Providing Ambient Naturalness in ANR Headphones

• US 20160351183A1
• Filed: 08/12/2016
• Published: 12/01/2016
• Est. Priority Date: 11/02/2012
• Status: Active Grant

• Current Assignee: Bose Corporation
• Original Assignee: Bose Corporation
• Inventors: Gauger, Daniel M. Jr., Harlow, Jason
• Granted Patent: US 11,477,557 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G10K 11/17821 characterised by the analysis of the input signals only
• 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 11/17881 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 2210/3036 Modes, e.g. vibrational or spatial modes
• CPC Class Codes: G10K 2210/3055 Transfer function of the acoustic system
• CPC Class Codes: G10K 2210/3056 Variable gain
• CPC Class Codes: H04R 1/1008 Earpieces of the supra-aural or circum-aural type
• 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 2460/01 Hearing devices using active noise cancellation
• CPC Class Codes: H04R 2460/05 Electronic compensation of the occlusion effect
• CPC Class Codes: H04R 3/002 Damping circuit arrangements for transducers, e.g. motional feedback circuits

Abstract

In an active noise reducing headphone, a signal processor applies filters and control gains of both the feed-forward and feedback active noise cancellation signal paths. The signal processor is configured to apply first feed-forward filters to the feed-forward signal path and apply first feedback filters to the feedback signal path during a first operating mode providing effective cancellation of ambient sound, and to apply second feed-forward filters to the feed-forward signal path during a second operating mode providing active hear-through of ambient sounds with ambient naturalness.

Claims

1. A computer-implemented method comprising:

receiving a first external audio signal from a microphone of a noise-reducing device;

generating a noise-cancellation signal for cancelling the first external audio signal;

causing a speaker of the noise-reducing device to generate audio corresponding to the noise-cancellation signal in an active noise reduction (ANR) mode;

receiving a second external audio signal from the microphone of the noise-reducing device;

determining that at least a first portion of the second external audio signal indicates that the noise-reducing device should transition from the ANR mode to a hear-through mode;

transitioning to the hear-through mode, the transitioning comprises facilitating presentation of at least a second portion of the second external audio signal at the noise-reducing device by modifying noise cancellation for at least the second portion of the second external audio signal.

2. The method of claim 1, wherein the second external audio signal comprises a voice or an alarm.

3. The method of claim 1, wherein the second external audio signal comprises a voice of a user of the noise-reducing device.

4. The method of claim 1, wherein the hear-through mode comprises at least one of:

passive monitoring, direct talk-through, and active hear-through.

5. The method of claim 1, wherein modifying noise cancellation for at least the second portion of the second external audio signal comprises:

modifying one or more filter coefficients for at least one of;

a feed-forward and feedback path of the noise-reducing device, wherein the modified filter coefficients result in less attenuation of sounds within the human speech band than of sounds outside of the human speech band.

6. The method of claim 5, wherein the modified filter coefficients cause a corresponding filter to have at least one right-half-plane zero in the vicinity of a transition between sounds within the human speech band and sounds outside of the human speech band.

7. The method of claim 3, wherein the noise-reducing device remains in the hear-through mode at least as long as the voice of the user of the noise-reducing device is detected and for a predetermined time period after the voice of the user of the noise-reducing device is last detected.

8. The method of claim 1, further comprising:

selecting the hear-through mode from a plurality of hear-through modes.

9. The method of claim 8, wherein selecting the hear-through mode from a plurality of hear-through modes comprises:

detecting a level of ambient noise; and

selecting the hear-through mode from the plurality of hear-through modes based on the level of ambient noise.

10. A noise-reducing device comprising:

an ear piece configured to couple to a wearer'"'"'s ear, the ear piece providing passive attenuation of ambient sound into the wearer'"'"'s ear;

a first microphone acoustically coupled to an external environment and electrically coupled to a first active noise cancellation signal path having a first filter with configurable coefficients;

an output transducer acoustically coupled to the wearer'"'"'s ear canal when the ear piece is coupled to the wearer'"'"'s ear and electrically coupled to the first active noise cancellation signal path; and

a signal processor configured to apply the coefficients of the first filter, wherein;

in an active noise reduction (ANR) mode, the first microphone is configured to receive a first external audio signal, the first active noise cancellation signal path is configured to generate a noise cancellation signal for cancelling the first external audio signal, and the output transducer is configured to generate audio corresponding to the noise cancellation signal;

the first microphone is configured to receive a second external audio signal; and

the signal processor is configured to;

determine that at least a first portion of the second external audio signal indicates that the noise-reducing device should transition from the ANR mode to a hear-through mode; and

transition the noise-reducing device to the hear-through mode, the transition comprises facilitating presentation of at least a second portion of the second external audio signal at the noise-reducing device by modifying noise cancellation for at least the second portion of the second external audio signal.

