| 摘要 |
PROBLEM TO BE SOLVED: To provide the hand-free telephone set of a voice switching system capable of easily judging the transmission/reception state without switching the transmission/reception state in the middle of a speech at the time of performing speech by the hand-free telephone set. SOLUTION: Whether or not the transmission voice of a speaker by hand-free inputted from a microphone 10 is higher than a prescribed voice level is detected in a peak detection circuit 12, and in the meantime, whether or not reception voice inputted through a telephone line is higher than the prescribed voice level is detected in the peak detection circuit 20. Based on both detection values, a half duplex control part 22 maintains the one of the transmission state and the reception state so as to continuously transmit the voice for which it is detected that it is higher than the prescribed voice level first. A green LED 24 is lighted in the transmission state and a red LED 26 is lighted in the reception state.
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