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

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.