| 摘要 |
<p>The device comprises: a circuit for gathering acoustic signals with a microphone (18); a circuit for restoring audio signals with an amplifier (30) and a loudspeaker (16); a circuit (20) for interfacing with a telephone network or a portable telephone; and a circuit for digital processing of the audio signals, comprising means for reducing the acoustic echo resulting from the interaction of the loudspeaker with the microphone. These means comprise: an echo cancellation stage (40), with a linear adaptive filter able to subtract from the signal picked up by the microphone a reference signal derived from the signal received at the output of the interfacing means; a stage (42) for removing the residual echo with gain control; and a stage (44) for selectively reducing the background noise present in the signal received at the output of the echo removal stage. A filtering a digitizing stage (54, 56) receives as input the signal applied by the amplifier (30) to the loudspeaker (16) and delivers as output a corresponding filtered and digitized signal, applied as reference signal to the echo cancellation stage (40).</p> |
