artificial harmonic
A harmonic produced by stopping a string with one finger and lightly touching it with another finger a perfect fourth above
In Depth
Artificial harmonics allow the player to produce harmonic tones from any stopped pitch, not just open strings. The stopped finger acts as a new nut, and the touching finger isolates the fourth partial, producing a note two octaves above the stopped pitch. The technique is demanding because both fingers must be placed with extreme accuracy. Artificial harmonics extend the violin's range far above the fingerboard and produce an ethereal, glassy tone used for magical and atmospheric effects.
Ravel's Tzigane opens with an extended passage of artificial harmonics that sounds otherworldly — and is extraordinarily difficult to play in tune.