acoustics
 

Hi, everybody, i want to do a simle acoustic wave analysis, like how Acoustics waves propogates on a simple flat surface, but i have this type of problem, wheh i want to turn on the acoustic mode it says "the acoustic model is not available with curretn model settings "can anyone help me?
https://www.dropbox.com/s/c8uvr9j84hhel6c/des.png