Included are a loudspeaker unit for generating sound waves, a sound conduit tube connected to the loudspeaker unit, and an ear tip connected to the sound conduit tube and having a shape having at least one opening. The sound conduit tube has a shape having: a sound hole having a first opening through which the sound waves generated by the loudspeaker unit enter, and a second opening from which the sound waves are released and to which the ear tip is connected； and a vent hole formed independently of the sound hole, and having a third opening through which a portion of the sound waves released from the second opening enters and a fourth opening from which the portion of the sound waves is released. The second opening of the sound hole and the third opening of the vent hole are connected to an identical opening of the ear tip.
