XPost: sci.electronics.basics   
   From: trevor@home.net   
      
   "Don Pearce"  wrote in message   
   news:4ec7817b.5640231@news.eternal-september.org...   
   >>> 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.   
      
   In the real world cliffs are not usually one straight smooth edge of course.   
      
      
   >>> 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.   
      
   If you prefer to simplify things so much you at least need to point that   
   out.   
      
      
   >>>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.   
      
   Or simplify it to the point of being wrong. To paraphrase Einstein, things   
   should be as simple as possible, not simpler.   
      
   Trevor.   
      
   --- SoupGate-Win32 v1.05   
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