Method and apparatus for reducing the effect of environmental noise on listeners

• US 9,135,907 B2
• Filed: 06/16/2011
• Issued: 09/15/2015
• Est. Priority Date: 06/17/2010
• Status: Active Grant

• Current Assignee: Guangdong OPPO Mobile Telecommunications Corporation Limited
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Fellers, Matthew C., Seefeldt, Alan J., Crockett, Brett G., Davidson, Grant A., Fielder, Louis D.
• Primary Examiner(s): HOLDER, REGINA NEAL
• Application Number:
  US13/703,844
• Publication Number:
  US 20130083939A1
• Time in Patent Office: 1,552 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G10K 11/002 Devices for damping, suppressing, obstructing or conducting sound in acoustic devices G10K1/06 - G10K1/10 take precedence; for electro-mechanical transducers for communication H04R3/002
• CPC Class Codes: G10K 11/17827 Desired external signals, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 11/17833 by using a self-diagnostic function or a malfunction prevention function, e.g. detecting abnormal output levels
• CPC Class Codes: G10K 11/17854 the filter being an adaptive filter
• CPC Class Codes: G10K 11/17873 using a reference signal without an error signal, e.g. pure feedforward
• CPC Class Codes: G10K 11/17875 using an error signal without a reference signal, e.g. pure feedback
• 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: G10L 21/0208 Noise filtering
• 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 2420/01 Input selection or mixing for amplifiers or loudspeakers for hearing aids H04R25/43
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

A method and apparatus for enhancing a desired audio signal for delivery through an electroacoustic channel include obtaining a noise estimate attributable to an external disturbance, applying the noise estimate to a dynamic noise compensation (DNC) process to thereby condition the desired audio signal as a function of the spectral characteristics of the noise estimate, applying the noise estimate to an adaptive equalization (AEQ) process to thereby condition the desired audio signal as a function of the electroacoustic response of the electroacoustic channel, and applying the noise estimate to an active noise cancellation (ANC) process configured to generate anti-noise for delivery into the electroacoustic channel.

Claims

1. A method for enhancing a desired audio signal for delivery through an electroacoustic channel, comprising:

obtaining a noise estimate attributable to an external disturbance;

applying the noise estimate and the desired audio signal to a dynamic noise compensation (DNC) process to thereby generate a DNC-conditioned desired audio signal as a function of the spectral characteristics of the noise estimate; and

applying the noise estimate and the DNC-conditioned desired audio signal to an adaptive equalization (AEQ) process to thereby generate the enhanced desired audio signal as a function of the electroacoustic response of the electroacoustic channel.

2. The method of claim 1, further comprising:

applying the noise estimate to an active noise cancellation (ANC) process configured to generate anti-noise for delivery into the electroacoustic channel.

3. The method of claim 1, wherein the noise estimate is generated by:

subtracting, from a sensed electroacoustic channel sound signal, a filtered and/or delayed output of the DNC process.

4. The method of claim 3, wherein the filtered and/or delayed output is filtered by a desired response filter having a non-flat frequency response.

5. The method of claim 4, further comprising applying an output of the DNC process to an adaptive equalization filter of the AEQ process.

6. A method for enhancing a desired audio signal for delivery through an electroacoustic channel using a driver, the method comprising:

obtaining a noise estimate based on an external disturbance;

applying the noise estimate and the desired audio signal to a dynamic noise compensation (DNC) process to generate a dynamic noise compensation (DNC)-conditioned desired signal by conditioning the desired audio signal as a function of the spectral characteristics of the noise estimate;

generating an anti-noise signal using the noise estimate;

combining the DNC-conditioned desired signal and the anti-noise signal to generate a composite signal; and

driving the driver using the composite signal.

7. The method of claim 6, wherein generating an anti-noise signal using the noise estimate constitutes an active noise cancellation process that is a feedback-based process in which the noise estimate is derived by subtracting, from a sensed electroacoustic channel sound level signal, an estimate of the composite signal.

8. The method of claim 6, wherein conditioning the desired audio signal as a function of the spectral characteristics of the noise estimate comprises applying frequency-band specific gain and/or attenuation control of selective portions of the audio signal.

9. The method of claim 6, further comprising applying adaptive equalization as a function of a plant model.

10. A method for enhancing a desired audio signal for delivery through an electroacoustic channel using a driver in the presence of a noise disturbance, the method comprising:

obtaining a first noise estimate based on the external disturbance;

obtaining a second noise estimate based on the external disturbance;

generating a dynamic noise compensation (DNC)-conditioned signal by conditioning the desired audio signal as a function of the spectral characteristics of the first noise estimate;

generating an anti-noise signal using the first and second noise estimates;

generating a composite signal from the DNC-conditioned signal and the anti-noise signal; and

driving the driver using the composite signal,

wherein the first noise estimate contains an anti-noise component but no DNC-conditioned component.

11. The method of claim 10, wherein one or both of the first and second noise estimates are derived in response to a plant model filter characterized at least in part by the electroacoustic channel.

12. The method of claim 10, wherein generating the anti-noise is conducted in a feed-forward based process in which the second noise estimate is derived from a dedicated transducer.

13. The method of claim 10, wherein generating anti-noise is conducted in a feed-back process in which the second noise estimate is derived by subtracting, from a sensed electroacoustic channel sound level signal, an estimate of the composite signal.

14. An audio enhancement system for enhancing a desired audio signal, comprising:

a dynamic noise compensation (DNC) module configured to receive a first noise estimate and the desired audio signal, and to generate a DNC-conditioned signal, the DNC module including a spectral shaping filter operable to apply spectral shaping to the desired audio signal based on spectral characteristics of the first noise estimate; and

an adaptive equalization (AEQ) module configured to receive the first noise estimate and the DNC-conditioned signal, and to generate an AEQ-conditioned signal, the AEQ module including an adaptive equalization control filter operable to receive the DNC-conditioned signal and apply thereto adaptive equalization as a function of the first noise estimate.

15. The system of claim 14, wherein the adaptive equalization filter is updatable using a first update signal that is a function of an electroacoustic response of an electroacoustic channel.

16. The system of claim 14, further including:

an active noise cancellation module configured to generate an anti-noise signal based on the first noise estimate; and

a combiner operable to combine the anti-noise signal with the AEQ-conditioned signal.

17. The system of claim 14, further comprising:

a cross correlator operable to selectively limit a level of the first noise estimate based on a convergence operation of the adaptive equalization control filter; and

a desired response filter configured to receive the DNC-conditioned signal, the convergence operation being a convergence of the characteristics of the adaptive equalization control filter towards a ratio of the desired response filter to a model of the electroacoustic channel.

18. An audio enhancement system for enhancing a desired audio signal for delivery through an electroacoustic channel, comprising:

a dynamic noise compensation (DNC) module configured to generate a DNC-conditioned signal, the DNC module including a spectral shaping filter operable to apply spectral shaping to the desired audio signal based on spectral characteristics of a first noise estimate;

an active noise cancellation (ANC) module including a control filter having filter characteristics updatable by the first noise estimate and having a first input for receiving a second noise estimate and generating therefrom an anti-noise signal; and

a first combiner for combining the DNC-conditioned signal and the anti-noise signal to generate a composite signal.

19. The system of claim 18, further comprising a second combiner operable to subtract the DNC-conditioned signal from a sensed electroacoustic channel signal to thereby generate the first noise estimate.

20. The system of claim 19, further comprising a third combiner for subtracting the composite signal from the sensed electroacoustic channel signal to thereby generate the second noise estimate.