JPH04216597A - Background noise eliminating circuit of voice recognition device - Google Patents

Abstract

PURPOSE:To eliminate the necessity for adjusting the frequency characteristics of a filter circuit and to remove unnecessary background noise without any adjustment even though noise environment is changed. CONSTITUTION:The device has a voice microphone 11 which converts voice into electrical signals and a noise microphone 21 which converts environmental noise into electrical signals. These signals are amplified by a voice amplifying circuit 12 and a noise amplifying circuit 22, respectively. The environmental noise component level entered to the voice microphone 11 and the environmental noise component level entered to the noise microphone 21 become the same level by adjusting the amplifications of the voice amplifying circuit 12 and the noise amplifying circuit 22 and these signals are supplied to a differential amplifying circuit 31 which outputs the difference between the two signals.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a background noise removal circuit for a speech recognition device.

0002

2. Description of the Related Art In general, a speech recognition device cannot perform accurate speech recognition if ambient noise (background noise) enters in addition to the target speech signal.

[0003] For this reason, the noise removal circuit of a conventional speech recognition device inputs an audio signal from a microphone to a filter circuit, removes unnecessary background noise components by adjusting the frequency characteristics of this filter circuit, and then , is input to the speech recognition circuit.

0004

[Problems to be Solved by the Invention] The background noise removal circuit of the conventional speech recognition device described above removes unnecessary background noise components by adjusting the frequency characteristics of the filter circuit. If the noise condition changes over time, the surrounding conditions will also change, so the frequency characteristics of the filter circuit must be adjusted again. The disadvantage is that it is difficult to adjust each time. .

An object of the present invention is to provide a background noise removal circuit for a speech recognition device that can remove unnecessary background noise components without using a filter circuit and making adjustments.

[0006]

[Means for Solving the Problems] A background noise removal circuit for a speech recognition device of the present invention includes a speech microphone for converting recognized speech into an electrical signal, and a speech microphone for converting ambient noise into an electrical signal. a noise microphone, an audio amplifier circuit that amplifies the output signal of the audio microphone, a noise amplifier circuit that amplifies the output signal of the noise microphone, the audio amplifier circuit, and the noise amplifier circuit. and a differential amplifier circuit that receives the output signals of and outputs the difference between these two signals, so that the output levels of the surrounding noise components outputted from the audio amplifier circuit and the noise amplifier circuit are the same. It has been configured and adjusted accordingly.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, which includes an audio microphone 11 and an audio amplification circuit 12 for amplifying the audio signal from the audio microphone 11.
, a noise microphone 21, a noise amplification circuit 22 that amplifies the noise signal from the noise microphone 21,
A differential amplifier circuit 31 is provided.

The audio microphone 11 is for converting the voice to be recognized into an electrical signal, and is a microphone having directional characteristics in the direction of the speaker. Further, the noise microphone 21 is for converting ambient noise into an electrical signal, and is a non-directional microphone placed a little further away than the installation position of the audio microphone 11. Therefore, the output signal from the audio microphone 11 includes the surrounding noise in addition to the target audio. Similarly, the output signal from the noise microphone 21 includes not only the surrounding noise but also the target sound.

Here, the amplification degrees of the audio amplification circuit 12 and the noise amplification circuit 22 are respectively adjusted to adjust the signal level of the ambient noise component from the audio microphone 11 and the ambient noise component from the noise microphone 21. Make sure that the signal level is the same. After adjusting in this way, if the two signals are input to the differential amplifier circuit 31 and a difference signal is output, the ambient noise component included in the audio microphone 11 will be changed from the ambient noise component from the noise microphone 21. This cancels out the background noise.

[0011]

Effects of the Invention As explained above, the background noise removal circuit of the speech recognition device of the present invention uses not only the audio microphone that converts recognized speech into electrical signals, but also the background noise removal circuit that converts ambient noise into electrical signals. A differential microphone is installed to amplify each signal, and the level of the ambient noise component input to the audio microphone is adjusted to be the same as the level of the ambient noise component input to the noise microphone. By supplying the signal to an amplifier circuit and outputting the difference between these two signals, unnecessary background noise can be removed without using a filter circuit. Therefore, even if the noise environment changes, there is no need to adjust the frequency characteristics of the filter circuit as in the conventional case, and unnecessary background noise can be removed without adjustment.

[Brief explanation of the drawing]

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

[Explanation of symbols]

11 Audio microphone 12 Audio amplification circuit 21 Noise microphone 22 Noise amplification circuit 31 Differential amplifier circuit

Claims (1)

[Claims] 1. An audio microphone for converting voice recognition into an electrical signal, a noise microphone for converting ambient noise into an electrical signal, and amplifying the output signal of the audio microphone. an audio amplification circuit; a noise amplification circuit that amplifies the output signal of the noise microphone; and a difference that receives the output signals of the audio amplification circuit and the noise amplification circuit, respectively, and outputs the difference between these two signals. a dynamic amplification circuit, and is adjusted so that output levels of surrounding noise components outputted from the audio amplification circuit and the noise amplification circuit are the same, respectively. Noise removal circuit.