In the context of boreholelogging, measurements of acoustic signals that are in the hundreds of kilohertz to the low-megahertz range. Such ultrasonic instruments are mostly of the pulse-echo type, and are used in the borehole televiewer, and in various cased-hole devices to determine corrosion and cement-bond quality.

Related Terms:

acoustic transducer
borehole televiewer
sonic measurement
ultrasonic caliper