"Guitar tuner" redirects here, but can also refer to the string tension adjusters also called machine heads. For the radio receiver component, see Tuner (radio)In music, an electronic tuner is a device that detects and displays the pitch of musical notes. Simple tuners indicate—typically with a needle-dial, LED, or LCD display—whether a pitch is lower, higher, or equal to the desired pitch. Software applications can turn a smartphone, tablet, or personal computer into a tuner.