JP3143562B2 - Audio processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice processing apparatus for processing voice, and more particularly, to detecting wind noise generated when a wind hits the microphone when the voice is picked up by a microphone or the like. It is for doing.

[0002]

2. Description of the Related Art When recording sound outdoors, if the wind hits a microphone for sound collection, the microphone collects the sound of the wind, causing a problem of generating wind noise. .

Since the wind noise is mainly concentrated on low frequency components, the sound signal output from the microphone is removed by passing it through a high-pass filter (hereinafter referred to as HPF) or the like. Was. However, in this case, since the audio signal is always passed through the HPF, the low frequency component of the audio signal is not recorded at all. Therefore, a circuit for detecting the occurrence of wind noise is provided, and when the wind noise is generated, the audio signal passed through the HPF is output, and when the wind noise is not generated, the audio signal not passed through the HPF is output. A circuit that can be automatically switched to record a signal has been considered.

A circuit for detecting the occurrence of wind noise as described above includes, for example, a band-pass filter (hereinafter, referred to as BPF) mainly passing wind noise, and an audio signal other than wind noise. A passing BPF is provided, and the occurrence of wind noise is detected by comparing the output levels of the respective BPFs with a comparison circuit.

That is, when the output of the wind noise BPF is greater than the output of the audio signal BPF, it is determined that wind noise is occurring, and a signal instructing wind noise removal is output. The output from the comparison circuit, the characteristics of the HPF are switched in accordance with the output from the comparison circuit, and whether or not the audio signal is passed through the HPF is switched, thereby automatically removing wind noise. It was done.

As described above, conventionally, the presence / absence of wind has been detected by comparing the level of wind noise and the level of other audio signals.

[0007]

However, in the above-described conventional detection circuit, when an audio signal having a frequency component similar to that of wind noise is input at a predetermined level, merely comparing the levels is not sufficient. If it is not possible to determine whether it is wind noise or the original audio signal, and if it is incorrectly determined that it is wind noise, the audio signal to be recorded is removed without recording. Problem.

The present invention has been made in view of the above-mentioned conventional problems, and accurately and stably generates wind noise without erroneously detecting an audio signal having a low frequency component as wind noise. It is an object of the present invention to provide a voice processing device capable of detecting a sound.

[0009]

According to the present invention, there is provided an audio processing apparatus comprising: left and right audio signal output means for converting and outputting audio generated from a sound source to audio signals; Detecting means for receiving an output audio signal and detecting whether or not the polarities of the input left and right audio signals match; and inputting the right and left audio signals according to the detection signal output from the detecting means. And a comparison unit for detecting a wind noise by comparing a period in which the polarities coincide with a period in which the polarities do not coincide with each other every predetermined period.

[0010]

According to the above arrangement, it is possible to accurately and stably detect the occurrence of wind noise without erroneously detecting an audio signal having a low frequency component as wind noise.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments of the present invention.

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

In FIG. 1, reference numerals 1 and 2 denote low-pass filters (hereinafter referred to as LPFs), which extract only low-frequency components from an input audio signal. That is, since the frequency component of the wind noise is substantially biased to the low frequency region, a signal of the frequency component in which the wind noise exists can be extracted by the LPF.

Reference numeral 3 denotes a polarity discriminator which discriminates the polarity of the signal output from the LPFs 1 and 2, and determines the polarity of the signal output from the LPFs 1 and 2 such that the polarity is positive and positive or negative and negative, respectively. If the polarity is the same, the same polarity counter 4
And outputs a signal indicating "0" to the different polarity counter 5. The signals output from the LPFs 1 and 2 have different polarities such as positive and negative or negative and positive, respectively. In this case, a signal indicating “0” is output to the same polarity counter 4 and a signal indicating “1” is output to the different polarity counter 5.

Reference numeral 4 denotes a same polarity counter for counting the same polarity, and 5 denotes a different polarity counter for counting the different polarities. "1" output
Is counted, and the count value is incremented. The count values of the counters 4 and 5 are configured to be reset at predetermined intervals by a reset signal output from the reset circuit 6 at predetermined intervals, and are output from the LPFs 1 and 2 respectively. The number of cases where the polarity of the signal is the same polarity and the case where the signal polarity is different within a predetermined period is counted.

Reference numeral 7 denotes a comparison circuit which compares the count values output from the counters 4 and 5 at predetermined intervals, and when the count value of the counter 4 is larger, wind noise is generated. If the count value of the counter 5 is larger, a signal indicating that wind noise is occurring is output.

