Demonstration of using acoustic localization to turn a chalkboard into a touch surface. Milwaukee School of Engineering senior design project, 2011.
Technical details: The waveforms coming from the accelerometer are matched against a library of waveforms collected during calibration. The calibration point with the best match (according to a cross-correlation of the two waveforms) determines where the click is positioned on the screen.
See our report at http://www.scribd.com/doc/56148660/Tap-Assisted-Projection-Acoustic-Research-...