Controlling Ambient Sound Volume

• US 20170150246A1
• Filed: 11/24/2015
• Published: 05/25/2017
• Est. Priority Date: 11/24/2015
• Status: Active Grant

• Current Assignee: Bose Corporation
• Original Assignee: Bose Corporation
• Inventors: Rule, John Allen, Gauger, JR., Daniel M.
• Granted Patent: US 9,949,017 B2
• Time in Patent Office: Days
• CPC Class Codes: G10K 11/17823 Reference signals, e.g. ambient acoustic environment
• CPC Class Codes: G10K 11/1783 handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions
• CPC Class Codes: G10K 11/17837 by retaining part of the ambient acoustic environment, e.g. speech or alarm signals that the user needs to hear
• CPC Class Codes: G10K 11/17853 of the filter
• CPC Class Codes: G10K 11/17854 the filter being an adaptive filter
• CPC Class Codes: G10K 11/17861 using additional means for damping sound, e.g. using sound absorbing panels
• CPC Class Codes: G10K 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone
• CPC Class Codes: G10K 11/17885 additionally using a desired external signal, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 2210/1081 Earphones, e.g. for telephones, ear protectors or headsets
• CPC Class Codes: G10K 2210/3026 Feedback
• CPC Class Codes: G10K 2210/3027 Feedforward
• CPC Class Codes: G10K 2210/3028 Filtering, e.g. Kalman filters or special analogue or digital filters
• CPC Class Codes: G10K 2210/511 Narrow band, e.g. implementations for single frequency cancellation
• CPC Class Codes: 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
• CPC Class Codes: H04R 2410/05 Noise reduction with a separate noise microphone
• CPC Class Codes: H04R 2430/01 Aspects of volume control, not necessarily automatic, in sound systems
• CPC Class Codes: H04R 2430/03 Synergistic effects of band splitting and sub-band processing
• CPC Class Codes: H04R 2460/01 Hearing devices using active noise cancellation
• CPC Class Codes: H04R 2460/05 Electronic compensation of the occlusion effect
• CPC Class Codes: H04R 29/001 for loudspeakers H04R29/007 takes precedence
• CPC Class Codes: H04R 3/002 : Damping circuit arrangements for transducers, e.g. motional feedback circuits
• CPC Class Codes: H04R 3/04 : for correcting frequency response

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

1. An apparatus comprising:

an earpiece having 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;

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,

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 5 dBA for a majority of changes between any two adjacent filter sets in the sequence.

2. 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.

3. 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.

4. 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.

5. 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.

6. The apparatus of claim 5, 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.

7. 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.

8. The apparatus of claim 1, further comprising a user interface, wherein the user interface provides a two-directional control that when activated in the first direction or the second direction selects the corresponding next or previous filter to the present filter in the sequence.

9. The apparatus of claim 8, wherein the user interface comprises a pair of buttons, one of the buttons selecting the next filter in the sequence and the other button selecting the previous filter in the sequence.

10. The apparatus of claim 8, wherein the user interface comprises a continuous control, moving the control in a first direction selecting higher filters in the sequence, and moving the control in the second direction selecting lower filters in the sequence.

11. An apparatus comprising:

an earpiece having 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;

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,

at least some of the feed-forward filters cause ambient sound to be added to the sound output by the speaker at a first frequency range, and ambient sound to be cancelled by the sound output by the speaker in a second frequency range different from the first frequency range.

12. The apparatus of claim 11, wherein the first frequency range corresponds to a range where the feedback filters provide a high level of noise reduction.

13. The apparatus of claim 11, wherein the first frequency range corresponds to a range where the earpiece provides a high level of passive noise reduction.

14. The apparatus of claim 11 wherein the total overall sound at the ear of a user is substantially constant in value, as measured on real heads, over at least at least 3 octaves of frequency, for at least a subset of the sets of filters.

15. The apparatus of claim 14, wherein the three octaves correspond to the voice-band.

16. The apparatus of claim 15, wherein the sequence of filters provide a total overall sound at the ear that preserves the voice-band while controlling levels outside of the voice-band.

17. The apparatus of claim 11, wherein a first subset of the sets of filters provide a total overall sound at the ear that preserves the voice-band while decreasing levels outside of the voice-band, and a second subset of the sets of filters provide a total overall sound at the ear that is spectrally flat but reduces total sound level over a wide frequency band.

18. The apparatus of claim 11, wherein at least two of the sets of filters further include feedback filters that each provide a different frequency-dependent amount of cancellation.

19. The apparatus of claim 11, further comprising an array of microphones external to the earpiece, and wherein at least two of the sets of filters further include microphone array filters that each provide a different frequency-dependent amount of audio from the microphone array to the speaker.

20. A method of operating an earpiece having 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, a memory storing an ordered sequence of sets of filters for use by the digital signal processor, and a user input providing two-directional input commands, the method comprising

in response to receiving a command from the user input,

loading a set of filters from the memory that 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,

the overall sound level at the ear when using the loaded set of filters, for a given ambient sound level, differs from the overall sound level at the ear when using the previously-loaded set of filters by no more than 5 dBA for a majority of changes between any two adjacent filter sets in the sequence.