JPH1032894A - Voice processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attenuate only unwanted wind noise components, without cutting the low-band components of voices to be collected by performing the prescribed addition/subtraction between the 1st and 2nd low-frequency band signals and the 1st and 2nd high-frequency band signals and then outputting these added/ subtracted signals. SOLUTION: The left and right channel microphones are connected to the input terminals 1 and 2 respectively. Then the voice signals L, centering around the left and the voice signals R centering around the right, are inputted to the terminals 1 and 2 via their microphones respectively. The signals L and R are supplied to an amplifier 3 and a delay circuit 5 and to an amplifier 4 and a delay circuit 6 respectively. The outputs of the amplifier 3 and the circuit 6 are supplied to a subtraction circuit 7 and undergo subtraction processing there. Then the outputs of the amplifier 4 and the circuit 5 are supplied to a subtraction circuit 8 and undergo the subtraction processing there.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio processing device capable of reducing wind noise generated in audio picked up by a microphone.

[0002]

2. Description of the Related Art Examples of recording / reproducing apparatuses provided with a microphone include a tape recorder and a camera-integrated video. In particular, a camera-integrated video is often used outdoors, and is easily affected by the wind during recording, resulting in wind noise peculiar to a microphone, which affects the sound to be recorded.

[0003] It is known that the best way to prevent this effect is to attach a windscreen to the sound pickup opening of the microphone, and it is also excellent in performance. However, in this method, if an attempt is made to enhance the effect of reducing wind noise, the windscreen covering the sound pickup opening of the microphone becomes considerably large. In particular, in a device such as a camera-integrated video device, which is characterized by its small size and light weight, the above-described wind screen is not suitable.

In view of the above, a sound processing circuit as shown in FIG. 3 has been conventionally considered because it has a feature that a large amount of wind noise is distributed in a low frequency range.

[0005] In FIG. 3, the sound centered on the left side is
The switch 2 is converted into an audio signal by a left microphone (not shown), input from an input terminal 101, amplified by an amplifier 103, and directly connected to a changeover switch 107 and a high-pass filter (hereinafter, HPF) 105.
7 has a path connected to it. The output of the switch 107 is connected to the output terminal 109 and is output to an audio processing circuit (not shown). Similarly, the sound centered on the right side is converted into an audio signal by a right microphone (not shown), input from the input terminal 102, amplified by the amplifier 104, and directly connected to the changeover switch 108, and the HPF 106
There is a path through which the switch 108 is connected. The output of the switch 108 is connected to an output terminal 110 and output to an audio processing circuit (not shown).

Normally, when there is no influence of wind, the changeover switches 107 and 108 are connected in the direction of off in the drawing, and the signals amplified by the amplifiers 103 and 104 are output as they are. . When the wind is blowing, the changeover switches 107 and 108 are connected in the on direction in the figure to pass the HPF and output an audio signal in which a low-frequency component containing a large amount of wind noise is attenuated. By doing so, the level of wind noise was reduced.
The wind noise reduction effect of the configuration shown in FIG.
Can be changed by changing the setting of.

[0007]

However, in the conventional apparatus as described above, if the characteristics of the HPF are set so as to enhance the effect of reducing wind noise, the bass range of the sound to be picked up by the influence is also increased. This results in unnatural sound quality due to being cut off, and the effect of reducing wind noise has been reduced when trying to reduce the influence on the sound to be picked up.

It is an object of the present invention to provide an audio processing circuit device capable of attenuating only an extra wind noise component without removing a low-frequency component of a sound to be collected.

[0009]

