Abstract: An earphone includes a cylindrical portion having an opening in one end and an audio output unit which outputs sound from one face. The audio output unit is fixed to the cylindrical portion such that another face is in contact with an end face of the one end of the cylindrical portion. The audio output unit and the cylindrical portion are insertable at least partially in the external auditory canal of a human being. The earphone further includes a thin-wall part provided in the cylindrical portion and a ring, made of a material of a greater specific gravity than the cylindrical portion, which is fixed to the inner surface. The ring is fixed in a position such that the ring overlaps in the axial direction of the cylindrical portion with respect to the thin-wall part.

Abstract: An ear piece to be detachably attached to a sound tube protruding from a housing of an earphone has a base portion with a through hole. The through hole has an inner wall with a first, a second, and a third portion continuously provided in order when viewed from the housing. The first portion protrudes inwardly and has a first distance from a protruding inner surface of the first portion to an axis line passing through the cross section of the base portion and the through hole. The second portion has a circumferential inner surface having a second distance longer than the first distance to the axis line. The third portion is formed continuously with the second portion, having a circumferential inner surface with a third distance longer than the second distance to the axis line.

Abstract: An earphone has a main body, a first tube portion that protrudes from the main body in a first direction, a speaker unit provided at a protruding top of the first tube portion, and a second tube portion that protrudes from the main body in a second direction that is different from the first direction. The second tube portion communicates with the first tube portion through the main body. The speaker unit is provided with a space at one side thereof. The space is formed in the first and second tube portions and extends from the protruding top of the first tube portion to a protruding top of the second tube portion through the main body.

Abstract: An ear piece to be detachably attached to a sound tube protruding from a housing of an earphone has a base portion with a through hole. The through hole has an inner wall with a first, a second, and a third portion continuously provided in order when viewed from the housing. The first portion protrudes inwardly and has a first distance from a protruding inner surface of the first portion to an axis line passing through the cross section of the base portion and the through hole. The second portion has a circumferential inner surface having a second distance longer than the first distance to the axis line. The third portion is formed continuously with the second portion, having a circumferential inner surface with a third distance longer than the second distance to the axis line.

Abstract: A headphone housing has a first and a second summit in cross section. A sound emitter protrudes from the housing in side section. In the cross section, the first summit protrudes as being away from a point of intersection of an axis line of the sound emitter, that is horizontal and vertical to the side and cross sections, respectively, and a first straight line going through a cord guide located in an outer edge of the cross section, in a first side with respect to the first line and in a second side far from the cord guide with respect to a second straight line going through the point and intersecting with the first line. The second summit protrudes as being away from the point in the second side and in a third side, the opposite of the first side with respect to the first line.

Abstract: An earphone includes a cylindrical portion having an opening in one end and an audio output unit which outputs sound from one face. The audio output unit is fixed to the cylindrical portion such that another face is in contact with an end face of the one end of the cylindrical portion. The audio output unit and the cylindrical portion are insertable at least partially in the external auditory canal of a human being. The earphone further includes a thin-wall part provided in the cylindrical portion and a ring, made of a material of a greater specific gravity than the cylindrical portion, which is fixed to the inner surface. The ring is fixed in a position such that the ring overlaps in the axial direction of the cylindrical portion with respect to the thin-wall part.

Abstract: A silicon wafer comprising a substrate of single crystal silicon, a silicon oxide film 1 to 8 .ANG. in thickness formed on one surface of said substrate, and a polysilicon layer formed on said silicon oxide film and possessing an excellent gettering ability, is prepared by oxidizing single crystal silicon, thereby forming a silicon oxide film 1 to 8 .ANG. in thickness on said surface, and exposing said silicon oxide film to a gaseous silane at an elevated temperature, thereby forming a polysilicon layer on said silicon oxide film.