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.
Moving iron speaker
The first moving iron transducer, the telephone receiver or earphone, evolved with the first telephone systems in the 1870s. Moving iron horn loudspeakers developed from earphones after the first amplifying device which could drive a speaker, the triode vacuum tube, was perfected around 1913. They were used in radio receivers and the first public address systems. Moving iron cone loudspeakers appeared around 1920. Around 1930 they were replaced by the moving coil cone loudspeaker developed in 1925 by Edward Kellogg and Chester Rice. Today the moving iron driver mechanism is still used in some earphones.