# US 10,872,593 B2 · Ambient noise sense auto-correction audio system

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- Number: US 10,872,593 B2
- Document ID: US10872593B2
- Status: Granted
- Kind: B2
- Application number: 16/007,492
- Filed: 2018-06-13
- Published: 2018-12-13
- Granted: 2020-12-22
- Earliest claimed: 2017-06-13
- Assignees: Crestron Electronics, Inc.
- Applicants: Crestron Electronics, Inc.
- Inventors: Dennis Fink
- Web page: https://patentgrep.com/patent/US10872593B2

## CPC

- G10K 11/17823: {Reference signals, e.g. ambient acoustic environment}
- G10K 11/17853: {of the filter}
- G10K 11/17855: {for improving speed or power requirements}
- G10L 25/51: for comparison or discrimination
- H04R 3/04: for correcting frequency response
- H04R 29/001: {for loudspeakers (H04R29/007 takes precedence)}
- H04S 7/305: {Electronic adaptation of stereophonic audio signals to reverberation of the listening space (H04S7/301 takes precedence)}
- G10K 2210/108: Communication systems, e.g. where useful sound is kept and noise is cancelled
- G10K 2210/3011: Single acoustic input
- G10K 2210/3028: Filtering, e.g. Kalman filters or special analogue or digital filters
- H04R 2430/01: Aspects of volume control, not necessarily automatic, in sound systems
- H04R 2430/03: Synergistic effects of band splitting and sub-band processing
- H04S 7/307: {Frequency adjustment, e.g. tone control (H04S7/301 takes precedence)}
- G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- 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

An audio noise calibration circuit is provided comprising: a speaker, the speaker including a driver input; a switch having a first terminal, a second terminal, and an output, and wherein the switch is adapted to be responsive to a switching signal having at least a first switching state and a second switching state such that the first terminal of the switch is connected to the output of the switch when the switching signal is in the first switching state such that there is electrical connectivity between the first terminal and the output, and the second terminal of the switch is connected to the output of the switch when the switching signal is in the second switching state such that there is electrical connectivity between the second terminal and the output, and further wherein the output of the switch is connected to the driver input of the speaker; and an audio processing unit adapted to generate the switching signal such that when in the first switching state, an audio signal generated by the audio processing unit is transferred to the first terminal and then to the driver input of the speaker to be broadcast, generate the switching signal such that when in the second switching state, the driver input of the speaker is connected to a first portion of the audio processing unit such that the speaker operates as a microphone to acquire ambient noise sound, and an electrical output of the microphone that represents the ambient noise sound is processed by the first portion of the audio processing unit to generate a digitized ambient noise sound, and modify a next output audio signal based on the digitized ambient noise sound.

## Claims

### Claim 1

An audio noise calibration circuit, comprising:
a speaker, the speaker including a driver input;
a switch having a first terminal, a second terminal, and an output, and wherein
the switch is adapted to be responsive to a switching signal having at least a first switching state and a second switching state such that
the first terminal of the switch is connected to the output of the switch when the switching signal is in the first switching state such that there is electrical connectivity between the first terminal and the output, and
the second terminal of the switch is connected to the output of the switch when the switching signal is in the second switching state such that there is electrical connectivity between the second terminal and the output, and further wherein
the output of the switch is connected to the driver input of the speaker; and
an audio processing unit adapted to
generate the switching signal such that when in the first switching state, an audio signal generated by the audio processing unit is transferred to the first terminal and then to the driver input of the speaker to be broadcast,
generate the switching signal such that when in the second switching state, the driver input of the speaker is connected to a first portion of the audio processing unit such that the speaker operates as a microphone to acquire ambient noise sound, and an electrical output of the microphone that represents the ambient noise sound is processed by the first portion of the audio processing unit to generate a digitized ambient noise sound, and
modify a next output audio signal based on the digitized ambient noise sound, wherein
the audio processing unit is further adapted to modify the next audio signal based on a comparison between the next audio signal and the digitized ambient noise sound, and further wherein the audio processing unit is further adapted to modify the next audio signal by
generating a frequency analysis of the next audio output signal and the digitized ambient noise signal such that a first plurality of frequency bands is determined for the next audio output signal and a second plurality of frequency bands is determined for the digitized ambient noise signal,
determining which of the first plurality of frequency bands of the next audio signal substantially overlap the second plurality of frequency bands of the digitized ambient noise signal, and
generating a first plurality of gain factors to be applied to the next audio output signal for the substantially overlapping frequency bands.

### Claim 2 (depends on 1)

The audio noise calibration circuit according to claim 1, wherein
the audio processing unit is further adapted to substantially continuously generate an average of all digitized ambient noise sounds and use the substantially continuously generated average digitized ambient noise sound to modify the next output audio signal.

### Claim 3 (depends on 1)

The audio noise calibration circuit according to claim 1, wherein
the audio processing unit is further adapted to generate a root mean square (RMS) value of the digitized ambient noise sounds and use the RMS value of the digitized ambient noise sound to modify the next output audio signal.

### Claim 4 (depends on 3)

The audio noise calibration circuit according to claim 3, wherein
the audio processing unit is further adapted to substantially continuously generate RMS values previously digitized ambient noise sounds and use an average value of the RMS values of the previously generated digitized ambient noise sound to modify the next output audio signal.

### Claim 5 (depends on 1)

The audio noise calibration circuit according to claim 1, wherein
the audio processing unit is further adapted to modify the next audio output by increasing or decreasing an amplitude of the next audio output based on a magnitude of the digitized ambient noise sound.

### Claim 6

A method for calibrating an output of an audio system in view of ambient noise, the method comprising:
generating a switching signal to a switch to connect an input driver of a speaker to a digitizing circuit;
digitizing an output of the speaker that represents ambient noise acquired by the speaker acting as a microphone;
using an amplitude of the digitized ambient noise to change a next output audio signal to compensate for the digitized ambient noise;
generating a frequency analysis of the next audio output signal and the digitized ambient noise signal such that a first plurality of frequency bands is determined for the next audio output signal and a second plurality of frequency bands is determined for the digitized ambient noise signal;
determining which of the first plurality of frequency bands of the next audio signal substantially overlap the second plurality of frequency bands of the digitized ambient noise signal; and
generating a first plurality of gain factors to be applied to the next audio output signal for the substantially overlapping frequency bands.

### Claim 7 (depends on 6)

The method according to claim 6, wherein the step of using an amplitude of the digitized ambient noise comprises:
determining a first amplitude of the digitized ambient noise; and
increasing or decreasing an amplitude of the next audio output signal by an amount corresponding to the first amplitude.

### Claim 8 (depends on 7)

The method according to claim 7, wherein the step of determining a first amplitude comprises:
determining a root mean square (RMS) value of the digitized ambient noise.

### Claim 9 (depends on 8)

The method according to claim 8, wherein the step of determining an RMS value comprises:
averaging over time a plurality of RMS values on a substantially continuous basis.

### Claim 10 (depends on 8)

The method according to claim 8, wherein the step of determining an RMS value comprises:
averaging over a fixed, specific period of time a plurality of RMS values.

### Claim 11 (depends on 7)

The method according to claim 7, wherein the step of determining a first amplitude comprises:
averaging over time a plurality of digitized ambient noise values on a substantially continuous basis.

### Claim 12 (depends on 7)

The method according to claim 7, wherein the step of determining a first amplitude comprises:
averaging over a fixed, specific period of time a plurality of digitized ambient noise values.