Patent ID: 6799062
Filing Date: 2004-09-28
Classification: H04M

Abstract:
A bi-directional hands-free communication device, comprising:a microphone for transmitting a signal along a transmit path; a speaker receiving a signal transmitted along a receive path and outputting a corresponding output signal; an echo canceller, positioned in the transmit path and the receive path, cancelling echo signals induced by the microphone from the speaker and outputting a corresponding cancelled signal along the transmit path; and a transparency circuit distributing additional loss to the transmit path and the receive path to reduce residual echo signals output from the echo canceller, the transparency circuit comprising a first voice activity detector and a second voice activity detector, the first voice activity detector detecting signals in the transmit path and the second voice activity detector detecting signals in the receive path, wherein the present distribution of the additional loss is dependent on both a previous and a current voice activity state of the transmit path and the receive path.