| 摘要 |
PROBLEM TO BE SOLVED: To provide a telephone set in which the sound volume of a sidetone is easily adjusted by user operation to prevent the degradation of service quality caused by its echo. SOLUTION: A multifunctional telephone set 1 that has a reception-side passage 22 for transmission of a reception voice signal from a telephone line 20 and a transmission-side passage 23 for transmission of a transmission voice signal to the telephone line, is provided with a sidetone adjustment circuit 29 which extracts the transmission voice signal transmitted to the transmission-side passage as a sidetone signal and adjusts the sound volume of this extracted sidetone signal, a first adder 31 which adds this adjusted sidetone signal to the reception voice signal during transmission to the reception-side passage and transmits the resultant reception voice signal to the reception-side passage, a sound volume adjustment key 15 for adjustment of the sound volume of the sidetone signal, and a microcomputer 25 which controls the sidetone adjustment circuit in order to adjust the sound volume of the sidetone signal in accordance with the key operation of the sound volume adjustment key 15.
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