A gamelan is an ensemble of tuned percussion, consisting mainly of gongs, metallophones and drums. Gamelan instruments may be made of bronze, iron, brass, wood or bamboo, with wooden frames, which are often intricately carved and painted.

The largest bronze gamelans in Indonesia are found in Central Java . A complete Javanese gamelan is made up of two sets of instruments, one in each of two scales - the five-note laras slendro and the seven-note laras pelog. The two sets are laid out with the corresponding instruments at right angles to each other. Various hanging and mounted gongs are arranged at the back and provide the structure and form of the music. In the middle, the metallophones play the central melody. At the front are the more complex instruments, which lead and elaborate the melody. These include metallophones, a wooden xylophone, spike fiddle, bamboo flute and zither. The full ensemble also includes vocalists - a male chorus and female solo singers - and is led by the drummer in the centre of the gamelan. Although a large gamelan may be played by as many as thirty musicians , there is neither a conductor nor any visual cues, as the players all sit facing the same way. Gamelan musicians learn all the instruments and so develop a deep understanding of the music plus great flexibility in ensemble playing. It is a communal form of music-making - there are no soloists or virtuosos. Most village halls and neighbourhoods in Central Java have a gamelan for use by the local community, and the majority of schoolchildren learn basic gamelan pieces.

Most villages in Bali boast several gamelans owned by the local music club. The club members meet in the evenings to rehearse, after earning their living as farmers, craftsmen or civil servants. Gamelan playing is traditionally considered a part of every man's education, as important as the art of rice growing or cooking ceremonial food. When the Dutch took control of Bali in the early twentieth century, the island's courts all but disappeared. The court gamelans were sold or taken to the villages where they were melted down to make new gamelans for the latest style that was taking Bali by storm: kebyar , a fast, dynamic music, full of dramatic contrasts, changes of tempo and sudden loud outbursts. It is this dynamic new virtuoso style that makes much Balinese gamelan music today sound so different from the Javanese form. The rhythmic vitality of Balinese music comes from lively interlocking patterns played on the bronze gangsas (similar to the Javanese gender but struck with hard wooden mallets), a pair of drums and the reong (a row of small kettle-gongs in a frame, played by four people). The various pairs of instruments are tuned slightly "out" with each other, so that when two instruments are played together, there is a "harmonic beating". This gives the sound of the Balinese gamelan its characteristic shimmering quality.

The sound of Sundanese (West Javanese) degung is arguably the most accessible of all gamelan music to Western ears. Its musical structures are clear and well-defined, and the timbres of the instruments blend delicately with one another without losing any of their integrity or individuality. The ensemble is small, consisting only of a few instruments, but includes the usual range of gongs and metallophones found in all gamelan.

By Jenny Heaton and Simon Stepto