Using Audition as a sound meter

Technically you can use it as part of a recording system that will accurately record what's sent to it - but that's not actually the issue. No arguments about any measurements stand up unless you've used a precision mic and preamp, and most importantly, calibrated the mic against a known sound pressure level standard. And you have to record that calibration, with its level indication, at the start of your file and alter no levels. The only way to calibrate the mic is to use a precision calibrator designed to go with the mic, and these aren't cheap. I have one, and a precision mic to go with my SPL meter, and the mic plus calibrator in the US would cost well in excess of $1500.

And even then, you're not out of the woods, as you have to make a series of measurements, and log absolutely everything about them - where they were made, what the temperature and weather conditions were if you're doing it outdoors (yes, really), what the time was, etc. On top of that, the chances are that the results will vary a lot, and this will be down to the fact that within a building, you get what's known as flanking transmission, where the construction of the building itself significantly alters the results. And even if you've done all that, the chances are that any other party involved would question your measurements anyway, as you were the complainant - so you're biased, aren't you? You simply can't prove that you haven't fiddled around with the recordings, so all bets are firmly off. There are a load more constraints on this too, but I imagine you're getting the idea...

Basically, you really can't do this yourself and stand any chance of getting anywhere at all. I don't know how it is where you are, but here in the UK it's the local civic authority's job to patrol this (you invite them) and prosecute offenders, and they have much more power in this line than we do. If I do this sort of environmental noise job (which fortunately I don't have to any more), then I have to do it nowhere near where I live!

Class 2 Sound Level Calibrator for Sound Level Meters and 1/2" Microphones and that's only a class 2 - really you need a class 1, and a class 1 mic.