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Systems and methods for providing adaptive playback equalization in an audio device

  • US 10,382,864 B2
  • Filed: 12/10/2013
  • Issued: 08/13/2019
  • Est. Priority Date: 12/10/2013
  • Status: Active Grant
First Claim
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1. A personal audio device comprising:

  • a personal audio device housing;

    a transducer coupled to the housing for reproducing an output audio signal including an equalized source audio signal for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer;

    an error microphone coupled to the housing in proximity to the transducer for providing an error microphone signal indicative of the acoustic output of the transducer and the ambient audio sounds at the transducer;

    one or more processing circuits that implement;

    a noise cancellation system that generates the anti-noise signal to reduce the presence of the ambient audio sounds heard by the listener based at least on the error microphone signal;

    an adaptive playback equalization system that generates the equalized source audio signal from a source audio signal by adapting, based at least on the error microphone signal, a response of the adaptive playback equalization system to minimize a difference between the source audio signal and the error microphone signal, wherein the adaptive playback equalization system comprises;

    an adaptive equalization filter having a response that generates the equalized source audio signal from the source audio signal to reduce the effects of an electro-acoustical path of the source audio signal through the transducer;

    a coefficient control block that shapes the response of the adaptive equalization filter in conformity with the error microphone signal and the source audio signal by adapting the response of the adaptive equalization filter to minimize the difference between the error microphone signal and the source audio signal; and

    a secondary path estimate filter for modeling the electro-acoustical path and having a response that generates a secondary path estimate from the source audio signal and wherein the coefficient control block shapes the response of the adaptive equalization filter in conformity with the secondary path estimate and a delay corrected error, wherein the delay corrected error is based on a difference between the error microphone signal and a delayed source audio signal;

    a noise injection portion for injecting respective noise signals into the secondary path estimate and the delay corrected error in order to bias, to below a predetermined maximum, a magnitude of the response of the adaptive equalization filter corresponding to a frequency in which the response of the secondary path estimate filter is substantially zero.

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