listener

Etymology

From listen + -er.

noun

1. Someone who listens, especially to a speech or a broadcast.
   […] she would set herself going, telling the most interminable stories, until the last listener was fast asleep[…] 1904, William Henry Hudson, “chapter 2”, in Green Mansions
   And then her words tumbled out in a passion of communication, as though she hurried before her listener could be taken away. 1937, John Steinbeck, Of Mice and Men
2. (computing, programming, chiefly Java) A function that runs in response to an event; an event handler.
3. (slang) A person's ear.
   Fancy Gazette, quoted in 1823, John Badcock, Slang, a Dictionary of the Turf, the Ring, the Chase, the Pit, of Bon-Ton, and the Varieties of Life Gas now planted his favourite hit under the left listener of his antagonist, which sent him to dorse.
4. (formal) A musical anthology.