Native American music in North America is almost entirely monophonic, but there are notable exceptions. Traditional Native American music often centers around drumming. Rattles, clappersticks, and rasps were also popular percussive instruments. Flutes were made of rivercane, cedar, and other woods. The tuning of these flutes is not precise and depends on the length of the wood used and the hand span of the intended player, but the finger holes are most often around a whole step apart and, at least in Northern California, a flute was not used if it turned out to have an interval close to a half step. The Apache fiddle is a single stringed instrument.