Commodore 128D - Advanced Sound and Music in C128 Mode; A Brief Background: the Characteristics of Sound

Advanced Sound
and Music in
C128 Mode
A Brief Background: The Characteristics of Sound
Every sound you hear is actually a sound wave traveling through the
air. Like any wave, a sound (sine) wave can be represented graphi
cally and mathematically (see Figure 7-1).
Figure 7-1. Sine Wave
The sound wave moves (oscillates) at a particular rate (frequency)
which determines the overall pitch (the highness or lowness of the
sound).
The sound is also made up of harmonics, which are accompanying
multiples of the overall frequency of the sound or note. The combina
tion of these harmonic sound waves give the note its qualities, called
timbre. Figure 7-2 shows the relationship of basic sound frequencies
and harmonics.
.RESULTANT WAVE
FUNDAMENTAL (1ST HARMONIC)
2ND HARMONIC 3RD HARMONIC
Figure 7-2. Frequency and Harmonics
The timbre of a musical tone, (i.e., the way a tone sounds,) is deter
mined by the tone's waveform. The Commodore 128 can generate
four types of waveforms: triangle, sawtooth, variable pulse and
noise. See Figure 7-3 for a graphic representation of these four
waveforms.
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USING C128 MODE—Sound and Music in C128 Mode
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