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
Xiaodong Wang (electrical engineer) Conference. Wang has many research interests, but chooses to focus on the areas of information theory, signal processing, and communications. Furthermore, he has influential published research in the areas of wireless communications, statistical signal processing, parallel and distributed computing, nanoelectronics, and quantum computing. In 2003 he published a book entitled "Wireless Communication Systems: Advanced Techniques for Signal Reception", published by Prentice Hall. Recently he is also working on the emerging field of genomics signal processing and information theoretic genomics. Xiaodong Wang (electrical engineer) Xiaodong Wang () is an information theorist and professor of Electrical Engineering at Columbia University. He earned