Source : Webster's Revised Unabridged Dictionary (1913)

Audibility \Au`di*bil"i*ty\, n.
   The quality of being audible; power of being heard; audible
   capacity.

Source : WordNet®

audibility
     n : quality or fact or degree of being audible or perceptible by
         the ear [syn: {audibleness}] [ant: {inaudibility}]