Mridanga which means body of clay is the most ancient of all percussion instruments. It is commonly used in south as an accompaniment to the vocal and instrumental performances. In the north mridanga is known as pakhawaj and a slight difference is observed in both. In Bengal and Manipur, mridanga is popularly known as khol.
The mridangam is hollowed out of a block of wood and is about 60cm in length. It has the shape of a barrel with the bulge slightly to one side and the right face is smaller than the left. The left face which is called 'tappi' has two lamina. The outer one is a flat ring of leather and at its periphery attached to a plait known as the pinnal. This layer holds on its inner side another parchment which is a circular piece and has a diameter approximating to the outer skin. The whole unit is fixed to the left head. The right face has three laminations. The inner and the outer are rings. The middle circular layer is held taut by pasting along its periphery the annular rings of leather. This entire complex called 'valan talai' is stitched on to a pinnal or plait and mounted onto the right mouth of the barrel. The two faces are joined and held together tight by leather straps which pass in and out of the pinnals or braids on both sides.
A mixture of flour and water is applied on the middle of the left side to lower the tone to the desired pitch. This gives a full, bass sound. This is removed each time after use. The center of the right side has a permanent coating of a black substance called siyahi (or soru, karanai and marundu) which is a mixture of boiled rice, manganese dust, iron filings and other substances. This layer gives characteristic tone to the mridangam and facilitates tuning to a particular pitch.
Tuning of the drum is done by striking the right pinnal with a wooden block, hand or with any substance. Varieties of tone can be obtained from different parts of the instrument in various ways. In the south, the mridangam is the only drum used in classical music recitals except in Nagaswaram recitals.