Walter Wilhelm is known as the creator of the microphone with two separate chambers and membranes. An electrician by profession, from 1894-95, Wilhelm experimented with telephone transmitters and, as a result, invented a unique and futuristic microphone. In 1896 he patented his invention and two years later, in 1898, set up the Wilhelm Telephone Mfg Company in the U.S., which began to produce telephones with his microphone. His devices had a high enough demand and were installed in private homes and in various U.S. institutions.
According to some reports, Wilhelm tried to sell his patent to Bell but, for unknown reasons, an agreement was not reached. In 1913, the Wilhelm Telephone Mfg Company ceased to exist. But later microphones, invented by the electrician Walter Wilhelm, were used by many handset manufacturers.