The in ear headphone includes a main body, an ear pad and a speaker. The main body includes a first wall and a second wall. The first wall defines a chamber, and the first and second walls collectively define a gap. One end of the gap and one end of the chamber are both directed toward an ear canal. The other end of the gap is directed toward surrounding air. The ear pad corresponds to one end of the gap and the chamber. The ear pad conformingly contacts the ear canal. The speaker is disposed in the chamber.
