Systems and methods for performance and stability control for feedback adaptive noise cancellation

摘要

A method for cancelling ambient audio sounds in the proximity of a transducer may include receiving an error microphone signal indicative of the output of the transducer and ambient audio sounds at the transducer. The method may also include generating an anti-noise signal for countering the effects of ambient audio sounds at an acoustic output of the transducer, wherein generating the anti-noise signal comprises applying a feedback filter having a response that generates a feedback anti-noise signal based on the error microphone signal and applying a variable gain element in series with the feedback filter. The method may further include monitoring whether an ambient audio event is occurring that could cause the feedback filter to generate an undesirable component in the anti-noise signal and controlling the gain of the variable gain element to reduce the undesirable component.

主权项

1. An integrated circuit for implementing at least a portion of a personal audio device, comprising:
an output for providing an output signal to a transducer including both a source audio signal for playback to a listener and an anti-noise signal for countering an effect of ambient audio sounds at an acoustic output of the transducer; an error microphone input for receiving an error microphone signal indicative of the acoustic output of the transducer and the ambient audio sounds at the acoustic output of the transducer; a reference microphone input for receiving a reference microphone signal indicative of the ambient audio sounds; and a processing circuit that implements:
a secondary path estimate filter configured to model an electro-acoustic path of the source audio signal and have a response that generates a secondary path estimate from the source audio signal; anda secondary path estimate coefficient control block that shapes the response of the secondary path estimate filter in conformity with the source audio signal and a playback corrected error by adapting the response of the secondary path estimate filter to minimize the playback corrected error, wherein the playback corrected error is based on a difference between the error microphone signal and the secondary path estimate;a feedback path comprising:
a feedback filter having a response that generates at least a portion of the anti-noise signal based on the error microphone signal; anda variable gain element in series with the feedback filter; andan event detection and oversight control that detects that an ambient audio event is occurring that could cause the feedback filter to generate an undesirable component in the anti-noise signal and controls a gain of the variable gain element to reduce the undesirable component, wherein the ambient audio event comprises a change in a noise boost of the integrated circuit, further wherein the noise boost is based on a difference between a magnitude of the playback corrected error and a magnitude of the reference microphone signal.