@mingteck said: simple acoustical modelling It depends on what you mean by simple. Using standard formulas based on volume and surface area by absorption is one thing, much past that and the calc time might be a bit long...

Many thanks, guys. Looks like I just needed that reminder about where to locate the .rb files. You're right, Dave R. What I did was try to install the .rb files using Install Extension button inside the Extensions page of the Preferences menu. I was able, using that to open another folder in my computer but it doesn't recognise any of the .rb or .rbz files in those other folders. Transferring the files into the right folder solved all the issues, .