Multiphonic

Multiphonic-like sounds on string instruments, both bowed and hammered, have also been called multiphonics, for lack of better terminology and scarcity of research.

It is said to be impossible to recreate exactly the conditions between one player and the next, due to minute differences in instruments, reeds, embouchure, and other things.

Another method is referred to as "lip multiphonics", in which a brass player alters the airflow to blow between partials, in the harmonic series of the slide position/valve.

A third method, known as 'split tones' or double buzz, produces multiphonics when players make their lips vibrate at different speeds against each other.

This is well known for achieving a spacey "ring modulation" sound (e.g. by Jim Carrey in The Truman Show).

By controlling the air flow through the instrument and the shape of the column (by changing fingering or valve position), a player may produce two distinct tones not part of the same harmonic series.

When exact pitches are specified, one method of notation is simply to indicate a chord, leaving the performer to figure out what techniques are necessary to achieve it.

Approximate pitches may be specified by wavy lines or in cluster notation to designate acceptable ranges of sound.

Piano multiphonic notation can include, among other factors, the numbers of sounding partials or fingering distances on the string.

[citation needed] Woodwind multiphonics and brass lip multiphonics did not make appearances in classical music until the 20th century, with pioneering compositions such as Luciano Berio's Sequenzas for solo wind instruments[3][4] and Proporzioni for solo flute by Franco Evangelisti using them extensively in 1958.