| 摘要 |
PROBLEM TO BE SOLVED: To provide a voice output unit in which external noise being mixed through an earphone cord or a headphone cord can be removed effectively. SOLUTION: A noise detection line NL is provided along a voice signal line AL for feeding a voice signal outputted from the voice reproducing section 20 of a portable telephone terminal 100 to the earphone speaker 201 of an earphone 200. The noise detection line NL has an impedance equal to that of the voice signal line AL. A noise mixed into the noise detection line NL is subjected to phase inversal by a phase inverter 27 while keeping the amplitude, as it is, and added to a voice signal on the voice signal line AL by means of an adder 23. |
