labialize vs sound out

labialize and sound out both are verbs.

Word	Noun	Adjective	Verb	Adverb
labialize	No	No	Yes	No
sound out	No	No	Yes	No

As verbs, sound out is a hypernym of labialize; that is, sound out is a word with a broader meaning than labialize:

Other hypernyms of labialize include articulate, enounce, enunciate, pronounce, say.

labialize (verb)	sound out (verb)
pronounce with rounded lips	try to learn someone's opinions and intentions
	speak, pronounce, or utter in a certain way