| 摘要 |
PROBLEM TO BE SOLVED: To provide a vibration damping structure for a cover member that can effectively damp a diaphragm vibration without an increase in weight. SOLUTION: A cover member 40 has a plate portion 41, and a mounting portion 42 formed along the peripheral edge of the plate portion 41. The plate portion 41 has a plurality of substantially parallel ribs 46 on the surface. The plate portion 41 formed with the plurality of ribs 46 has a recessed portion 44 reentrant to the back side in the longitudinal middle regions of the plurality of ribs 46. The height of the ribs 46 formed in the recessed portion 44 is set larger than that of the ribs 46 in the other regions.
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