Microphone
German inventor Johann Philipp Reis designed an early sound transmitter that used a metallic strip attached to a vibrating membrane that would produce intermittent current. Better results were achieved with the "liquid transmitter" design in Scottish-American Alexander Graham Bell's telephone of 1876 – the diaphragm was attached to a conductive rod in an acid solution. These systems, however, gave a very poor sound quality.
The first microphone that enabled proper voice telephony was the (loose-contact) carbon microphone. This was independently developed by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent (after a long legal dispute) in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, and most historians credit him with its invention. The carbon microphone is the direct prototype of today's microphones and was critical in the development of telephony, broadcasting and the recording industries. Thomas Edison refined the carbon microphone into his carbon-button transmitter of 1886. This microphone was employed at the first ever radio broadcast, a performance at the New York Metropolitan Opera House in 1910.
In 1916, E.C. Wente of Western Electric developed the next breakthrough with the first condenser microphone. In 1923, the first practical moving coil microphone was built. The Marconi-Sykes magnetophone, developed by Captain H. J. Round, became the standard for BBC studios in London. This was improved in 1930 by Alan Blumlein and Herbert Holman who released the HB1A and was the best standard of the day.
David Edward Hughes
In 1878 Hughes published his work on the effects of sound on the powered electronic sound pickups, called "transmitters", being developed for telephones. He showed that the change in resistance in carbon telephone transmitters was a result of the interaction between carbon parts instead of the commonly held theory that it was from the compression of the carbon itself. Based on its ability to pick up extremely weak sounds, Hughes referred to it as a ""microphone" effect" (using a word coined by Charles Wheatstone in 1827 for a mechanical sound amplifier). He conducted a simple demonstration of this principle of loose contact by laying an iron nail across two other nails connected to a battery and galvanometer. His paper was read before the Royal Society of London by Thomas Henry Huxley on May 8, 1878 and his new "microphone" was covered in the July 1 edition of "Telegraph Journal and Electrical Review". Hughes published his work during the time that Thomas Edison was working on a carbon telephone transmitter and Emile Berliner was working on a loose-contact transmitter. Both Hughes and Edison may have based their work on Philipp Reis' telephone work. Hughes would refine his microphone design using a series of "carbon pencils" stuck into blocks of carbon to better pick up sound but never patented his work, thinking it should be publicly available for development by others.