String noise


In guitar and string instrument technique, string noise is the noise created by the movement of the fingers of the left hand up or down on the strings such as when shifting on one string or changing from one string to another caused by continued contact with the string while moving the finger. It is generally relatively quiet but parallel string motion brings out higher, more dissonant, harmonics than perpendicular string motion. However this should not be confused with parallel rather than perpendicular bowing, which is relatively quite loud and harsh.
If the pressure was consistent then the result would be a glissando, if the pressure is eliminated then string noise does not result but the movement is more difficult. On fretted string instruments the frets guide the movement of the hand, making the movement easier, but the frets increase the amount of contact, making fret noise more difficult to avoid.
While it is often an unwanted side-effect, especially when playing with high distortion, it can be used as a stylistic choice.