The [[gamelan]] orchestra, based on metallic [[percussion instrument|percussion]] with [[wind instrumentidiophone|windsidiophones]] and [[drum]]s, is perhaps the form which is most readily identified as being distinctly "Javanese" by outsiders. In various forms, it is ubiquitous to Southeast [[Asia]]. In Java, the full [[gamelan]] also adds a [[bowed string instrument]] (the [[rebab]], a name illustrative of [[Islamic]] influence), plucked [[siter]], vertical flute [[suling]] and voices. The rebab is one of the main melodic instruments of the ensemble, (together with the xylophonemetallophone "[[gendér]]"); these and isthe [[kendang]] drums are often played by the seniormost [[musician]]experienced musicians. Voices usually consist of a male andchorus female choruses[[gerong]], together with soloistsa female soloist [[sindhen|pesindhen]]; however, the voices are not usually featured in court gamelan (as opposed to [[wayang kulit]], [[shadow puppet]] theatre) and are supposed to be heard discreetly in the middle of the orchestral sound. In these [[Abstract music|abstract]] pieces, the words are largely secondary to the music itself.
There are two scalestuning systems in Javanese gamelan music, "[[slendro]]" ([[pentatonic]]) and "[[pelog]]" ([[heptatonic]] in full, but focussing on a pentatonic group). Tuning is not standard, rather each gamelan set will have a distinctive tuning. A complete gamelan consists of a pair of sets, one tuned in each of the scales and intended to be played together in manytuning instancessystem. Different gamelan sets have different sonorities, and are used for different pieces of music; many are very old, and used for only one specific piece. Musical forms are defined by the [[rhythm]]ic cycles. These consist of major cycles subdivided by smaller cycles, each marked by the striking of successively smaller [[gong]]s. The melodic interplay takes place within this framework (technically called "[[colotomic structure]]"). There are also distinct melodic modes ("[[patet]]") within the division of scale.
