Patent ID: 8958571
Filing Date: 2015-02-17
Classification: G10K,G10L,H04M

Abstract:
1. A personal audio device, comprising: a personal audio device housing; a transducer mounted on the housing for reproducing an audio signal including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in the proximity of an acoustic output of the transducer; a plurality of microphones, including a first microphone mounted on the housing that, when unobstructed, provides a first microphone signal indicative of the ambient audio sounds, wherein a second microphone of the plurality of microphones is mounted on the housing and that, when unobstructed, provides a second microphone signal indicative of the ambient audio sounds; and a processing circuit that implements a first adaptive filter having a response that generates the anti-noise signal from the first microphone signal, a second adaptive filter for generating shaped source audio from the source audio and a combiner for removing the shaped source audio from the second microphone signal to generate an error signal provided to a coefficient control block that controls coefficients of the first adaptive filter, wherein the processing circuit implements a first signal level detector for detecting a first amplitude of the first microphone signal to generate a first microphone level signal and at second signal level detector for detecting a second amplitude of the second microphone signal to generate a second microphone level signal, and wherein the processing circuit further compares the first microphone level signal and a signal level of one of the plurality of microphones other than the first microphone and, in response to determining that a first differences between the first microphone level signal and the signal level of the one of the plurality of microphones other than the first microphone indicates that the first microphone is at least partially obstructed, halts adaptation of the first adaptive filter so that first coefficients of the first adaptive filter are maintained at their existing values to prevent the anti-noise signal from being generated erroneously, and wherein the processing circuit compares the second microphone level signal and a signal level of one of the plurality of microphones other than the second microphone, and in response to determining that a second difference between the second microphone level signal and the signal level of the one of the plurality of microphones other than the second microphone indicates that the second microphone is at least partially obstructed, halts adaptation of the first adaptive filter and the second adaptive filter and resets the first coefficients and the second coefficients to predetermined values.