Of sound or hearing (5)
I believe the answer is:
audio
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">of sound</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">hearing</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ ></span>
(Other definitions for audio that I've seen before include "Reproduction of recorded sound" , "Prefix indicating hearing or sound" , "Prefix indicating sound or word" , "shown in reproduction" , "Prefix signifying sound or hearing" .)