Say out loud (5)
'say out loud' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for utter that I've seen before include "To say, articulate" , "(Of counterfeit money) put into circulation - say" , "Express audibly" , "Thoroughgoing" , "Express; complete" .)
(Other definitions for voice that I've seen before include "Articulate" , "tenor, say" , "Sound with which one speaks" , "Articulation, speech" , "Sound produced by humans" .)