The Harmonium is essentially a western instrument. But for more than a century it has been adapted in such a way so as to suite Indian music. One of the most popular accompanying instruments, it is also creating a place for itself as a solo instrument. Since its appearance in the Indian music milieu, it has raised many controversies. But nevertheless hardly any artist performs without its accompaniment.

A rectangular cabinet is the base unit in a Harmonium. It contains most of the components of the instrument.

At the base of the backside of this cabinet, an external bellow is attached. This allows for a free movement of the bellow when pulled. The bellow has a rectangular hole which is covered by a thin wooden plank with holes. The inside of this plank has a piece of velvet fixed at the top. This facilitates a regulated suction of air. The external bellow has 1, 2 or as many as 7 flaps made of cardboard and joined at the sides with leather strips.

Inside the cabinet, at the bottom, there is an internal bellow. This works on spring action. A spring, in the shape of a pyramid is located at the bottom of the bellow. This is covered by a thin wooden plank with 2 or 3 holes. These holes regulate the air supply to the reeds. On this plank, there are fixings for the stoppers which can be pulled and pushed back inside from the front side. Stoppers open or close the various reed lines. Another thin plank is placed in a frame on top of the previous one but with a slight distance between then to let the air circulate equally and freely. Underneath this second plank, more fixings for the stoppers are attached. This plank too has holes for the air supply to reach the reeds.

The Reed board: This is a thick wooden plank fixed with four walls so as to make it another hollow cabinet. This is divided in the centre by another wooden plank. This cabinet is attached to the main cabinet very firmly at the bottom. It can be lifted up easily in order to access the reeds and other inside components.

The plank dividing the second cabinet has 2 reed lines fixed on either side. These lines are first attached to a very thin wood plank which has holes to let the air sucked in through the bellows, reach the reeds. Reeds are fixed at the bottom but are free to vibrate from the top. This part is called the tongue. The reeds are fixed from left to right i.e. from the lower to the higher octave. They are metal tongues which vibrate freely when air flows over them. Reed size is directly proportional to the frequency of the note.

Key board: On the upper side of the reed board, the keys are fixed. But before that, underneath each key, two small holes are cut out for the air to escape as sound. There is also another wooden bridge with grooves for the keys to fit in and allow a free movement. This is called the comb line.

The keys are made of thin strips of very light wood and at one end are covered by black and white plastic pieces stuck together. These keys once fixed on the comb line are pressed in place with individual springs.

The last part is the lid which covers the top cabinet. This lid has holes in form of a design and is covered on one side with a velvet paper. The sound produced is heard from the top of the Harmonium after resonating in the inside cavities.

Sound production: An external feeder bellow pumps the air and inflates an internal reservoir bellow. From this bellow, air escapes through different sized holes and reaches the reeds which vibrate when the keys are pressed. The reeds vibrate freely i.e. the edges do not touch the frames on which they are fixed. So when a key is pressed down and air pumped in, sound is produced.