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
Pehr Hörberg fiddle and nyckelharpa (keyed fiddle) are among the most common Swedish folk instruments. This instrumental genre is the biggest one in Swedish traditional music. A nyckelharpa (literally "key harp", plural nyckelharpor or sometimes keyed fiddle) is a traditional Swedish musical instrument. It is a string instrument or chordophone. Its keys are attached to tangents which, when a key is depressed, serve as frets to change the pitch of the string. The nyckelharpa is similar in appearance to a fiddle or the bowed Byzantine lira but is more closely related to the hurdy-gurdy, both employing key-actuated tangents to change the pitch.