JPH04303900A - Sound detector - Google Patents

Abstract

PURPOSE:To surely detect a sound even under high noisy environment, to prevent malfunction from occurring, to dispense with level adjustment, etc., and to improve convenience of using and serviceableness. CONSTITUTION:This detector is equipped with a sound zone separating part 3 to obtain a signal component St of frequency band area relating to the sound from a detection signal Se that can be obtained by the detection of a microphone 2, a signal processing part 4 which converts the signal component St to, for example, a sound DC-forming signal Su, a noise zone separating part 5 to obtain a signal component Sm of frequency band area relating to the noise from the detection signal Se, a signal processing part 6 which converts the signal component Sm to, for example, a noise DC-forming signal Sn, and a comparison processing part 7 which outputs a sound detection signal Sp when the size of the sound DC-forming signal Su is larger than that of the noise DC-forming signal Sn.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice detection device suitable for use in the automatic recording function of a tape recorder and the automatic transmission function of a transceiver.

0002

[Prior Art] An automatic recording function is known, which detects the presence or absence of voice based on an audio signal obtained from a microphone, and automatically switches a tape recorder to recording mode when voice is detected. The recorder has a built-in voice detection device for automatic recording function.

A conventional voice detection device is shown in FIGS. 5 and 6. The voice detection device 50 shown in FIG. 5 functions as follows. The audio signal Sa obtained from the microphone 51 is input to the input amplifier 5.
2, and further converted into DC by a detection circuit 53. The obtained direct current signal Sd is sent to the comparator 54
is applied to one input part of the comparator 5.
A reference signal Ss is applied to the other input part of the comparator 54, and when the magnitude of the DC signal Sd becomes larger than the magnitude of the reference signal Ss, the comparator 54 outputs a high-level audio detection signal Sc. . Therefore, by applying the audio detection signal Sc to the switching transistor 55 and turning on the transistor 55, the tape recorder can be switched to the recording mode. Note that the reference signal Ss is provided from a reference voltage source 57 including a voltage regulator 56 that can vary the magnitude of the voltage.

[0004] Furthermore, the voice detection device 60 shown in FIG. 6 functions as follows. Audio signal S obtained from microphone 61
The signal a is amplified by an input amplifier 63 including a gain adjustment section 62, and further converted into DC by a detection circuit 64. Therefore, the output of the detection circuit 64 becomes the audio detection signal Sc, which turns on the switching circuit 65.

[0005]

[Problems to be Solved by the Invention] However, in both the conventional voice detection devices 50 and 60 described above, the microphone 5
By using the signal obtained from 1 and 61 as is,
In order to obtain the audio detection signal Sc, sounds other than audio, e.g.
There is a problem in that the sound detection signal Sc is output due to noise such as ambient noise and wind noise, making it easy to malfunction.

For this reason, the level of the reference signal Ss etc. is usually variably adjusted to cancel low-level noise, but this adjustment is troublesome and not easy because it needs to be done depending on the situation. Furthermore, it is completely ineffective against high-level noise and is insufficient to address the above problem.

[0007] The present invention solves the problems existing in the conventional technology, and detects sound reliably even in a high-level noise environment, prevents malfunctions, and eliminates the need for level adjustment. The purpose of this invention is to provide a voice detection device that can improve usability and convenience.

[0008]

[Means for Solving the Problems] The present invention provides a microphone 2
When configuring the voice detection device 1 that outputs the voice detection signal Sp based on the detection signal Se obtained by the detection of This signal component St is
For example, a signal processing unit 4 that converts into an audio DC signal Su;
A noise band separator 5 that obtains a signal component Sm in a frequency band related to noise from the detection signal Se, and this signal component Sm,
For example, the signal processing unit 6 converts the noise DC signal Sn, and the magnitude of the audio DC signal Su is determined by the noise DC signal Sn.
It is characterized by comprising a comparison processing section 7 that outputs a sound detection signal Sp when the magnitude is larger than the magnitude of the sound detection signal Sp. In this case, the audio band separator 3 divides the frequency band from 30Hz to 1.5Hz.
In addition to using a bandpass filter 3f set within the range of kHz, the noise band separator 5 divides the frequency band into 800kHz.
It is desirable to use a bandpass filter 5f set within the range of Hz to 3.5kHz.

