MIC COVERING DETECTION IN PERSONAL AUDIO DEVICES

摘要

A personal audio device, such as a wireless telephone, includes noise canceling circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone may also be provided proximate the speaker to estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit uses the reference and/or error microphone, optionally along with a microphone provided for capturing near-end speech, to determine whether one of the reference or error microphones is obstructed by comparing their received signal content and takes action to avoid generation of erroneous anti-noise.

主权项

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 a given one of the first microphone signal or the second microphone signal to generate a microphone level signal and a second signal level detector for detecting a second amplitude of one of the plurality of microphones other than the given microphone to generate a reference level signal, wherein the processing circuit compares the microphone level signal and the reference level signal, in response to determining that differences between the microphone level signal and the reference level signal indicate that the first microphone is at least partially obstructed, halts or resets adaptation of a given one of at least one of the first adaptive filter or the second adaptive filter to prevent the anti-noise signal from being generated erroneously.