[Asterisk-Users] Why echo occurs

[Robert Hajime Lanning]

<quote who="Steve Underwood">
> Wrong. Look at any cellular phone or IP phone. They all have echo
> cancellers. If you switch these cancellers off the results are
> generally bad. What they need to remove is the acoustic spill
> from the earpiece to the mike. This can be a surprisingly strong
> signal.

While acoustic "spill" can be an issue, I do not believe it is
the primary source of 90% of the echo experienced.

I do not know of any IP phone that contains an echo canceler other
than speaker phones.

Find a situation where you think the echo is acoustic spill, then
try it with a hands free head set.

If you notice, the echo is a repeat once type of echo.  Not the
fading echo of a loop, that acoustic spill would cause.

All the echo that I have been talking about, you hear yourself once,
just delayed.

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       -MCP