String instrument rosin than players of lower-pitched instruments, who tend to favor darker, softer rosin. The ravanahatha is one of the oldest string instruments. Ancestors of the modern bowed string instruments are the rebab of the Islamic Empires, the Persian kamanche and the Byzantine lira. Other bowed instruments are the rebec, hardingfele, nyckelharpa, kokyū, erhu, igil, sarangi and K'ni. The hurdy-gurdy is bowed by a wheel. Rarely, the guitar has been played with a bow (rather than plucked) for unique effects. The third common method of sound production in stringed instruments is to strike the string. The piano and hammered dulcimer use
Hurdy-gurdy to keys that change the vibration length of the string, much as a guitarist uses his or her fingers on the fretboard of a guitar. In the earliest hurdy-gurdies these keys were arranged to provide a Pythagorean temperament, but in later instruments the tunings have varied widely, with equal temperament most common because it allows easier blending with other instruments. However, because the tangents can be adjusted to tune individual notes, it is possible to tune hurdy-gurdies to almost any temperament as needed. Most contemporary hurdy-gurdies have 24 keys that cover a range of two chromatic octaves. To achieve proper