[0009]

[Operation] According to the voice detection device 1 according to the present invention, the detection signal Se obtained by the detection of the microphone 2 is passed through the bandpass filter 3f whose frequency band is set within the range of 30Hz to 1.5kHz to the voice side. The signal component St
Separate. Also, the frequency band is set to 80 from the detection signal Se.
The noise side signal component Sm is separated through a bandpass filter 5f set within the range of 0Hz to 3.5kHz.

By the way, in general, as is clear from the spectral characteristics shown by the dotted line in FIG. 2, 80% of the spectrum of a voice is approximately within the range of 100 Hz to 800 Hz, which characterizes the nature of the voice. Further, as is clear from the spectrum characteristics shown by the two-dot chain line in FIG. 2, noise, for example white noise, spans a wide frequency band, and there is almost no level difference in the voice band range of 300 Hz to 3 kHz. Therefore, as shown in FIG. 3, even if the same level of voice and noise (S/N=0 dB) exist at the same time, the voice spectrum will certainly become large in the range of approximately 100 Hz to 800 Hz. Furthermore, even if there is noise at a higher level than the voice level, the entire spelttle characteristic in Figure 3 will simply shift by the amount of noise increase, so the spelttle of the voice will definitely increase as well. It is.

Therefore, by using the bandpass filters 3f and 5f having different frequency bands, the audio side signal component St within the range of 30Hz to 1.5kHz from the detection signal Se and the signal component St within the range of 800Hz to 3.5kHz can be separated from the detection signal Se. If the signal component Sm on the noise side is obtained and the level difference between the two is detected, the voice can be reliably detected.

On the other hand, the signal component St on the audio side is converted into the audio DC signal Su by the signal processing section 4, and the signal component Sm on the noise side is converted into the noise DC signal Sn by the signal processing section 6. Then, the magnitude of the audio DC signal Su and the noise DC signal Sn are compared by the comparison processing section 7, and when the audio DC signal Su becomes larger than the noise DC signal Sn, A sound detection signal Sp is output from the comparison processing section 7.

[0013]

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

First, the configuration of the voice detection device 1 will be explained with reference to FIG.

2 is a microphone, and input amplifier 11
Connect to the input side of the Further, the output side of the input amplifier 11 is connected to the input sides of bandpass filters 3f and 5f. The frequency band of the bandpass filter 3f is 100Hz to 1
kHz (generally within the range of 30Hz to 1.5kHz)
, the frequency band of the bandpass filter 5f is 1kHz to 3kHz.
kHz (generally within the range of 800Hz to 3.5kHz).

On the other hand, the signal processing section 4 on the audio side includes a detection circuit 12 at the front stage and an integration circuit 13 at the rear stage, and the output side of the bandpass filter 3f is connected to the input side of the detection circuit 12, and The output side is connected to one input section x of the comparison processing section (comparator) 7. On the other hand, the signal processing section 6 on the noise side includes a front-stage detection circuit 15 and a rear-stage integration circuit 16, and the output side of the bandpass filter 5f is connected to the input side of the detection circuit 15, and the integration circuit 1
The output side of 6 is connected to the other input section y in the comparison processing section 7 via the offset adjustment section 17. The offset adjustment section 17 is composed of an addition section 18 and an offset voltage supply section 19, and applies a constant offset voltage to the input section y of the comparison processing section 7 even when the microphone 2 is in a no-input state, thereby reducing the voltage caused by an unstable state. Prevent malfunction. Also, resistor R1
, R2, diode D, capacitor C, and switching transistor Q constitute an output circuit section 20.

Next, the operation of the voice detection device 1 according to the present invention will be explained.

