Carbon microphone
The first microphone that enabled proper voice telephony was the (loose-contact) carbon microphone (then called transmitter). This was independently developed around 1878 by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent 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.
Emile Berliner
After some time working in a livery stable, he became interested in the new audio technology of the telephone and phonograph, and invented an improved telephone transmitter (one of the first type of microphones). The patent was acquired by the Bell Telephone Company (see "The Telephone Cases"). In America, Thomas Edison and Berliner fought a long legal battle over the patent rights. But on February 27, 1901 the United States Court of Appeal declared the patent void and awarded Edison full rights to the invention, stating "Edison preceded Berliner in the transmission of speech...The use of carbon in a transmitter is, beyond controversy, the invention of Edison" and the Berliner patent was ruled invalid. Berliner subsequently moved to Boston in 1877 and worked for Bell Telephone until 1883, when he returned to Washington and established himself as a private researcher. Emile Berliner became a United States citizen in 1881. Berliner also invented what was probably the first radial aircraft engine (1908), a helicopter (1919), and acoustical tiles (1920s).
In 1886 Berliner began experimenting with methods of sound recording. He was granted his first patent for what he called the "Gramophone" in 1887. The patent described recording sound using horizontal modulation of a stylus as it traced a line on a rotating cylindrical surface coated with an unresisting opaque material such as lampblack, subsequently fixed with varnish and used to photoengrave a corresponding groove into the surface of a metal playback cylinder. In practice, Berliner opted for the disc format, which made the photoengraving step much less difficult and offered the prospect of making multiple copies of the result by some simpler process such as electrotyping, molding or stamping. In 1888 Berliner was using a more direct recording method, in which the stylus traced a line through a very thin coating of wax on a zinc disc, which was then etched in acid to convert the line of bared metal into a playable groove.