MOD'ULATE, verb transitive [Latin modulor, from modus, limit, measure.] 1. To form sound to a certain key, or to a certain proportion. 2. To very or inflect sound in a natural, customary or musical manner. Thus the organs of speech modulate the voice in reading or speaking. Could any person so modulate her voice as to deceive so many.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI