Building a Khaen — The Lao Free-Reed Mouth Organ

The khaen is the free-reed mouth organ of Laos and northeast Thailand: long bamboo pipes laid flat in a raft through a small windchest. Blow or draw, cover the holes, and it pours out drones and melody at once for mor lam music.

Cut a set of long, thin bamboo pipes in graduated lengths and lay them in two neat rows — a raft. Fourteen to sixteen pipes make a full khaen; start with fewer.

Carve a small hardwood block into a hollow windchest with a mouth-hole at one end. The whole raft of pipes will pass through this chest.

From thin metal, cut a tiny free tongue for each pipe — a springy strip that swings cleanly through a matching slot, fixed at one end and free at the other.

Set a reed into each pipe at the point where the pipe will cross inside the windchest, sealed airtight, with the tongue free to swing.

Pass all the pipes through the windchest so their reeds sit inside it, and seal every gap with black wax so no air can escape except through the reeds.

Cut one finger hole in each pipe, just outside the windchest. This hole is the on/off switch for that pipe's note.

Cup the windchest to your mouth, blow gently, and cover one pipe's hole. Covering the hole drives the air through that pipe's reed, and it sounds.

An open hole lets air escape and stays silent; a covered hole sings. Hold a couple of holes covered for a constant drone while your other fingers pick out notes.

Add a dab of wax to a reed's tip to LOWER its note, or file the tip thinner to RAISE it, tuning the pipes to the khaen's seven-note scale.

Hold a drone under a running melody and breathe IN as well as out — free reeds sound both ways, so the khaen never has to stop for breath. That endless ripple is the sound of mor lam.

The khaen works on the free reed, exactly like the Chinese sheng: a thin metal tongue that swings freely back and forth THROUGH a close-fitting slot as air flows past, chopping the airflow into a steady tone at the tongue's own pitch and speaking equally whether you blow or draw. But where the sheng gathers short pipes upright in a gourd bowl, the khaen lays long paired bamboo pipes flat in a raft that runs through a small hardwood windchest cupped in both hands — a different shape for the same idea, spread across Asia. Each pipe holds one reed, and its finger hole is a switch: only a covered hole forces air through the reed, so a player can hold some holes down for a continuous drone while other fingers pick out a melody above it, with no pause to breathe — the endlessly rippling texture of Lao and Isan mor lam song. The reeds are tuned by filing them thinner to raise the pitch or loading their tips with a dab of wax to lower it, set to the khaen's seven-note scale, and the whole windchest is sealed with black insect wax so that every breath goes only through the reeds. The free reed that both the khaen and the sheng are built on is the ancestor of the Western harmonica, accordion and reed organ, and its distant cousin is the plucked tongue of the jaw harp. The national instrument of Laos, the khaen is recognised by UNESCO as part of humanity's living heritage.