| 摘要 |
PURPOSE: A receiver unit is provided to form a cavity structure for flattening a sound pressure characteristic of the receiver unit and reducing the size of a handset equipped with the receiver unit. CONSTITUTION: A sound characteristic of a receiver main body(1) is made flat by adding a cavity(22) on a back or a front, or the front and the back of the receiver main body. The cavity includes a Helmholtz resonant structure. The cavity comprises a leakage path(23) acoustically communicating with external space. The cavity is formed by an internal space of a cabinet(2) that houses the receiver main body. A through-hole(24) to which the leakage path is formed is provided for a cabinet wall. An internal space of a handset of a portable information terminal device is used as an external space. A mounting piece is provided for the cabinet. The cabinet is housed in an electrical insulator holder.
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