On a stringed instrument such as a piano or a guitar, the frequency is affected by the length and thickness of the string. Longer strings have lower frequencies.Thicker strings have lower frequencies.

• The tension on a string also affects the rate at which it vibrates.
• Increasing the tension on a string causes it to vibrate at a faster rate. 

A guitar tuning mechanism is used to increase the tension on the string by winding it more tightly.