Electronic and Experimental Music: Pioneers in ... - Aaaaarg

16 ELECTRONIC AND EXPERIMENTAL MUSIC
depicted as a ramp that goes up, levels off, and then goes down again. In
electronic music, the envelope of a sound wave can be controlled with great
precision.
Waveforms
Sound waves can be represented graphically by their two basic characteristics,
pitch and loudness. In electronic music, pitch is referred to as frequency and is
defined by the number of vibrations that occur each second (also known as hertz,
or Hz). The loudness of a sound is its amplitude. In a diagram of a wave,
amplitude is represented by the height of the wave.
A complex tone is composed of several sound waves. It will have a
fundamental frequency and additional sidebands or overtones. The fundamental
is the wave with the lowest frequency or the highest amplitude and thus
dominates the combination of tones. Overtones add color to the sound, giving it
character or timbre.
While most of the sounds we hear in electronic music are combinations of
multiple waves or are specially treated for added tone color, it is possible to
catalog a few basic waveforms, or waveshapes, that serve as the building blocks
of the electronic music composer. Computer sound cards and music synthesizers
provide electronic audio oscillators capable of generating any one of these waves
in an approximately pure form.
Sine wave: This is the simplest type of wave. Theoretically, it should contain
no harmonics or overtones. Although some liken the sound of a sine wave to
that of a flute, even the flute has more body and depth than a pure sine tone. The
sine is a thin, precise tone, similar to a whistle.
Triangle wave: A triangle wave is similar to a sine wave but has a number of
harmonics, or sidebands, added. Its sound has more body and depth than a
sine wave and a more hollow effect, like that of a flute, trumpet, or musical
saw.
Sawtooth wave: This waveform has a sharp, angular shape like the teeth of a
saw. It has twice as many harmonics as a sine wave. It has a full, buzzing
sound, like a reed instrument such as the saxophone.
Pulse wave: This waveform has the same number of overtones as a triangle
wave but the grittiness and reedy sound of a sawtooth. The waveform jumps
instantly from the lowest point of its waveshape to the highest. When
diagrammed, it consists only of right angles and is often called a square or
rectangular wave. A pulse wave has a sound that is somewhat like the
combined sounds of a flute and an oboe. It can also be used to create sharp
rhythmic sounds more easily than the other basic waveforms.