# US 10,484,781 B2 · Controlling ambient sound volume

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- Number: US 10,484,781 B2
- Document ID: US10484781B2
- Status: Granted
- Kind: B2
- Application number: 15/918,057
- Filed: 2018-03-12
- Published: 2018-07-19
- Granted: 2019-11-19
- Earliest claimed: 2015-11-24
- Applicants: Bose Corporation
- Inventors: John Allen Rule; Daniel M. Gauger, Jr.
- Web page: https://patentgrep.com/patent/US10484781B2

## CPC

- H04R 1/1083: {Reduction of ambient noise (active noise reduction per se G10K11/175; protective devices for the ear, e.g. providing acoustic protection A61F11/06)}
- G10K 11/17823: {Reference signals, e.g. ambient acoustic environment}
- G10K 11/1783: {handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions}
- G10K 11/17837: {by retaining part of the ambient acoustic environment, e.g. speech or alarm signals that the user needs to hear}
- G10K 11/17853: {of the filter}
- G10K 11/17854: {the filter being an adaptive filter}
- G10K 11/17861: {using additional means for damping sound, e.g. using sound absorbing panels}
- G10K 11/17881: {the reference signal being an acoustic signal, e.g. recorded with a microphone}
- G10K 11/17885: {additionally using a desired external signal, e.g. pass-through audio such as music or speech}
- H04R 3/04: for correcting frequency response
- H04R 29/001: {for loudspeakers (H04R29/007 takes precedence)}
- G10K 2210/1081: Earphones, e.g. for telephones, ear protectors or headsets
- G10K 2210/3026: Feedback
- G10K 2210/3027: Feedforward
- G10K 2210/3028: Filtering, e.g. Kalman filters or special analogue or digital filters
- G10K 2210/511: Narrow band, e.g. implementations for single frequency cancellation
- H04R 3/002: {Damping circuit arrangements for transducers, e.g. motional feedback circuits}
- H04R 2410/05: Noise reduction with a separate noise microphone
- 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
- H04R 2460/01: Hearing devices using active noise cancellation
- H04R 2460/05: Electronic compensation of the occlusion effect
- 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)
- 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

## Abstract

An earpiece includes a feed-forward microphone coupled to the environment outside the headphones, a feedback microphone coupled to an ear canal of a user when the earpiece is in use, a speaker coupled to the ear canal of the user when the earpiece is in use, a digital signal processor implementing feed-forward and feedback noise compensation filters between the respective microphones and the speaker, and a memory storing an ordered sequence of sets of filters for use by the digital signal processor. Each of the sets of filters includes a feed-forward filter that provides a different frequency-dependent amount of sound pass-through or cancellation, which in combination with residual ambient sound reaching the ear results in a total insertion gain at the ear of a user.

## Claims

### Claim 1

An apparatus comprising:
an earpiece having a feed-forward microphone coupled to the environment outside the earpiece, a speaker coupled to the ear canal of the user when the earpiece is in use, a digital signal processor implementing feed-forward noise compensation filters between the feed-foward microphone and the speaker, and a memory storing an ordered sequence of sets of filters for use by the digital signal processor; wherein
each of the sets of filters includes a feed-forward filter that provides a different frequency-dependent amount of sound pass-through or cancellation, which in combination with residual ambient sound reaching the ear results in a total insertion gain at the ear of a user,
at least a subset of the sets of filters further providing the same response over at least 3 octaves in the human voice band, and adding ambient sound at different levels outside of the human voice band when compared to the insertion gain achieved in a full active noise reduction (ANR) mode.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the change in overall sound level at the ear when switching between adjacent filters in the sequence is substantially constant over the whole sequence of filters.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein the change in overall sound level at the ear when switching between adjacent filters in the sequence is a substantially smooth function over the whole sequence of filters.

### Claim 4 (depends on 3)

The apparatus of claim 3, wherein the function progresses from a smaller amount of change between filters providing less total noise reduction to a larger amount of change between filters providing more total noise reduction.

### Claim 5 (depends on 1)

The apparatus of claim 1, wherein the overall sound level at the ear when using each of the sets of filters, for a given ambient sound level, differs from the overall sound level at the ear when using the adjacent set of filters in the sequence by an amount that is not perceptible to a typical human.

### Claim 6 (depends on 1)

The apparatus of claim 1, wherein the overall sound level at the ear when using each of the sets of filters, for a given ambient sound level, differs from the overall sound level at the ear when using the adjacent set of filters in the sequence by no more than 3 dBA for a majority of changes between any two adjacent filter sets in the sequence.

### Claim 7 (depends on 6)

The apparatus of claim 6, wherein the overall sound level at the ear when using each of the sets of filters, for a given ambient sound level, differs from the overall sound level at the ear when using the adjacent set of filters in the sequence by no more than 1 dBA for a majority of changes between any two adjacent filter sets in the sequence.

### Claim 8 (depends on 1)

The apparatus of claim 1, wherein the change in overall sound level at the ear when switching between adjacent filters in the sequence is a substantially smooth function over the whole sequence of filters.

### Claim 9 (depends on 8)

The apparatus of claim 8, wherein the function progresses from a smaller amount of change between filters providing less total noise reduction to a larger amount of change between filters providing more total noise reduction.