Trouble    Cause   Solution 
Weak Sound    Battery malfunction   Replace battery   
     Battery incorrectly placed   Correct battery position
     VC set in wrong position   Tune VC to right position Ear mold/tip or sound tube blocked Clean ear mold or tube
         
 Odd Sound    Battery malfunction    Replace battery
     Ear tip or ear mold placed improperly    Re-orientate the tip or mold
         
 Too loud or Hissing        Turn the volume down
     Feedback or Whistle Ear tip or mold inserted improperly    Adjust the position of the tip
         
 Low battery       Replace battery
         
 If Your Pro Hear Whistles       Whistling/squealing may sometimes occur as you cup your hand over your ear and adjust the volume control. This action directs sound leaking from the ear plug into the microphone, resulting in a whistle. This should disappear when you take your hand away. If not, check to make sure the ear plug is inserted properly.