Sound recording and reproduction 1920s when several radio-related developments in electronics converged to revolutionize the recording process. These included improved microphones and auxiliary devices such as electronic filters, all dependent on electronic amplification to be of practical use in recording. In 1906, Lee De Forest invented the Audion triode vacuum tube, an electronic valve that could amplify weak electrical signals. By 1915, it was in use in long-distance telephone circuits that made conversations between New York and San Francisco practical. Refined versions of this tube were the basis of all electronic sound systems until the commercial introduction of the first transistor-based audio devices in
Christopher Rose (electrical engineer) Christopher Rose (electrical engineer) Christopher Rose (born January 9, 1957) is a professor of engineering and associate dean of the faculty at Brown University in Rhode Island and a founding member of WINLAB at Rutgers University in New Jersey. He was educated at the Massachusetts Institute of Technology; SB'79, SM'81, Ph.D'85 all in Course VI (Electrical Engineering and Computer Science). On September 2, 2004, an article by Christopher Rose and Gregory Wright, titled "Inscribed matter as an energy-efficient means of communication with an extraterrestrial civilization", appeared on the cover of "Nature" with the headline "Dear ET...". The article argued that