Editing Overtone (section)

==="Overtones" in choral music===
In [[barbershop music]], a style of four-part singing, the word ''overtone'' is often used in a related but particular manner. It refers to a [[psychoacoustic]] effect in which a listener hears an audible pitch that is higher than, and different from, the fundamentals of the four pitches being sung by the quartet. The barbershop singer's "overtone" is created by the interactions of the upper partial tones in each singer's note (and by sum and difference frequencies created by nonlinear interactions within the ear). Similar effects can be found in other ''a cappella'' polyphonic music such as the music of the [[Georgia (country)|Republic of Georgia]] and the [[Music of Sardinia|Sardinian]] ''[[cantu a tenore]]''. Overtones are naturally highlighted when singing in a particularly resonant space, such as a church; one theory of the development of [[polyphony]] in Europe holds that singers of [[Gregorian chant]], originally monophonic, began to hear the overtones of their monophonic song and to imitate these pitches - with the fifth, octave, and major third being the loudest vocal overtones, it is one explanation of the development of the [[triad (music)|triad]] and the idea of [[consonance]] in music.

The first step in composing choral music with overtone singing is to discover what the singers can be expected to do successfully without extensive practice. The second step is to find a musical context in which those techniques could be effective, not mere special effects. It was initially hypothesized that beginners would be able to:<ref name=hnm>{{cite journal |last1=Hinds |first1=Stuart |title=New Music for chorus with Overtone Singing |journal=The Choral Journal|publisher=[[American Choral Directors Association]]|date=April 2007 |volume= 47| issue = 10 |pages=20–31|jstor=23557310}}</ref>

*[[glissando]] through the partials of a given fundamental, ascending or descending, fast, or slow
*use vowels/text for relative pitch gestures on indeterminate partials specifying the given shape without specifying particular partials
*improvise on partials of the given fundamental, [[Ad libitum|''ad lib.'']], freely, or in giving style or manner
*find and sustain a particular partial (requires interval recognition)
*by extension, move to an adjacent partial, above or below, and alternate between the two

Singers should not be asked to change the fundamental pitch while overtone singing and changing partials should always be to an adjacent partial. When a particular partial is to be specified, time should be allowed (a beat or so) for the singers to get the harmonics to "speak" and find the correct one.<ref name=hnm/>