How does electricity represent sound?
How does electricity represent sound?


There are many ways, these can be characterised as analogue or digital representations.

The most direct analogue representation has voltage proportional to air pressure.

A sound wave in air is a pressure wave where the pressure reaching your ears is alternately of higher than ambient pressure and lower than ambient pressure. The electric representation of this, as produced by a simple microphone has a voltage proportional to this pressure.


Image from Electronics-Tutorials.ws

However, when you copy an MP3 file from your PC onto an SD-card, an electrical representation of a sound wave is travelling through the wires leading to the SD-card. This digital representation is very different and much more complex.