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On Sat, 19 Nov 2011 10:16:43 GMT, (Don Pearce) wrote:

On Sat, 19 Nov 2011 20:22:43 +1100, "Trevor" wrote:


"Don Pearce" wrote in message
...
On Fri, 18 Nov 2011 13:51:37 -0800 (PST), RichD
wrote:

What's the difference between reverb, echo, and feedback?

Echo is a single reflection of a sound - the kind you hear when you
shout "Hello" near a cliff.

Multiple reflections are also common in such instances.


No they are not. One cliff, one echo. No choice.

Two walls of said cliff; multiple echoes. If you're on the edge of the cliff
with no opposing wall there will be zero echo.

Feedback is a situation you only get when you have an amplifier and a
speaker. The sound arriving from the speaker is a little louder than
the one that originally hit the microphone, so that comes out of the
speaker a little louder still. This loop will build until the system
howls.

That would be *acoustic feedback* only, There are MANY other types of
course.

In the context of the question it would simply be confusing to discuss
- or even mention - other kinds.

You cure it by turning down the amplifier so the sound from the
speaker is always a little softer than the original when it hits the
microphone.

Or any other method that reduces the loop gain at the feedback frequency,
notch filtering being a common example.


Again, given the question, no need to complicate the answer.

But you found it necessary to bring up loop gain. Interesting. You wouldn't
be an audiophool, by chance?