There is a wooden cover on the thoombaa called the tabli. The tabli stretches along the length of the hollow wooden tube affixed with the thoombaa. The tube is called dand. This is the basic structure, to which is added the wires. To facilitate fixation of the wire with the body, animal bone is used, as is more steel.
Some sitars have another thoombaa fixed with the bottom of the dand.
That the sitar is so shaped helps to manoeuvre the wires to the left and to the right. However it is difficult to create a uniform sound for long periods of time. Pandit Ravi Shankar, a living sitar legend, has created over the years a universally appreciated 'baaj' or style. Thus it is seen that the idiom of music is uniform and universal. Despite its many troubles and tribulations Indian music today has its niche.