also: イヤピース
noun
earpiece
General term for any small device worn in or on the ear, such as for hearing aids, communication devices, or earphones.
補聴器のイヤーピースを交換した。
I replaced the earpiece of my hearing aid.
noun
eartip; ear tip
Specifically the soft silicone or foam tip that goes into the ear canal on in-ear headphones or earphones.
イヤーピースのサイズが合わないと音漏れする。
If the eartip size doesn't fit, sound leaks out.