Next, a description will be given of a method for distinguishing between wind noise and voice having a low frequency component in the present embodiment.

FIG. 2 shows a case where a normal sound generated from a sound source is picked up by an Lch (left) microphone and an Rch (right) microphone. A stereo audio signal output from the microphone is shown on two-dimensional coordinates formed by an axis indicating the level of the audio signal output from the Lch microphone and an axis indicating the level of the audio signal output from the Rch microphone. It is a thing.

The ellipse shown in FIG. 2 shows the state of the level of the audio signal output from the Lch microphone and the Rch microphone when the sound from the sound source hits the microphones almost from the front.

As shown in FIG. 2, when a sound source is located almost in front of both microphones, almost the same phase of sound is input to the Lch microphone and the Rch microphone. It will show a + 45 ° slope. In this state, when the sound source is shifted to the left or right with respect to both microphones, the inclination also changes with the movement of the sound source, but the inclination is still positive. (Especially, even if there is a sound source only at a position facing the Lch microphone or the Rch microphone, it will only be along the axis of the Lch or Rch.)

On the other hand, when wind is applied to both microphones and wind noise is generated from both microphones, there is no correlation between the audio signal output from the Lch microphone and the audio signal output from the Rch microphone. It has no characteristics and is shown on the two-dimensional coordinates formed by an axis indicating the level of the audio signal output from the microphone for Lch and an axis indicating the level of the audio signal output from the microphone for Rch in the same manner as a normal audio. Is as shown in FIG.

As shown in FIG. 3, when there is no correlation between the audio signal output from the Lch microphone and the audio signal output from the Rch microphone, in an extreme case, the rightward slope is −45 °. Will be shown.

Therefore, the audio signal output from the Lch microphone and the audio signal output from the Rch microphone are instantaneously viewed as normal stereo audio. Many appear in the first and fourth quadrants on the two-dimensional coordinates formed by the axis indicating the level and the axis indicating the level of the audio signal output from the Rch microphone, and have the same polarity. In the case of wind noise, many appear in the second quadrant and the third quadrant on the two-dimensional coordinates, and have different polarities.

Therefore, in this embodiment, L is set every predetermined period.
Audio signal output from microphone for ch and Rch
By detecting the polarity of the audio signal output from the microphone for use and comparing the period indicating the same polarity state with the period indicating the different polarity state, it is possible to determine whether the sound has wind noise or low-frequency sound. Distinction.

The audio signals output from the Lch microphone and the Rch microphone both have a DC offset removed.

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

FIG. 4 is a diagram showing the configuration of the second embodiment of the present invention.

In FIG. 4, LPFs 1 and 2 extract only low-frequency components from an input audio signal. That is, since the frequency component of the wind noise is substantially biased to the low frequency region, a signal of the frequency component in which the wind noise exists can be extracted by the LPF.

A polarity discriminator 3 discriminates the polarity of the signal output from the LPFs 1 and 2, and determines the polarity of the signal output from the LPFs 1 and 2 such that the polarity is positive and positive or negative and negative, respectively. If the polarity is the same, the same polarity LPF 8
When a signal indicating "1" is output as a signal indicating "0" to the different polarity LPF 9 and the signals output from the LPFs 1 and 2 have different polarities such as positive and negative or negative and positive, respectively. Outputs a signal indicating “0” to the LPF 8 of the same polarity and a signal indicating “1” to the LPF 9 of the opposite polarity.

Reference numeral 8 denotes a same-polarity LPF for smoothing a signal indicating the same polarity, and reference numeral 9 denotes a different-polarity LPF for smoothing a signal indicating the different polarity. The period during which the polarities of the signals output from the LPFs 1 and 2 are the same is long, and many signals of “1” are supplied from the polarity discriminator 3 to the LPFs 8 of the same polarity.
9 is supplied with a large number of “0” signals,
The level of the output signal of the PF8 approaches "1" and the opposite polarity L
The level of the output signal of the PF 9 approaches “0”, and the period during which the polarities of the signals output from the LPFs 1 and 2 are different is longer.
Many signals of "0" are supplied to the PF8,
When a large number of "1" signals are supplied to the
The level of the output signal of F8 approaches "0" and the opposite polarity LP
The level of the output signal of F9 approaches "1".

Therefore, based on the level of the signals output from the LPFs 8 and 9, it is determined how much the polarity of the signals output from the LPFs 1 and 2 is the same or different. Is output.

Reference numeral 7 denotes a comparison circuit, which is provided at every predetermined period.
The levels of the signals output from the PFs 8 and 9 are compared. If the level of the signal output from the LPF 8 is higher, a signal indicating that no wind noise is generated is output. If the level of the output signal is higher, a signal indicating that wind noise is occurring is output.

