Patent ID: 8265327

Claim:
An ear piece to be detachably attached to a sound tube portion that protrudes from a housing of an earphone, the ear piece comprising: a base portion having a through hole; and a filter unit including: a filter holder having a bottom portion with an opening and having a circumferential wall portion that rises from around the bottom portion; and a filter attached to the filter holder to cover the opening of the bottom portion, wherein the through hole of the base portion has an inner wall that is formed by a first engaging portion, a second engaging portion, and a third engaging portion that are continuously provided in order when viewed from the housing, wherein the first engaging portion protrudes inwardly and has a first distance from a protruding inner surface of the first engaging portion to an axis line that passes through a cross section of the base portion and the through hole, the first distance being the minimum distance from the protruding inner surface to the axis line when the protruding inner surface has no constant distance from the axis line; the second engaging portion has a circumferential inner surface having a second distance to the axis line, the second distance being longer than the first distance and being the minimum distance from the circumferential inner surface to the axis line when the circumferential inner surface has no constant distance from the axis line; and the third engaging portion is formed continuously with the second engaging portion and has a circumferential inner surface having a third distance to the axis line, the third distance being longer than the second distance and being the minimum distance from the circumferential inner surface of the third engaging portion to the axis line when the circumferential inner surface of the third engaging portion has no constant distance from the axis line, wherein the filter unit is installed in the through hole of the base portion so that the circumferential wall portion of the filter holder is fit in the third engaging portion of the through hole and the bottom portion of the filter holder is located in a specific position on the axis line and within a length of the third engaging portion.