Microphone

A microphone was a piece of technology meant to amplify voice. The Eleventh Doctor described them as amplifying one's natural abilities. (TV: Hide) Microphones were often used for communication purposes, most often as a component in something more elaborate, allowing those who used them to communicate across long distances. (TV: The Dalek Invasion of Earth, The Rescue etc.)

Microphones were used by singers as early as the 1940s. (TV: The Empty Child)