Multiphonic

Frequency spectrum of this sound

On woodwind instruments—e.g., saxophone, clarinet, oboe, bassoon, flute, and recorder—multiphonics can be produced either with new fingerings, by using different embouchures, or voicing the throat with conventional fingerings. There have been numerous fingering guides published for the woodwind player to achieve harmonics. Multiphonics on reed instruments can also be produced in the manners described below for brass instruments.

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. This, however, is not entirely true; the multiphonic will depend on the room temperature and other such things, but essentially multiphonics sound the same due to the harmonic structure of the multiphonic. A multiphonic fingering that works for one player may not work for that same player on a different instrument, or a different player on the same instrument, or even after switching reeds. This is often the result of slightly different construction of two instruments from different makers.

In brass instruments, the most common method of producing multiphonics is by simultaneously playing the instrument and singing into it. When the sung note has a different frequency than the played note (preferably within the harmonic series of the played note), several new notes that are the sums/differences of the frequencies of the sung note and the played note are produced; leading to the popular term trumpet/trombone/horn growl. This technique is also called "horn chords". The tone sung doesn't necessarily have to be in the played tone's harmonic series, but the effect is more audible if it is. The tone quality of brass multiphonics is influenced strongly by the voice of the player.

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. The outcome is just as stable as any multiphonic and perfectly structured. When the frequencies add together or subtract from each other (essentially merge), the fundamental is recreated. For example: A 440 and A 220. This would combine to make 660, creating a new fundamental of the second lowest B of the piano.

A third method, known as 'split tones' or double buzz, produces multiphonics when players make their lips vibrate at different speeds against each other. The most common result is a perfect interval, but the range of intervals produced can vary broadly.

String instruments can also produce multiphonic tones when strings are bowed or hammered (as in piano multiphonics) between the harmonic nodes. This works best on larger instruments like double bass and cello.[1] Another technique involves the rotational oscillation mode of the string, which might be twisted to adjust the rotational tension. Other multiphonic extended techniques used are prepared piano, prepared guitar and 3rd bridge.

The technique of producing multiphonics with the voice is called overtone singing (typically with secondary resonant structure) or throat singing (typically with additional tones from throat trills).

There is another technique done in whistling, where whistlers hum in their throats while whistling with the front parts of their mouths. This is well known for achieving a spacey "ring modulation" sound (e.g. by Jim Carrey in The Truman Show). All three vibrations—whistle, voice and throat trill—can be combined also.