First, when the microphone 2 is in a no-input state, a constant offset voltage is applied to the input section y of the comparison processing section 7, and the output section z of the comparison processing section 7 is at a low level, so that no sound is detected. The signal Sp is not output. For this reason,
The switching transistor Q of the output circuit section 20 is off.

On the other hand, it is assumed that the situation shifts from this state to the environment shown in FIG. 3 in which the voice and noise are at the same level. Thereby, the microphone 2 detects voice and noise simultaneously, and its output signal is amplified by the input amplifier 11. The detection signal Se obtained from the input amplifier 11 is applied to both band-pass filters 3f and 5f, and the band-pass filter 3f separates the signal component St of 100 Hz to 1 kHz, and the band-pass filter 5f separates the signal component St of 1 kHz to 1 kHz. A 3 kHz signal component Sm is separated.

Further, the signal component St is applied to the detection circuit 12 and detected, and is further converted into the audio DC signal Su by the integration circuit 13. On the other hand, the signal component S
The signal m is applied to the detection circuit 15 and detected, and is further converted into a noise DC signal Sn by the integration circuit 16. In this case, as described above, the magnitude of the audio DC signal Su is greater than the magnitude of the noise DC signal Sn.

Therefore, the input voltage of one input section x in the comparison processing section 7 becomes higher than the input voltage of the other input section y, and an inverted high-level audio detection signal is output from the output section z of the comparison processing section 7. Sp outputs. This turns on the switching transistor Q in the output circuit section 20 and activates necessary control.

FIG. 4 illustrates a transceiver with a built-in automatic transmission function that includes the voice detection device 1 according to the present invention. In this figure, the same parts as those in FIG. 1 are given the same reference numerals to clarify the structure.

The transceiver 30 includes a transmitting function section M1 and a receiving function section M2, and the transmitting function section M1 has a microphone 2,
The receiving function section M2 includes an input amplifier 11, a modulating section 31, and a transmitting section 32, and a receiving section M2 includes a receiving section 33 and a demodulating section 3.
4, an output amplifier 35, and a speaker 36. Further, 37 is an antenna, which is connected to the transmitter 32 and the receiver 33 via a changeover switch 38 using a relay switch, for example. Furthermore, a power line 39 is connected to the transmitting section 32 (or transmitting function section M1) and the receiving section 33 (or receiving function section M2) via a changeover switch 40 using a relay switch, for example.

On the other hand, 1 is a voice detection device, and a microphone 2 and an input amplifier 11 are also used as a transmission function section M1. The detection circuit 1s after the bandpass filters 3f and 5f is connected to the output side of the input amplifier 11, and the detection circuit 1s controls the changeover switches 38 and 40 via the output circuit section 20.

Therefore, unless the user utters a voice, the voice detection device 1 is in a non-detection state, so that the voice detection signal Sp
is not output, and the switching transistor Q in the output circuit section 20 is also turned off. As a result, for example, the relay coil connected to the same transistor Q becomes de-energized,
Changeover switches 38 and 40 constituted by relay switches
are respectively switched to the receiving circuit section M2 side, and the antenna 3
7 is connected to the receiving section 33, and the power line 39
is connected to the receiving section 33. This state is shown in FIG.

On the other hand, when the user utters a voice, the voice detection device 1 enters the detection state, outputs the voice detection signal Sp, and turns on the switching transistor Q in the output circuit section 20. As a result, the transistor Q
Since the relay coil connected to is excited, the changeover switches 38 and 40 are switched to the transmission circuit section M1 side, the antenna 37 is connected to the transmission section 32, and the power line 39 is connected to the transmission section 32. .

As described above, the voice detection device 1 according to the present invention
The transceiver 30 with a built-in device detects audio based on the user's utterances and automatically switches from a receiving state to a transmitting state. Moreover, this switching can be performed reliably even under a usage environment with a high noise level.

