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echo cancellation
(redirected from Acoustic Echo Cancelling)

   Also found in: Wikipedia 0.01 sec.
echo cancellation
The elimination of an echo in a two-way voice transmission. Echo is created in the telephone company's central office switch when two-wire lines from the customer are converted to four-wire lines for backbone trunks. The echo is exacerbated over longer distances and by certain kinds of network equipment. A delay of 30ms or more is noticeable, and 50ms is annoying. To eliminate it, the carriers put echo cancellers on their switch ports and in their long-distance trunks at 500 mile intervals.

Using sophisticated DSP circuits that isolate the echo and transmit a reverse frequency to cancel it, echo cancellation is also built into analog modems, speakerphones and quality sound cards. See echo suppression and noise cancellation.
echo cancellation - A process which removes unwanted echoes from the signal on a telephone line. Echoes are usually caused by impedance mismatches along an analogue line.


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The sale includes exclusive manufacturing rights and technology license for "large room" acoustic echo cancelling for video and teleconferencing applications.
 
 
 
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