Abstract: In a speakerphone system, the signal that is directed to a loudspeaker is filtered by a dynamically controllable highpass filter. The filter characteristics are adjusted on the basis of the power of the signal and the degree of recent microphone activity. The filtered signal is a far-talker signal, while the microphone activity is represented as a near-talker signal that includes an echo component as a consequence of loudspeaker-to-microphone coupling. The degree of microphone activity is determined by a subband analyzer. A noise floor estimator may be used to determine the degree to which the near-talker signal is comprised of background noise, so that the noise can be eliminated in the process of controlling the highpass filter.

Abstract: A full duplex speakerphone system and a method of detecting a valid near-end talker component within an outgoing signal utilize a near-talker estimator that produces a near-talker energy estimate using a spectrum analysis. The near-talker energy estimate is indicative of the amount of the valid near-end talker component within the outgoing signal. Depending on the near-talker energy estimate, the system may attenuate the outgoing signal and/or incoming signal and adjust the filter process executed by an adaptive filter of the system in order to provide a clear voice communication between connected parties. In the preferred embodiment, the near-talker estimator operates with at least one processing unit to sample the outgoing signal that has been filtered, or “cancelled,” of echo by an acoustic echo canceller of the system.

Abstract: An echo canceller system and a method of filtering an outgoing signal utilize a volume compensator that operates in tandem with a primary adaptive filter to cancel echo due to a change in echo response of the system within a broadcasting environment. In particular, the volume compensator is designed to quickly adapt to a change in echo response due to an increase or decrease in the broadcast volume of a loudspeaker of the system. The echo canceller system may be incorporated into a personal computer system for a full-duplex speakerphone application. The volume compensator includes a supplementary adaptive filter that operates in parallel with the primary adaptive filter to cancel echo. The primary adaptive filter operates on the outgoing signal to cancel echo that may have been introduced into the outgoing signal along with speech of a near-end caller.