We spent most of a week in Jogja, including night time visits to rehearsals of the Royal shadow puppet (Golek Menak) theater and daytime Gamelan concerts.
We still attend Gamelan concerts at Wesleyan University near our Connecticut home. Gamelan is the most complex musical system I have ever encountered. There is an astonishing array of largely percussive instruments, different tunings, notations -- one with five notes to the octave at even intervals, another with seven at irregular intervals. Paired instruments are tuned slightly apart to produce interference beats.
The compositional form is so complex it stretches my understanding and defies my vocabulary.