earpiece

noun

1. A speaker placed inside or held near to the ear.

   “Holonym: headpiece (sometimes holonymous)”

   “Holding the earpiece to my ear, I could hear him speaking clearly.”

2. A receiver of a telephone to hold near to one's ear.
3. The arm on a pair of glasses that hooks over the ear to hold them in place.

   “My glasses won't stay on, as I've broken the left earpiece.”