[LAU] room acoustics simulation

I've been trying to find a simulator for room acoustics which will allow me to construct a non-rectangular shaped room, specify absorptive characteristics of the surfaces, specify sound sources, and listening position. I'd like the output of the software to be an impulse response, so that I can listen to the predicted response, and some depiction of the standing waves versus frequencies. Does anything like that exist for Linux? For what it's worth, web searches lead me to some rudimentary software to show room modes of rectangular box shaped rooms, and there is a lot of theory out there too. But, the finished "product" software seems scarce, or at least hard for me to find. Thanks.... -- Kevin