audible tones

Suddenly Firefox has begun to play bell tones for clicks with my mouse. I am unable to disable this new behavior. It is ONLY happening with Firefox. No other browsers behave in this manner. My PC sounds are shut off. I never want bell tones ever at any time. Please help me discontinue this behavior as soon as possible. As someone who works with professional audio recording this is especially undesirable and disturbing. Please. Somebody. Stop the madness. Thanks!!