Reginald Aubrey Fessenden (1866-1932), a Canadian chemist and inventor best known as the first person to broadcast words and music over radio waves (1906). Fessenden was the originator of the concept of reflection and refraction surveying (1917). During the 1880s, Fessenden worked as a chemist for Thomas Edison and later for Westinghouse. He went on to start his own company where he invented the modulation of radio waves, the "heterodyne principle", which allowed the reception and transmission on the same aerial without interference. This principle is the basis for amplitude modulation (AM) radio.
On Christmas Eve, 1906, Fessenden transmitted the first radio broadcast from Brant Rock Station, Massachusetts. Ships at sea heard a broadcast that included Fessenden playing O Holy Night on the violin and reading a passage from the Bible.
Inspired by the sinking of the Titanic, he developed the “fathometer”, a device whose receiver picked up a reflected wave and determined the distance to an object. Fessenden also saw the potential of his device for exploration. In 1913, he invented seismic instruments that were used to record both refractions and reflections through Earth formations near Framingham, Massachusetts. In 1917, he filed an application for a patent on a ‘method and apparatus for locating ore bodies.’ Using a mechanical oscillator and microphones, the system measured deviations in reflection and refraction waves to identify anomalies. This seismic technology would greatly improve the efficiency of oil and gas exploration.
Reginald Fessenden - Biography (Canada's Digital Collections, Government of Canada)
Reginald Aubrey Fessenden: Some Biographical Notes (University of Groningen, Netherlands)
United States Early Radio History (EarlyRadioHistory.us)