Measuring With Sound
This article suggests that non-destructive testing has found good use for ultrasonic testing. The term "ultrasound" refers to sound energy with a frequency, or pitch, too high to be heard by the human ear. Ultrasonic sound waves can help measure material thickness, integrity, and other physical properties in manufacturing or in-service situations. Using these techniques, it is possible to take quick and reliable measurements of the thickness of a part's wall or to find hidden internal flaws without cutting or sectioning a part. Since sound-transmission properties of different materials vary, ultrasonic material analysis is a comparative process. Generally, a test is set up using reference standards representing the range of conditions to be quantified. Once test results are obtained from these references, they can serve to establish the properties of other, similar parts or batches.