Making Panpipes — A Row of Tuned Bamboo Tubes

Panpipes are one of the oldest melody instruments: a row of closed tubes, each cut to a length that sounds a single note when you blow across its top.

Pick straight bamboo about a finger-width thick. You want lengths that each keep a solid node (the natural wall inside) to seal one end.

Saw a tube about 18 cm long, cutting just below a node so the bottom is sealed. This will be your lowest note.

Cut five or six more tubes, each about 2 cm shorter than the last, always keeping a sealed node at the bottom. Shorter tubes give higher notes.

Rub the open top edge of each tube smooth and level, so your breath splits cleanly across it.

Stand the tubes side by side in order, longest to shortest, with all the open tops level in a straight line.

Lash the tubes together with twine, wrapping firmly near the top and again near the bottom so the row sits flat and rigid.

Rest the top edge of the longest tube on your lower lip and blow ACROSS it, not into it — like blowing over a bottle. A clear note appears.

Slide along the row, blowing across each tube in turn. The notes rise as the tubes get shorter — that is your scale.

Measure each tube with a ruler and note its pitch on a free tuner app. Longer tube, lower note — plot the pairs and see the pattern.

Drop a small pellet of beeswax into the bottom of the tube. Shortening the air column raises its pitch — add wax a little at a time until it matches.

You cannot make a tube longer, so cut a fresh, slightly longer tube instead. A longer air column always gives a lower note.

Blowing across the top sets the air INSIDE the tube vibrating as a standing wave. Because the bottom is closed and the top is open, the tube is a 'stopped pipe': the longest wave that fits is about four times the tube's length, so the note's frequency is roughly f = v / (4L), where v is the speed of sound (about 343 m/s in air) and L is the tube length. That is why halving a tube's length raises its note by one octave, and why beeswax in the bottom (which shortens the air column) raises the pitch. Stopped pipes sound an octave lower than an open pipe of the same length and produce only the odd harmonics, giving panpipes their soft, hollow tone. Chain many tuned pipes together and add a wind supply and you have the pipe organ; the same idea lives on in the ancient Greek syrinx, the Andean siku and zampoña, and the Chinese paixiao.