Reported volume of gentle sounds (5)
I believe the answer is:
sighs
'gentle sounds' is the definition.
(I've seen this before)
'reported volume' is the wordplay.
'reported' shows a homophone (sound like).
'volume' becomes 'size' (I've seen this before).
'size' sounds like 'SIGHS'.
'of' is the link.
(Other definitions for sighs that I've seen before include "Sounds of weariness" , "Lamentations" , "Bridge of - - (Venice)" , "Moans" , "Exhales sadly" .)