Magnetic tape
The third wave of development in audio recording began in 1945 when the allied nations gained access to a new German invention: magnetic tape recording. The technology was invented in the 1930s but remained restricted to Germany (where it was widely used in broadcasting) until the end of World War II. Magnetic tape provided another dramatic leap in audio fidelity — indeed, Allied observers first became aware of the existence of the new technology because they noticed that the audio quality of obviously pre-recorded programs was practically indistinguishable from live broadcasts.