Analyzing room tone

Not really...

The only semi-reliable way to get information back from a room is to excite it with a known impulse and record the result, which you can analyse using a waterfall graph. Or if it's a big space you can get a bit of a clue from the reverb decay. But with just room tone, you tend to have noise sources being a major component in it, and generally your ears can give you a better clue.

The reason that a frequency analysis on its own doesn't really help is that it only represents a snapshot in time, and doesn't actually tell you how the room is responding temporally - that's where the waterfall graph comes in. This gives you a series of time slices when you start recording from an impulse, and it's much easier to spot similarities between different responses. But it absolutely won't work without an impulse - without excitation, there's nothing to analyse.