This article describes how Pulse Touch (APR) technology works

Pulse Touch, also known as APR (Acoustic Pulse Recognition) is touch technology that was retired in 2012. It is no longer available on any of our product offerings

How Pulse Touch worked: A finger touch on a glass plate generates sound waves that propagate within the glass. These sound waves are detected with “microphones” in the form of piezoelectric transducers (piezos) bonded to the glass. When touch occurs, mechanical energy (bending waves) radiates from the touch location and is detected by the transducers. The transducers pinpoint the touch location by generating a unique sound for that location on the glass.