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 (e.g.). 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 ear trumpets 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!