otacousticon

Etymology
From combining form of +, neuter of.

Noun

 * 1)  An instrument to aid hearing, such as an ear trumpet or hearing aid.
 * , New York Review of Books, 2001, p.69:
 * Gyges' invisible ring, or some rare perspective glass, or otacousticon, which would so multiply species that a man might hear and see all at once […].