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Table Of Contents
A tone played at twice the frequency of the first harmonic is called the second harmonic.
A tone played at four times the frequency of the first harmonic is called the fourth
harmonic, and so on.
Each of these harmonics has a different timbral quality from the fundamental tone. In
general, harmonics that can be multiplied or divided by a whole number–such as octaves,
odd-numbered or even-numbered harmonics, and so on–sound more “musical.”
Tones that cannot be multiplied or divided by a whole number are known as inharmonic
overtones, or partial tones. When you combine a number of these inharmonic overtones,
it tends to sound noisy.”
The Frequency Spectrum
A fundamental tone, when combined with various harmonics of different levels, is
perceived as a sound. The level relationships between these sonic elements change over
time (controlled by envelopes, discussed later in this appendix). The combination of a
number of harmonics is referred to as the harmonic spectrum or, more commonly, the
frequency spectrum.
The frequency spectrum shows all the individual sonic elements in a sound. It is shown
low to high from left to right. The respective levels of all harmonics are reflected vertically,
with taller spikes indicating higher levels.
Frequency spectrum graphic
of an organ sound
The illustration shows the level and frequency relationships between the fundamental
tone and the harmonics at a particular moment in time. These relationships constantly
change over time, which results in continuous changes to the frequency spectrum and,
therefore, changes to the sound.
349Appendix Synthesizer Basics