| 摘要 |
PROBLEM TO BE SOLVED: To provide a sounder which is built into various kinds of mobile communication terminals, etc., is used for calling sound and makes it possible to obtain a calling sound of a high sound pressure level. SOLUTION: This sounder is constituted by forming the outer peripheral part of a diaphragm 2 of a material having a specific gravity smaller than the specific gravity of the central part, and with which a calling sound of a high sound pressure level can be obtained.
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