| 摘要 |
Audio signals with opposite relative phases are recorded on two tracks. A dual track head reproduces the signals from the two tracks and introduces another phase reversal of one signal relative to the other. Noise which was not present in the record circuit, but enters the system at the playback head, is out of phase in the signals which the playback head applies to the playback circuit. Combining the out-of-phase noise components of the two signals substantially cancels the noise.
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