# US 12,003,927 B2 · Method and system for monitoring and reporting speaker health

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- Number: US 12,003,927 B2
- Document ID: US12003927B2
- Status: Granted
- Kind: B2
- Application number: 17/633,102
- Filed: 2020-08-14
- Published: 2022-10-20
- Granted: 2024-06-04
- Earliest claimed: 2019-08-14
- Assignees: Dolby Laboratories Licensing Corporation
- Applicants: Dolby Laboratories Licensing Corporation
- Inventors: Luca Revelli; William Joseph Dymek
- Web page: https://patentgrep.com/patent/US12003927B2

## CPC

- H04R 29/001: {for loudspeakers (H04R29/007 takes precedence)}
- G10L 21/0232: Processing in the frequency domain
- H03G 3/3005: {in amplifiers suitable for low-frequencies, e.g. audio amplifiers (H03G3/32, H03G3/34 take precedence)}
- H04R 3/007: {Protection circuits for transducers}
- H04R 3/04: for correcting frequency response
- H04R 9/06: Loudspeakers
- H04R 29/003: {of the moving-coil type}
- H04S 3/008: {in which the audio signals are in digital form, i.e. employing more than two discrete digital channels (data reduction aspects thereof based on psychoacoustics G10L19/02)}
- H04S 7/301: {Automatic calibration of stereophonic sound system, e.g. with test microphone}
- H04S 2400/01: Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved
- H04S 2400/13: Aspects of volume control, not necessarily automatic, in stereophonic sound systems
- 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)
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
- H03G: CONTROL OF AMPLIFICATION
- H04S: STEREOPHONIC SYSTEMS

## Abstract

A method is provided, including: defining a plurality of frequency bins; sending, during a training phase, a test signal at different amplitude levels to one or more speakers, and gathering resulting test voltage (V) and current (I) points for the different amplitude levels and for each frequency bin; for each frequency bin, applying a linear regression algorithm to the gathered test voltage and current points for the different amplitudes to obtain a reference electrical impedance of said one or more speakers; sending, during a monitoring phase subsequent to said training phase, an audio signal to said one or more speakers, and gathering resulting new voltage and current points to obtain an operating electrical impedance for said one or more speakers for each frequency bin, determining a deviation between the operating and the reference electrical impedance, and, if the deviation exceeds a defined tolerance, reporting the deviation to a user.

## Claims

### Claim 1

A method comprising:
defining a plurality of frequency bins;
sending, during a training phase, a test signal at different amplitude levels to each speaker of a plurality of speakers, and gathering respective resulting test voltage (V) and current (I) points for the different amplitude levels and for each frequency bin;
for each frequency bin, applying a linear regression algorithm to the respective test voltage and current points for the different amplitudes to obtain a respective reference electrical impedance of each speaker;
sending, during a monitoring phase subsequent to said training phase, audio signals to the plurality of speakers, and gathering resulting new respective voltage and current points to obtain respective operating electrical impedances for the plurality of speakers for each frequency bin;
for each speaker of the plurality of speakers, determining a respective deviation between the respective operating electrical impedance and the respective reference electrical impedance to identify a speaker for which the respective deviation exceeds a defined tolerance; and
modifying one or more audio signals sent to one or more other speakers of the plurality of speakers to compensate for sound changes caused by the respective deviation of the identified speaker.

### Claim 2 (depends on 1)

The method of claim 1, wherein the plurality of frequency bins is arranged in ⅓ octave steps.

### Claim 3 (depends on 1)

The method of claim 1, wherein the different amplitude levels correspond to a range of −40 dB to 0 dB.

### Claim 4 (depends on 1)

The method of claim 1, wherein the test signal is a pink noise test signal.

### Claim 5 (depends on 1)

The method of claim 1, wherein the defined tolerance is amplitude or frequency dependent.

### Claim 6 (depends on 1)

The method of claim 1, wherein the linear regression algorithm is a minimum square error algorithm.

### Claim 7 (depends on 1)

The method of claim 1, further comprising re-rendering one or more of the audio signals based on the respective operating electrical impedance of the identified speaker.

### Claim 8 (depends on 1)

A non-transitory computer-readable medium storing instructions that, when executed by a computer, cause the computer to perform operations comprising the method of claim 1.

### Claim 9 (depends on 1)

The method of claim 1, wherein the modifying includes one or more of:
changing one or more audio characteristics of an audio signal;
changing equalization (EQ) of an audio signal;
changing a phase of an audio signal;
cutting power to one or more audio channels; and
boosting one or more audio channels.

### Claim 10 (depends on 1)

The method of claim 1, further comprising cutting or attenuating power to the identified speaker.

### Claim 11

An apparatus, comprising:
a calibration component configured to, during a training phase, provide a test signal at different amplitude levels to each speaker of a plurality of speakers, and to gather respective resulting test voltage (V) and current (I) points for the different amplitude levels for a plurality of frequency bins;
a test data processor configured to, for each frequency bin, apply a linear regression algorithm to the respective test voltage and current points for the different amplitude levels to obtain a respective reference electrical impedance of each speaker; and
a monitoring component configured to, during an operating phase subsequent to the training phase, send audio signals to the plurality of speakers and gather resulting new voltage and current points, to obtain respective operating electrical impedances for the plurality of speakers for each frequency bin, and further configured to determine a respective deviation between the respective operating electrical impedance and the respective reference electrical impedances to identify a speaker for which
the respective deviation exceeds a defined tolerance,
wherein the apparatus is configured to modify one or more audio signals sent to one or more other speakers of the plurality of speakers to compensate for sound changes caused by the respective deviation of the identified speaker.

### Claim 12 (depends on 11)

The apparatus of claim 11, wherein the plurality of frequency bins is arranged in ⅓ octave steps.

### Claim 13 (depends on 11)

The apparatus of claim 11, wherein the different amplitude levels correspond to a range of −40 dB to 0 dB.

### Claim 14 (depends on 11)

The apparatus of claim 11, wherein the test signal is a pink noise test signal.

### Claim 15 (depends on 11)

The apparatus of claim 11, wherein the defined tolerance is amplitude or frequency dependent.

### Claim 16 (depends on 11)

The apparatus of claim 11, wherein the linear regression algorithm is a minimum square error algorithm.

### Claim 17 (depends on 11)

The apparatus of claim 11, further comprising a renderer configured to re-render one or more of the audio signals based on the respective operating electrical impedance of the identified speaker.