Sonography is the process of using sound waves as an imaging device, typically for medical purposes.
Background
Indeed, the principles of sonography come from the natural world. For example, bats and whales are mammals that use sound waves for navigation. In 1794, after performing medical studies on bats, Lazzaro Spallanzani gained a basic understanding of ultrasound physics.
In 1880, French brothers Jacques and Pierre Curie discovered piezoelectricity. Simplifying, piezoelectricity is an electric current generated by deforming certain crystals. For example, flint-less cigarette lighters and inkjet printers both utilize the piezo effect. Getting to the point, piezoelectricity enables ultrasound transducers that emit and receive soundwaves.
On April 14, 1912, the RMS Titanic famously struck an iceberg and sank, killing about 1,500 people. Accordingly, government agencies around the world called for some method to better detect icebergs. Eventually, In 1914, Paul Langevin built on the work of Reginald Fessenden (of AM radio) to invent the first ultrasound transducer aimed at icebergs. His machine detected icebergs up to about two miles away but had no directional capability. To clarify, it could detect there was an iceberg somewhere close but not in which direction.
Ultrasound as Weaponry
The use of submarines in World War I increased the need for directional ultrasound in water. Eventually, Langevin and Constantin Chilowsky created a high-frequency ultrasound machine with directional capabilities. On April 23, 1916, their “hydrophone” was used to sink a German U-boat.
Medical Imaging
Eventually, in 1942, Austrian Neurologist Karl Dussik used sonography to detect brain tumors. Dussik used a method where sound waves were beamed towards the head of a patient partially submerged in water and the resulting echo recorded on heat-sensitive paper. Specifically, this became the first ultrasound image. Eventually, George Lewig used ultrasounds to detect gallstones and kidney stones.
Progress continued with physicians and engineers using ultrasound to measure various fluid-based organs. Most notable are studies in cardiology and obstetrics. By the 1970s, Doppler and color Doppler ultrasound imaging became commonplace. In the 1980s, Kazunori Baba of Japan developed 3D ultrasound.
By the 1990s, with the help of computers, real-time 3D ultrasound enabled surgeons to see inside a body during biopsies. Today, ultrasound machines are common, especially in obstetrics. Unlike radiation-based imaging devices, the ultrasound machines are entirely harmless.