How is audio represented with numbers in computers?

Question

I like thinking about how everything can be and is represented by numbers. For example, plaintext is represented by a code like ASCII, and images are represented by RGB valu

Answer 1

The simplest way to represent sound as numbers is PCM (Pulse Code Modulation). This means that the amplitude of the sound is recorded at a set frequency (each amplitude value is called a sample). CD quality sound for example is 16 bit samples (in stereo) at the frequency 44100 Hz.

A sample can be represented as an integer number (usually 8, 12, 16, 24 or 32 bits) or a floating point number (16 bit float or 32 bit double). The number can either be signed or unsigned.

For 16 bit signed samples the value 0 would be in the middle, and -32768 and 32767 would be the maximum amplitues. For 16 bit unsigned samples the value 32768 would be in the middle, and 0 and 65535 would be the maximum amplitudes.

For floating point samples the usual format is that 0 is in the middle, and -1.0 and 1.0 are the maximum amplitudes.

The PCM data can then be compressed, for example using MP3.