JP3131716B2 - Voice detection 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 detecting apparatus having a noise canceling function using an adaptive filter.

[0002]

2. Description of the Related Art Generally, a voice detection apparatus having a noise canceling function is used for detecting voice in a noise environment.

FIG. 5 shows a conventional voice detecting device 50. The voice detection device 50 includes a first detection unit 51 including a microphone for detecting voice and noise and an analog-to-digital converter, a second detection unit 52 including a microphone for detecting noise and an analog-to-digital converter, and an adaptive filter (adaptive filter). A filter 53 and a subtraction processing unit 54 are provided. Such a voice detection device 50 obtains the digital first signal Da from the first detection unit 51 and obtains the digital second signal Db from the second detection unit 52. The digital second signal Db is applied to the adaptive filter 5.
3 and a subtraction processing unit 5
4, the output signal Dc of the adaptive filter 53 is subtracted from the digital first signal Da, whereby an audio signal containing only an audio component from which a noise component has been canceled is obtained at the output of the subtraction processing unit 54.

[0004]

By the way, the principle of the above-described conventional voice detection device 50 is to estimate a transfer function in a voice detection circuit system based on a detection signal from a second detection unit 52 for detecting noise. is there. However, in general, when noise having a wide dynamic range such as white noise is included, the transfer function G [d
B] shows a complicated change as shown in FIG. 2 and the phase P [ra] with respect to the frequency f [Hz].
The characteristic curve Mp of d) also shows a complicated change as shown in FIG. For this reason, when noises with a wide dynamic range are included, the amount of noise cancellation by the conventional voice detection device 50 becomes insufficient, and there is a problem that voices cannot be detected with high quality.

The present invention has been made to solve the problem existing in the prior art, and can detect a high-quality sound by sufficiently removing the noise even when the noise includes a wide dynamic range. It is intended to provide a voice detection device.

[0006]

According to the present invention, a first microphone 2 capable of detecting voice and noise, a second microphone 3 capable of detecting noise, and each of the microphones 2, 3 are provided.
, An analog-to-digital conversion processing unit 4 for converting the detection signal from the digital signal into a digital first signal Df and a digital second signal Ds, respectively, filtering the digital second signal Ds with an adaptive filter, and converting the digital first signal into an adaptive filter In configuring the speech detection device 1 including the noise canceling function unit 5 that outputs the digital output signal Do in which the output signal is subtracted to cancel the noise, in particular, the first microphone 2
Signal component removal circuit 1 for removing in-phase or out-of-phase signal components in each detection signal from the second and third microphones 3
0, a digital filter unit 7 for dividing the digital first signal Df and the digital second signal Ds into a plurality of bands Za, Zb, Zc, respectively, and a plurality of noise canceling function units 5a, 5b, 5c corresponding to each band. , The digital output signal D of each noise canceling function unit 5a, 5b, 5c
It is characterized by including an addition processing section 8 for adding oa, Dob, and Doc.

In this case, it is desirable that the first microphone 2 and the second microphone 3 are integrally provided in a single casing 9.

[0008]

According to the voice detection device 1 of the present invention, voice including noise is detected by the first microphone 2 and noise is detected by the second microphone 3, and the detection signal from each of the microphones 2 and 3 is The analog-digital conversion processing unit 4 converts the digital signal into a digital first signal Df and a digital second signal Ds, respectively.

The digital first signal Df and the digital second signal Ds are divided into a plurality of bands Za, Zb, Zc by the digital filter unit 7, respectively. Then, a plurality of noise canceling function units 5 corresponding to each band
Noise cancellation processing is performed by a, 5b, and 5c, respectively. That is, one noise canceling function unit 5a
(The same applies to 5b and 5c), the digital second signal Dsa
Is filtered by the adaptive filter 11a, and the output signal Dma of the adaptive filter 11a is subtracted from the digital first signal Dfa. Thereby, each noise canceling function unit 5a, 5b, 5c
, Digital output signals Doa, Dob, and Doc in which noise is canceled for each band are obtained. Each of the digital output signals Doa, Dob, and Doc is added by the addition processing unit 8, and the digital output signal Do output from the addition processing unit 8 is converted into an analog signal Ao by, for example, the digital-analog conversion processing unit 6. You. Therefore, the analog signal Ao is a noise-free audio signal. When digital recording is performed, the digital output signal Do can be directly used.

[0010]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the configuration of the voice detection device 1 according to the present embodiment will be described.

