| 摘要 |
PROBLEM TO BE SOLVED: To suppress audible and continuous noise to be characteristically generated to the other side of communication by attaching a noise filter with an attenuation effect in carrier frequency to an earphone cord device to be utilized as an exterior device. SOLUTION: The earphone cord device 7 with microphone to be used as the exterior device via a connection plug 2 in an earphone cord connection terminal 9 with microphone of a PHS or a cellular telephone terminal 1 is electrically connected with a microphone 5. The device 7 is provided with an earphone 4, a cord 3, the connection plug 2 and the noise filter 6 attached in the vicinity or the inside of the connection plug 2. Cut off frequencies, for example, 100 Hz, 20 kHz, 10 MHz, 100 MHz are created for the cases that all are LC filters and attached as the noise filter 6. The noise is not heard in all cases when the similar confirmation is performed by attaching various noise filters 6 to the earphone cord device 7 with microphone.
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