acute ear; good ear
Refers to a person's ability to hear well or to be perceptive about sounds, music, or subtle auditory details. Often used in the phrase 聞く耳を持つ (to have a good ear).
He has a good ear, so he doesn't miss even faint sounds.
A musician needs an acute ear.
Compound of 聞く (to hear) and 耳 (ear). The phrase literally means 'hearing ear' and is used idiomatically to describe a person's auditory ability.