In order to achieve the above-mentioned object, in a sound processing apparatus according to a first aspect of the present invention, a left sound centering on a sound signal corresponding to a sound emitted from a left direction is provided. A first input terminal to which a signal is input, a second input terminal to which a right audio signal centering on an audio signal corresponding to audio emitted from the right direction is input, and an input from the first input terminal. First delay means for delaying and outputting the left audio signal, and second delay means for delaying and outputting the right audio signal input from the second input terminal; and First subtraction means for subtracting the signal output from the second delay means from the input left audio signal and outputting the same, and the first delay from the right audio signal input from the second input terminal The signal output from the means The second subtraction means for subtracting and outputting the signal of the first low frequency band and the signal of the first high frequency band from the signal output from the first subtraction means, and outputting A first frequency band signal extracting means,
A second frequency band signal extracting unit that extracts a signal of a second low frequency band and a signal of a second high frequency band from the signal output from the second subtracting unit, and outputs the second frequency band signal extracting unit, The signal of the first low frequency band output from the one frequency band signal extracting means and the signal of the second low frequency band output from the second frequency band signal extracting means are added and output. A first addition unit, an arbitrary value capable of changing the signal of the first low frequency band output from the first frequency band signal extraction unit and the signal output from the first addition unit; And output as a first variable addition signal, and the second low frequency band signal output from the second frequency band signal extraction means and the first addition means Any value that can change the output signal Variable addition means for adding at the arithmetic ratio and outputting as a second variable addition signal; and a signal of the first high frequency band output from the first frequency band signal extraction means and the variable addition means. Second adding means for adding and outputting the first variable addition signal output, and a signal of the second high frequency band output from the second frequency band signal extracting means and the variable A third adding means for adding the second variable addition signal output from the adding means and outputting the added signal, and a sound processing apparatus according to a second aspect of the present invention. ,
A first input terminal to which a left audio signal centering on an audio signal corresponding to a sound emitted from the left direction is input, and a right audio signal centering an audio signal corresponding to a sound emitted from the right direction are input. A second input terminal, delaying the left audio signal input from the first input terminal,
The first delay means for outputting, the second delay means for delaying and outputting the right audio signal input from the second input terminal, and the second audio signal from the left audio signal input from the first input terminal. Subtracting the signal output from the second delay means,
First subtraction means for outputting, a second subtraction means for subtracting a signal output from the first delay means from a right audio signal input from the second input terminal, and outputting the subtracted signal; A first frequency band signal extracting unit that extracts a signal of the first low frequency band and a signal of the first high frequency band from the signal output from the subtracting unit, and outputs the extracted signal; Extracting a signal of the second low frequency band and a signal of the second high frequency band from the signal output from the means,
A second frequency band signal extracting means for outputting, a first low frequency band signal output from the first frequency band signal extracting means, and a second signal output from the second frequency band signal extracting means. First addition means for adding and outputting the signal of the low frequency band of the first frequency band, and the signal of the first low frequency band output from the first frequency band signal extraction means and the first addition. Select one of the signals output from the means, and output it as a first selection signal, and the signal of the second low frequency band output from the second frequency band signal extraction means A selection output unit that selects one of the signals output from the first addition unit and outputs the selected signal as a second selection signal; and the first output unit that is output from the first frequency band signal extraction unit. High frequency band signal And the first selection signal output from the selection output means, and the second addition means for outputting the second selection signal, and the second high frequency band output from the second frequency band signal extraction means And a third adding means for adding and outputting the second selection signal output from the selection output means and the second selection signal.

(Operation) With the above-described structure, the low-frequency component of the sound to be picked up is hardly affected, and only the unnecessary wind noise component is continuously attenuated by a necessary amount. The effect of reducing wind noise can be interrupted only when necessary.

[0011]

FIG. 1 shows a first embodiment of the present invention.
This will be described in detail with reference to FIG.

In FIG. 1, an input terminal 1 is connected to a left channel microphone, and an input terminal 2 is connected to a right channel microphone.

The input terminal 1 receives an audio signal L centered on the left, and the input terminal 2 receives an audio signal R centered on the right from both microphones.

The left audio signal L is supplied to an amplifier 3 and a delay circuit 5
, And the right audio signal R is connected to the amplifier 4 and the delay circuit 6. Output of amplifier 3 and delay circuit 6
Is connected to a subtraction circuit 7, and the subtraction circuit 7
Performs a subtraction process. Further, the output of the amplifier 4 and the output of the delay circuit 5 are connected to a subtraction circuit 8, and the subtraction circuit 7 performs a subtraction process.

At this time, it is ideal that only the left audio signal is input to the input terminal 1 and only the right audio signal is input to the input terminal 2. The sound signal on the opposite side is also mixed and picked up. Particularly, when the directivity of the microphone used is omnidirectional, there is almost no difference, and the sense of stereo is lost. Therefore, in the apparatus of the present embodiment, the phase difference between the sound signals picked up by the two microphones is reduced. By using, the audio signals output from each other's microphone are respectively delayed and subtracted from the audio signal of the other party, thereby attenuating the signal components collected and mixed,
I try to improve the channel separation.

