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Table Of Contents
Other Waveform Properties
A sound wave, as discussed earlier, has a frequency. Other properties of sound waves
include amplitude, wavelength, period, and phase.
Amplitude
Wavelength
Amplitude: The amplitude of a waveform indicates the amount of air pressure change.
It can be measured as the maximum vertical distance from zero air pressure, or “silence”
(shown as a horizontal line at 0 dB in the illustration). Put another way, amplitude is
the distance between the horizontal axis and the top of the waveform peak, or the
bottom of the waveform trough.
Wavelength: The wavelength is the distance between repeating cycles of a waveform
of a given frequency. The higher the frequency, the shorter the wavelength.
Period: The (wave) period is the amount of time it takes to complete one full revolution
of a waveform cycle. The higher and faster the frequency, the shorter the wave period.
Phase: Phase compares the timing between waveforms and is measured in
degrees—from 0 to 360.
When two waveforms begin at the same time, they are said to be in phase or phase aligned.
When a waveform is slightly delayed in comparison to another waveform, the waveforms
are said to be out of phase.
Note: It is difficult to discern a constant phase difference over the entire wave period,
but if the phase of one of the waveforms changes over time, it will become audible. This
is what happens in common audio effects such as flanging and phase shifting.
350 Appendix Synthesizer Basics