Since I shared plenty of links discussing audio this morning, I think I'll briefly describe how digital audio works.
A speaker or microphone is a fluctuating magnet(s) inside a coil(s) of wire producing or receiving sound waves. Resisters inside a digital-analog-converter can convert digital numbers into voltages for a transister to amplify. Also we can wrap a DAC with a circuit to find the digital number which matches the anolog voltage.
