In music, a drone is a harmonic or monophonic effect or accompaniment where a note or chord is continuously sounded throughout most or all of a piece. The word drone is also used to refer to any part of a musical instrument that is just used to produce such an effect.
Musical effect 
A drone effect can be achieved through a sustained sound or through repetition of a note. It most often establishes a tonality upon which the rest of the piece is built. A drone can be instrumental, vocal or both.
History and distribution 
The systematic (not occasional) use of drones originated in instrumental music of ancient Southwest Asia, including that of Australian Indigenous peoples, and spread north and west to Europe, east to India, and south to Africa (van der Merwe 1989, p.11). It is used in Indian music and is played with the tanpura (or tambura) and other Indian drone instruments like the ottu, the ektar, the dotara (or dotar; dutar in Persian Central Asia), the surpeti, the surmandal (or swarmandal) and the shank (conch shell). In the West, they are found since the 1960s in modern drone music.
In vocal music drone is particularly widespread in traditional musical cultures, particularly in Europe, Polynesia and Melanesia. It is also present in some isolated regions of Asia (like among Pearl-divers in Persian Gulf, some national minorities of South-West China, Taiwan, Vietnam, Afghanistan); Drone (both instrumental and vocal) can be placed in different ranges of the polyphonic texture: in the lowest part, in the highest part, or in the middle.
Part(s) of a musical instrument 
Drone is the name of the part of a musical instrument intended to produce the drone effect's sustained pitch, generally without the ongoing attention of the player. Different melodic Indian instruments (e.g. the sitar, the sarod, the sarangi and the rudra veena) contain a drone. For example, the sitar features three or four resonating drone strings, and Indian notes (sargam) are practiced to a drone. Bagpipes (like the Great Highland Bagpipe and the Zampogna) feature a number of drone pipes, giving the instruments their characteristic sounds. A hurdy-gurdy has one or more drone strings. The fifth string on a five-string banjo is a drone string with a separate tuning peg that places the end of the string five frets down the neck of the instrument; this string is usually tuned to the same note as that which the first string produces when played at the fifth fret, and the drone string is seldom fretted. The bass strings of the Slovenian drone zither also freely resonate as a drone.
Effect in musical compositions 
Composers of Western classical music occasionally used a drone (especially one on open fifths) to evoke a rustic or archaic atmosphere, perhaps echoing that of Scottish or other early or folk music. Examples include the following:
- Haydn, Symphony No. 104, "London", opening of finale, accompanying a folk melody
- Beethoven, Symphony No. 6, "Pastoral", opening and trio section of scherzo
- Berlioz, Harold in Italy, accompanying oboes as they imitate the pifferi of Italian peasants
- Bartók, in his adaptations for piano of Hungarian and other folk music
- Mahler, Symphony No. 1, introduction; a seven-octave drone on A evokes "the awakening of nature at the earliest dawn"
However, drones are less often used in common practice classical music, because equal temperament causes slight mistunings, which become more apparent over a drone, especially when also sustained. On the other hand, drones may be purposely dissonant, as often found in the music of Phill Niblock. The best-known drone piece in the concert repertory is the Prelude to Wagner's Das Rheingold (1854) wherein the bass instruments sustain an Eb throughout the entire movement (Erickson 1975, p. 94). Later drone pieces include Loren Rush's Hard Music (1970), Folke Rabe's Was?? (1968), and Robert Erickson's Down at Piraeus.
Contemporary classical musicians who make prominent use of drones, often with just or other non-equal tempered tunings, include La Monte Young and many of his students, David First, the band Coil, the early experimental compilations of John Cale (Sun Blindness Music, Dream Interpretation, and Stainless Gamelan), Pauline Oliveros and Stuart Dempster, Alvin Lucier (Music On A Long Thin Wire), Ellen Fullman, Lawrence Chandler and Arnold Dreyblatt. The music of Italian composer Giacinto Scelsi is essentially drone-based. Shorter drones or the general concept of a continuous element are often used by many other composers. Other composers whose music is entirely based on drones include Charlemagne Palestine and Phill Niblock.
Drone was virtually absent in original Rock'n'Roll music, but gained popularity after The Beatles used drone in a few popular compositions (for example, "Blackbird" has a drone in the middle of a texture throughout the whole song, "Tomorrow Never Knows" has a drone in the bass). They also used high drone for the dramatic effect in some sections of several of their compositions (like the last verses of "Yesterday" and "Eleanor Rigby"). The rock ensemble U2 uses drones in their compositions particularly widely. Also the avant-garde guitarist Glenn Branca uses drones extensively.
A drone differs from a pedal tone or point in degree or quality. A pedal point may be a form of nonchord tone and thus required to resolve unlike a drone, or a pedal point may simply be considered a shorter drone, a drone being a longer pedal point.
Use for musical training 
Drones are used by a number of music education programs for ear training and pitch awareness, as well as a way to improvise ensemble music. A Shruti box is often used by vocalists in this style of musical training.
See also 
- Drone music or "dronology" - a post-classical, minimalist music genre with heavy emphasis on the drone harmonic effect.
- Drone metal - a form of heavy metal music focusing almost entirely on droning, heavily downtuned electric guitar and bass guitar, often lacking vocals or drums.
- Burden (music) - archaic word for drone
- Joseph Jordania (2006). Who Asked the First Question? The Origins of Human Choral Singing, Intelligence, Language and Speech. Tbilisi: Logos. ISBN 99940-31-81-3.
- Erbsen, Wayne (2004). Bluegrass Banjo for the Complete Ignoramus, p.13. ISBN 1-883206-44-8.
- Oshinsky, James (January 2008). Return to Child - Music for People’s Guide to Improvising Music and Authentic Group Leadership (Second Edition ed.).
- Clint Goss (2011). "Reference Drones". Flutopedia. Retrieved 2011-11-08.
- Erickson, Robert (1976). Sound Structure in Music. University of California Press. ISBN 0-520-02376-5.
- van der Merwe, Peter (1989). Origins of the Popular Style: The Antecedents of Twentieth-Century Popular Music. Oxford: Clarendon Press. ISBN 0-19-316121-4.