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Appendix B Synthesizer Basics 472
Sound basics
Sound basics overview
Prior to considering any of the sound-generating components you will nd in a synthesizer, it’s
important that you understand sound itself.
Technically, sound is the conversion of physical energy—such as a hand clap—to an air pressure
disturbance. This change in air pressure is transmitted as a series of vibrations—a sound wave—
through the air. Sound vibrations can also be transmitted through other matter, such as a wall or
oor.
If the vibrations follow a periodic pattern, the sound is said to have a waveform.
The gure above shows an oscillogram—a graphical representation—of a sine wave, the
simplest and purest kind of waveform.
If the vibrations do not follow a discernible pattern, the sound is called noise.
A repetition of a waveform—each peak and trough in the oscillogram—is known as a cycle. The
number of cycles that occur per second determines the basic pitch of the waveform—commonly
known as the frequency. Most instruments provide an oscillator frequency control, measured in
Hertz (Hz), that determines the number of cycles per second—and therefore the basic pitch of
your sound.