Speakerphone feedback attenuation

摘要

A method is disclosed for acoustic feedback attenuation at a telecommunications terminal. A speakerphone equipped with a loudspeaker and two microphones is featured. Signals from the two microphones are subjected to a calibration stage and then to a runtime stage. The purpose of the calibration stage is to match the microphones to each other by advantageously using both magnitude and phase equalization across the frequency spectrum of the microphones. During the runtime stage, the microphones monitor the ambient sounds received from sound sources, such as the speakerphone's users and the loudspeaker itself, during a conference call. The speakerphone applies the generated set of filter coefficients to the optimized microphone's signals. By combining the signal from the reference microphone with the filtered signal from the optimized microphone, the speakerphone is able to attenuate the sounds from the loudspeaker that would otherwise be transmitted back to other conference call participants.

主权项

1. A method comprising:
receiving an ambient sound at a first microphone and at a second microphone from at least one of i) a person and ii) a loudspeaker,
wherein the person and the loudspeaker are spatially distinct,wherein the first microphone and the second microphone operate as a differential array with respect to sounds received from the loudspeaker, andwherein the loudspeaker is located in the near-field of the first microphone and the second microphone, and the person is located in the far-field of the first microphone and the second microphone; and transmitting an electromagnetic signal that is based on:
i) the ambient sound as received by the first microphone,ii) the ambient sound as received by the second microphone, andiii) a filter whose set of recalculable filter coefficients is based on the frequency spectrum of a calibration sound that is transmitted from the loudspeaker, the calibration sound comprising a stationary wideband signal.