1. A part of an instrument (as a stethoscope or hearing aid) which is inserted into the outer opening of the ear; especially; earphone
2. One of the two

Mouthpiece and earpiece mounted on a single handle; SYN. French telephone.

Someone who listens attentively; SYN. listener, auditor.

One who listens; one who pays attention.

(Linguistics) An individual sound unit of speech without concern as to whether or not it is a phoneme of some language; SYN. speech sound, sound.
A speech sound considered as a physical event without regard to its place in the sound system of a language