Friction idiophones is designation 13 in the Hornbostel-Sachs system of musical instrument classification. These idiophones produce sound by being rubbed either against each other or by means of a non-sounding object. Instruments of this type are not very common; possibly the best known examples are the musical saw and the nail violin.
According to musicologist Curt Sachs:[1]
See main article: List of idiophones by Hornbostel–Sachs number.
131.1 Individual friction sticks.
131.2 Sets of friction sticks.
131.21 Without direct friction.
131.22 With direct friction.
132.1 Individual friction plaques.
132.2 Sets of friction plaques.
133.1 Individual friction vessels.
133.2 Sets of friction vessels.