We don't have synonyms for sound out yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are stand out, send out and round out.
(v) :
(transitive) To pronounce a word or phrase by articulating each of its letters or syllables slowly in sequence.
(v) :
(transitive) To question and listen attentively in order to discover a person's opinion, intent, or preference, especially by using indirect conversational remarks.
(v) :
(intransitive) To speak or sing loudly, to call out.
(v) :
(transitive) To pronounce a word or phrase by articulating each of its letters or syllables slowly in sequence.
(v) :
(transitive) To question and listen attentively in order to discover a person's opinion, intent, or preference, especially by using indirect conversational remarks.
(v) :
(intransitive) To speak or sing loudly, to call out.