What is Ultrasound? Human beings can normally hear soundwaves between 20Hz – 20000Hz. Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound devices operate with frequencies higher than 20 kHz up to several gigahertz. Physiologist Lazzaro Spallanzani was the first to study echolocation among bats in 1794, which […]