patent Application LaidOpen No. 2001-352594 Japanese Patent Application Laid-Open No. 2003-299183 Japanese
Patent Application Laid-Open No. 10-32894
04-05-2019
9
[0025]
The problem to be solved by the present invention is as a wind noise reduction method
particularly suitable for a sound collection system in which a plurality of microphones are closely
integrated, such as a recent digital video camera for home use. A noise reduction device capable
of significantly minimizing wind noise over conventional measures by selecting and recombining
signals from multiple microphones appropriately at a predetermined time interval as appropriate.
And a noise reduction method, a noise reduction program, and a sound collection device for the
electronic device.
[0026]
According to a first aspect of the present invention, there is provided a noise reduction apparatus
comprising: input means for inputting a plurality of audio signals from a plurality of audio
channels; a plurality of band extraction means for extracting a predetermined band from a
plurality of speech signals; Of the signals from the plurality of band extracting means, and a
plurality of first level detecting means for detecting the signal level of the signals from the
plurality of band extracting means; Selecting the signal having the smallest level value among the
level values detected by the second level detection means for detecting the plurality of first level
detection means and the plurality of second level detection means at predetermined intervals
Means, band limiting means for band limiting the signal from the selecting means, the signal
from the band limiting means and band signals other than the extraction bands in the plurality of
band extracting means And a subband synthesizing means for band synthesis for each Yan'neru,
in which the output of the band synthesizing means is each audio channel output signal.
[0027]
According to a second aspect of the present invention, there is provided a noise reduction
apparatus comprising: input means for inputting a plurality of audio signals from a plurality of
audio channels; a plurality of band extraction means for extracting a predetermined band from a
plurality of audio signals; Of the signals from the plurality of band extracting means, and a
plurality of first level detecting means for detecting the signal level of the signals from the
plurality of band extracting means; Of the second level detecting means for detecting the second
level detecting means, the level values from the plurality of first level detecting means, and the
level values from the second level detecting means for each audio channel at a predetermined
time interval. Selection means for selecting a signal having a plurality of band limiting means for
band limiting the signal from the selecting means, signals from the plurality of band limiting
means, and a plurality of band extraction means It has a band synthesizing means for band
synthesis and the band signal other than each band for each audio channel output, in which the
output of the band synthesizing means is each audio channel output signal.
04-05-2019
10
[0028]
The noise reduction method according to the third aspect of the present invention comprises the
steps of: inputting a plurality of audio signals from a number of audio channels; extracting a
predetermined band from the plurality of audio signals; and averaging the signals from the
plurality of band extraction processes. Calculating the first signal level in a predetermined period
of the signal from the plurality of band extracting steps; detecting the second signal level in the
predetermined period of the signal from the calculating step; Selecting the signal having the
smallest level value among the level values detected from the process of detecting the signal level
of 1 and the process of detecting the second signal level, and the process of selecting the signal
from the selecting process The process of band limitation includes the process of band
combining the signal from the band limitation process and the band signal other than the
extraction band in the plurality of band extraction processes for each voice channel. The output
of the process is obtained by each audio channel output signal.
[0029]
The noise reduction method according to the fourth aspect of the present invention comprises a
process of inputting a plurality of audio signals from a plurality of audio channels, a process of
extracting a predetermined band from a plurality of audio signals, and an average of signals from
a plurality of band extraction means. Calculating the first signal level in a predetermined period
of the signals from the plurality of band extracting means; detecting the second signal level in the
predetermined period of the signal from the calculating means; A selection process for selecting a
signal having a smaller level value at predetermined intervals in each audio channel for the level
value from the process of detecting the signal level of 1 and the level value from the process of
detecting the second signal level A plurality of band limiting processes for band limiting the
signal from the selection process, the signals from the plurality of band limiting processes, and
the band signals other than the extraction bands in the plurality of band extraction processes.
And a step of band synthesis for each channel, in which the output of the band synthesis process
and each audio channel output signal.
[0030]
According to a fifth aspect of the present invention, there is provided a noise reduction program
comprising: input means for inputting a plurality of audio signals from a plurality of audio
channels; a plurality of band extraction means for extracting predetermined bands from a
plurality of audio signals; Of the signals from the plurality of band extracting means, and a
plurality of first level detecting means for detecting the signal level of the signals from the
plurality of band extracting means; Selecting the signal having the smallest level value among the
level values detected by the second level detection means for detecting the plurality of first level
04-05-2019
11
detection means and the plurality of second level detection means at predetermined intervals
Means, band limiting means for band limiting the signal from the selecting means, the signal
from the band limiting means, and band signals other than the extraction bands in the plurality
of band extracting means And a subband synthesizing means for band synthesis for each audio
channel, in which the output of the band synthesizing means is each audio channel output signal.
