# US 10,771,895 B2 · Audio signal processing device

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- Number: US 10,771,895 B2
- Document ID: US10771895B2
- Status: Granted
- Kind: B2
- Application number: 16/484,258
- Filed: 2017-03-14
- Published: 2020-01-02
- Granted: 2020-09-08
- Earliest claimed: 2017-03-14
- Assignees: Mitsubishi Electric Corporation
- Applicants: Mitsubishi Electric Corporation
- Inventors: Kosuke Hosoya; Masaru Kimura
- Web page: https://patentgrep.com/patent/US10771895B2

## CPC

- H04R 3/007: {Protection circuits for transducers}
- H04R 3/02: for preventing acoustic reaction {, i.e. acoustic oscillatory feedback (specially adapted for hearing aids H04R25/453)}
- H04R 3/04: for correcting frequency response
- H04R 29/001: {for loudspeakers (H04R29/007 takes precedence)}
- 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)

## Abstract

An audio signal processing device includes a high pass filter to convert an input audio signal into a first audio signal and to output the first audio signal, a displacement estimation unit to estimate displacement amplitude of a speaker diaphragm when the input audio signal is inputted, a saturation processing unit to perform saturation processing to the displacement amplitude estimated in the displacement estimation unit or to a signal obtained by correcting the displacement amplitude, an audio signal generation unit to generate a second audio signal by using displacement amplitude obtained after the saturation processing in the saturation processing unit, and an output generation unit to generate an output signal by using the first and the second audio signals. With this configuration, a cracking sound of a speaker is reduced and a user is allowed to feel low frequency components.

## Claims

### Claim 1

An audio signal processing device comprising processing circuitry to:
perform high-pass filtering to convert an input audio signal into a first audio signal and to output the first audio signal,
estimate displacement amplitude of a speaker diaphragm when the input audio signal is inputted,
perform saturation processing on the displacement amplitude that is estimated or on a signal obtained by correcting the displacement amplitude,
generate a second audio signal by using displacement amplitude obtained after the saturation processing, and
synthesize the first audio signal and the second audio signal.

### Claim 2 (depends on 1)

The audio signal processing device according to claim 1, wherein the processing circuitry estimates the displacement amplitude of the speaker diaphragm by using a resonance frequency or volume information of the speaker that reproduces the input audio signal.

### Claim 3 (depends on 2)

The audio signal processing device according to claim 2, wherein the processing circuitry further performs functions to:
generate a signal obtained by adjusting the first audio signal,
control a frequency characteristic of harmonics generated by the saturation processing of the displacement amplitude, and
generate the second audio signal by using a signal obtained after controlling the frequency characteristic of the harmonics.

### Claim 4 (depends on 3)

The audio signal processing device according to claim 3, wherein a sum of gain in a frequency characteristic to be used in adjusting the first audio signal and gain in a frequency characteristic to be used in controlling the frequency characteristics of the harmonics in a frequency domain is constant throughout a frequency band where an input audio signal exists.

### Claim 5 (depends on 4)

The audio signal processing device according to claim 4, wherein the processing circuitry further performs functions to:
correct the displacement amplitude that is estimated, by using a Q factor of the speaker that reproduces the input audio signal, thereby generating a signal obtained by the correction of the displacement amplitude,
correct the signal obtained after controlling the frequency characteristic of the harmonics using an inverse of a frequency characteristic with respect to a frequency characteristic in correcting the displacement amplitude that is estimated, and
generate the second audio signal by using a signal obtained after the inverse correction.

### Claim 6 (depends on 3)

The audio signal processing device according to claim 3, wherein the processing circuitry further performs functions to:
correct the displacement amplitude that is estimated, by using a Q factor of the speaker that reproduces the input audio signal, thereby generating a signal obtained by the correction of the displacement amplitude,
correct the signal obtained after controlling the frequency characteristic of the harmonics using an inverse of a frequency characteristic with respect to a frequency characteristic in correcting the displacement amplitude that is estimated, and
generate the second audio signal by using a signal obtained after the inverse correction.

### Claim 7 (depends on 2)

The audio signal processing device according to claim 2, wherein the processing circuitry further performs functions to:
correct the displacement amplitude that is estimated, by using a Q factor of the speaker that reproduces the input audio signal, thereby generating a signal obtained by the correction of the displacement amplitude,
correct the signal obtained after controlling the frequency characteristic of the harmonics using an inverse of a frequency characteristic with respect to a frequency characteristic in correcting the displacement amplitude that is estimated, and
generate the second audio signal by using a signal obtained after the inverse correction.

### Claim 8 (depends on 1)

The audio signal processing device according to claim 1, wherein the processing circuitry further performs functions to:
generate a signal obtained by adjusting the first audio signal,
control a frequency characteristic of harmonics generated by the saturation processing of the displacement amplitude, and
generate the second audio signal by using a signal obtained after controlling the frequency characteristic of the harmonics.

### Claim 9 (depends on 8)

The audio signal processing device according to claim 8, wherein a sum of gain in a frequency characteristic to be used in adjusting the first audio signal and gain in a frequency characteristic to be used in controlling the frequency characteristics of the harmonics in a frequency domain is constant throughout a frequency band where an input audio signal exists.

### Claim 10 (depends on 9)

The audio signal processing device according to claim 9, wherein the processing circuitry further performs functions to:
correct the displacement amplitude that is estimated, by using a Q factor of the speaker that reproduces the input audio signal, thereby generating a signal obtained by the correction of the displacement amplitude,
correct the signal obtained after controlling the frequency characteristic of the harmonics using an inverse of a frequency characteristic with respect to a frequency characteristic in correcting the displacement amplitude that is estimated, and
generate the second audio signal by using a signal obtained after the inverse correction.

### Claim 11 (depends on 8)

The audio signal processing device according to claim 8, wherein the processing circuitry further performs functions to:
correct the displacement amplitude that is estimated, by using a Q factor of the speaker that reproduces the input audio signal, thereby generating a signal obtained by the correction of the displacement amplitude,
correct the signal obtained after controlling the frequency characteristic of the harmonics using an inverse of a frequency characteristic with respect to a frequency characteristic in correcting the displacement amplitude that is estimated, and
generate the second audio signal by using a signal obtained after the inverse correction.

### Claim 12 (depends on 1)

The audio signal processing device according to claim 1, wherein the processing circuitry further performs functions to:
correct the displacement amplitude that is estimated, by using a Q factor of the speaker that reproduces the input audio signal, thereby generating a signal obtained by the correction of the displacement amplitude,
correct the signal obtained after controlling the frequency characteristic of the harmonics using an inverse of a frequency characteristic with respect to a frequency characteristic in correcting the displacement amplitude that is estimated, and
generate the second audio signal by using a signal obtained after the inverse correction.