The history and evolution of diagnostic ultrasonography has been founded on the combined efforts of physicists, engineers, computer scientists, doctors, sonographers, physiologists, university researchers, as well as large commercial companies and individual entrepreneurs. Early Evolution of High Frequency Sound (1794 – 1893) 1794 – Lazzaro Spallanzani, an Italian physiologist and biologist, discovers that bats navigate in the dark through the reflection of high frequency sounds (echolocation). Spallanzani’s discovery becomes the basis of ultrasound physics. 1801 […]