Determining an acoustic coupling between a far-end talker signal and a combined signal

摘要

An improved determination of an acoustic coupling between a loudspeaker and a microphone, which results in a better estimate of the acoustic coupling during double talk, is achieved in a device for determining an acoustic coupling between a far-end talker signal as produced by the loudspeaker and a combined signal as picked up by the microphone. The combined signal comprises an echo of the far-end talker signal and a near-end talker signal. The acoustic coupling is derived from a ratio of changes in an envelope of the combined signal to changes in the envelope of the far-end talker signal in a predetermined time interval. In this way, a systematic error during double talk is strongly reduced.

主权项

1. A device for determining an acoustic coupling between a far-end talker signal and a combined signal that comprises an echo of the far-end talker signal and a near-end talker signal, the device comprising:
inputs for receiving the far-end talker signal and the combined signal; and circuitry for deriving the acoustic coupling from a ratio of changes in an envelope of the combined signal to changes in an envelope of the far-end talker signal in a predetermined time interval, wherein the circuitry comprises an adaptive filter and a subtractor, the adaptive filter being configured to filter the changes in the envelope of the far-end talker signal, and the subtractor being configured to determine a residual signal by calculating a difference between an output signal of the adaptive filter and the changes in the envelope of the combined signal, wherein the adaptive filter is controlled by the residual signal to adjust coefficients of the adaptive filter in such a way that an energy of the residual signal is minimized, and wherein the residual signal is provided to the adaptive filter for adjusting the coefficients of the adaptive filter, and wherein the circuitry further comprises a first changes-in-envelope determining circuit for determining changes in the envelope of the far-end talker signal and a second changes-in-envelope determining circuit for determining changes in the envelope of the combined signal.