The damru is the most popular amongst the family of hour-glass drums. Although other representatives (e.g., udaku, hurduk, idakka, etc) can also be found in use, they are very rare.
The damru is in stark contrast to the abundance of forms that are found carved on temple walls. Instead, the damru is almost apparently identical to the dhad. The dhad is played by striking the hands onto the drums rather than the knotted chords. The dhad is very popular in the Sikh bardic tradition.
The Damru is known as a power drum, and when played tends to bring spiritual energy. It is associated with the Hindu deity Shiva.
Shiva devotees believe that beating of the damru by Shiva produced the very first sound (nada). This first sound was created from nothingness. Shiva began his dance of creation to the rhythm of the damru. From his dance, the world came into being.
Damru is a single-handedly played instrument. The leather chords are tied around the waist of the instrument and towards the end of leather cords the strikers are fastened appropriately. In place of the strikers, leather knots or any crochet material can also be used as drum-hitters. A beautiful sound is produced when the strikers are beaten repeatedly on the drumheads with a twisting wrist movement.
Playing damru is indeed an art, especially when played in larger assemblies. When it is played in the assemblies, the instrument must move in unison with the umdze, the chant master. As he makes an outward or inward stroke, the chorus must follow. The technique of snapping and stopping the damru, at once by all in the group is a real art. Damru playing in various rituals is accompanied by ringing bells and vajras in unison. Here the role of umdze is quite essential and is the centre of attraction as bells and vajra play in tune with the umdze. The whole group thus creates a pious ambience with their perfect musical unison and harmony.