The nadaswaram, is one of the most popular classical musical instruments in the Tamil Nadu and the world's loudest non-brass acoustic instrument. It is a wind instrument similar to the North Indian shehnai but much longer, with a hardwood body and a large flaring bell made of wood or metal. In South Indian Hindu culture, the nadaswaram is considered to be very auspicious, and it is a key musical instrument played in almost all Hindu weddings and temples of the South Indian tradition. It is part of the family of instruments known as mangala vadya. The instrument is usually played in pairs, and accompanied by a pair of drums called thavil, it can also be accompanied with a drone from a similar oboe called the ottu.
The nadaswaram contains three parts namely, kuzhal, thimiru, and anasu. It is a double reed instrument with a conical bore which gradually enlarges toward the lower end. The top portion has a metal staple into which is inserted a small metallic cylinder which carries the mouthpiece made of reed. Besides spare reeds, a small ivory or horn needle is attached to the instrument, and used to clear the reed of saliva and other debris and allows free passage of air. A metallic bell forms the bottom end of the instrument.
Traditionally the body of the nadaswaram is made out of a tree called aacha although nowadays bamboo, sandalwood, copper, brass, ebony and ivory are also used. For wooden instruments, old wood is considered the best, and sometimes wood salvaged from demolished old houses is used.
The nadaswaram has seven finger-holes, and five additional holes drilled at the bottom which can be stopped with wax to modify the tone. The nadaswaram has a range of two and a half octaves, similar to the Indian bansuri flute, which also has a similar fingering. Unlike the flute where semi and quarter tones are produced by the partial opening and closing of the finger holes, in the nadaswaram they are produced by adjusting the pressure and strength of the air-flow into the pipe. Due to its intense volume and strength it is largely an outdoor instrument and much more suited for open spaces than indoor concerts.