Inspired by
habrahabr.ru/post/200912/.
Who knows. Enough to be the microphone sensitivity medium phone for android, to the distance meter is an 80% chance to be and to distinguish pressed keys on the average keyboard? With softovoi part of all is clear (the signal processing is not yet entirely forgotten) — but the physics imagine bad.
(As a topic for diploma students is not bad. But you need to be sure of the feasibility ;-)