If you edit the .m file (iso226.m) you'll see that there is a simple set of 2 equations that are used to calculate SPL at frequencies, given an input SPL @ 1kHz.
I ran it for 1 to 90 dB (the limits of the data) in 1 dB increments and put them in a spreadsheet. Unfortunately I can't seem to attach anything (says I don't have permissions.)
If you are actually using the data, you might want to run the equations themselves at the frequencies you're interested in, to get a more accurate number. Contours just give you a general trend. You can edit the file with wordpad or something similar... you don't need Matlab to do that.
I'll try to upload the spreadsheet from home later on. I could e-mail it too.
