Invention of the telephone
The carbon microphone 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.
Raymond A. Litke
Litke invented a wireless microphone in 1957 while employed as an electronics expert at San Jose State College. His supervisor challenged him to invent a microphone to use in educational presentations which would be free of wires.