Patent ID: 6985592

Claim:
An earphone apparatus for an audio device and a portable communication terminal device, comprising: a first plug for disconnectable connection with the audio device; a second plug for disconnectable connection with the portable communication terminal device; an electroacoustical transducer; first means connected to the second plug for detecting a level of an electric speech signal outputted from the portable communication terminal device; second means connected to the first plug, the second plug, the electroacoustical transducer, and the first means for automatically disconnecting the first plug from the electroacoustical transducer and automatically connecting the second plug to the electroacoustical transducer when the level detected by the first means is equal to or higher than a predetermined reference level; third means connected to the first plug, the second plug, the electroacoustical transducer, and the first means for automatically disconnecting the second plug from the electroacoustical transducer and automatically connecting the first plug to the electroacoustical transducer in cases where the level detected by the first means drops below the predetermined reference level and then remains lower than the predetermined reference level for a duration longer than a predetermined time length; and fourth means connected to the first plug, the second plug, the electroacoustical transducer, and the first means for holding the first plug disconnected from the electroacoustical transducer and holding the second plug connected to the electroacoustical transducer in cases where the level detected by the first means drops below the predetermined reference level and then remains lower than the predetermined reference level during the predetermined time length or shorter.