Why does a guitar makes noice?

Answer 1

First off, noise is made by the vibration of the guitar strings, with pitch being changed by how fast or slow the strings are vibrating.

In the case of an Electric Guitar, the sound is picked up by the pickups, which can be thought of like microphones in your guitar that detect the noise and send the signal to an amplifier to process and deliver the "noise"

In the case of a standard acoustic guitar, the vibration of the strings is amplified by the large, hollow body of the guitar(think of how your voice sounds in a large empty room-same principle).

In both cases, the "noise" you are asking about can be changed by the type of wood the guitar is made of, and its density.

Hope this helped.

-professional guitarist