Now, a wind noise WL is applied to the left audio signal L of the input terminal 1 and a wind noise component W is applied to the right audio signal R of the input terminal 2.
Assume that R is mixed. The audio signal input from the input terminal 1 is L + WL, which is amplified by the amplifier 3,
Since the signal component does not change, the output of the amplifier 3 is the same, that is, L + WL. This signal is directly input to the subtractor 7 and the delay circuit 5. Similarly, the output of the amplifier 4 of the audio signal input from the input terminal 2 is R + WR.

Here, as the delay circuit 5 and the delay circuit 6, L
Consider the case where PF is used. Expressing the audio signal L + WL which is the input signal of the delay circuit 5 in more detail,
The left signal L can be considered separately as a left audio low frequency component LL and a left audio high frequency component LH. That is, the output of the delay circuit 5 is LL + LH + WL. Similarly, an audio signal which is an input signal of the delay circuit 6 can be expressed as RL + RH + WR.

In this case, the output of the delay circuit 5 passes through the low-frequency component of the voice without delay or attenuation because the delay circuit is an LPF, but the higher frequency components are delayed and attenuated. As a result, assuming that the delayed and attenuated high-frequency component of LH is I, the wind noise component WL is a low-frequency component and is not delayed or attenuated.
LL + I + WL. Similarly, the output of the delay circuit 6 is represented by r, where r is the delayed and attenuated high frequency component of RH.
RL + r + WR.

Therefore, the input signal of the subtraction circuit 7 is LL + L
H + WL- (RL + r + WR), and the output signal a is
(LL-RL) + (LH-r) + (WL-WR). Since the first and second terms of this equation are audio signals, they can be treated as a composite signal of audio signals having a phase difference. On the other hand, the wind noise component is generated by the structural elements of the microphone, and the eddy current is the main component.Therefore, the wind noise collected by the left and right microphones has no correlation with each other and can be treated as a composite signal. Can not. Therefore, (LL-R
L) = LL ′ and (LH−r) = LH ′, the subtraction circuit 7
Is a signal LL ′ + LH ′ + (WL−WR).

Similarly, the output signal b of the subtraction circuit 8 is
RL ′ + RH ′ + (WR−WL).

The output signal a is composed of the LPF 9 and the HPF 1
At 1, the signal is divided into a high-frequency component and a low-frequency component. That is, the output signal c of the LPF 9 is LL ′ + (WL−WR),
The output signal e of the HPF 11 becomes LH ′, and the output signal c of the LPF 9 is input to the input terminal A of the adder 15 and the level adjuster 16. Similarly, the output signal b is output from the LPF 10 and H
The input signal to the PF 12 and the output signal d of the LPF 10 are R
L ′ + (WR−WL), and the adder 15 and the level adjuster 1
6 input terminal B. The output signal f of the HPF 12 becomes RH '.

Therefore, the output signal g of the adding circuit 15 is L
L '+ (WL-WR) + RL' + (WR-WL) = LL '+ R
L ′, the wind noise component is not canceled,
It can be seen that the remaining component is a composite signal of the low frequency component of the input audio signal.

The output signal g of the adder 15 is input to the input terminal B of the level adjuster 16. In this level adjuster 16, the signal input from the input terminal A and the input terminal B
And a function of simultaneously and continuously varying the mixing ratio of the signal input from the input terminal C and the mixing ratio of the signal input from the input terminal C and the signal input from the input terminal B. , The signals j and k output from the variable output terminals D and E are the signals c input from the input terminal A and the signal g input from the input terminal B according to the position where the variable output terminal D is connected. Can be adjusted.

When the connection position of the variable output terminal D is the input terminal A, the coefficient n (0 ≦ 0) indicating the connection position of the variable output terminal C is used.
Assuming that (n ≦ 1) becomes 1, the signal j output from the variable output terminal C is expressed as j = cn + g (1-n).
Similarly, when the connection position of the variable output terminal E is the input terminal C, the coefficient n (0 ≦ n ≦
Assuming that 1) becomes 1, the signal k output from the variable output terminal E is represented as k = dn + g (1-n).

As can be seen from the above equation, the variable output terminal D
The connection position of the variable output terminal E and the variable output terminal E are configured to change in conjunction with each other. For example, as the connection position of the variable output terminal D approaches the input terminal A, the connection position of the variable output terminal E also changes to the input terminal C. It works to get closer to.

