linguistic:voice_change
Tension

Pitch can be adjusted by varying the 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. 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: