Vary the pitch (8)
I believe the answer is:
modulate
(Other definitions for modulate that I've seen before include "Adjust tone or pitch" , "Adjust, soften" , "adjust the volume" , "Attune" , "Change tone, pitch etc" .)
I believe the answer is:
modulate
(Other definitions for modulate that I've seen before include "Adjust tone or pitch" , "Adjust, soften" , "adjust the volume" , "Attune" , "Change tone, pitch etc" .)