While research on ultrasonics has been covered in earlier volumes of the Physical Acoustics series, Volumes 23 and 24 demonstrate the successful commercialization of devices and instruments arising from research in this area. These volumes will assist in the process of bringing research output into the marketplace to the benefit of customers. The chapters are liberally illustrated with pictures of actual commercial objects which have been or are in use. Included are Medical Ultrasonic Diagnostics, Nondestructive Testing (NDT), Acoustic Emission, Process Control, Surface Acoustic Wave (SAW) Dev.