The Gamelan

The music of the gamelan, played often for the pleasure of the hearers, has also special compositions reserved for ceremonial occasions.

In Bali, for example, the gamelan is an integral part of religious life of the community in that it forms the sonorous background of ceremonies and prayers in the temples. When the Balinese march in procession, carrying the images of the gods, to the sea, they are accompanied by a special melody of the gamelan  called the "bleganjur". For the cremation ceremonies , the "gambang" composition is played. And the "sanghyang" with vocal accompaniment is performed during the sacred dance of little girls in trance.

In Java too, specific compositions are played for weddings, and for official or religious ceremonies. One of the principal occasions for the playing of the gamelan is the shadowplay during which performance the three successive states of mind are of primary importance for the corresponding accompaniment. Hence the most fundamental feature of gamelan music for the accompaniment of the shadowplay, is the tonality of the melody chosen to correspond to the mood of the play during its various phases.

The choice of tone c.q. tonality is particularly important since the change of key, across the successive acts of the repertoire to recite, symbolizes the quest of man straining towards the highest significance of life. The act begins with the base key called "patet nem", but at midnight, the mood changes and the gamelan passes on to a higher key; the music then corresponds to the most calm and mysterious moment of the night. When dawn arrives and life begins anew, the orchestra passes to a higher key and plays a vivid melody. The change of tonality punctuates the different phases of the repertoire, it symbolizes the slow rise of the subject matter across human desires to the final intelligence of the divine. Thus the shadowplay and its gamelan music accompaniment are no longer a simple diversion, but contain a vigorous moral and acquire a metaphysical significance.

For a wayang kulit performance the Javanese gamelan orchestra may consist of some stringed instruments like the rebab (a bi-or sometimes tri-chord violin type) and the chelempung ( a Javanese zither), a wind instrument the suling ( a bambo0 flute) and of some percussion instruments like the kendang ( a type of Javanese drum ), the gender (a Javanese metallophone instrument), the gong, etc.

The Balinese gamelan accompaniment, however, is much simpler in strength and consists only of some gender instruments for such performance. The gamelan plays then a polyponic dramatical music composed either on pentatonic scale called the selendro, or on a diatonic scale called the pelog, such according to the nature of the acts of the shadowplay.

Selendro: A pentatonic scale of five notes, i.e. barang-gulu-dada-lima-nem, on the base of three patet's (read : tonality), i.e. patet nem, patet manyura, and patet sanga.

Pelog: A diatonic scale of seven notes, i.e. bem-gulu-dada-pelog-lima-nem-barang based on four patet's, i.e. patet lima, nem, manyura, and barang.

However, in the practice only three of these patet's are used for wayang kulit performance. Briefly, each patet of both scales the selendro and the pelog, is put in accordance with one of the three periods of the wayang kulit theater as indicated by the following schedule:

Key	1st Period, Eve	2nd Period, Midnight	3rd Period, Dawn
Selendro	patet nem	patet sanga	patet manyura
Pelog	patet lima	patet nem	patet barang

The difference between the selendro and the pelog lies in the scale systems employed by each, however, neither of the two are corresponding with the note intervals of Westrn music.
When using a specific measurement, first introduced by the physicist Ellis, the so-called 'cent' inwhich a whole tone is measured by 200 cent and a half tone by 100 cent, the selendro and the pelog scale can be denoted by undermentioned table:
Selendro:
Barang  -  Gulu  -  Dada  -  Lima  -  Nem  -  (Barang-alit)
         240c      240c     240c      250c      240c

Pelog:
Bem  -  Gulu  -  Dada  -  Pelog  -  Lima  -  Nem  -  Barang  -  (Bem-alit)
      120c     150c      240c      150c     120c      150c        270c

In general the selendro system is used a.o to accompany a wayang kulit performance, although in the coastal regions of Central java only the pelog is prevailing for such occasion and the selendro plays the role of giving some variations from time to time to the whole gamelan composition.