Trywww.spectraplus.com you can download their software for a free 30 day trial. I got it recently and it seems very good though with all the features a little complex. I still need to pickup the SPL meter from radioshack to use it.
If anyone else is reading this where can I find the corections for the SPL meter and how do I load it into spectra plus. Also how much do you think the sound card will affect results and is there a way to compensate for it.
While not free, I believe the $149 for the ETF5 program is very reasonable. Plus, the website has an in-depth example room setup and step-by-step results evaluation that really teaches you about speaker-room acoustics. www.etfacoustic.com
I'm just a satisfied user.
BruceD