In the second embodiment, the period for detecting the occurrence of wind noise is determined by the time constant of the LPFs 8 and 9.

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

FIG. 5 is a diagram showing the configuration of the third embodiment of the present invention.

In FIG. 5, LPFs 1 and 2 extract only low frequency components from an input audio signal. That is, since the frequency component of the wind noise is substantially biased to the low frequency region, a signal of the frequency component in which the wind noise exists can be extracted by the LPF.

A polarity discriminator 3 discriminates the polarity of the signals output from the LPFs 1 and 2, and determines the polarity of the signals output from the LPFs 1 and 2 such that the polarities are positive and positive or negative and negative, respectively. If the polarity is positive, a signal indicating "0" is output to the counter 10. If the polarity of the signals output from the LPFs 1 and 2 is different, such as positive and negative or negative and positive, respectively. The signal indicating "1" is output to the counter 10
Output to

Reference numeral 10 denotes a counter that counts different polarities, counts a signal indicating "1" output from the polarity discriminator 3, and increments the count value. The count value of the counter 10 is configured to be reset every predetermined period by a reset signal output every predetermined period from the reset circuit 11, and the polarity of the signals output from the LPFs 1 and 2 respectively. Are different polarities within a predetermined period, the number of times is counted.

A comparison circuit 7 compares the count value output from the counter 10 every predetermined period with a preset reference count value output from a reference count value generator 12, and compares the magnitude with the reference count value. When the reference count value is larger, a signal indicating that wind noise is not generated is output. When the count value in the counter 10 is larger, it is determined that wind noise is generated. Output the signal shown.

Note that in the third embodiment, the first
In the embodiment of the present invention, a counter provided to count how long the polarities of the signals respectively output from the LPFs 1 and 2 are the same polarity and the polarities are different within a predetermined period is 1 This is suitable for simplifying the circuit configuration and reducing costs.

In this embodiment, the LPFs 1, 2
If the polarities of the signals output from the LPFs 1 and 2 are the same, such as positive and positive or negative and negative, a signal indicating "1" is counted. 10. When the polarities of the signals output from the LPFs 1 and 2 are different from each other, such as positive and negative or negative and positive, a signal indicating "0" is output to the counter 10. The same effect can be obtained even if the container 3 is used.

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

FIG. 6 is a diagram showing the configuration of the fourth embodiment of the present invention.

In FIG. 6, LPFs 1 and 2 extract only low-frequency components from an input audio signal. That is, since the frequency component of the wind noise is substantially biased to the low frequency region, a signal of the frequency component in which the wind noise exists can be extracted by the LPF.

A polarity discriminator 3 discriminates the polarity of the signals output from the LPFs 1 and 2, and determines the polarity of the signals output from the LPFs 1 and 2 such that they are positive and positive or negative and negative, respectively. In the case of polarity, a signal indicating "0" is LP
When the polarity of the signals output from the LPFs 1 and 2 are different from each other, such as positive and negative or negative and positive, a signal indicating "1" is output to the LPF 13.

Reference numeral 13 denotes an LPF for smoothing a signal indicating that the signals have different polarities. For example, in the polarity discriminator 3, the period during which the polarity of the signals output from the LPFs 1 and 2 is the same is long. From polarity discriminator 3 to LPF13 "
When a large number of "0" signals are supplied, the level of the output signal of the LPF 13 approaches "0", and the level of the LPF1,
In the case where the period during which the polarity of the signal output from 2 is a different polarity is long and many signals of “1” are supplied from the polarity discriminator 3, the level of the output signal of the LPF 13 approaches “1”. become.

Therefore, based on the magnitude of the level of the signal output from the LPF 13, a signal indicating how much the polarity of the signal output from each of the LPFs 1 and 2 is different when the polarity is different is output. Will be.

Reference numeral 7 denotes a comparison circuit, which is provided at every predetermined period.
The level of the signal output from the reference level signal generator 14 is compared with the level of a signal having a preset reference level output from the reference level signal generator 14. If the level is higher, a signal indicating that wind noise is not generated is output. If the level of the signal output from the LPF 13 is higher, wind noise is generated. Is output.

In the fourth embodiment, the period for detecting the occurrence of wind noise is determined by the time constant of the LPF 13.

Note that, in the fourth embodiment, the second
In the embodiment of the present invention, only one LPF is required for smoothing a signal indicating that the polarity of the signal output from each of the LPFs 1 and 2 is the same and the polarity is different within a predetermined period. Therefore, it is suitable for simplifying the circuit configuration and reducing costs.

