Reflections of sound waves (6)
I believe the answer is:
echoes
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">reflections of sound waves</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 echoes that I've seen before include "Resounds, reverberates" , "repercussions" , "Repetitions of sounds" , "Sounds reverberating" , "parrots" .)