Hi, all. I was wondering what happens to sound if you've got two identical parabolas facing each other. Apparently, from what I can read, a parabola concentrates all the incoming sound into its focal point. Once at the focal point, it bounces back to the parabola, where it is sent out in straight (would you call it coherent?) parallel lines away from the parabola. Now, if that sound coming off Parabola A is recaptured by Parabola B (and again concentrated at its focal point, then bounced off Parabola B toward Parabola A again)... would the sound continue bouncing back and forth? Would it degenerate into heat? What happens? Now imagine those two parabolas inside a cylindrical container... and that you're continually adding more sound pulses (say, from an exhaust pipe on an engine) through a hole in the center of Parabola A (but far enough back from its focal point that the flow isn't impeded by a reverse pressure wave traveling back up the pipe)... and you're exhausting the gasses around the outer edges of Parabola B. Does the sound pressure just keep building up between Parabola A and Parabola B? Does it somehow slip out along with the exhaust gasses past the outer edges of Parabola B? What happens? This is a thought exercise in trying to come up with the smallest, lightest, quietest muffler possible for a small single cylinder engine. My thoughts are to divorce the gas flow from the sound pulses somehow, make the sound pulses bounce around until they convert to heat, and extract the gas flow sans the sound.