1827: Sir Charles Wheatstone was the first person to coin the phrase “microphone.” A renowned English physicist and inventor, Wheatstone is best known for inventing the telegraph. His interests were varied, and he devoted some of his time the study of acoustics during the 1820s. Wheatstone was among the first scientists to formally recognize that sound was “transmitted by waves through mediums.” This knowledge led him to explore ways of transmitting sounds from one place to another, even over long distances. He worked on a device that could amplify weak sounds, which he called a microphophone.

Source:
https://www.thoughtco.com/history-of-microphones-1992144