To mishear (transitively) — to hear something incorrectly or mistake what someone said.
彼の名前を聞き違えて、別の名簿に登録してしまった。
I misheard his name and registered it on the wrong list.
電話で言われた数字を聞き違えてしまった。
I misheard the number that was told to me on the phone.
先生の指示を聞き違えて、課題を間違えた。
I misheard the teacher's instructions and did the assignment wrong.