Notes the sound of male voices (7)
I believe the answer is:
tenners
'notes' is the definition.
(ten pound notes)
'sound of male voices' is the wordplay.
'sound of' indicates a 'sounds like' (homophone) clue.
'male voices' becomes 'tenors' (I've seen this before).
'tenors' sounds like 'TENNERS'.
'the' is the link.
(Other definitions for tenners that I've seen before include "Monetary notes" , "PS10 notes" .)