CAKEWALK Cakewalk SONAR, User Manual

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Digital Audio Fundamentals
Digital audio is a numeric representation of sound; it is sound stored as numbers. In order to
understand what the numbers mean, you need to start with the basic principles of acoustics , the
science of sound.
Basic Acoustics
Sound is produced when molecules in the air are disturbed by some type of motion produced by a
vibrating object. This object, which might be a guitar string, human vocal cord, or a garbage can, is set
into motion because energy is applied to it. The guitar string is struck by a pick or finger, while the
garbage can is hit perhaps by a hammer, but the basic result is the same: they both begin to vibrate.
The rate and amount of vibration is critical to our perception of the sound. If it is not fast enough or
strong enough, we won't hear it. But if the vibration occurs at least twenty times a second and the
molecules in the air are moved enough, then we will hear sound.
Example—A Guitar String
To understand the process better, let's take a closer look at a guitar string.
When a finger picks a guitar string, the entire string starts to move back and forth at a certain rate.
This rate is called the
frequency of the vibration. Because a single back and forth motion is called a
cycle , we use a measure of frequency called cycles per second , or cps . This measure is also known as
Hertz , abbreviated Hz . Often the frequency of vibration of an object is very fast, so we can also express
the frequency in thousands of cycles per second, or kilohertz (abbreviated kHz ).
The actual distance the string moves is called its displacement . This is proportional to how hard the
string is plucked. A greater displacement results in a louder sound.