Speaker damage prevention in adaptive noise-canceling 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. A processing circuit monitors a level of the anti-noise signal, determines that the anti-noise signal may cause damage to the transducer and adjusts the generation of the anti-noise signal such that damage to the transducer is prevented.

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 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 that provides an error microphone signal indicative of the acoustic output of the transducer; and a processing circuit within the housing for adaptively generating the anti-noise signal from the reference microphone signal such that the anti-noise signal causes substantial cancellation of the ambient audio sounds, and wherein the processing circuit further monitors a level of the anti-noise signal, determines that the anti-noise signal may cause damage to the transducer and adjusts the generation of the anti-noise signal such that damage to the transducer is prevented, and wherein the processing circuit implements an adaptive filter having a response that shapes the anti-noise signal to reduce the presence of the ambient audio sounds in the error microphone signal, and wherein the processing circuit, in response to determining that the anti-noise signal may cause damage to the transducer, freezes adaptation of the adaptive filter.