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 a functionally significant component of telephones. (TV: The War Machines) In addition, microphones were also potential components of some forms of headphones (TV: The Ark in Space) and earpieces. (TV: Dalek)

Smaller microphones were worn on the clothing of television presenters and newsreaders to allow their voice to be picked up easily. (TV: Army of Ghosts etc.)

Davros had a throat microphone that enhanced his damaged voice. (TV: Genesis of the Daleks)

The Eleventh Doctor's sonic screwdriver could function as a microphone. (TV: The God Complex)

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