What creates sound and pitch of a drum?

Answer 1

When a drum head is struck, the air inside the drum between the two heads is moved vibrating both the top and the bottom head and creating the sound.
The pitch of a coventional drum is determined by the diameter of the drum, and the tightness of the drum head. Generally, the smaller the diameter, and the tighter the head, the higher the pitch.
There are some exceptions to that rule though including Tama's Octoban drums. These tube like drums are all the same diameter, and the pitch is controlled by the length of the drum. These also have no bottom head, meaning the sound is created by only the top head and the air rushing out of the end of the drum.
I hope this helps.

Answer 2

You provide the energy by striking the drum with your hand or a stick. The drum head flexes and stretches in response to your hitting it, then snaps back to it's original position and past it, vibrating back and forth anywhere fro a few tens to a few hundred times a second. The size, material and tightness of the drum head determine it's resonant frequency or pitch.

Answer 3

The vibrations resonate in the shell of the drum bounce and create the sound.