out-of-phase.... explain


A single tone can be represented as a simple waveform called a sine wave. It starts at zero, rises to a positive peak, falls back through zero, continues to a negative peak, and then comes back to zero again. That would be one cycle.

"Out of phase" means that you generate an accompanying tone that starts at zero and falls to a negative peak first, etc., etc.

The negative parts of the out-of-phase tone cancel the positive parts of the original tone, and the positive parts of the out-of-phase tone cancel the negative parts of the original tone.

This effect occurs if you hook up one of your stereo speakers backwards. You get a cancellation in the middle of the room, because when one speaker is pushing air towards you, the other speaker is pulling air away from you.


thanks .... did i hear somewhere that they were experimenting with this technology at airports for the jet noise?