String instrument strings, or play them by rolling the bell of a brass instrument such as a trombone on the array of strings. However, these are relatively rarely used special techniques. Other keyed string instruments, small enough for a strolling musician to play, include the plucked autoharp, the bowed nyckelharpa, and the hurdy-gurdy, which is played by cranking a rosined wheel. Steel-stringed instruments (such as the guitar, bass, violin, etc.) can be played using a magnetic field. An E-Bow is a small hand-held battery-powered device that magnetically excites the strings of an electric string instrument to provide a sustained, singing tone reminiscent
Barrel organ that of the English inventor John Burberry. The term hurdy-gurdy is sometimes mistakenly applied to a small, portable barrel organ that was frequently played by organ grinders and buskers (street musicians), but the two terms should not be confused. Although the hurdy-gurdy is also powered by a crank and often used by street performers, it produces sound with a rosin-covered wheel rotated against tuned strings. Another key difference is that the hurdy-gurdy player is free to play any tune he or she desires, while the barrel organist is generally confined to pre-programmed tunes. Some also confuse the barrel organ with