[0031]
A noise reduction program according to a sixth aspect of the present invention comprises input
means for inputting a plurality of audio signals from a plurality of audio channels, a plurality of
band extraction means for extracting a predetermined band from a plurality of audio signals, and
a plurality of band extraction means Of the signals from the plurality of band extracting means,
and a plurality of first level detecting means for detecting the signal level of the signals from the
plurality of band extracting means; Of the second level detecting means for detecting the second
level detecting means, the level values from the plurality of first level detecting means, and the
level values from the second level detecting means for each audio channel at a predetermined
time interval. Selection means for selecting a signal having a plurality of band limiting means for
band limiting the signal from the selecting means, signals from the plurality of band limiting
means, and a plurality of band extracting means A band signal other than the extraction zone
kicking and a band synthesizing means for band synthesis for each audio channel each, in which
the output of the band synthesizing means is each audio channel output signal.
[0032]
According to a seventh aspect of the present invention, there is provided an electronic apparatus
sound collecting device including: a plurality of electronic devices having sound collecting means
for collecting a plurality of audio signals from a plurality of audio channels; Band extraction
means, operation means for calculating an arithmetic mean of signals from the plurality of band
extraction means, and first level detection means for detecting the signal level of signals from the
plurality of band extraction means in a predetermined period; Second level detection means for
detecting the signal level in a predetermined period of the signal from the arithmetic means, and
the level value having the smallest level value among the plurality of first level detection means
and second level detection means Selection means for selecting a signal having each of the
predetermined periods, band limiting means for band limiting the signal from the selecting
means, signals from the band limiting means, and extraction bands in a plurality of band
extracting means And a subband synthesizing means for band synthesis and an outer band
signals each for each audio channel, in which the output of the band synthesizing means is each
audio channel output signal.
04-05-2019
12
[0033]
According to an eighth aspect of the present invention, there is provided an electronic apparatus
sound collecting device comprising: a plurality of electronic devices having sound collecting
means for collecting a plurality of audio signals from a plurality of audio channels; Band
extraction means, operation means for calculating an arithmetic mean of signals from the
plurality of band extraction means, and first level detection means for detecting the signal level
of signals from the plurality of band extraction means in a predetermined period; The second
level detection means for detecting the signal level in a predetermined period of the signal from
the arithmetic means, the level values from the plurality of first level detection means, and the
level values from the second level detection means Selection means for selecting a signal having
a smaller level value at predetermined intervals, a plurality of band limiting means for band
limiting the signal from the selecting means, and signals from a plurality of band limiting means
And a subband synthesizing means for band synthesis and the band signal other than the
extraction zone for each audio channel of each of the plurality of band extracting means, in
which the output of the band synthesizing means is each audio channel output signal.
[0034]
According to the first, third, fifth, and seventh inventions of the present invention, the minimum
(minimum value) selection process is performed according to the present invention in
comparison with the conventional wind noise reduction process for monauralization (additional
averaging). Since it is possible to extract strongly only the in-phase component contained in a
plurality of signals, a signal with strong correlation like the audio signal from the built-in
microphone of the video camera is extracted as the in-phase component, correlation like wind
noise signal A signal which is not present is largely removed, and a noise reduction device and a
noise reduction method capable of increasing the reduction effect of wind noise components, a
noise reduction program, and a sound collection device for the electronic device are obtained.
[0035]
According to the second, fourth, sixth, and eighth aspects of the present invention, in the
conventional wind noise reduction processing for monauralization (additional averaging), the
band obtained by the addition and averaging becomes monaural. In the present invention, by
performing minimum (minimum value) selection processing on a sound signal and a signal
subjected to monaural processing (additional averaging) processing, the wind noise is reduced
while the sound field feeling (independence of each sound channel is reduced). Noise reduction
apparatus and noise reduction method and noise reduction program capable of maintaining the
noise reduction apparatus, and a sound collection apparatus for the electronic device.
