Students at Georgia Tech have created an audio analysis program that lets you blow at your computer as a way to control it. It only uses one microphone, and after a quick calibration, it’s ready to go.
This is a way to support blowing at a laptop or computer screen to directly control certain interactive applications. Localization estimates are produced in real-time to determine where on the screen the person is blowing. You can do this by using a single microphone, such as those that are already embedded in a standard laptop or one placed near a computer monitor by using audio fingerprinting.
Georgia Tech research paper on blowable interface – Link.