| 摘要 |
A communication helmet having an enhanced noise reduction effect. The communication helmet incorporates a microphone disposed in the vicinity of the mouth of the speaker wearing the helmet. The microphone is an optical microphone comprising a diaphragm (31) vibrating with sound pressure, a case (40) containing the diaphragm (31) and having a first opening (38) and a second opening (39) open in symmetric positions and facing the diaphragm (31), a light source (32) for projecting a light beam to the diaphragm (31), and a photodetector (35) receiving part of the reflected light of the light beam projected to the diaphragm (31) and outputting a signal corresponding to the vibration of the diaphragm (31). The optical microphone is fixed to a fixing base (250) at a predetermined angle so that the incoming sound wave may uniformly enter the first opening (38) and the second opening (39). The fixing base (250) is attached to the helmet with a space so that the external sound wave may uniformly enter the first opening (38) and the second opening (39).
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