biloquium means the ability to speak in two different voices, especially as a ventriloquist. Lexicurio rates it Sui generis — a strength score of 88 out of 100.
Why “biloquium” is a great word
BILOQUIUM — [Noun] The ability to speak in two distinct voices, a faculty of dual vocalization. Coined circa 1798–1800 by American novelist Charles Brockden Brown, from the Latin bi- ("two") + loquor ("to speak") + -ium (noun-forming suffix). Unlike "ventriloquism," which denotes the art of throwing a voice to create an illusion of distant source, or "polyglossia," which describes the social coexistence of many tongues, biloquium is the raw, intimate schism of a single throat. It is the performer's uncanny shift from a rasp to a warble, the child in a dark room answering her own fearful questions in a borrowed bass, the solitary horror of hearing an alien timbre emerge from your own lips—the self audibly divided, and thus never again whole.
noun
- The ability to speak in two different voices, especially as a ventriloquist.“"You are not apprized of the existence of a power which I possess. I know not by what name to call it. [* Biloquium, or ventrilocution. Sound is varied according to the variations of direction and distance. . . .] It enables me to mimic exactly the voice of another, and to modify the sound so that it shall appear to come from what quarter, and be uttered at what distance I please."”