Acoustics FAQ: An informal file of typical questions and answers on acoustical topics. Campanella Associates
BAE Systems (USA): Technical reference development and research data concerning acoustical imaging.
How Stuff Works: How Ultrasound Works: Illustrated narrative takes you inside the ultrasound machine and shows you how this technique is used to look inside you.
Piezo Solutions: an Engineering and Manufacturing Consulting Service which assists companies who manufacture and utilize piezoelectric ceramic elements in their products to improve performance, yield, quality and reliability.
Super High Resolution Ultrasonic Measurement System: 5-micro-meter resolution measurement by non contact system in the air; RS-232 interface; Thickness, Deviation, Distance, Level of any kind of material.