inaudible
1. [ adjective ] impossible to hear; imperceptible by the ear
Synonyms: unhearable
Examples:

"an inaudible conversation"

Related terms: audible supersonic silent infrasonic unheard silent breathed quiet imperceptible audibility
Similar spelling:   inedible
  inaudibly
  indubitable
  indivisible
  indubitably
  inaudibility
  indifferent