chest voice vs chest tone

chest voice and chest tone both are nouns.

Word	Noun	Adjective	Verb	Adverb
chest voice	Yes	No	No	No
chest tone	Yes	No	No	No

As nouns, chest voice and chest tone are synonyms defined as:

chest voice and chest tone: the lower ranges of the voice in speaking or singing

Other synonyms of chest voice include chest register.

chest voice (noun)	chest tone (noun)
the lower ranges of the voice in speaking or singing	the lower ranges of the voice in speaking or singing