Cl矇ment Ader (April 2, 1841 - May 3, 1925) was a French inventor and engineer. Ader was an innovator in a number of electrical and mechanical engineering fields. He originally studied electrical engineering, and in 1878 improved on the telephone invented by Alexander Graham Bell. After this he established the telephone network in Paris in 1880. In 1881, he invented the th矇璽trophone, a system of telephonic transmission where listeners received a separate channel for each ear, enabling stereophonic perception of the actors on a set; it was this invention which gave the first stereo transmission of opera performances, over a distance of 2 miles. Ader is still admired for his early powered flight efforts, and his aircraft gave the French language the word avion for a heavier-than-air aircraft. In 1938, France issued a postage stamp honoring him. Airbus named one of its aircraft assembly sites in Toulouse after him. Cl矇ment Ader has been referred to as "the father of aviation".