13
FM Tone Generation
Harmonics
Most sounds are made up of multiple tones that are different than the pitch (frequency).
Within these multiple tones, the one that determines the pitch of the entire sound is called
the fundamental tone (fundamental frequency). All the tones besides the fundamental tone
are called partials or overtones.
When all the harmonics that are related to a particular fundamental tone are arranged in
order, it is called a harmonic series. Each tone in the harmonic series is given a name in
order, with the fundamental tone being one, followed by the second harmonic, third har-
monic and so on.
The frequency of each harmonic in the harmonic series is a natural number multiple of the
frequency of the fundamental tone. Overtones that have frequencies that are not natural
number multiples of the fundamental are called unharmonic overtones.
Generally, the more harmonics the tone has, the brighter the sound. On the other hand, if
the amount of harmonics is reduced, the tone will sound darker. Furthermore, the voice
will change a lot according to the type and volume of the harmonics. For example, if there
are a lot of high pitched harmonics in the tone, it will have a brilliant, crisp sound. On the
other hand, a tone with a large amount of lower harmonics will have a rather massive,
dignified sound.
HarmonicsWaveform
Level
Time
Graph of the Harmonics
that Make Up the Tone
Level
Harmonics
Harmonics
Fundamental Wave
Second Harmonic
Third Harmonic
Natural Harmonic Series
(when C1 is the fundamental tone)
Frequency
Eighth Harmonic
Seventh Harmonic
Sixth Harmonic
Fifth Harmonic
Fourth Harmonic
Third Harmonic
Second Harmonic
Fundamental
Fourth Harmonic
Third Harmonic
Second Harmonic
Fundamental