| 摘要 |
PROBLEM TO BE SOLVED: To increase articulation by reducing sounds of babbles generated due to exhausted air together with respiratory sound for always confirming the respiratory sounds of a diving operator. SOLUTION: The overall frequency characteristics of a microphone and an amplifier having different frequency characteristics are set so as to be almost flat for a range from 200 to 3000 Hz. That is, this interphone is constituted of a microphone having frequency characteristics that frequencies lower than a peak frequency around 1500 Hz are attenuated by 6 dB or more per octave, and an amplifier with frequency characteristics that have a peak frequency between 300 and 600 Hz, and attenuate, for frequencies lower than the peak frequency, by 3 dB from the intensity at the peak frequency, the attenuation per octave is 12 dB or more.
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