The Collaborative International Dictionary of English v.0.48:
Audibleness \Au"di*ble*ness\, n. The quality of being audible. [1913 Webster]WordNet (r) 3.0 (2006):
audibleness n 1: quality or fact or degree of being audible or perceptible by the ear [syn: audibility, audibleness] [ant: inaudibility, inaudibleness]