Danish engineer who invented the telegraphone, the first practical device for recording and replaying sound—the forerunner of modern audio and video recording systems. Poulsen developed the telegraphone, an electromagnetic phonograph that could record and reproduce human speech on a steel wire, while employed with the Copenhagen Telephone Company. In 1903 he founded the American Telegraphone Company to market his invention, which by then was able to record for 30 continuous minutes. That same year he patented arc wireless transmission, a modification of Englishman William Duddell's "singing arc," which could generate continuous audio waves and paved the way for radio broadcasting.
"Valdemar Poulsen." Science and Its Times: Understanding the Social Significance of Scientific Discovery. . Encyclopedia.com. (September 25, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/valdemar-poulsen
"Valdemar Poulsen." Science and Its Times: Understanding the Social Significance of Scientific Discovery. . Retrieved September 25, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/valdemar-poulsen