Discovered Pages
[Discover] Sci.electronics FAQ - Ultrasonic transducer oscillator circuit (self-resonating) http://www.ee.washington.edu/circuit_archive/circuits/F_ASCII_Schem.html#ASCIISCHEM_016
(diy ultrasonic electronics) 
[Discover] ultrasonic - Google Code http://code.google.com/p/ultrasonic/ (windows mac linux software)
[Discover] Ultrasonic Ringtones - the new ringtones that only kids can hear! http://www.ultrasonic-ringtones.com/ (music sound funny science)
[Discover] Ultrasonic Imaging http://www.sciencedirect.com/science/journal/01617346 (journal)