A complete description of the nature and format of audio data is beyond the scope of this book. There are, however, numerous books available that provide complete discussions of digital audio data. You can use square-wave data to generate a sound based on a square wave. Usually, you specify a sound's frequency by a MIDI value. MIDI note values correspond to frequencies for musical notes, such as middle C, which is defined to have a MIDI value of 60, which on Macintosh computers is equivalent to 261.625 hertz.
Pitch is a lister's subjective interpretation of the sound's frequency.
The terms frequency and pitch are used interchangeably in this chapter. In the Sound Manager, durations are usually specified in half-milliseconds. The amplitude of a sound is the loudness at which it is being played. Two sounds played at the same amplitude might not necessarily sound equally loud. Or, a sampled sound of a fleeting whisper might sound softer than a sampled sound of continuous gunfire, even if your application plays them at the same amplitude.