Where to learn all about sound?

[BigToque]

I would like to learn all about frequencies, decibels, octives, designing boxes, etc... where's a good place to start?

I've got a very basic knowledge, but I want to know it in and out...

 

[Howard]

An octave is essentially a doubling of the frequency... i.e. a tone at 440Hz is an octave lower than one at 880Hz, and is an octave higher than one at 220Hz.

Box construction is pretty deep. I'd suggest you browse the diyaudio.com forums (the Loudspeaker forum to be precise) and make posts whenever you need to.

Decibels are a logarithmic way of expressing sound pressure so that the numbers don't get too big. You can use Google for this one.

In fact, you can use Google for all of those topics you mentioned.