When the connection positions of the variable output terminals D and E are both input terminals B, the signals j and k output from the variable output terminals D and E are both the signals output from the adder 15. g.

Therefore, the final output signal h, which is a composite signal of the signal j and the signal e, is j = (LL '+ (WL-WR)). N + (LL'). + RL ') ・ (1
−n) Since e = LH ′, h = j + e = LL ′ · n + (LL ′ + RL ′) · (1-n) + (WL−WR) · n + LH ′ = LL ′ + (1-n) RL '+ (WL-WR) .n + LH'.

Similarly, the finally output signal i which is a composite signal of the signal k and the signal f is the signal k and the signal f is k = (RL '+ (WR-WL)). N (LL '+ RL') ・ (1
−n) Since f = RH, i = RL ′ + (1-n) LL ′ + (WR−WL) · n + RH ′.

That is, the finally output audio signal h,
i is each variable output terminal D, E in the level adjuster 16
If the coefficient n indicating the connection position of is zero, the wind noise component
(WL−WL), the wind noise reduction effect is maximized, and the final output signals h and i at that time are h
= LL '+ RL' + LH ', and i = RL' + LL '+ RH'.

As can be seen from the above equation, the low-frequency component of the voice is a synthesized voice signal obtained by synthesizing the left voice signal and the right voice signal. However, human hearing has little inconvenience even with a synthesized voice signal because the detection capability of channel separation is not so high for low-frequency components of voice. There is a case where it is not always necessary to maximize the wind noise reduction effect, such as when there is no influence, or when the wind noise is collected at an appropriate volume to give a sense of realism.

Therefore, in such a case, in this embodiment,
The connection positions of the variable output terminals D and E in the level adjuster 16 are made closer to the input terminals A and C, respectively.

For example, assuming that the value of the coefficient n indicating the connection position of the variable output terminals D and E is 0.5, the signals h and i output from the variable output terminals D and E are respectively: h = LL '+ 0.5RL '+0.5 (WL-WR) + LH' i = RL '+ 0.5LL' + 0.5 (WR-WL) + RH ', and the level of the wind noise component is smaller than when there is no effect of reducing the wind noise. It will be half the size.

As described above, in this embodiment, the amount of wind noise reduction is adjusted by changing the connection position of the variable output terminals D and E of the level adjuster 16.

Next, a second embodiment of the present invention will be described in detail with reference to FIG.

The subscripts 21 to 35 in the figure correspond to 1 to 15 in the embodiment shown in FIG.
Here, the description is omitted.

In FIG. 2, reference numeral 36 denotes a switch,
, A signal c to be input, a signal d to a contact D, and a contact B
And C are supplied with a signal g.

A signal from the contact A or the contact B is selectively output from the output terminal E, and a signal from the contact D or the contact C is selectively output from the output terminal F.

In the figure, a signal c is a low-frequency component sound signal including wind noise of the left channel, a signal g is a synthesized voice signal of low-frequency components of the left channel and right channel without wind noise, and a signal d is a signal. The low-frequency component audio signal including wind noise of the right channel is shown.

When an instruction to cancel the effect of reducing wind noise is given by operating an operation switch (not shown), the switch 36 connects the output terminal E to the contact A,
When the output terminal F is connected to the contact D to make the wind noise reduction effect ineffective, and by operating the operation switch to give an instruction to make the wind noise reduction effect effective, the switch 36 Connect output terminal E to contact B,
By connecting the output terminal F to the contact C, the effect of reducing wind noise is maximized.

That is, in the present embodiment, the switching operation of the switch 36 can switch the intermittent effect of the wind noise reduction effect, and the intermittent effect of the wind noise reduction effect can be selected only when necessary. become.

[0041]

As described above, according to the speech processing apparatus of the present invention, only the unpleasant wind noise component is hardly affected on the low-frequency component of the sound to be picked up. Attenuate continuously as much as needed,
The effect of reducing wind noise can be interrupted only when necessary.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram of a conventional audio processing device.

