1. The problem statement, all variables and given/known data This is a problem I've been pondering, and I simply need some recommendations for texts to read on the topic. Suppose you have an enclosed air chamber with an acoustic source on one end (http://beckerexhibits.wustl.edu/did/images1/hatpatent.jpg" [Broken]). How can one predict the amplification, distortion, and dissipation of the sound that ends up on the other end of the chamber? I am especially interested in what I think are likely basic mathematics that explain the amplification of the sound if the chamber is conical. This is akin to http://www.thehistoryblog.com/wp-content/uploads/2008/05/horn.jpg" [Broken] used for many years. Why does the sound get amplified? What are the relevant acoustic formulations? 2. General questions and Attempt What text should I look into to help me understand this topic and answer these kinds of questions? The only thing that I've heard, in a very unscientific way, is that sound is amplified by a factor equal to the Entry Cross section / Exit Cross section (so in a cone where the sound enters the larger end, the sound is amplified by some factor 'x'). But this alone is insufficient for my cause (i.e. I want some sort of mathematical basis for this kind of statement). Thank you!