| 摘要 |
PROBLEM TO BE SOLVED: To simply confirm a phase state of a stereo audio signal at a location site or a relay site by providing a means that substantially short-circuits L, R monitor signal terminals of a stereo audio device and/or opens connection of ground terminals of the stereo audio device and a stereo headphone. SOLUTION: Monitor terminals L, R and a ground terminal G of a stereo audio device connect respectively to signal terminals L, R and a ground terminal G of a stereo headphone and a switch SW1 having a normally open contact is inserted between the signal terminals L, R. The switch SW1 is usually open to allow the user to hear a conventional stereo audio program. When the switch SW1 is closed, the user hears a sub signal (L+R). In this case, when audio signals at the signal terminals L, R are of the same phase the user hears the signal at the same level as that of a stereo signal, but when the audio signals at the terminals L, R are of opposite phase, the level of the sound placed in the middle of the frequency band is extremely decreased when the user hears a stereo signal. |
