Apple Soundtrack - Manual (Page 14)

14 Chapter 1 Audio and Music Basics
The depth or intensity of a sound is called its amplitude, and is expressed in decibels
(dB). We hear amplitude as the volume or loudness of a sound. The range of audible
loudness is roughly 0–130 dB. Higher decibel levels are painful to human hearing.
Musical Sounds
Musical sounds typically have a regular frequency, which we hear as the sound’s pitch.
Pitch is expressed using musical notes, such as C, Eb, and F#. What we hear as the pitch
is only the lowest, strongest part of the sound wave, called the fundamental. Every
musical sound also has higher, softer parts called overtones or harmonics, which occur
at regular multiples of the fundamental frequency. We don’t hear the harmonics as
distinct pitches, but rather as the tone color (also called the timbre) of the sound, which
lets us distinguish one instrument or voice from another, even when both are playing
the same pitch. When you turn up the treble on your stereo, or adjust an EQ effect, you
raise the volume of some of the harmonics in the music, but don’t change the
fundamental frequencies.
Fundamental
First harmonic
Second harmonic
Time
Time
Time