mumble vs vocalization

mumble and vocalization both are nouns.

Word	Noun	Adjective	Verb	Adverb
mumble	Yes	No	Yes	No
vocalization	Yes	No	No	No

As nouns, vocalization is a hypernym of mumble; that is, vocalization is a word with a broader meaning than mumble:

Other hypernyms of mumble include utterance.

mumble (noun)	vocalization (noun)
a soft indistinct utterance	the sound made by the vibration of vocal folds modified by the resonance of the vocal tract
	the use of uttered sounds for auditory communication

mumble (verb)	vocalization (verb)
talk indistinctly; usually in a low voice
grind with the gums; chew without teeth and with great difficulty