The term [Gamelan] refers more to the set of instruments than the players of those instruments. A gamelan as a set of instruments is a distinct entity, built and tuned to stay together -- instruments from different gamelan are not interchangeable.

Quite possibly, Indonesian Gamelans are purely tuned or pitched by Western standards of sound purity, so all we hear is hammering tinkering. But interested professionals like Ravel may distinguish in there great tunes and harmonize them.