learning by ear
memory of having heard something before
子供が聞き覚えで歌を弾いた。
The child played a song by ear.
彼はジャズを全て聞き覚えだけで習得した。
He mastered all of his jazz repertoire purely by ear.
祖母は楽譜なしで聞き覚えの民謡を演奏する。
My grandmother plays folk songs she learned by ear, without sheet music.