Poulsen obtient le brevet du télégraphone avec son assistant, Peder O. Pedersen. 

Magnetic recording had been around since Valdemar Poulsen's 'Telegraphone' of 1899 - a wire recorder without amplification (the carbon microphone - as used in telephones - was connected directly to the recording head) which could just about drive headphones. However there were many technical difficulties, and it was not until the late 1920s that a moderately practicable magnetic recorder was developed in Germany.

Willy Aubert