Who invented the first practical magnetic recording device, the telegraphone, patented in 1898?

Valdemar Poulsen invented the first practical magnetic recording device, the telegraphone, patented in 1898.

Poulsen was a Danish engineer who discovered that sound could be recorded by magnetizing a moving steel wire. His telegraphone used a wire and an electromagnet to record and reproduce speech, making it an early ancestor of tape recorders and computer magnetic storage.

Poulsen demonstrated the invention at the 1900 Paris Exposition, where it attracted attention as a way to record telephone conversations and messages. The device was technically important even though it did not immediately become a mass-market success.

Thomas Edison’s phonograph recorded sound mechanically in grooves, so it represents a different technology. Poulsen’s telegraphone instead used magnetic changes along wire, the principle later developed into magnetic tape recording.