Sound reproduction (4)
'sound reproduction' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for audio that I've seen before include "Sound recording" , "Car" , "TV sound" , "Prefix relating to sound" , "Recording of acoustic signals" .)
This clue is a double definition.
'sound' is the first definition.
(I know that echo is a type of noise)
'reproduction' is the second definition.
(I've seen this before)
(Other definitions for echo that I've seen before include "Rebounding sound" , "Reverberation of sound" , "call back" , "Reflected sound" , "Ape" .)