speech communication vs voice communication

speech communication and voice communication both are nouns.

Word	Noun	Adjective	Verb	Adverb
speech communication	Yes	No	No	No
voice communication	Yes	No	No	No

As nouns, speech communication and voice communication are synonyms defined as:

speech communication and voice communication: (language) communication by word of mouth

Other synonyms of speech communication include language, oral communication, speech, spoken communication, spoken language.

speech communication (noun)	voice communication (noun)
(language) communication by word of mouth	(language) communication by word of mouth