String Instrument - Production of Multiple Notes

Production of Multiple Notes

A string at a certain tension and length will only produce one note, so to obtain multiple notes, string instruments employ one of two methods. One is to add enough strings to cover the range of notes desired; the other is to allow the strings to be stopped. The piano and harp are examples of the former method, where each note on the instrument has its own string or course of multiple strings. (Many notes on a piano are strung with a "choir" of three strings tuned alike.)

Some zithers combine stoppable (melody) strings with a greater number of "open" harmony or chord strings. On instruments with stoppable strings, such as the violin or guitar, the player can shorten the vibrating length of the string, using their fingers directly (or more rarely through some mechanical device, as in the nyckelharpa or the hurdy gurdy). Such instruments usually have a fingerboard attached to the neck of the instrument, that provides a hard flat surface athe player can stop the strings against. On some string instruments, the fingerboard has frets, raised ridges perpendicular to the strings that stop the string at precise intervals, in which case the fingerboard is also called a fretboard.

Moving frets during performance is usually impractical. The bridges of a koto, on the other hand, may be moved by the player, occasionally in the course of a single piece of music. Many modern Western harps include levers, either directly moved by fingers (on Celtic harps) or controlled by foot pedals (on orchestral harps), to raise the pitch of individual strings by a fixed amount. The middle Eastern zither, the qanun, is equipped with small levers called mandal that allow each course of multiple strings to be incrementally retuned "on the fly" while the instrument is being played. These levers raise or lower the pitch of the string course by a microtone, less than a half step.