| 摘要 |
A remotely installed transmitter capable of clearly picking up only the voice of a person who is talking despite being installed away from the speaker's mouth and without causing feedback despite increased sensitivity, and a hands-free two-way voice terminal device using such a transmitter. In the remotely installed transmitter, a bidirectional microphone is installed at a central position of two pipes, two sound pick-up chambers are formed on both the right side and the left side of the pipes, the two sound pick-up chambers are stuffed with a sound-absorbing material, the shapes and sizes of the sound pick-up chambers are determined so that minimum voice resonance frequencies of the two sound pick-up chambers when they are not stuffed with the sound-absorbing material are both higher than the used upper-limit frequency of voice of the transmitter, and the amount of the sound-absorbing material is adjusted so that the voice frequency characteristics acquire monotonous attenuation characteristics in a voice frequency band higher than the used upper-limit frequency of voice.
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