Amazon.com, Inc.
Adaptive howling suppressor

Abstract:

A system configured to perform adaptive feedback reduction, such as howling suppression, to prevent feedback from occurring when two devices are acoustically coupled during a communication session. To reduce feedback between the acoustically coupled devices, a device monitors input audio data from a microphone and determines whether feedback is present in individual frequency subbands. For example, the device determines an expected value for a first subband using neighboring subbands (e.g., averaging subbands surrounding the first subband) and compares the expected value to an actual value for the first subband. If the actual value is noticeably higher than the expected value, the device determines that feedback is present in the first subband and attenuates the first subband. If the feedback is not present, the device passes the first subband without attenuation.