Playing gamelan washes the brain. It’s an amazing experience. It is famously difficult to make decent recordings of gamelan, but even the best recording doesn’t compare to sitting surrounded by sounds. In Javanese gamelan, there are patterns within patterns. Density increases when the structure is slowed, so the slower you play, the faster the music gets. You can hear these things on recordings, but the shimmering effect is lost.
Balinese gamelan is very different from Javanese. While Javanese love subdividing and gradual changes in speed and dynamics, the Balinese love complex interlocking rhythms and contrast. Changes from loud to soft are immediate in Balinese gamelan. I used to spend Saturday afternoons playing Javanese gamelan and Wednesday evenings playing Balinese gamelan. I wonder how my brainwave patterns differed during practice sessions.