[0036]
04-05-2019
13
Hereinafter, one embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a system diagram showing an embodiment of the noise reduction apparatus of the
present invention, FIG. 2 is a system diagram of level value detection / determination means used
for the noise reduction apparatus of the present invention, and FIG. 3 is a wind of the noise
reduction apparatus of the present invention Fig. 4 is a flowchart of level value detection /
determination means used for noise reduction according to the present invention, and Fig. 5 is a
system diagram showing a second embodiment of the noise reduction apparatus according to the
present invention. FIG. 6 is an operation waveform diagram for explaining the wind noise
reduction method of the noise reduction device of the second embodiment of the present
invention, FIG. 7 is a system diagram showing a third embodiment of the noise reduction device
of the present invention, FIG. 9 is a waveform diagram showing divided bands of the third
embodiment, FIG. 9 is a system diagram showing a fourth embodiment of the noise reduction
apparatus of the present invention, and FIG. 10 shows one embodiment of the automatic noise
reduction apparatus of the present invention FIG. 11 is a system diagram showing a fifth
embodiment of the noise reduction apparatus of the present invention, and FIG. It is a system
diagram schematically showing the automatic noise reduction device.
[0037]
Hereinafter, the present invention will be described with reference to FIGS.
First, the noise reduction device of the present invention will be described with reference to FIG.
FIG. 1 shows a two-channel wind noise reduction apparatus. The Rch and Lch signals input from
the terminals 40 and 41 are respectively input to the HPF 42 and the LPF 43, and the HPF 45
and the LPF 44, and the Rch low band signal from the LPF 43 The Lch low-pass signal from the
LPF 44 is input to the adder 46, the fixed value contacts L and N of the level value detection /
determination means 48 and the changeover switch (SW) 49, respectively.
Further, the output of the adder 46 is multiplied by 1⁄2 by the multiplier 47 and is input to the
fixed contact M of the level value detection / determination means 48 and the SW 49 as a (L + R)
ch signal.
04-05-2019
14
[0038]
Here, the block configuration of the level value detection / determination means 48 will be
described with reference to FIG.
In FIG. 2, the Rch, (L + R) ch and Lch signals from the terminals 60, 61 and 62 are converted to,
for example, positive values by the absolute value processing means 63, 64 and 65, respectively.
The level detection means 66, 67, 68 detect the respective levels, the level value judgment means
69 at the subsequent stage compares the respective level values, and the judgment result is
outputted from the judgment output terminal 70.
[0039]
Here, in FIG. 1, the movable contact of the switching SW 49 is appropriately switched according
to the determination output to select the Rch, (L + R) ch and Lch signals, and the LPF 51 outputs
the output of the HPF 42 by the adder 51 And the Rch signal is output from the output terminal
53, and the adder 52 similarly adds the Rch signal to the output of the HPF 45, and the Lch
signal is output from the output terminal 54.
[0040]
The operation of the level value detection / determination means 48 of FIG. 1 described above
will be described with reference to FIG.
First, the LPFs 43 and 44 pass the wind noise band shown in FIG.
Here, the output of the LPF 44 is the signal of Lch shown in FIG. 3A and the output of the LPF 43
is the signal of Rch shown in FIG. 3B, and further, multiplication processing by the adder 46 and
the 1⁄2 multiplier 47 The (L + R) / 2 composite signal shown in FIG. 3C is generated.
Further, in the level value detection / determination means 48, as shown in FIG. 2, respective
signals inputted to the output terminals 60, 61, 62 are absolute value processing means 63, 64,
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65 and level detection means 66, 67, 68 The level comparison is performed by the level value
determination unit 69 through the process of FIG. 4. The operation of the level value
determination unit 69 will now be described with reference to the flowchart of FIG.
[0041]
In FIG. 4, in the first step ST1, a signal of Rch is input to the input terminal 60, the signal level
value of Rch is detected based on the absolute value processing means 63 and the level detection
means 66, and in the second step ST2 The Lch signal is input to the terminal 62, the signal level
value of the Lch is detected based on the absolute value processing means 65 and the level
detection means 68, and in the third step ST3, the combined signal of (L + R) ch is input to the
input terminal 61. Then, based on the absolute value processing means 64 and the level
detection means 67, the synthetic signal level value of (L + R) ch is detected.
[0042]
After the completion of the first to third steps ST1 to ST3, the process proceeds to the fourth step
ST4, and in the level value judging means 69, it is judged whether the signal of (L + R) ch is a
composite signal ≦ Lch, and if NO In step ST6, it is determined whether the signal of Rch ≦
Lch or not. If YES , the process proceeds to the fifth step ST5 to determine whether the
combined signal of (L + R) ch ≦ Rch.
