Tending to reinforce sounds (8)
I believe the answer is:
resonant
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tending to reinforce sounds</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 resonant that I've seen before include "Continuing to sound clearly and deeply" , "Evoking memories" , "Deep, clear and continuing to sound or reverberate" , "(Of sound) deep and ringing" , "Booming" .)