10.6

701Logic Pro Instruments
If the vibrations follow a periodic pattern, the sound is said to have a waveform.
The figure 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.
Tones, overtones, harmonics, and partials
The base, or core, frequency of a sound is known as its fundamental tone.
The waveforms of all sounds, apart from a basic sine wave, consist of the fundamental tone
and many other tones of different frequencies.
Non-fundamental tones that are whole-number multiples of the fundamental tone are
known as overtones or harmonics. A tone with a frequency that is a fraction of the
fundamental tone is referred to as a subharmonic.
• The fundamental tone is referred to as the first harmonic. This is generally louder than
the other harmonics.