voice communication vs spoken language

voice communication and spoken language both are nouns.

Word	Noun	Adjective	Verb	Adverb
voice communication	Yes	No	No	No
spoken language	Yes	No	No	No

As nouns, voice communication and spoken language are synonyms defined as:

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

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

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