to both ears vs binaurally

to both ears and binaurally both are adverbs.

Word	Noun	Adjective	Verb	Adverb
to both ears	No	No	No	Yes
binaurally	No	No	No	Yes

As adverbs, to both ears and binaurally are synonyms defined as:

Other synonyms of to both ears include in both ears.

to both ears (adverb)	binaurally (adverb)
in a binaural manner	in a binaural manner