Musical traditions are as diverse as the population, but the one musical expression best known and most widely associated with the country is probably the gamelan. A complete gamelan orchestra may consist of as many as eighty instruments, the largest part comprsing various types and sizes of metal percussion instruments. Drums, a zither (celempung), a rebab two-stringed upright lute, a flute and often a few other instruments complete the ensemble. Although there are variationas known within each, the gamelan orchestra is basically tuned two systems, the old pentatonic slendro and the younger seventone pelog, each producing its own mood and having its own uses in the musical or theatrical repertoire. The creation of moods or “colour” is further archieved by teh use of three principal modes (pathet) within each tuning system. The most elaborate form of gamelan is that of Central Java (Yogyakarta and Surakarta). West Java has its own gamelan ensemble, usually simpler than tha Javanese, with more stress on flute, drums and the bonang family of horizontally placed kettle gongs. But the most brilliant is that of Bali, where sets of “male” and “female” megalophones produce a beautiful timbre associated with the Balinese gamelan. In much more simple forms, the “gamelan” is also known in other islands of Indonesia, from southern Sumatra to Sulawesi and Kalimantan. Bamboo xylophones are used in North Sualwesi and the bamboo “angklung”instruments of West Java are well-known for their unique tinkling notes which can be adapted to any melody. The Bataks of North Sumatra are famous for their popular singing groups who today entertain visitors in many international hotel.
Performances of Javanese gamelan can be heard every Sunday in the Kraton of Yogyakarta. The Central Museum in Jakarta has performances of Sundanese (West Javanese) gamelan every Sunday morning. Javanese gamelan also accompanies the shortened wayang kulit perfomances given at the Wayang Museum in Jakarta every Sunday morning.