Get the most out of Piezo disc

"In fact, sometimes piezo sensors are called contact microphones. Some common applications include acoustic guitar pickups and drum triggers, but there really is no reason why you couldn’t use piezo sensors anywhere that produces vibration (and therefore, sound)." by Dan Connor.
Because it only pick up the contact vibration, most of ambient sound can be avoided. It sometimes creat interesting lo-fi result. For instance attach under a piano .



http://members.cox.net/ampage/triggers.htm How to make drum by piezo disc


http://www.instructables.com/id/Acoustic-Guitar-Pickup/ How to create lo- fi sound by attach to guitar