Is it possible to estimate the number of people in a room from a limited number of simultaneously recorded audio samples?
Note: I struggled to decide the appropriate site for this question, between http://physics.stackexchange.com/, http://avp.stackexchange.com/, http://math.stackexchange.com/, and even http://linguistics.stackexchange.com/. However, I felt that the Audio-Video Production and Linguistics communities might not provide the mathematically inspired answer I'm looking for, and the Mathematics community might dismiss the question as being ill-defined—I thought the Physics community might come up with important points and counterpoints to practical applications, in addition to having mathematical background.
Is it possible to estimate the number of people in a room from a limited number of simultaneously recorded audio samples?
I'm searching on Google Scholar by combinations of keywords like [tag:recording], [tag:audio], [tag:extrapolate], [tag:crowd], [tag:number], [tag:voices], etc. and not coming up with any papers related to my question. 151
It's made me wonder whether there's some mathematical or physical impasse that makes the task necessarily impossible. If so, what are the principles that exclude this possibility? If not obviously impossible, could someone perhaps point me to some research regarding this particular problem?
To be more specific, though I'm sure it's naive, my idea was to take two stereo recordings from different locations in a crowded room, and to analyze certain linguistic features like the rate of hisses (or other utterances and features of a language that are easy to isolate), to derive a statistically useful range estimating the number of persons in the crowd. (Of course, such a system would have to be calibrated to a uniform language or dialect.)
I'm aware of various difficulties, both technical (such as how to synchronize the recordings, how to achieve high sensitivity with low noise, etc.) and fundamental (such as how to distinguish between one person speaking profusely and others barely speaking), but I'm more trying to find out if one or more principles of mathematics or physics regarding an audio signal itself, in its "flattened" form, might preemptively shut down this idea. I'm afraid I don't know enough physics myself to explore the problem :-(
Thank you in advance for any insights or references. 587