Take a message
The origins of audio recordings and the telephone answering machine

The world’s first audio recordings were made on a “Phonograph,” invented by Thomas Alva Edison in 1877. It used cylinders that were covered in tin foil, followed, in later models, by cylinders coated in wax. These were mechanical means of recording sound, but around the same time, a different approach was also being taken, using electromagnetism. In last month’s Pioneers’ Page, we asked which world leader features in the earliest surviving sound recording made by these means. The answer is: Emperor Franz Josef of the Austro-Hungarian Empire. At the Paris World Exhibition in 1900, the emperor spoke a few words of congratulation into a machine that had won the Grand Prix for its inventor: Valdemar Poulsen.

Poulsen was born in November 1869 in Copenhagen, the son of a judge at the Danish High Court. At the urging of his father, the young man began studying medicine; however, he soon left university to join the technical department of the Copenhagen Telephone Company in 1893. During this period, Poulsen might have come across the suggestion by Oberlin Smith that — in theory — an electromagnet could be used to record sound onto a string coated in iron filings. It seems likely, though, that the Danish engineer discovered the principle independently; in any case, he transformed it into a practical device that he patented in 1898. The “Telegraphone” was born.

The Telegraphone

The principle of the Telegraphone is described in Poulsen’s patent: “The invention is based upon the fact that when a body made of magnetisable material is touched at different points and at different times by an electromagnet included in a telephonic or telegraphic circuit, its parts are subject to such varied magnetic influences that, conversely, by the action of the magnetisable body upon the electromagnet, the same sounds or signals are subsequently given out in the telephone or recording instrument.”

The machine used a wire as the audio storage device, rather than recording tape. A steel wire of about 2200 metres in length was needed for one hour’s play; however, this could be contained on a spool of less than 10 centimetres in diameter, because the wire was no thicker than a human hair. In the original machine, this very thin wire was wrapped into grooves around a brass cylinder, with an electromagnet travelling across the wire to make the recording through a connected microphone. This was replaced by a telephone earpiece when the recording was played back. Later, the Telegraphone was developed into a reel-to-reel machine for moving the wire over a static recording head.

Compared with Phonograph recordings, those made on the Telegraphone were more free from noise and could play for longer periods. Just as cylinder recordings on the Phonograph later became disk recordings, Poulsen also developed a version of the Telegraphone that used metal disks, rather than wire. This provided more permanent recordings, which could only be erased under a strong magnetic force, in contrast with the wire-version Telegraphone, which could be used to record new material over the old.

David Morton/recording-history.org

An American advertisement for the Telegraphone stresses its capacity for recording again and again on the same wire. “No records to shave” refers to the need for Phonograph wax cylinders to be professionally shaved smooth before they could be re-used.

An answering machine too

One of the first uses of the Telegraphone was to expand the capacity of telegraph lines by recording Morse code messages at high speed. These could then be replayed more slowly for operators to decipher. Another application was for recording telephone conversations. This technique was also employed in transmitting a recorded message via the phone line to multiple recipients, and it could be used to record a caller’s message. In other words, Poulsen had also invented a telephone answering machine.

Extending the range of radio

The Telegraphone had some practical problems: it had low sound output, and the fine wires easily became tangled when being rewound for a new recording to be made. The devices did not become a commercial success. In any case, as the 20^th century began, Poulsen turned his attention to radio.

The Poulsen Arc converter, (or transmitter), was patented in 1903. This could produce continuous radio waves that allowed much more efficient use of radio transmitters with less interference than the previously used sparkgap method of generating waves. The invention meant that speech could be transmitted by radio over a distance of some 240 kilometres. Within 20 years, the Poulsen Arc had been improved to achieve a range of more than 4000 kilometres.

From wire to tape

Meanwhile, the technology of audio recording was progressing, in ways that Poulsen himself had predicted. He had experimented with steel tape (rather than wire) in the Telegraphone, and this technique was developed further by Semi Joseph Begun, in Germany. Recording onto paper tape coated with magnetic powder is an invention that is credited to both American inventor J. A. O’Neill and German engineer Fritz Pfleumer in the late 1920s. Plastic, magnetized tape first appeared in Germany in 1935, and became the basis for the later mass production of tape recorders.

Nowadays, although cassette tapes are still popular in many parts of the world, digital means of storing sound are ubiquitous. And increasingly, people are downloading music from the internet as well as — or instead of — storing it at home. But we should not forget the pioneers, such as Valdemar Poulsen, who first made practical the astonishing idea of recording sound.