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 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. 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. Vocal multiphonics 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. How multiphonics work In general, when playing a wind instrument, the tone that comes out consists of the fundamental—the pitch usually identified as the note being played—as well as pitches with frequencies that are integer multiples of the frequency of the fundamental. (Only pure sine wave tones lack these overtones.) Normally, only the fundamental pitch is perceived as being played. 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. Notation Multiphonics may be notated in score in a variety of ways. When exact pitches are specified, one method of notation is simply to indicate a chord, leaving the performer to