Ultrasonic nondestructive testing (NDT) is a well-established technique that utilizes high frequency sound waves to locate cracks and other hidden flaws in metals, composites, and plastics.

As the use of fiberglass and carbon fiber composites in manufacturing has grown, so has the need for reliable nondestructive testing, both in the initial fabrication stage and while in service.

Some modern technology has ancient roots. Hundreds of years ago, foundry workers used sound waves to test the integrity of metal castings by tapping them with a hammer and listening to the tone of the ring.