What happens to sound when it is entered into a pc through a mic, and where itis stored?

Natural sound is created when a vibrating body (your vocal cords for instance) causes an increase and decrease in air pressure. This "pressure vibration" moves through the air just like the ripples move through a pond when you throw in a rock. The microphone contains a very thin diaphragm which vibrates with this change in air pressure. This vibration generates a voltage which rises and falls in sync with the physical vibration. A wire carries this voltage "wave" into the computer and it is fed to a Analog to Digital converter. This circuit measures that constantly changing voltage at tiny time intervals ( 40,000 or more times per second ) That measured voltage is stored as binary data just like any other data on your hard drive. When you listen back to the recording, the process is reversed. The rapid stream of numbers are converted back to a varying voltage. Wires carry the voltage to a speaker which works like the microphone in reverse. The voltage fluctuations go into a magnet which draws and repels the speakers diaphragm. This causes a vibration in the speaker to vary the air pressure in the same way the original sound was created.