Editing String instrument (section)

===Tension===

Pitch can be adjusted by varying the [[Tension (physics)|tension]] of the string. A string with less tension (looser) results in a lower pitch, while a string with greater tension (tighter) results in a higher pitch. Pushing a pedal on a [[pedal steel guitar]] raises the pitch of certain strings by increasing tension on them (stretching) through a mechanical linkage; release of the pedal returns the pitch to the original. Knee levers on the instrument can lower a pitch by releasing (and restoring) tension in the same way.<ref>{{cite web|last=Brenner|first=Patrick|title=Early History of the Steel Guitar|url=http://steelguitaramerica.com/instruction/history/|website=steelguitaramerica.com|publisher=Patrick Brenner|access-date=March 17, 2021}}</ref> A homemade [[washtub bass]] made out of a length of rope, a broomstick and a washtub can produce different pitches by increasing the tension on the rope (producing a higher pitch) or reducing the tension (producing a lower pitch). The frequency is proportional to the square root of the tension:

:<math>
f \propto \sqrt{T}
</math>