If the fifth step ST5 is "YES", the process proceeds to the seventh step ST7 to set the combined
signal of (L + R) ch as the determination output, and if "NO", the process proceeds to the eighth
step ST8 to determine the Rch signal as the determination output Set
If the sixth step ST6 is "YES", the process proceeds to the eighth step ST8 to set the Rch signal as
the determination output.
If the sixth step ST6 is "NO", the process proceeds to a ninth step ST9 to set the Lch signal as the
determination output.
After the seventh to ninth steps ST7 to ST9, the process proceeds to a tenth step ST10, where a
determination output is output to the determination output terminal 70.
04-05-2019
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[0043]
Therefore, the output terminal 70 operates so that the signal with the lowest level is always
selected.
Then, in FIG. 1, when the judgment output of the judgment output terminal 70 is inputted to the
SW 49 and operated so as to select the minimum signal, as shown by a thick line in FIG. A signal
with the smallest level is selected and output from the Lch, the Rch signal in FIG. 3B, and the (L +
R) / 2 composite signal in FIG. 3C, and passing through the LPF 50 to suppress harmonic
components. , As shown in FIG. 3 (E). Then, the band signals other than the wind noise band from
the HPFs 42 and 45 are added by the adders 51 and 52, and band recomposition is performed to
generate Rch and Lch signals with reduced wind noise.
[0044]
By the way, the conventional wind noise countermeasure is to increase the monaural of multichannel signals, and the first control means 31 shown by the broken line in FIG. 13 is a process
to convert 2 ch signals to monaural. Here, the (L + R) ch signal in FIG. 3C is a monaural signal,
and it can be said that it is a signal after the conventional wind noise countermeasure, but FIG. 3E
which is a signal after the wind noise countermeasure of the present invention is The level is
significantly reduced even compared to, and components that are not correlated between
channels such as wind noise components are strongly removed, and only components that are
highly correlated between channels such as audio signals are extracted doing.
[0045]
Next, a second embodiment of the two-channel wind noise reduction device of the present
invention will be described. The system diagram shown in FIG. 5 is to reduce wind noise without
making the wind noise band monaural as in the noise reduction device of FIG. First, the Rch and
Lch signals input from the input terminals 71 and 72 are input to the HPF 75 and the LPF 73,
and the HPF 76 and the LPF 74, respectively, and the low-pass signal of the Rch from the LPF 73
is the adder 77 and the first level value detection The low band signal of Lch from the LPF 74 is
input to the adder 77, and the fixed contact V of the second level value detection / determination
means 80 and SW82.
04-05-2019
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[0046]
Further, the output of the adder 77 is multiplied by 1⁄2 by the multiplier 78, and as the (L + R) ch
signal, the fixed contacts S and U of the first and second level value detection / determination
means 79 and 80 and the SW 81 and 82 are generated. Is input to Here, the first and second
level value detection / determination means 79 and 80 operate in the same manner as the level
value detection / determination means 48, and appropriately determine which of the levels of the
signal to be input is smaller. , 82 as Rch determination output and Lch determination output, and
the outputs determined by SW 81 and 82 are selected and added to the output of HPF 75 by
adder 85 via LPFs 83 and 84 respectively, and output terminal 87 The signal is output as an Rch
signal, and is similarly added to the output of the HPF 76 by an adder 86 and output as an Lch
signal from a terminal 88.
[0047]
Here, with respect to the configuration shown in FIG. 5, the operation of the noise reduction
device will be described with the signal waveform of FIG. First, the LPFs 73 and 74 pass the wind
noise band described in FIG. 14 to the input signals supplied to the input terminals 71 and 72.
The output of the LPF 74 is an Lch signal shown in FIG. 6A, and the output of the LPF 73 is an
Rch signal shown in FIG. 6B. Further, the (L + R) / 2 composite signal of FIG. 6C is generated by
the adder 77 and the 1/2 multiplier 78. The Lch signal shown in FIG. 6A and the minimum value
of the (L + R) / 2 composite signal shown in FIG. 6C are always selected by the first level value
detection / determination means 79 and SW 81, as shown in FIG. The Lch signal is output like
the thick line of). Further, when the LPF 83 is passed in order to suppress harmonic components,
the Lch signal minimized as shown in FIG. 6E is output. Similarly, the second level value detection
/ determination means 80 and the SW 82 select the minimum value of the Rch signal shown in
FIG. 6B and the (L + R) / 2 composite signal shown in FIG. 6C via the SW 82. Then, the Rch signal
minimized as shown by the thick line shown in FIG. 6F is output, and when it passes through the
LPF 84 to suppress harmonic components, the signal is minimized as shown in FIG. 6G. Be done.