FIG. 1 shows a block circuit of a voice detection device 1, 2 is a first microphone capable of detecting voice and noise, and 3 is a second microphone capable of detecting noise. As shown in FIG. 4, the microphones 2 and 3 are integrally provided in a single casing 9. In this case, each of the microphones 2 and 3 uses a directional microphone, and the sound receiving unit 2f in each of the microphones 2 and 3 is used.
And 3f are arranged in the opposite directions by 180 °. The microphones 2 and 3 may be separately provided. Reference numeral 10 denotes a same-sound signal component removing circuit that removes signal components of opposite phases (or in-phase) in the detection signals from the first microphone 2 and the second microphone 3.

Reference numeral 4 denotes an analog-to-digital conversion processing unit, which includes an analog-to-digital converter 4f for converting a detection signal from the first microphone 2 output from the same-tone signal component removing circuit 10 into a digital first signal Df, and a same-tone signal component. It comprises an analog-digital converter 4s for converting a detection signal from the second microphone 3 output from the removal circuit 10 into a digital second signal Ds.

Numeral 7 designates the digital first signal Df and the digital second signal Ds as a plurality of bands Za, Zb, Zc, respectively.
This is a digital filter section that divides the data into two. In the embodiment, as shown in FIG. 2, the divided bands Za, Zb, and Zc are set to a low band, a middle band, and a high band, respectively. Therefore, the digital filter unit 7 filters a pair of low-pass filters 12a and 13a having the same characteristic for filtering the low band, a pair of middle-pass filters 12b and 13b having the same characteristic for filtering the middle band, and filters the high band. It is composed of a pair of high-pass filters 12c and 13c having the same characteristics. In this case, it is desirable to use a digital FIR filter having a linear phase characteristic for each of the filters 12a... 13c, thereby preventing a phase shift in each band.

Reference numeral 5 denotes a noise canceling function unit, which comprises three noise canceling function units 5a, 5b, and 5c corresponding to each band, that is, a low band, a middle band, and a high band. The noise canceling function unit 5a for processing the low band includes an adaptive filter 11a for filtering the digital second signal Dsa obtained from the low band filter 13a, an output signal Dma of the adaptive filter 11a, and a low band filter on the digital first signal Df side. It is provided with a subtraction processing unit 14a that performs subtraction processing on the output signal Dfa from the output signal 12a. On the other hand, a noise canceling function unit 5 for processing the middle range and the high range
b and 5c are configured similarly to the noise canceling function unit 5a. Note that 11b and 11c denote adaptive filters, and 14b and 14c denote subtraction processing units. Each of the adaptive filters 11a, 11b, 11c is connected to a state signal generator 15.

Reference numeral 8 denotes an addition processing unit, which has a function of adding digital output signals Doa, Dob, and Doc output from the noise canceling function units 5a, 5b, and 5c.
6 is a digital output signal Do output from the addition processing unit 8
Is a digital-to-analog conversion processing unit (digital-to-analog converter) that converts the analog signal into an analog signal Ao.

Next, the operation of the voice detection device 1 according to the present embodiment will be described.

First, when no sound is generated, the filter coefficients of the adaptive filters 11a, 11b and 11c provided in the noise canceling function units 5a, 5b and 5c are set (changed).

That is, in this case, the voice including noise is detected by the first microphone 2 and the noise is detected by the second microphone 3. The detection signal (analog signal) from each of the microphones 2 and 3 is applied to the same-sound signal component removing circuit 10, and the opposite-phase (or in-phase) signal component in each detection signal, for example, a collision sound when an object or the like hits the casing 9. Are removed. And
The respective detection signals output from the same sound signal component removal circuit 10 are respectively applied to analog-digital converters 4f and 4s, and the detection signal from the first microphone 2 is converted into a digital first signal Df and the second microphone 3 Is converted into a digital second signal Ds.

On the other hand, the digital first signal Df and the digital second signal Ds are respectively filtered by the digital filter section 7 into three bands Za, Zb, Zc of a low band, a middle band, and a high band.
Is divided into That is, from the digital first signal Df and the digital second signal Ds applied to the low-pass filters 12a and 13a, the digital first signal D
fa and the digital second signal Dsa, respectively, and from the digital first signal Df and the digital second signal Ds applied to the mid-pass filters 12b and 13b, the digital first signal Dfb and the digital first Two digital signals Dsb are obtained, and further, from the digital first signal Df and the digital second signal Ds applied to the high-pass filters 12c and 13c, the digital first signal Dfc and the digital second signal Dsc including only the high-frequency component are obtained. Respectively.

