# US 10,320,964 B2 · Hands-free control apparatus

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- Number: US 10,320,964 B2
- Document ID: US10320964B2
- Status: Granted
- Kind: B2
- Application number: 15/759,122
- Filed: 2015-10-30
- Published: 2018-10-04
- Granted: 2019-06-11
- Earliest claimed: 2015-10-30
- Assignees: Mitsubishi Electric Corporation
- Applicants: Mitsubishi Electric Corporation
- Inventors: Hironori Kotera
- Web page: https://patentgrep.com/patent/US10320964B2

## CPC

- H04M 1/6075: {adapted for handsfree use in a vehicle (H04M1/6058 takes precedence; arrangements for holding telephones in a vehicle B60R11/0241)}
- G10L 21/0232: Processing in the frequency domain
- H04M 1/60: including speech amplifiers
- H04M 1/605: {involving control of the receiver volume to provide a dual operational mode at close or far distance from the user}
- H04R 1/406: {microphones}
- H04R 2499/13: Acoustic transducers and sound field adaptation in vehicles
- H04S 7/303: {Tracking of listener position or orientation}
- H04M: TELEPHONIC COMMUNICATION (circuits for controlling other apparatus via a telephone cable and not involving telephone switching apparatus G08)
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)
- H04S: STEREOPHONIC SYSTEMS

## Abstract

Characteristics of noise contained in input signals of a plurality of microphones are adjusted to be equal to each other at each frequency, and an input signal of a microphone identified to be a microphone through which a speaker has input uttered speech from among the microphones subjected to adjustment of the noise characteristics is switched to a signal to be transmitted to a person on another end of call.

## Claims

### Claim 1

A hands-free control apparatus comprising:
processing circuitry
to identify from among a plurality of microphones a microphone through which a speaker inputs uttered speech;
to adjust characteristics of noises, each contained in an input signal of one of the plurality of microphones, to be equal to each other at each frequency; and
to switch an input signal of the identified microphone among the input signals of the plurality of microphones whose noise characteristics are adjusted, to a signal to be transmitted to a person on another end of call.

### Claim 2 (depends on 1)

The hands-free control apparatus according to claim 1, wherein the processing circuitry is configured to identify the microphone through which the speaker inputs the uttered speech by comparing signal levels obtained by subtracting background noise levels from signal levels of the input signals of the plurality of microphones.

### Claim 3 (depends on 1)

The hands-free control apparatus according to claim 1, wherein the processing circuitry is configured to adjust the characteristics of the noises contained in the input signals at each preset frequency width in a frequency band to be adjusted.

### Claim 4 (depends on 3)

The hands-free control apparatus according to claim 3, wherein the frequency band to be adjusted is changeable.

### Claim 5 (depends on 3)

The hands-free control apparatus according to claim 3, wherein the frequency width is changeable.

### Claim 6 (depends on 5)

The hands-free control apparatus according to claim 5, wherein the processing circuitry is configured to narrow the frequency width in a frequency band in which an amount of change in noise level is larger than a predetermined threshold within the frequency band to be adjusted.

### Claim 7 (depends on 1)

The hands-free control apparatus according to claim 1, wherein when a signal level of an input signal of the identified microphone becomes equal to or less than a signal level of an input signal of another microphone, the processing circuitry is configured not to identify the other microphone as microphone through which the speaker inputs uttered speech until a retention time elapses.