Then, the band signals other than the wind noise band from the HPFs 75 and 76 and the
minimized Lch and Rch signals of the LPFs 83 and 84 are added by the adders 85 and 86 and
band recomposition is performed to reduce the wind noise Rch. And Lch signals are generated.
[0048]
Accordingly, in the second embodiment, as shown in FIGS. 6E and 6G, the (L + R) / 2 composite
04-05-2019
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signal of FIG. 6C formed by the conventional wind noise device is obtained. It is possible to
reduce the level of the wind noise component and to leave the Lch and Rch signal components
without being monaural.
[0049]
Here, the sampling interval for selecting the minimum value in the present invention and the
band limiting frequency after that will be described.
In FIG. 3D and FIGS. 6D and 6F described above, the time unit for selecting the minimum value
by level comparison is set to the sampling interval, which is the minimum time unit of the digital
signal. If the sampling frequency is Fs, the band-limiting frequency in F may be set to Fs / 2 or
less according to the sampling theorem. However, since the wind noise band is generally a low
frequency of 1 kHz or less as shown in FIG. 14, it is also possible to increase the sampling
interval of the minimum value selection to about 0.5 ms (2 kHz). That is, the level detection may
be performed every 0.5 ms at the maximum, and the level minimum signal in that period may be
selected.
[0050]
Next, a system diagram of the third embodiment of the noise reduction device will be described
with reference to FIG. The same reference numerals as in the system diagram of the noise
reduction device shown in FIG. FIG. 7 illustrates the case where the frequency band other than
the wind noise band is band 3 and the wind noise band frequency is divided into band 1 and
band 2 as in the frequency band characteristic curve shown in FIG.
[0051]
First, the Rch and Lch signals input from the input terminals 111 and 112 are band-divided by
band pass filters (hereinafter referred to as BPF1, 115, 116, BPF2, 117, 118 and BPF3, 113,
114), and wind noise The band frequency is processed by BPF 1, 115, 116 and BPF 2, 117, 118
for each of the divided band frequencies of band 1 and band 2. First, the minimum value is
selected by the level value detection / determination means 48a and the SW 49a for the Rch
signal and Lch signal from the BPFs 1, 115 and 116, and the (L + R) ch signal from the adder 46a
04-05-2019
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and the multiplier 47a. , And are input to the adder 119 via the LPF 50a. Similarly, the Lch and
Rch signals from BPF2, 117 and 118, and the (L + R) ch signal from adder 46b and multiplier
47b are selected at their minimum values by level value detection / determination means 48b
and SW 49b. Through the adder 119. Then, band 1 and band 2 are band synthesized in adder
119, and band 3 from HPF 3, 113 and 114 is band synthesized in adders 51a and 52b, and Rch
is output from output terminal 53a and Lch is output from output terminal 54b. Be done. By
performing the band division in this way and selecting the minimum value for each band, wind
noise can be reduced while improving the reproducibility of the audio signal that is the in-phase
component. Although the wind noise band frequency is divided into the band 1 and the band 2 in
the third embodiment, the divided band may be further increased and the same processing may
be performed.
[0052]
FIG. 9 shows a fourth embodiment of the noise reduction apparatus according to the present
invention, and by performing fast Fourier transform (hereinafter referred to as FFT), it is possible
to use a speech signal more than the third embodiment described in FIG. This is an example in
which the reproducibility is further enhanced. Here, the Rch and Lch signals input from the input
terminals 135 and 136 are converted by the FFT means 139 and 141 into time axis signals of
the voice band into m frequency axis signals of frequencies f1 to fm. Further, the combined
signal of (L + R) ch from the adder 137 and the 1⁄2 multiplier 138 is similarly converted by the
FFT means 140 into m frequency axis signals of frequencies f1 to fm. Here, in each of the FFT
means 139, 140, 141, the frequency axis signal of the frequency f1 to fm is divided into the
frequency f1 to fn of the wind noise band and the frequency f (n + 1) to fm other than the wind
noise band. The Rch and Lch signals of fn and the (L + R) ch signal are input to the level
comparison / selection unit 142, level comparison is performed for each of the frequencies f1 to
fn, and all the operations for selecting the signal of the channel with the lowest level are all The
frequency f1 to fn of
[0053]
Then, the selected signal is input to the band combining means 143 and 144, band combined
again with the signal of frequency f (n + 1) to fm, and the signal of frequency f1 to fm is
subjected to inverse fast Fourier transform (hereinafter referred to as IFFT). The signal is sent to
the means 145, 146, and the frequency axis signal is inversely converted into a time axis signal,
and output as an Rch signal and an Lch signal from the terminals 147, 148.
