Wikipedia
The idakka , also spelt edaykka, is an hourglass-shaped drum from Kerala in south India. This handy percussion instrument is very similar to the pan-Indian damaru. While the damaru is played by rattling knotted cords against the resonators, the idakka is played with a stick. Like the damaru, the idakka's pitch may be bent by squeezing the lacing in the middle.
The idakka is slung over the left shoulder and the right side of the instrument is beaten with a stick. The left hand is used for tightening and loosening the tape wound round the middle. Varying the tension of the tape produces variations in tones. Simple melodies extending over one octave can be played in this instrument. The idakka is considered to be Devavadyam (a divine instrument) and is customarily played standalone during the puja at temples or as the accompaniment to the Sopanam music just outside the sanctum sanctorum, customarily by the Ambalavasi community Marar or Poduval. More popularly, it is one of the five instruments that constitute the panchavadhyam ensemble of Kerala.
Kathakali, the classical dance-drama from Kerala, also gives a slot to playing the idakka when a female character holds the stage (when the Chenda is not played). In Koodiyattam too, the Idakka gives good support to the mizhavu (pot drum). The idakka is an indispensable accompaniment for other dance forms, most notably Mohiniyattam and Krishnanattam. It has become an accepted member of several dance troupes outside Kerala. Idakka is also used to present the traditional concert called Thayambaka.
Idakka is regarded as a difficult instrument to master, given that the rolls are produced from a single stick (not two unlike in the case of the chenda) and that the practitioner should have a good sense of both rhythm and music. There are many institutions in Kerala where idakka is being taught, the most important among them being Kerala Kalamandalam and Kshetra Kalapeetham in Vaikom.
Of the current lot of Idakka artists, the most famous include Thiruvilvamala Hari, Tripunithura Krishnadas, Chottanikara Subhash Marar, Tichur Mohanan, Chendamangalam Unni,Thiruvillwamala Jayan, Tripunithura Harikrishnan and Anand k r. The one name that is always synonymous with idakka and Sopana sangeetham in the second half of the 20th century has been the legendary Pallavur Appu Marar—he, unlike many others, was an expert in using it both as a percussion and musical instrument.