11. The noise-reducing device of claim 10, wherein the second external audio signal comprises a voice or an alarm.

12. The noise-reducing device of claim 10, wherein the second external audio signal comprises a voice of the wearer of the noise-reducing device.

13. The noise-reducing device of claim 10, wherein the hear-through mode comprises at least one of:

passive monitoring, direct talk-through, and active hear-through.

14. The noise-reducing device of claim 10, wherein modifying noise cancellation for at least the second portion of the second external audio signal comprises:

modifying one or more of the coefficients applied to the first filter, wherein the modified filter coefficients result in less attenuation of sounds within the human speech band than of sounds outside of the human speech band.

15. The noise-reducing device of claim 14, wherein the modified filter coefficients cause the first filter to have at least one right-half-plane zero in the vicinity of a transition between sounds within the human speech band and sounds outside of the human speech band.

16. The noise-reducing device of claim 12, wherein the signal processor causes the noise-reducing device to remain in the hear-through mode at least as long as the voice of the wearer of the noise-reducing device is detected and for a predetermined time period after the voice of the user of the noise-reducing device is last detected.

17. The noise-reducing device of claim 10, wherein the hear-through mode is selected from a plurality of hear-through modes.

18. The noise-reducing device of claim 17, wherein the hear-through mode is selected from the plurality of hear-through modes based on a level of ambient noise.

19. The noise-reducing device of claim 10, further comprising:

a second microphone acoustically coupled to the wearer'"'"'s ear canal when the ear piece is coupled to the wearer'"'"'s ear and electrically coupled to a second active noise cancellation signal path having a second filter with configurable coefficients, wherein

the output transducer is also electrically coupled to the second active noise cancellation signal path,

the signal processor is further configured to apply the coefficients of the second filter, and wherein modifying noise cancellation for at least the second portion of the second external audio signal comprises modifying the coefficients of the second filter.

20. The noise-reducing device of claim 10, further comprising a wireless connection to an audio source.

21. The noise-reducing device of claim 10, further comprising a visual indicator, the visual indicator configured to be in a first state that indicates the noise-reducing device is in the ANR mode, and a second state that indicates the noise-reducing device is in the hear-through mode.

22. An active noise reducing headphone comprising:

an audio input unit configured to receive an external audio signal;

a noise cancellation unit configured to perform noise cancellation using a first portion of the external audio signal in an active noise reducing (ANR) mode; and

a processor configured to;

determine that a second portion of the external audio signal indicates that the active noise reducing headphone should transition from the ANR mode to an active hear-through mode;

transition the active noise reducing headphone to the active hear-through mode, the transition comprising facilitating presentation of at least a third portion of the external audio signal at the active noise reducing headphone by modifying noise cancellation for at least the third portion of the external audio signal.

23. The active noise reducing headphone of claim 22, wherein the processor determines that the second portion of the external audio signal indicates that the active noise reducing headphone should transition from the ANR mode to the active hear-through mode based on a user input.

24. The active noise reducing headphone of claim 22, wherein the processor determines that the second portion of the external audio signal indicates that the active noise reducing headphone should transition from the ANR mode to the active hear-through mode based on detecting a voice of the wearer of the active noise reducing headphone.

25. The active noise reducing headphone of claim 22, wherein the processor determines that the second portion of the external audio signal indicates that the active noise reducing headphone should transition from the ANR mode to the active hear-through mode based on detecting a voice of someone other than the wearer of the active noise reducing headphone.

26. The active noise reducing headphone of claim 22, wherein modifying noise cancellation for at least the third portion of the external audio signal comprises:

modifying one or more coefficients applied to a filter in the noise cancellation unit, wherein the modified filter coefficients result in less attenuation of sounds within the human speech band than of sounds outside of the human speech band.

27. The active noise reducing headphone of claim 26, wherein the modified filter coefficients cause the filter to have at least one right-half-plane zero in the vicinity of a transition between sounds within the human speech band and sounds outside of the human speech band.

28. The active noise reducing headphone of claim 23, wherein the processor causes the active noise reducing headphone to remain in the active hear-through mode at least until an additional user input is received.

29. The active noise reducing headphone of claim 24, wherein the processor causes the active noise reducing headphone to remain in the active hear-through mode at least as long as the voice of the wearer of the active noise reducing headphone is detected and for a predetermined time period after the voice of the wearer of the noise-reducing device is last detected.