High-frequency impulse-measurement

HFIM, acronym for high-frequency-impulse-measurement, is a type of measurement technique in acoustics, where structure-borne sound signals are detected and processed with certain emphasis on short-lived signals as they are indicative for crack formation in a solid body, mostly steel. The basic idea is to use mathematical signal processing methods such as Fourier analysis in combination with suitable computer hardware to allow for real-time measurements of acoustic signal amplitudes as well as their distribution in frequency space.

Source: Wikipedia — High-frequency impulse-measurement (CC BY-SA 4.0)