Adobe AUDITION 1.5 - Manual (Page 278)

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Digital Audio Primer
Two simple waves combine to create a complex wave.
Analog audio
A microphone works by converting the pressure waves of sound into changes in voltage
on a wire. These changes in voltage match the pressure waves of the original sound: high
pressure is represented by positive voltage, and low pressure is represented by negative
voltage. Voltages travel down the microphone wire and can be recorded onto tape as
changes in magnetic strength or onto vinyl records as changes in amplitude in the groove.
A speaker works like a microphone in reverse, taking the voltage signals from a micro-
phone or recording and vibrating to re-create the pressure wave.
Digital audio
Unlike analog storage media such as magnetic tape and vinyl records, computers store
audio information digitally as a series of zeroes and ones. In digital storage, the original
waveform is broken up into individual samples. This process is typically known as
digitizing or sampling the audio, but it is sometimes called analog-to-digital conversion.
The sampling rate defines how often a sample is taken. For example, CD-quality sound has
44,100 samples for each second of a waveform.
Sampling rate
The sampling rate determines the frequency range of an audio file. The higher the
sampling rate, the closer the shape of the digital waveform will be to that of the original
analog waveform. Low sampling rates limit the range of frequencies that can be recorded,
which can result in a recording that poorly represents the original sound.
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