Gamelan

Western music has been influenced  by non-Western music for roughly the last, oh, thousand years. Or perhaps for as long as there has been Western music. One of the most interesting and recent influences is Gamelan music, the music of the Indonesian islands of Java and Bali. Here is the Wikipedia article. Western composers like Claude Debussy first heard a gamelan at the Paris Exposition of 1889. A gamelan is an orchestra of mostly tuned percussion. Here is an illustration of the various instruments which include a variety of gongs, gong chimes and various kinds of metallophones. The rebab or spike fiddle, a bowed instrument, some drums and voice also appear. Here is a sample:

The scale used is mostly a five-note one but with the octave roughly divided up equally. A seven-note scale is also used. These don't correspond to equal-tempered Western intervals. Each gamelan, the name for the whole orchestra, is tuned differently. An orchestra may be created, built, and tuned and then be used for a very long time. Hundred year old gamelans are not unusual. Here is another example, this time with flute:

The interesting characteristic of gamelan music from a Western point of view is the unique sound composed of layers of tuned metallic percussion overlaid with the single bowed string or flute. Higher pitched percussion play shorter notes, middle level ones longer notes and so on until you get to the deep gongs that are only played at major structural points. The orchestra has a shimmering sound that comes from paired instruments being tuned slightly apart so that the two frequencies 'beat' against one another. This is a subtle and complex texture. The idea of repeated rhythmic cells has been picked up by a number of 20th century Western composers. It is hard to say whether people like Stravinsky were influenced (and it is not something he would be likely to admit) but rhythmic cells, common in his and other modern music, are not found before gamelan music was heard in Europe. Someone like Steve Reich, however, is certainly influenced.

Gamelan music has two sides to it. The Javanese is tranquil, floating. The Balinese version is quite different:

Now that's cool! I have a feeling that this music does not record terribly well. Instruments like gongs are very hard to record and effects like the shimmering 'difference' tones are also something you partly feel by being in the space. Rather unexpectedly there is also a choral version of this kind of music called Kecak or Monkey Chant:

It's not often that you hear a really interesting and unique kind of music and it is easy to see what a big impression this made in Paris in 1889.