In-ear headphones offer great sound in a small and convenient package
In ear headphones (also called in-ear monitors, IEM, earphones, ear
canal headphones, and canalphones) are small earphones that fit into and
'seal' the ear canal, much like standard earplugs.
In ear headphones are also commonly used by pro performers to monitor
sound mixes; this prevents possible feedback from stage monitors and
isolates the artist from audience noise.