Audio noise cancelling

摘要

A noise canceling system comprises a microphone (103) for generating a captured signal representing sound in an audio environment and a sound transducer (101) for radiating a sound canceling audio signal in the audio environment. A feedback path (105, 107, 109, 111, 113) exists from the microphone (103) to the sound transducer (101) and comprises a feedback filter (109). A tone processor (119) determines a tone component characteristic for a tone component of a feedback signal of the feedback path (105, 107, 109, 111, 113) and an adaptation processor (121) adapts the feedback path in response to the tone component characteristic. The invention allows detection of the onset of instability and dynamic compensation to mitigate or prevent such instability. Accordingly increased design freedom for the feedback filter is achieved resulting in improved noise cancellation.

主权项

1. A noise canceling system comprising:
a microphone configured to capture an audio signal representing sound in an audio environment; a sound transducer configured to radiate a sound canceling audio signal in the audio environment; a first feedback path from the microphone to the sound transducer, the first feedback path comprising
a feedback filter having a loop filter configured to receive the captured audio signal anda variable gain circuit configured to generate a drive signal for the sound transducer from the filtered captured audio signal; and a second feedback path from the microphone to the sound transducer, the second feedback path comprising
a tone processor configured to determine a tone component characteristic for a tone component of the captured audio signal, andan adaptation circuit configured to adapt a gain of the variable gain circuit in response to the determined tone component characteristic.