[Explanation of symbols]

4, 23, 24, 103, 104 Amplifiers 5, 6, 9, 10, 29, 30 Low-pass filters 11, 12, 31, 32, 105, 106 High-pass filters 7, 8, 27, 28 Subtractors 13, 14, 15 , 33, 34, 35 Adder 16 Level adjuster 36, 107, 108 Switch circuit

Claims (4)

[Claims] 1. A first input terminal for inputting a left audio signal centered on an audio signal corresponding to a sound emitted from the left direction, and a right input center centering on an audio signal corresponding to a sound emitted from the right direction. A second input terminal to which an audio signal is input, a first delay means for delaying and outputting a left audio signal input from the first input terminal, and a right input from the second input terminal A second delay unit for delaying and outputting an audio signal, and a first subtraction for subtracting a signal output from the second delay unit from a left audio signal input from the first input terminal and outputting the same. Means, a second subtraction means for subtracting a signal output from the first delay means from a right audio signal input from the second input terminal, and outputting the signal, and an output from the first subtraction means. First low frequency band The first frequency band signal extracting means for extracting the signal of the band and the signal of the first high frequency band, and outputting the signal of the second low frequency band from the signal output from the second subtracting means. A second frequency band signal extracting means for extracting and outputting a signal and a signal of a second high frequency band, and a signal of a first low frequency band output from the first frequency band signal extracting means And a second low frequency band signal output from the second frequency band signal extracting means, and outputs the result. The first adding means outputs the signal, and the signal is output from the first frequency band signal extracting means. The signal of the first low frequency band and the signal output from the first addition means are added at an addition ratio of any variable value, and output as a first variable addition signal, The output from the second frequency band signal extracting means Variable addition means for adding the signal of the second low-frequency band and the signal output from the first addition means at an addition ratio of any variable value, and outputting as a second variable addition signal, A second addition for adding and outputting the signal of the first high frequency band output from the first frequency band signal extraction means and the first variable addition signal output from the variable addition means; Means for adding the second variable addition signal output from the variable addition means and the signal of the second high frequency band output from the second frequency band signal extraction means, and outputting An audio processing apparatus comprising: three adding means. 2. The variable addition means variably adds a signal in the first low frequency band output from the first frequency band signal extraction means and a signal output from the first addition means. The signal of the second low frequency band output from the second frequency band signal extraction unit and the signal output from the first addition unit at the same value of the addition ratio as the value of the addition ratio in the operation. 2. The audio processing apparatus according to claim 1, wherein the audio processing apparatus is configured to add a second variable addition signal and output the second variable addition signal as a second variable addition signal. 3. A first input terminal for inputting a left audio signal centered on an audio signal corresponding to a sound emitted from the left direction, and a right input center centering on an audio signal corresponding to a sound emitted from the right direction. A second input terminal to which an audio signal is input, a first delay means for delaying and outputting a left audio signal input from the first input terminal, and a right input from the second input terminal A second delay unit for delaying and outputting an audio signal, and a first subtraction for subtracting a signal output from the second delay unit from a left audio signal input from the first input terminal and outputting the same. Means, a second subtraction means for subtracting a signal output from the first delay means from a right audio signal input from the second input terminal, and outputting the signal, and an output from the first subtraction means. First low frequency band The first frequency band signal extracting means for extracting the signal of the band and the signal of the first high frequency band, and outputting the signal of the second low frequency band from the signal output from the second subtracting means. A second frequency band signal extracting means for extracting and outputting a signal and a signal of a second high frequency band, and a signal of a first low frequency band output from the first frequency band signal extracting means And a second low frequency band signal output from the second frequency band signal extracting means, and outputs the result. The first adding means outputs the signal, and the signal is output from the first frequency band signal extracting means. Selecting one of the signal of the first low frequency band and the signal output from the first adding means, outputting the selected signal as a first selection signal, and extracting the second frequency band signal The second low frequency band output by the means And one of the signals output from the first addition means and a selection output means for outputting as a second selection signal, and an output from the first frequency band signal extraction means. A second adding means for adding and outputting the signal of the first high frequency band and the first selection signal output from the selection output means, and an output from the second frequency band signal extraction means; And a third adding means for adding and outputting the signal of the second high frequency band and the second selection signal output from the selection output means. apparatus. 4. The selective output means selectively outputs a signal in the first low frequency band output from the first frequency band signal extracting means and a signal output from the first adding means. A structure for performing a selective output operation of the signal of the second low frequency band output from the second frequency band signal extracting means and the signal output from the first adding means in conjunction with the operation. 4. The voice processing device according to claim 3, wherein the voice processing is performed.