The adaptive filter 1 provided in each of the noise canceling function units 5a, 5b, 5c is provided by the noise canceling function units 5a, 5b, 5c corresponding to each band.
The filter coefficients of 1a, 11b and 11c are respectively changed. That is, in the low-frequency noise canceling function unit 5a,
The digital second signal Dsa is applied to the adaptive filter 11.
a, and further subtracted by
a, a difference signal D obtained by subtracting the output signal Dma of the adaptive filter 11a from the digital first signal Dfa
ea is obtained, and the filter coefficient of the adaptive filter 11a is changed so that the difference signal Dea becomes zero. At this time, the adaptive filter 1
The state signal Sc for changing the filter coefficient is given from the state signal generator 15 to 1a. On the other hand, also in the noise cancellation function units 5b and 5c, the filter coefficients are changed similarly to the noise cancellation function unit 5a. 14b and 14c are subtraction processing units, Dmb and Dmc are output signals of the adaptive filters 11b and 11c, De
b and Dec indicate difference signals obtained from the subtraction processing unit 14b and the subtraction processing unit 14c.

On the other hand, at the time of actual voice detection, the state signal S 15 for fixing the filter coefficient is output from the state signal generator 15.
s is given to each of the adaptive filters 11a, 11b, 11c. In this case, the filter coefficient is fixed by the state signal Ss. Alternatively, the change width (step gain) of the filter coefficient may be made smaller by the state signal Ss than the change width by the state signal Sc.
Therefore, the method of changing the filter coefficient can be changed by the state signals Sc and Ss.

Then, by similarly picking up sound and noise from the microphones 2 and 3, each of the subtraction processing units 14a, 14b, 14c allows the digital first signal Dfa,
Dfb, Dfc to adaptive filter 11a, 11
b, 11c are subtracted from the output signals Dma, Dmb, Dmc, and the digital output signal Do from which noise has been cancelled.
a, Dob, and Doc are output. Then, the digital output signals Doa, Dob, and Doc are added by an addition processing unit 8 and output as a digital output signal Do. The digital output signal Do is converted into an analog signal Ao by a digital-analog conversion processing unit 7. , To obtain a target audio signal with noise cancelled.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment.
For example, a sound is a concept including all sounds to be detected. Further, although the embodiment exemplifies the case where the band is divided into three, the band may be divided into two or four or more. On the other hand, if necessary, a band-pass filter (digital FIR filter) is provided before the digital-analog conversion processing section.
May be inserted. In addition, it is possible to arbitrarily change the detailed configuration, method, and the like without departing from the gist of the present invention.

[0025]

As described above, the voice detection device according to the present invention comprises a voice signal component elimination circuit for removing in-phase or anti-phase signal components in each detection signal from the first and second microphones, A digital filter section for dividing the digital first signal containing noise and the digital second signal containing noise into a plurality of bands, respectively, filtering the digital second signal with an adaptive filter, and outputting an output signal of the adaptive filter from the digital first signal A digital output signal in which the noise is canceled by subtracting the noise, a plurality of noise canceling function units corresponding to each band, and an addition processing unit for adding the digital output signal of each noise canceling function unit, so that the dynamic range Noise, even if it contains wide noise Min to remove a marked effect of being able to detect the sound of high quality.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a voice detection device according to the present invention,

FIG. 2 is a frequency-amplitude transfer function characteristic diagram of a voice detection circuit system in the voice detection device.

FIG. 3 is a characteristic diagram of a frequency versus phase transfer function of a voice detection circuit system in the voice detection device.

FIG. 4 is a layout diagram of microphones in the voice detection device.

FIG. 5 is a block circuit diagram of a voice detection device according to the related art;

[Explanation of symbols]

 Reference Signs List 1 voice detection device 2 first microphone 3 second microphone 4 analog-digital conversion processing unit 5 noise cancellation function unit 5a noise cancellation function unit 5b noise cancellation function unit 5c noise cancellation function unit 7 digital filter unit 8 addition processing unit 9 casing 10 Same sound signal component removal circuit Df Digital first signal Ds Digital second signal Do Digital output signal Za band (low band) Zb band (middle band) Zc band (high band) Doa digital output signal Dob digital output signal Doc digital output signal

Claims (2)

(57) [Claims] 1. A first microphone capable of detecting voice and noise, a second microphone capable of detecting noise, and an analog-digital converter for converting a detection signal from each microphone into a digital first signal and a digital second signal, respectively. A voice detection device comprising: a conversion processing unit; and a noise cancellation function unit that filters a digital second signal by an adaptive filter, and outputs a digital output signal in which noise is canceled by subtracting an output signal of the adaptive filter from the digital first signal. A homophonic signal component elimination circuit that eliminates in-phase or anti-phase signal components in each detection signal from the first microphone and the second microphone; and a digital device that divides each of the digital first signal and the digital second signal into a plurality of bands. A filter section, A voice detection device comprising: a plurality of noise canceling function units corresponding to respective bands; and an addition processing unit for adding digital output signals of the respective noise canceling function units. 2. The voice detection device according to claim 1, wherein the first microphone and the second microphone are provided integrally in a single casing.