sound wave speed and other ways they behave/react.

I have this week free to play with acoustic treatments and more. I looking for more info, some type of reference if you will. It need not be a thousand pages long, something to guide me. Im planning to build more absorption and diffusers. That sort of reference would be helpful. Illustrations of frequencies and how they behave across the spectrum, there width and speed, that sort of thing. I have a room to work on and I’m starting with a clean canvass, 18L’ x 12’H x 7 1/2H.

All that exists is a cloth 3 seater sofa and an area rug that covers approximately 80% of the cork floor. I will leave an equal sized border at all four sides for now The walls are framed, all but one contain fibreglass pink. The option is there to add pink between the floor joists. As it is they are all open. I’m trying to stay away from a suspended ceiling. But sound before looks, I would rethink the covering.