Is there any way to focus a sound wave BEHIND an acoustic lens i.e. the source and receiver are on different sides of the lens? Will it result in a significant loss of sound energy?
Not a metal - a very light weight foam, which has been designed for the purpose. If you use metal, most of the sound energy will be reflected and not transmitted through; you need a material with a not too dissimilar impedance to that of the air.So basically if I make something which looks like an optical concave lens, but I make it out of a metal, I will solve my problem? Since sound travels faster in solids than in the fluid medium, it will focus the sound waves?(Assuming Fermat's principle holds for sound waves for relatively short distances)
Also, Will the waves being focused arrive in phase(assuming they were in phase from a single source before hitting the lens?)