| 摘要 |
PROBLEM TO BE SOLVED: To provide a noise reduction structure for easily reducing a noise generated from a vibrating element without suppressing the vibration velocity of the vibrating element as a sound source. SOLUTION: A sound deadening layer 3 for reducing sound pressure on a radiating surface 6 of the vibrating element 2 from which a sound wave propagates through air, is provided on the radiating surface 6 of the vibrating element 2. Since by reducing the sound pressure on the radiating surface 6, a radiation impedance can be reduced and acoustic radiation power of the vibrating element 2 can be reduced, and also the noise generated from the vibrating element can be reduced. Since the sound deadening layer 3 is formed on the radiating surface 6 without suppressing the vibration velocity of the vibrating element 2, the noise from the vibrating element 2 can be reduced without eliminating the vibration from the vibrating element 2. The sound deadening layer 3 can be easily formed without enlarging the noise reduction structure 1 relative to the vibrating element 2 after installing the vibrating element 2.
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