The great highland bagpipe has three drones used for harmonies. The big one is called a “bass drone” and the two little one are called the tenors. These three drones are tuned on the same note and give the background sound that harmonizes with the chanter. The length of the drones can be adjusted to tune them. If the length is shorten, the pitch will be sharper, if it’s lengthen, the pitch will be lower. 