In this embodiment, the LPFs 1, 2
The polarity of the signals output from the LPFs 1 and 2 is determined, and if the polarity of the signals output from the LPFs 1 and 2 is the same, such as positive and positive or negative and negative, the signal indicating “1” is converted to the LPF 13. And a polarity discriminator 3 that outputs a signal indicating "0" to the LPF 13 when the polarities of the signals outputted from the LPFs 1 and 2 are different from each other such as positive and negative or negative and positive. The same effect can be obtained by using.

[0052]

As described above, according to the present invention,
Since the occurrence of wind noise is detected based on the polarity of the left audio signal and the right audio signal in the stereo audio signal, an audio signal having a low frequency component is not erroneously detected as wind noise. It is possible to accurately and stably detect the occurrence of wind noise.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing, on two-dimensional coordinates, a left level and a right level of a stereo audio signal when normal audio generated from a sound source is collected by a stereo microphone.

FIG. 3 is a diagram showing, on two-dimensional coordinates, a left level and a right level of a stereo audio signal when audio containing much wind noise is collected by a stereo microphone.

FIG. 4 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 6 is a diagram showing a configuration of a fourth embodiment of the present invention.

[Explanation of symbols]

 1, 2, 8, 9, 13 LPF 3 Polarity discriminator 4, 5, 10 Counter 6, 11 Reset circuit 7, 22 Comparison circuit 12 Reference count value generator 14 Reference level signal generator

────────────────────────────────────────────────── ─── Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) G10L 15/00-17/00 G10L 21/02 H04R 3/00 320 INSPEC (DIALOG) JICST file (JOIS) WPI (DIALOG)

Claims (6)

(57) [Claims] 1. A left and right audio signal output means for converting and outputting a sound generated from a sound source to an audio signal, and an audio signal output from the left and right audio signal output means, respectively. Detecting means for detecting whether or not the polarities of the left and right audio signals are coincident with each other; An audio processing apparatus comprising: a comparing unit that detects a wind noise by comparing a period in which the noise has not been detected with a predetermined period. 2. Left and right voice signal output means for converting and outputting voice generated from a sound source into voice signals, and voice signals output from the right and left voice signal output means, respectively. A detection unit that detects whether or not the polarities of the left and right audio signals match each other for a predetermined period, and outputs a detection signal indicating a period in which the polarities match, and a detection signal output from the detection unit. A sound processing apparatus comprising: a comparing unit that detects wind noise by comparing a length of a period with a reference value. 3. Left and right voice signal output means for converting and outputting voice generated from a sound source into voice signals, and voice signals output from the left and right voice signal output means, respectively, A detection unit that detects whether or not the polarities of the left and right audio signals match each other for a predetermined period, and outputs a detection signal indicating a period in which the polarities do not match; and a detection signal output from the detection unit. A sound processing apparatus comprising: a comparing unit that detects wind noise by comparing a length of a period with a reference value. 4. Right and left sound signal output means for converting and outputting sound generated from a sound source to sound signals, and sound signals output from the right and left sound signal output means, respectively, Detecting means for detecting whether or not the polarities of the left and right audio signals match, a smoothing means for smoothing and outputting a detection signal output from the detecting means, and a detection smoothed by the smoothing means A comparison unit that detects a wind noise by comparing a period in which the polarities of the input left and right audio signals match and a period in which the polarities do not match in accordance with the signal at predetermined intervals. Characteristic speech processing device. 5. Left and right sound signal output means for converting and outputting sound generated from a sound source to sound signals, and sound signals output from the right and left sound signal output means, respectively, Detecting means for detecting whether or not the polarities of the left and right audio signals match each other for each predetermined period, and outputting a detection signal indicating a period during which the polarities match, and smoothing the detection signal output from the detecting means; And a smoothing means for outputting, and a comparing means for detecting wind noise by comparing a length of a period indicated by the detection signal smoothed by the smoothing means with a reference value. Audio processing device. 6. Left and right sound signal output means for converting and outputting sound generated from a sound source to sound signals, and sound signals output from the right and left sound signal output means, respectively. Detecting means for detecting whether or not the polarities of the left and right audio signals match each other at predetermined intervals, and outputting a detection signal indicating a period in which the polarities do not match; and smoothing the detection signal output from the detecting means. And a smoothing means for outputting, and a comparing means for detecting wind noise by comparing a length of a period indicated by the detection signal smoothed by the smoothing means with a reference value. Audio processing device.