[0054]
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In the above-described configuration, wind noise reduction in two channels of Lch and Rch has
been described, but the present invention can also cope with three or more channels.
A fifth embodiment of the three-channel noise reduction device of the present invention will be
described with reference to FIG. First, the Rch and center channel (hereinafter referred to as Cch)
and Lch signals are input from the input terminals 180, 181 and 182, and the HPF 183 and LPF
186, HPF 184 and LPF 187, and HPF 185 and LPF 188 provide wind noise and no wind. The
noise is divided into noise bands, and the wind noise band signals Rch, Cch, and Lch from the
respective LPFs are input to the SW 192 and the level value detection / determination means
191.
[0055]
The outputs of the LPFs 186, 187, and 188 are also input to the adder 189, all of which are
added, multiplied by one-third multiplier 190, averaged, and output as the (L + R + C) ch signal,
SW192 and level The value is input to the value detection / determination means 191. The signal
with the lowest level is determined by the level value detection / determination means 191 every
predetermined sampling period, and the signal is selected by the SW 192 and the non-wind from
each HPF 183, 184, 185 of each channel via the LPF 193. The noise band signal is bandcombined by the adders 195, 194 and 196, and output as Rch, Cch and Lch signals from the
output terminals 197, 198 and 199, respectively.
[0056]
Even in the case of four or more channels, the wind noise reduction processing is possible by
changing the averaging processing of each channel and performing the minimum value selection
processing in the same manner. Also in the third to fifth embodiments described above, as in the
second embodiment, the averaging signal obtained by adding all the channels and the minimum
value selection processing of each channel signal are performed, and the independence of each
channel is determined. An enhanced wind noise reduction process may be performed. As
described above, the wind noise reduction device of the present invention can enhance the wind
noise reduction effect more than the conventional one and can maintain the independence of
each channel, but further detects the wind noise by combining with the conventional example.
Automation may be implemented to automatically reduce the
04-05-2019
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[0057]
A system diagram in the case of automation is shown in FIG. 12 and described below. In FIG. 12,
the input signal from the input terminal 90 is the mixing ratio control means 92, the wind noise
reduction means 91 of the present invention and the wind noise extraction means 93 described
in the first to fifth embodiments. Enter in Here, the signal inputted to the wind noise extraction
means 93 is used as a control value for controlling the mixing ratio control means 92 through
the detection means 94 and the control value generation means 95, which is indicated by the
wind shown by the broken line in FIG. The configuration is the same as the noise extraction unit
33, the detection unit 34, and the control value generation unit 35. In the mixing ratio control
means 92, the mixing ratio of the input signal and the output signal of the wind noise reduction
means 91 is 100% of the maximum ratio of the output of the wind noise reduction means 91
when the wind noise is large, and conversely the wind noise When it is zero, automation can be
achieved by controlling the maximum ratio on the input signal side to be 100%. Further, as
shown in FIG. 13, if the wind noise reduction means 91 of the present invention in the first to
fifth embodiments is the first control means 31, even if the second control means 33 is used in
combination as well. good.
[0058]
A specific system diagram of the automatic wind noise reduction device in this case will be
described with reference to FIG. The Rch side of the Rch and Lch audio signals including wind
noise signals input from the terminals 151 and 152 is input to the delay terminal (DL) 154 and
the minus terminal of the adder 160, and the Lch side is DL155 and the plus terminal of the
adder 160 The adder 160 computes the difference component (L-R) signal of the two and inputs
it to the LPF 161. As the wind noise signal has no correlation between L / R channels, a large
amount of wind noise component is extracted in the difference component (LR) signal. Only wind
noise signals are extracted (wind noise extraction means 93 in FIG. 12). Further, the output of the
LPF 161 is amplified by the AMP 162, and the level detection of the wind noise signal is
performed by the detector (DET) 163 (detection means 94 in FIG. 12), and a control coefficient
generator (MAKECOEF for coefficient generation) The control coefficient is shaped by the control
value generation means 95 of FIG. 12) to obtain a wind noise level detection signal with an attack
/ recovery time constant.
