This instructable is more of a how it works as opposed to a how to. Once you understand how it works, it is much easier to learn the how to.
Please note that I am constructing this from a sound engineer's point of view. Most of the content is theory, so please keep that in mind when you read this.
If you haven't read my first instructable "How Sound Works" yet, I suggest you read it first. You can find it here: http://www.instructables.com/id/How-Sound-Works/