NDT-net (Rolf Diederichs)
UT-Encyclopedia

Vibrationdata.com Tutorials
The tutorials and course materials require a username and password which can be obtained with an annual subscription fee.

Acoustics FAQ
An informal file of typical questions and answers on acoustical topics. Campanella Associates

Ultrasonics
IEEE Web Thesaurus - Keywords

Ultrasonics
Dedicated to the art and science of ultrasonic nondestructive testing and allied fields.

Nondestructive Testing Information Analysis Center (NTIAC)
NTIAC is a Defense Technical Information Center (DTIC) funded, Department of Defense (DoD) Information Analysis Center operated by Texas Research Institute Austin, Inc.

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.

Acoustical Standards
Acoustical Society of America

Nondestructive Material Testing with Ultrasonics
Introduction to the Basic Principles (Krautkrämer, NDt-net)

Acoustic Cavitation
TU Darmstadt (Germany)

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.

Ultrasound
Definition from encyclopedia.com

BAE Systems (USA)
Technical reference development and research data concerning acoustical imaging.

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.