The Great Highland Bagpipe is powered by four separate reeds. Three single-tongue reeds are inserted into the bottom of each drone. Their job is to produce a steady background of harmony. A double-reed is inserted into the top of the chanter and produces the sound with which the melody is played.
Reeds must be carefully and thoughtfully selected, broken-in, and adjusted to maximize the potential of both bagpipe and piper. I’ve tried to break things down into logical topics herein, but if you need something you don’t see, just ask.