Chapter 2 Tutorial: Phase

Whenever two or more waveforms arrive at a single location out-of-phase, their relative signal levels will be added together to create a combined amplitude level at that one point in time. Whenever two waveforms (having the same frequency, shape and peak amplitude) are completely in-phase (meaning that they have no relative time difference), the newly-combined waveform will have the same frequency, phase and shape... but will be double in amplitude. If the same two waves are combined completely out-of-phase (having a phase difference of 180°), they will cancel each other out when added. This results in a straight line of zero amplitude. If the second wave is only partially out-of-phase (by a degree other than 180°), the levels will be added at points where the combined amplitudes are positive, and reduced in level where the combined result is negative.

Do It Yourself Tutorial: Phase
  1. Download the PhaseWavFiles.ZIP file which contains the 2 audio files for this tutorial.
  2. Load the 0° file onto track 1 of the digital audio workstation (DAW) of your choice, making sure to place the file at the beginning of the track, with the signal panned center.
  3. Load the same 0° file again into track 2
  4. Load the 180° file into track 3.
  5. Listen to tracks 1 & 2 (by muting track 3) and listen to the results. It should produce a summed signal that’s 3 dB louder.
  6. Listen to tracks 1 & 3 (by muting track 2) and listen to the results. It should cancel, producing no output.
  7. Offsetting track 3 (relative to track 1) should produce varying degrees of cancellation.
  8. Feel free to zoom in on the waveforms, mix them down and view the results... Cool, huh?