Danish engineer Valdemar Poulsen (1869-1942) developed the first magnetic recording system. It was the direct antecedent of analog tape recording, the medium for which most audio was captured throughout the twentieth century.
The operating principles differed little from later analog recording systems. A motorized assembly pulled a spool of hair-thin wire at a constant speed across a magnetic recording head. The sound intended for capture was converted to electrical pulses that were then fed through a record head that imposed a pattern of magnetization onto the wire analogous to the original signal. The spool was then rewound, and the wire passed across a playback head that detected changes in the magnetic field stored on the wire; these were converted back to a continuous electrical signal that could then be heard.
Poulsen patented his Telegraphone in 1898. Two years later he took it to the World Exposition in Paris, where he recorded the voice of Austrian emperor Franz Joseph, which remains the oldest surviving magnetic audio recording. Poulsen was awarded the Grand Prix for scientific invention and found licensees for production in Europe and the United States.
In the first half of the twentieth century, the wire recorder was used as an office dictation machine. By the 1940s, the audio quality had improved and wire recorders were used in radio broadcasting. After World War II, manufacturers tried to introduce domestic wire recorders for home entertainment use, but the development of the magnetic tape recorder in the early 1950s all but rendered the medium obsolete.
