If you play a stringed instrument such as a violin or guitar, you can tighten or loosen the strings to alter their pitch. At a fairly early stage of your training you are taught how to use this tightening process to tune your instrument. This involves making the strings produce notes which are the correct distance apart in pitch. For example, the distance in pitch between any two adjacent violin strings is the same as the distance between ‘Baa’ and ‘Black’.