Mridangam is characterized by a rich and varied tone. Some strokes evoke clear pitched sounds while others evoke unpitched sounds. The following discussion is based upon the pitched strokes because they more clearly show the tonal differences.

The size of the mridangam is one of the important factor for the sound it produces. The pitch of the mridangam varies according to its size. The larger (Fig.1a) the mridangam, the lower the pitch and the smaller (Fig.1b) the mridangam, the higher the pitch.

Large Mridangam

Small Mridangam

Rim Stroke (right hand) - The rim stroke is a major stroke on the mridangam. Although the nomenclature varies, this stroke is usually called "Na" in the North and "Nam" in the South. On mridangam a predominant third harmonic is the main characteristic (Fig. 2 a, b; below). However, the fundamental may be seen in significant proportion in the mridangam while it is essentially absent in the tabla. Furthermore the second harmonic tends to be evoked in the tabla while it is suppressed in the mridangam.

Open stroke (right hand) - The open stroke is also a major stroke for both drums. This is called "Tun" in the North and "Dheem" in the South. Both strokes are characterized by a very prominent fundamental. However there is a significant difference in the second harmonic (Fig. 2 c,d).

Open stroke (left hand) - The open stroke of the left hand is called "Ga" in the North and "Thom" in the South. It shows a tremendous difference between the two instruments (fig. 2 e,f). It has been found that the tabla has a very pronounced fundamental and a long sustain. There are much fewer harmonics in this stroke. Conversely the mridangam has a much more complex harmonic spectrum and a significantly reduced sustain.

In order to know the physical and structural relation of the type of skin used in making the instrument and the sound produced, the cross sectional features of leather used in different instruments were studied. In various skins horizontal fibres running predominantly along the scales direction and the network structure flows perpendicular to the scales direction.

In goat skins, there is no horizontal running of fibre bundles and the fibres is in loose weaving. In sheep skin, the grain layer is comparatively larger than that of goat skin and fine fibres predominantly running along the hair follicles direction. The cross sections are plain and compact in cow calf leather. The fibres are glued together and from seperate blocks in all directions.

The theory of circular membranes considers them as two dimensional stretched strings. The fundamental frequency can be related as :

                                   fo1 = 0.382

                where,              fo1  =  fundamental frequency
                                          R  =  radius of the membranes
                                          T   =  circumferential tension/unit length
                                         ()  =  mass/unit area of the membrane

The pitch of the membrane, as in a stretched string depends on the size and weight of the membrane and the amount of tension it is under. The pitch lowers, as the size or weight is increased and rises when the tension is increased. In the case of drums, the sound produced by it depends on the resonator column and the properties of leather, the loudness depends on the amplitude, energy and the intensity.


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