| 摘要 |
PROBLEM TO BE SOLVED: To provide a waterproof microphone whose tympanum does not contact an electrode or whose space between the tympanum and the electrode does not spread excessively when external pressure fluctuates, and with which a good sound collection over a large frequency band can be performed. SOLUTION: The front surface of a platy electrode 7 partitioning the inside of a case 1 into a front chamber 5 and a rear chamber 6 is covered by the tympanum 11 at a space 10 through an O ring 9. Restrictions 12, 13 which do not substantially transmit the dynamic pressure fluctuation of the front chamber 5 to the rear chamber 6, but substantially transmits the static pressure fluctuation of the front chamber 5 to the rear chamber 6, are provided in the dorsal wall 3 of the tympanum 11 and the case 1, respectively. The space and front chamber 5 among the front chamber 5, a second dorsal wall 17 and the dorsal wall 3 are communicated with a communicating hole 18 provided in a case wall, and the whole case is covered by a waterproof cover 19 consisting of an elastic material. An electronic circuitry 20 including a plurality of equalizers 21 for correcting sound collection characteristics and sensitivity by the difference of an acoustic wave transmission medium and for matching impedance with an external output side circuit is provided in the rear chamber 6.
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