Patent ID: 9646595
Date: 2017-05-09
CPC Classifications: G10K

Claim:
1. A method of canceling ambient audio sounds in the proximity of a transducer of a personal audio device, the method comprising: first measuring ambient audio sounds with a reference microphone to provide a reference microphone signal; second measuring an output of the transducer with an error microphone to provide an error microphone signal; adaptively generating an anti-noise signal from the reference microphone signal for countering the effects of ambient audio sounds at an acoustic output of the transducer by adapting a response of an adaptive filter that filters an output of the reference microphone; combining the anti-noise signal with a source audio signal to generate an audio signal provided to the transducer; shaping the source audio using a secondary path adaptive filter having a secondary path estimated response to generate shaped source audio; removing the shaped source audio from the error microphone signal to provide an error signal indicative of the combined anti-noise and ambient audio sounds delivered to the listener, wherein the adaptively generating adapts the response of the adaptive filter to minimize the error signal; determining a degree of coupling between the transducer and an ear of the listener from values of coefficients of the secondary path adaptive filter and detecting changes in the degree of coupling; altering the response of the adaptive filter in conformity with detecting the changes in the degree of coupling between the transducer and the ear of the listener; combining the anti-noise signal with a source audio signal; and providing a result of the combining to the transducer to generate the acoustic output.