An electronic tuner is a device used by cellists to detect and display the pitch of notes played on the cello. The simplest tuners use LED lights or a needle to indicate approximately whether the pitch of the note played is lower, higher, or approximately equal to the desired pitch. More complex and expensive tuners indicate more precisely the difference between offered note and desired pitch.
Tuners vary in size from units that can fit in a pocket to table-top models or 19" rack-mount units. The more complex and expensive units are used by instrument technicians.
The simplest tuners only detect and display the tuning for a single pitch (often "A" or "E") or for a small number of pitches, such as the six pitches used in the standard tuning of a guitar (E,A,D,G,B,E). More complex tuners offer chromatic tuning, which allows all the 12 notes of the scale to be tuned. Some electronic tuners offer additional features, such as adjustable pitch calibration, different tempered scale options, the sounding of a desired pitch through an amplifier and speaker, and adjustable "read-time" settings which affect how long the tuner takes to measure the pitch of the note.
The most accurate tuning devices are strobe tuners, which work in a different way to regular electronic tuners; they are basically stroboscopes. These can be used to tune any instrument, including the initial "beating" of steelpan drums, bagpipes, accordions, calliopes, bells, the pins in Music Boxes or any audio device much more accurately than regular LED, LCD or needle display tuners. However, strobe units are generally much more expensive, and the mechanical elements of a mechanical (rather than electronic-display) strobe require periodic servicing. Therefore, these tuners are mainly used by specialists and professional instrument technicians.
Classical music In classical music, there is a longstanding tradition to tune "by ear", by adjusting the pitch of instruments to a reference pitch. In an orchestra, the oboe player gives a 440 Hz "A", and the different instrument sections tune to this note. In chamber music, either one of the woodwind players gives an "A", or if there are no wind players, the first violinist plays their open "A" string. More rarely, the cello player from a string quartet may give the tuning "A". Despite this tradition for tuning by ear, electronic tuners are still widely used in classical music. In orchestras, the oboist who plays the tuning "A" often has a high-end electronic tuner to ensure that his or her "A" is correct. As well, other brass or woodwind players may use electronic tuners to ensure that their instruments are correctly tuned. Classical performers also use tuners off-stage, for practice purposes, either to check their tuning or practice ear training with tuners that sound notes with a speaker.
Electronic tuners are also used in opera orchestras for offstage trumpet effects. In offstage trumpet effects, the trumpet player performs a melody from the backstage or from a hallway behind the stage, creating a haunting, muted effect. Since the trumpet player cannot hear the orchestra, they cannot know if they are in tune with the rest of the ensemble; to resolve this problem, some trumpet players use a high-end, sensitive tuner so that they can monitor the pitch of their notes.
Even piano tuners who work mostly "by ear" may use an electronic tuner to tune the first note on the piano, to which they then adjust the other notes.