Echoing effect (6)
I believe the answer is:
reverb
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">echoing effect</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for reverb that I've seen before include "Musical effect produced via an amplifier" , "Device causing a musical echo" , "(Device for producing) an artificial musical acoustic" , "Device creating artificial acoustics" , "Echo in music" .)