A multiphonic<span> is an </span>extended technique<span> on a </span>monophonic musical instrument<span> (one which generally produces only one note at a time) in which several notes are produced at once. This includes wind, reed, and brass instruments, as well as the human voice. Multiphonic-like sounds on string instruments, both bowed and hammered, have also been called multiphonics, for lack of better terminology and scarcity of research.</span>