Sine waves phase-cancel when delayed and undelayed versions of the same waveform in Graph A are mixed together. The red traces show the delayed versions of each waveform in graphs A, B1, B2 and B3. Graphs C1, C2 and C3 show the result of combining the different sine-wave components: the waves in Graph B1 only slightly phase-cancel, producing a combined sine wave of nearly twice the level of each of the individual sine waves; the waves in Graph B2 phase-cancel more heavily, producing a combined sine wave of only the same level as each of the individual sine waves; and the waves in Graph B3 are 180 degrees out of phase with each other, so completely phase-cancel.
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