Bird changes quality of sound (9)
I believe the answer is:
turnstone
'bird' is the definition.
(turnstone is a kind of bird)
'changes quality of sound' is the wordplay.
'changes' becomes 'turns' (turn is a kind of change).
'quality of sound' becomes 'tone' (I've seen this before).
'turns'+'tone'='TURNSTONE'
(Other definitions for turnstone that I've seen before include "Relative of sandpiper, named for how it seeks food" , "Sort of sandpiper" , "Small short-billed sandpiper" , "Shore bird" , "Flier" .)