[0059]
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First and second mixing ratio control means 157 and 158 control the level of the signal
processed by the wind noise reduction means 156 of the present invention according to the first
to fifth embodiments described above with the wind noise level detection signal However, when
the mixing ratio at this time is large wind noise, that is, when the level of the wind noise level
detection signal is large, the mixing ratio of the output of the wind noise reduction means 156 is
100%, and conversely, when there is no wind noise, the wind noise The level of the level
detection signal is made zero, and the outputs of DL 154 and 155 are controlled to be 100%
(mixing ratio control means 92 in FIG. 12). Further, the outputs of the first and second mixing
ratio control means 157 and 158 are input to DL 171 and 172, respectively, and are input to the
adder 170 to add them together, and the output is input to the LPF 173.
[0060]
The LPF 173 is set to a band for extracting a wind noise band. The output of the LPF 173 is level
controlled by the wind noise level detection signal from the MAKECO FE 164 in the level variable
unit 174, and is controlled to increase the output when the level of the wind noise level detection
signal is large, conversely wind noise When there is not, the level of the wind noise level
detection signal is controlled to be zero and the output to be zero. The output of the level
changer 174 is subtracted from the signal passed through DL 171 in an adder 175 and is
subtracted from the signal passed through DL 172 in an adder 176 (second control means 32 in
FIG. 13). The outputs of the adders 175 and 176 are output from the output terminals 177 and
178 as Rch and Lch signals, respectively. Thus, the reduction effect can be further enhanced by
combining the wind noise reduction means 156 of the present invention with the conventional
processing for attenuating the wind noise band.
[0061]
The signals from the microphones 1 and 2 are supplied to the input terminals of the series of
wind noise reduction devices described above as shown in FIG. 13 of the prior art, and the sound
collection system (method) or recording / Although the present invention may be configured as a
reproduction system (method), the present invention is not limited to this, and may be
implemented in a recording / reproduction device or an electronic device sound collection device.
It is also apparent that the present invention may be implemented as application software in a
computer, and may be implemented as non-real time processing when editing video / audio files,
converting files, and writing DVD disks.
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[0062]
According to Claim 1, Claim 8, Claim 10 and Claim 12 of the present invention, the minimum
(minimum value) selection process is performed on the conventional wind noise reduction
process for monauralization (additional averaging). Therefore, since only the in-phase component
contained in a plurality of signals can be strongly extracted, a signal having high correlation like
the audio signal from the built-in microphone of the video camera is extracted as the in-phase
component, correlation like the wind noise signal A signal having no noise is largely removed,
and a noise reduction device and a noise reduction method, a noise reduction program, and a
sound collection device for the electronic device that can increase the reduction effect of the
wind noise component can be obtained.
[0063]
According to claim 2, claim 9, claim 11, and claim 13 of the present invention, in the
conventional wind noise reduction processing to convert to monaural (adding and averaging), the
band obtained by the addition and averaging becomes monaural. In the present invention, the
sound field of each audio channel is reduced while the wind noise is reduced by performing
minimum (minimum value) selection processing on the audio signal of each channel and the
signal subjected to monauralization (additional averaging) processing. A noise reduction device
and a noise reduction method capable of maintaining feeling (independence), a noise reduction
program, and a sound collection device for the electronic device are obtained.
[0064]
According to claim 3 of the present invention, when the wind noise band is extracted, each voice
channel is extracted by the LPF, and the wind noise band is further divided into a plurality of
bands by a plurality of LPFs and BPFs. Noise reduction device, noise reduction method, and noise
reduction capable of improving the reproducibility of the audio signal of each audio channel
while reducing wind noise by performing minimum (minimum value) selection processing for
each band. A program and its electronic equipment sound collecting device are obtained.
[0065]
According to the fourth aspect of the present invention, when the wind noise band is extracted,
the wind noise is obtained by converting it into a frequency signal using FFT means and
performing minimum (minimum value) selection processing for each frequency signal. A noise
reduction device and a noise reduction method, a noise reduction program, and a sound
collection device for the electronic device, which can further improve the reproducibility of the
audio signal of each audio channel, can be obtained.
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[0066]
According to claim 5 of the present invention, the minimum time unit for performing the
minimum (minimum value) selection process is a sampling time if it is a digital signal, but the
wind noise band is generally a band of 1 kHz or less. Considering that, according to the sampling
theorem (Nyquist theorem), the lowest sampling frequency is 2 kHz, and the longest
predetermined time can be extended to 0.5 ms. The time length for performing the minimum
(minimum value) selection process of the present invention is A noise reduction device and a
noise reduction method which can select 1 / Fs to 0.5 ms, a noise reduction program and a sound
collection device for the electronic device are obtained.
