I'm working on an installation wich should generate data on the info I can get from my audio inputs.

I would like to know if there are people in the room, how many people (I think measuring loudness would be good enough for this) and count the amount of time there are people in the room, or the amount of time there weren't any people in the room.

getting-useful-information-from-audio-inputs

try snapshot~ for loudness, or the output from one of the audio meter objects. For determining how long they're in the room, choose a threshold for the audio level and start a timer, then when the timer exceeds a certain point, bang to what you want to do.

Getting useful information from audio inputs.