Panasonic Intellectual Property Management Co., Ltd.

The Yokohama Rubber Co., Ltd.

Matsumoto Yushi-Seiyaku Co., Ltd.

Shigeki Ito

Kenichi Kitano

Takeshi Inohara

Takamasa Kitamura

An earphone includes a housing having a space therein and having a path capable of ventilation from one end side on an external auditory canal side of a wearer to the other end side on an ambient environment side, a valve accommodated in the housing and configured to switch the path between an open state and a close state, a microphone disposed on one end side of the housing and configured to collect uttered voice of the wearer, and a control unit configured to control the open state and the close state. The control unit switches the path to the open state during a first operation in a call including an operation in which the uttered voice of the wearer is collected by the microphone, and switches the path either the open state or the close state during a second operation different from the first operation.

Earphone and acoustic control method

A tread rubber is made of a rubber composition containing 100 pbw of a diene rubber, 30 to 100 pbw of a reinforcing filler including at least 10 pbw of silica, and 1 to 20 pbw of microcapsules each encapsulating a heat-expandable substance. A sulfur-containing silane coupling agent is mixed in the rubber composition in an amount of 3 to 15 wt. % based on the weight of the silica. A shell material of each microcapsule is made of a thermoplastic resin which essentially contains a nitrile monomer. A vapor pressure of the heat-expandable substance is 1.4 to 3.0 MPa at 150&#xb0; C. An average diameter of the microcapsules is 20 to 30 &#x3bc;m before vulcanization of the rubber composition. An average diameter of the microcapsules expanded due to the vulcanization is 40 to 80 &#x3bc;m. The tread rubber has a proportion of a cell-occupying area of 5 to 30%.

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Osaka, Japan

Shigeki Ito