[0067]
According to the sixth and seventh aspects of the present invention, the reduction effect can be
varied by controlling the mixing ratio of the output signal of the wind noise reduction processing
and the input signal before the processing, and furthermore, the wind noise level As a result, by
changing the mixing ratio, a noise reduction device and a noise reduction method capable of
realizing an automatic wind noise reduction process, a noise reduction program and a sound
collection device for the electronic device can be obtained.
[0068]
Also, even when the wind noise reduction process of the present invention and the conventional
wind noise reduction process are implemented in combination, a noise reduction device and a
noise reduction method, and a noise reduction program that can increase the wind noise
reduction effect more than the conventional example. The electronic device sound collecting
device is obtained.
[0069]
It is a systematic diagram showing an example of 1 form of a noise reduction device of the
present invention.
It is a systematic diagram of the level value detection / determination means used for the noise
reduction apparatus of this invention.
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FIG. 3 is an operation waveform diagram for explaining the wind noise reduction method of the
noise reduction device of the present invention. FIG. 3 is a flowchart of level value detection /
determination means used for the noise reduction device of the present invention.
It is a systematic diagram which shows the 2nd example of a form of the noise reduction
apparatus of this invention.
It is an operation ¦ movement wave form diagram for demonstrating the wind noise reduction
method of the noise reduction apparatus of the 2nd example of a form of this invention.
It is a systematic diagram showing the 3rd embodiment of the noise reduction device of the
present invention.-It is a band frequency characteristic curve figure showing the division zone of
the 3rd embodiment.
It is a systematic diagram showing the example of the 4th form of the noise reduction device of
the present invention.
It is a concrete systematic diagram showing one example of an automatic noise reduction device
of the present invention. It is a systematic diagram which shows the 5th example of a form of the
noise reduction apparatus of this invention. FIG. 1 is a schematic system diagram of an automatic
noise reduction device according to the present invention. It is a systematic diagram showing the
outline of the conventional automatic noise reduction device. It is a frequency characteristic
curve figure for demonstrating a wind noise component. It is a systematic diagram which shows
the other structure of the conventional automatic noise reduction apparatus.
Explanation of sign
[0070]
1, 2, 201, 202 ... microphone, 3, 4, 22, 203, 204 ... amplifier (AMP) 5, 6 ... analog-to-digital
converter (ADC) 7, 8, 15, 16, 154, 155, 171, 172 ... delay device (DL), 9, 12, 13, 14, 19, 20, 46,
46a, 46b, 51, 51a, 52, 62b, 54, 77, 85, 86, 119, 137, 160, 170, 175, 176, 189, 194, 195, 196,
207, 208, 213, 215, 216 ... adders, 10, 17, 21, 43, 44, 50, 50a , 50b, 73, 74, 83, 84, 161, 173,
186, 187, 188, 193, 205, 206, 210, 211 ... low pass filter 11, 18 ... level variable device, 2 ...
Detector, 24 ... Control coefficient generator (MAKECOEF), 31 ... First control means, 32 ... Second
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control means, 34 ... Level detection means, 42, 45, 75, 76, 183, 184, 185, 209, 212 ... high pass
filter, 49, 81, 82, 49a, 49b, 192, 214 ... switch (SW), 40, 41, 60, 61, 62, 71, 72, 90, 111, 112,
135, 136, 151, 152, 180, 181, 182 ... input terminals, 25, 26, 53, 54, 87, 88, 96, 147, 148, 177
178, 197, 199 ... output terminal, 47, 47a, 47b, 78, 138, 190 ... multiplier, 48 ... level value
detection / determination means, 63, 64, 65 ... absolute value Processing means, 6 , 67, 68 ...
level detection means, 69 ... level value judgment means, 79 ... first level value detection /
judgment means, 80 ... second level value detection / judgment means, 91 · · · · · · Wind noise
reduction means 92 · · · mixing ratio control means 93 · · · wind noise extraction means 94 · · ·
detection means 95 · · control value generation means 139, 140, 141 · · · · · · · · Means, 142 ...
level comparison / selection means, 143, 144 ... band combining means, 145, 146 ... IFFT means,
113, 114, 115, 116, 117, 118 ... band pass filters
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