Lev Sergeyevich Termen (Russian: Ле́в Серге́евич Терме́н) (27 August [O.S. 15 August] 1896 – 3 November 1993), or Léon Theremin in the United States, was a Russian and Soviet inventor, most famous for his invention of the theremin, one of the first electronic musical instruments and the first to be mass-produced. He also devised the interlace technique[1] for improving the quality of a video signal, still widely used in video and television technology. His listening device, "The Thing", hung for seven years in plain view in the United States Ambassador's Moscow office and enabled Soviet agents to eavesdrop on secret conversations.