* String tension. The tighter the strings, the higher the pitch. This is because the strings vibrate faster when they are tight.
* String length. The longer the strings, the lower the pitch. This is because the strings vibrate slower when they are long.
* String mass. The heavier the strings, the lower the pitch. This is because the strings vibrate slower when they are heavy.
* Body size. The larger the body of the instrument, the lower the pitch. This is because the body of the instrument acts as a resonator, amplifying the sound of the strings.
In general, larger instruments with longer strings and thicker strings will produce lower sounds than smaller instruments with shorter strings and thinner strings. Some examples of low-pitched stringed instruments include the bass guitar, the double bass, and the cello.