Noun
English Wikipedia has an article on:multiphonicsWikipedia
multiphonics (uncountable)
(music) The sounding of two or more pitches simultaneously, either with the voice, or on an instrument that normally sounds only single notes.
Sheets of sound, tonal exploration, upper harmonics, and multiphonics were hallmarks of the creative possibilities that saxophones offered in the new realm. Source: Internet
The extended technique of playing multiphonics also produces harmonics. Source: Internet
This eliminates cracking, or brief multiphonics that happens without the use of this technique. Source: Internet