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Appendix B Synthesizer Basics 480
The square wave can be reshaped to make the waveform cycles, or pulses, more rectangular,
by using a pulse width modulation (PWM) control. The more rectangular the wave becomes,
the more nasal it sounds. When modulated in this way, the square wave is known as a pulse
wave, and contains fewer harmonics. It can be used for reeds, basses, and brass sounds.
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Triangle wave: A triangle wave contains only odd harmonics, as well as the fundamental tone.
The triangle wave’s higher harmonics roll o faster than those of a square wave, making the
triangle wave sound softer. It is ideal for creating ute sounds, pads, and vocal “oohs.”
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Noise: white, pink and red, blue: Noise is useful for emulating percussive sounds, such as snare
drums, or wind and surf sounds. There are more noise wave colors than those listed, but they
are rarely found in synthesizers.
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White noise: The most common noise waveform found on synthesizers. White noise contains
all frequencies—at full level—around a center frequency.
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Pink and red noise: These noise colors also contain all frequencies, but they are not at full
level across the frequency spectrum. Pink noise decreases the level of higher frequencies by
3 dB per octave. Red noise decreases the level by 6 dB per octave.