← DMS 206 Final Export Options Alphabetize Word-Def Delimiter Tab Comma Custom Def-Word Delimiter New Line Semicolon Custom Data Copy and paste the text below. It is read-only. Select All Pythagoras Greek mathematician who observed the relationship between sound pitch and frequency. He discovered the sonometer. Christian Johann Doppler Austrian scientist who studied the effect of motion on the pitch of sound. Called the Doppler effect. Curie Brothers discovered piezoelectricity. John Wild Helped develop the metal flaw detectors and naval sonar. Ian Donald Credited with perfecting the A-mode measurement of the fetal biparietial diameter making it possible to ultrasonically estimate fetal age, weight, and growth rate. Known as the "father of obstetrical ultrasound". Archytas of Tarentum 400 BC. Greek scholar, defined nature of sound. Sound is produced by the motion of one object striking another ... fast motion = high pitch ... slow motion = low pitch Aristotle 350 BC. Greek Philosopher and Scientist. Therory of Sound Propagation. Sound is carriewd to the ears by the movement of air. Boethius Roman Philosopher. First to compare sound wavws to the waves produced by dropping a pebble into a cal body of water. This theory is still used today. Leonardo Da Vinci 1500 AD. (Post renaissance period). Study of the physical properties of sound. Originated the idea that sound travels in waves. Credited with discovery that angle of reflection = angle of incidence. Galileo 1638. Frequency of sound waves determines pitch. Sir Isaac Neewton Late 1600's. Derivation of the theory of velocity. Robert Boyle Late 1600's. English Chemist. Popularized the theory of elasticity of air. Lord Rayleigh 1877. British scientist. THEORY OF SOUND published - marked the beginning of the modern study of acoustics. Lazzaro Spallanzani 1793. Italian Priest / Scientist. Studied activities of bats. Observation: bats could function if blinded in the dark, but not if deafened.... Theorized: bats were listening to something he could not hear - what it was he didn't know. G.W. Pierce 1938. Inveneted a sonic detector - pick up high frequency vibrations of bats and to convert them into audible sounds. Karl Dussik 1942. Austrian became the first physician to use ultrasound for diagnostic purposes ... used to detect brain tumors. George Ludwig 1947-1949. First used ultrasound to detect gallstones at MIT. A-Mode.