audio
au·dio
I
 /ˈɑːdiˌoʊ/  adj  , always used before a noun
  : of or relating to the sound that is heard on a recording or broadcast
   The school has new audio equipment. [=equipment used for recording sound or listening to recorded sound]
   The audio portion of the broadcast was fine but the picture was poor.
   They listened to an audio recording of the speech.
————————
II
  noun   [  noncount  ]
  : the sound that is heard on a recording or broadcast
   The picture was clear but the audio was very poor.