Alan Blumlein and the invention of stereo
Alan Blumlein was the pioneer of stereo sound, and the British Library has put recordings of his voice and of early experiments up on its sound recording website. At the 70th anniversary of his death it is a tribute to a genius whom few have heard of.
In 1931 Blumlein's GB 394325 was applied for by Electric and Musical Industries Limited, later better known as EMI. It enabled the first single track, two channel gramophone recordings. Here is the main set of drawings.
It is a classic patent in the history of electrical engineering, and has the then extraordinary number of 70 claims (half a dozen was normal at the time). The story goes that he thought of the basic idea when he and his wife were at the cinema. The early "talkies" had a single set of speakers which meant that the actor might be on one side of the screen while his voice seemed to come from the other side. Blumlein declared to his wife that he had found a way to make the sound follow the actor across the screen.
Blumlein is credited with 128 patents in a working life of 18 years (he was only 38 when he died, while engaged in radar experiments in a Halifax bomber). A true polymath, he worked in virtually every field of electrical engineering. The Espacenet database lists 119 patents by Alan Blumlein.