Sound wave theory 06
Phase and harmonics
- Video
- Script
Welcome to this tutorial on phase relationships in complex sound waves.
So far we have only looked at the simplest vibration, a sine wave. But almost all sounds are far more complex, especially those produced in nature. Complex soundwaves are formed from multiple individual vibrations, or sine waves, arriving at different times and of different frequencies.
Each individual vibration in a complex wave is known as a harmonic.
Caption - What is phase?
Phase in complex soundwaves, refers to the relationship between these harmonic vibrations, and it is essential for an understanding of how harmonics combine to create a single overall complex wave.
Caption - In phase signals
When two identical harmonics meet they produce a wave that is the sum of their amplitudes, stronger and louder. This is true for air pressure sound-waves and electrical and digital sound-waves in an electronic audio system such as a studio.
Caption - Out of phase signals
If one of the harmonics is the mirror image of the other, or is delayed in time by half a wavelength, they are said to be out of phase and completely cancel each other out.
Caption - Expressing phase relationships
These phase relationships can be expressed more precisely in degrees. 2 in-phase signals are said to have a phase relationship of 0 degrees, whilst 2 completely out of phase signals have a phase relationship of 180 degrees.
Both these situations represent the extremes of phase relationships. Between these extremes it is possible to have situations where the two soundwaves are partially in and out of phase.
Caption - Thanks for watching
The script for this tutorial, with accompanying screenshots, can be found at projectstudiohandbook.com
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