Construction & Playing Technique

The bansuri is a hollow bamboo tube which is closed at the upper end. It has six to seven finger holes and one blowing hole. Usually it has several tight thread bindings to prevent it from cracking. Bansuris in professional quality often have a varnished outer surface. The bamboo suitable for making a bansuri must be thin walled and straight with a uniform circular cross section and long internodes. Being a natural material, it is difficult to find bamboo shafts with all these characteristics, which in turn makes good bansuris rare and expensive. Suitable species of bamboo (such as Pseudostachyum) with these traits are endemic to the forests of Assam and Kerala.
 
After harvesting, the bamboo is seasoned to allow naturally present resins to strengthen it. Once ready, a cork stopper is inserted to block one end, next to which the blowing hole is burnt in. The holes must be burnt in with red hot skewers since drilling causes the fibrous bamboo to split along the length, rendering it useless. The approximate positions of the finger holes are calculated by measuring the bamboo shaft's inner and outer diameters and applying certain formulae. Flute makers have only one chance to burn the holes, and a single mistake ruins the flute, so they usually begin by burning in a small hole, after which they play the note and gradually make adjustments by sanding the holes in small increments.

The bansuri is blown sideways like the Western flute. Fully closing or opening the finger holes produces a diatonic scale. Half opening of the finger holes produces the half notes and micro intervals in between, thus enabling bansuri performers to play any note combination derived from the chromatic Western scale or from the Indian raga tradition. Instead of using the fingertips the finger joints are used to cover the holes. That way it is possible to grab even the long deep bansuris commonly used for classical solo performance. Smooth sliding of the fingers produces the glissando movements and microintervals so essential to Indian music. The tonic note Sa is produced by fully closing the first three finger holes. The lowest note is reached by closing all six fingerholes and is a fourth below the tonic Sa. India Instruments usually mentions both the tonic Sa and the lowest note in order to avoid any misunderstandings.

Fingering charts are available from various sources on the internet. Teaching material for beginners as well as for advanced players is available from India Instruments.