Patent ID: 9318090
Filing Date: 2016-04-19
CPC Classification: G10K

Claim Text:
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 an acoustic output of the transducer; a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds; an error microphone mounted on 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; and a processing circuit that generates the anti-noise signal from the reference microphone signal by adapting a first adaptive filter to reduce the presence of the ambient audio sounds heard by the listener in conformity with an error signal and the reference microphone signal, wherein the processing circuit implements a secondary path adaptive filter having a secondary path response that shapes the source audio and a combiner that removes the source audio from the error microphone signal to provide the error signal, wherein the processing circuit detects a frequency-dependent characteristic of the source audio that is independent of the ambient audio sounds using frequency selective filtering of the source audio and takes action to prevent improper generation of the anti-noise signal in response to detecting the characteristic of the source audio.