The Collaborative International Dictionary of English v.0.48:
Audibility \Au`di*bil"i*ty\, n. The quality of being audible; power of being heard; audible capacity. [1913 Webster]WordNet (r) 3.0 (2006):
audibility n 1: quality or fact or degree of being audible or perceptible by the ear [syn: audibility, audibleness] [ant: inaudibility, inaudibleness]