Sound output device

A sound output device, comprising:

• a pair of housings that includes a first housing and a second housing, wherein the first housing includes:
• a sound introduction hook;
• a case body that includes:
• a first speaker configured to output sound;
• and
• a control board configured to control the first speaker,
• wherein the sound introduction hook includes an internal space, a first portion, and a second portion, and
• wherein the sound introduction hook further includes an inner circumferential side portion and an outer circumferential side portion, and a hardness of a material of the outer circumferential side portion is lower than a hardness of a material of the inner circumferential side portion, and
• the internal space of the sound introduction hook is a sound introduction space for introduction of the sound output from the first speaker;
• and
• a switch board, wherein the switch board includes a power supply switch and a plurality of volume control switches on an external surface of the switch board,
• the second housing includes a battery and a second speaker, and
• the second housing is different from the first housing;
• and
• an ear pad portion continuous to the first housing,
• wherein the first portion of the sound introduction hook includes an opening through which the sound is emitted toward an ear,
• the opening is in a direction orthogonal to a longitudinal direction of the first portion of the sound introduction hook,
• a thickness of the first portion is variable towards an end of the first portion,
• the end of the first portion is in contact with the second portion,
• the sound introduction hook is mounted on a root portion of an auricle from a helix side of the ear, and
• the ear pad portion is mounted on the root portion of the auricle from an earlobe side of the ear.