This talk focuses on the remarkable impact of Paul Langevin’s research since he (in 1917) proposed to use the piezoelectric properties of quartz for underwater detection of ultrasound signals. Not only has his pioneering idea opened the field of quantitative measurements of acoustic waves, but it also had far-reaching implications for the development of modern ultrasound metrology, driven by the need to ensure the safety of ultrasound used in visualizing of internal human organs for diagnostic applications and maximizing the efficacy and precision of treatment in therapeutic application of ultrasound waves. In summarizing the current advances in ultrasound metrology, a succinct background explaining why, initially, both the scientific community and industry were skeptical about the existence of the nonlinear (NL) wave propagation in tissue will be given and the design of an adequately wideband piezoelectric polymer hydrophone probe that was eventually used to verify that the 1–5 MHz probing wave then used in diagnostic ultrasound imaging was undergoing nonlinear distortion and generated harmonics in tissue will be discussed. [ Work supported by the NIHNINR through Grant No. 5R01NR015995. The contents of this presentation are solely the responsibility of the authors and do not necessarily represent the official views of the NIH.]