Sound

Sound is a medium (air), vibrating.

Us humans make a distinction between sound and noise:

When air is displaced in certain patterns our brains can recognize, we call it sound. When air is displaced in patterns our brain can’t recognize, we call it noise.

Speakers

To generate sound from an electronic device we need something we commonly call a speaker.

A speaker works by converting electronic current to movement to vibrate air.

This electronic current is an analog signal, which means that it also has a wave pattern unlike a digital signal, which is an off-or-on current, 0’s and 1’s.