BeagleBone – Buzzer interfacing

A buzzer or beeper is an audio signalling device, which may be mechanical, electromechanical, or piezoelectric. Typical uses of buzzers and beepers include alarm devices, timers and confirmation of user input such as a mouse click or keystroke.for information on buzzer
http://learningembedded.com/beaglebone/beaglebone-buzzer-interfacing/