The embodiments have been described in detail above, but
The invention is not limited to such embodiments. For example, the audio band separation section and the noise band separation section may use functional components or functional circuits other than the bandpass filter (such as a combination of a lowpass filter and a highpass filter). Moreover, although the case where analog signal processing is performed by a signal processing unit that obtains a DC signal from a signal component is illustrated, it is of course possible to perform digital signal processing. In this case, a microcomputer etc. can be used, the signal processing section can be executed by an analog-to-digital conversion section, the comparison processing in the comparison processing section can be executed by software controlling the CPU, and the audio band separation section and the noise band separation section can be used. The section can be constructed using an analog-to-digital converter, a digital filter, and the like. Furthermore, the illustrated numerical values can be changed arbitrarily. Other details such as the circuit configuration can be arbitrarily changed without departing from the gist of the present invention.

[0029]

As described above, the voice detection device according to the present invention includes a voice band separation section that obtains signal components in a frequency band related to voice from a detection signal, and a voice band separation section that converts the signal components obtained from the voice band separation section into voice direct current. A signal processing unit that converts the signal into a signal, a noise band separation unit that obtains a signal component in a frequency band related to noise from the detection signal, and a signal processing unit that converts the signal component obtained from the noise band separation unit into a noise DC signal, for example. , includes a comparison processing unit that outputs a voice detection signal when the magnitude of the voice DC signal is larger than the noise DC signal, so voice can be reliably detected even in a high-level noise environment. This has the remarkable effect of preventing malfunctions, eliminating the need for troublesome level adjustments, and improving usability and convenience.

[Brief explanation of drawings]

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

[Figure 2] Individual spectral characteristics diagram of voice and noise with respect to frequency,

[Figure 3] Spectral characteristic diagram of adding voice and noise to frequency,

FIG. 4 is a block circuit diagram of a transceiver including the same voice detection device;

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

FIG. 6 is a block circuit diagram of another voice detection device according to the prior art;

[Explanation of symbols]

1 Voice detection device 2. Microphone 3 Audio band separation section 3f Bandpass filter 4 Signal processing section 5 Noise band separation section 5f band pass filter 6 Signal processing section 7 Comparison circuit section Se detection signal St Signal component Sm Signal component Su Audio DC signal Sn Noise DC signal Sp Audio detection signal

Claims (6)

[Claims] Claim 1: A voice detection device that outputs a voice detection signal based on a detection signal obtained by microphone detection, comprising: a voice band separation unit that obtains a signal component in a frequency band related to voice from the detection signal; A noise band separator that obtains signal components in the relevant frequency band compares the magnitude of the signal component obtained from the voice band separator with the magnitude of the signal component obtained from the noise band separator, and determines the magnitude of the signal component obtained from the voice band separator. A sound detection device comprising: a comparison processing section that outputs a sound detection signal when the magnitude of the signal component obtained from the noise band separation section is larger than the magnitude of the signal component obtained from the noise band separation section. 2. A voice detection device that outputs a voice detection signal based on a detection signal obtained by microphone detection, comprising: a voice band separation unit that obtains a signal component in a frequency band related to voice from the detection signal; A signal processing unit that converts the obtained signal component into an audio DC signal, a noise band separation unit that obtains a signal component in a frequency band related to noise from the detection signal, and converts the signal component obtained from the noise band separation unit into a noise DC signal. When the magnitude of the audio DC signal is larger than the noise DC signal,
A voice detection device comprising a comparison processing section that outputs a voice detection signal. 3. The voice detection device according to claim 1, wherein the voice band separation section uses a bandpass filter. [Claim 4] The frequency band of the bandpass filter is 3.
4. The voice detection device according to claim 3, wherein the frequency is set within a range of 0 Hz to 1.5 kHz. 5. The voice detection device according to claim 1, wherein the noise band separation section uses a bandpass filter. [Claim 6] The frequency band of the bandpass filter is 8.
6. The voice detection device according to claim 5, wherein the frequency is set within a range of 00Hz to 3.5kHz.