Falsetto (Italian diminutive of falso, false) is a singing technique that produces sounds that are pitched higher than the singer's normal range, in the treble range. The term is also used to describe a slightly artificially-raised sounding pitch that often occurs momentarily, if repeatedly, in boys during puberty as their voice changes.
During normal speech or singing, the vocal folds (when viewed with a stroboscope) are seen to contact with each other completely during each vibration, closing the gap between them fully, if just for a very short time. This closure cuts off the escaping air. When the air pressure in the trachea rises as a result of this closure, the folds are blown apart, while the vocal processes of the arytenoid cartilages remain in apposition. This creates an oval shaped gap between the folds and some air escapes, lowering the pressure inside the trachea. Rhythmic repetition of this movement, a certain number of times a second, creates a pitched note. This is how the chest voice is created.
In falsetto, the vocal folds are seen to be blown apart and in untrained falsetto singers a permanent oval orifice is left in the middle between the edges of the two folds through which a certain volume of air escapes continuously as long as the register is engaged (the singer is singing using the voice). In skilled countertenors, however, the mucous membrane of the vocal folds contact with each other completely during each vibration cycle. The arytenoid cartilages are held in firm apposition in this voice register also. The length or size of the oval orifice or separation between the folds can vary, but it is known to get bigger in size as the pressure of air pushed out is increased. 
The folds are made up of elastic and fatty tissue. The folds are covered on the surface by laryngeal mucous membrane which is supported deeper down underneath by the innermost fibres of the thyro-arytenoid muscle. In falsetto the extreme membranous edges, i.e. the edges furthest away from the middle of the gap between the folds, appear to be the only parts vibrating. The mass corresponding to the innermost part of the thyro-arytenoid musscle remains still and motionless.
Some singers feel a sense of muscular relief when they change from chest voice to falsetto.
Use of falsetto voice in western music is very old. Its origins are difficult to trace because of ambiguities in terminology. In a book by GB Mancini, called Pensieri e riflessioni written in 1774, falsetto is equated with 'voce di testa' (translated as 'head voice'). Possibly when 13th century writers distinguished between chest, throat and head registers (pectoris, guttoris, capitis) they meant capitis to refer to what would be later called falsetto.
By the 16th century the term falsetto was common in Italy. The physician Giovanni Camillo Maffei in his book Discorso della voce e del modo d'apparare di cantar di garganta in 1562 explained that when a bass singer sang in the soprano range, the voice was 'called falsetto'.
The falsetto register is used by male countertenors to sing in the alto and occasionally the soprano range, and was before women sang in choirs. Falsetto is occasionally used by early music specialists today, and regularly in British cathedral choirs by men who sing the alto line.
In Opera it is believed that the chest voice, middle voice and head voice occur in women. The head voice of a man is, according to David A. Clippinger most likely equivalent to the middle voice of a woman. This may mean the head voice of a woman is a man's falsetto equivalent. Although, in contemporary teaching, some teachers no longer talk of the middle voice, choosing to call it the head voice as with men. Falsetto is not generally counted by classical purists as a part of the vocal range of anyone except countertenors. There are exceptions, however, such as the Bariton-Martin which uses falsetto (see baritone article).
In Hawai'i, many Hawaiian songs feature falsetto, called "leo ki'eki'e", a term coined in Hawaiian in 1973. Falsetto singing, most often used by men, extends the singer's range to notes above their ordinary vocal range. The voice makes a characteristic break during the transition from the ordinary vocal register to the falsetto register. In Western falsetto singing, the singer tries to make the transition between registers as smooth as possible. In Hawaiian-style falsetto, the singer emphasizes the break between registers. Sometimes the singer exaggerates the break through repetition, as a yodel. As with other aspects of Hawaiian music, falsetto developed from a combination of sources, including pre-European Hawaiian chanting, early Christian hymn singing and the songs and yodeling of immigrant cowboys during the Kamehameha Reign in the 1800's when cowboys were brought from Mexico to teach Hawaiians how to care for cattle. Falsetto may have been a natural and comfortable vocal technique for early Hawaiians, since a similar break between registers called "ha'iha'i", is used as an ornament in some traditional chanting styles.
There is a difference between the modern usage of the "head voice" term and its previous meaning in the renaissance as a type of falsetto, according to many singing professionals. The falsetto can be coloured or changed to sound different. It can be given classical styling to sound as male classical countertenors make it sound, or more contemporary as is the case in modern R&B music (Justin Timberlake or Frankie J for example). It can be made in different tonalities as is often the case of its use in progressive rock (for example,Roger Meddows-Taylor, Matt Bellamy of the band Muse), heavy metal (for example, King Diamond of Mercyful Fate), and especially power metal (for example, Michael Kiske of Helloween). Chris Martin of the alternative/indie rock band Coldplay also frequently uses falsetto.
- THE NEW GROVE Dictionary of MUSIC & MUSICIANS. Edited by Stanley Sadie, Volume 6. Edmund to Fryklund. ISBN 1-56159-174-2, Copyright Macmillan 1980.
- The OXFORD DICTIONARY OF OPERA. JOHN WARRACK AND EWAN WEST, ISBN 0-19-869164-5
- Clippinger, David Alva (1917). The Head Voice and Other Problems: Practical Talks on Singing. Oliver Ditson Company. pp. Page 24. line feed character in
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- THE NEW GROVE Dictionary of MUSIC & MUSICIANS. Edited by Stanley Sadie, Volume 2. Back to Bolivia. ISBN 1-56159-174-2, Copyright Macmillan Publishers Limited 1980.
- Justin Timberlake: 'FutureSex/LoveSounds' by Christy Lemire - Associated Press - Sept. 11, 2006 - Timberlake's falsetto layering on top of one other as the songs build to their crescendos. link
- Glossary definition of falsetto at Virginia Tech's Web site