From: fmmck@aol.com   
      
   In article ,   
    Salmon Egg  wrote:   
      
   > Why does placing a finger over a microphone improve the   
   > intelligibility?   
      
   Salmon-   
      
   I don't know about hearing aids, but it works for telephones in a noisy   
   environment.  Placing fingers over the mouthpiece reduces background   
   sounds that are fed back to the earpiece as "sidetone".  (Sidetone is   
   the percentage of your voice that goes back to the earpiece to let you   
   know the phone is working.)   
      
   Fred   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)