Congress of the Alps Adria Acoustics Association 27 – 28 September 2007 , Graz – Austria CAPTURING THE RADIATION CHARACTERISTICS OF THE BONANG BARUNG

Virtual Gamelan Graz (VGG) is an interdisciplinary research project investigating gamelan musical structures, performance practices, and the acoustics of gamelan instruments. VGG tries to combine such different scientific fields as (ethno-)musicology, algorithmic composition, musical acoustics, and sound processing. One research interest within VGG is the real-time synthesis of gamelan sounds including their directional radiation characteristics. This paper demonstrates a method of capturing the directivity of sounds emitted by musical instruments, taking as a practical example the bonang barung (a kettle gong instrument in gamelan ensembles). Using a spherical microphone array, and taking simultaneous recordings of the array signals, we obtain a spatiotemporal description of the radiated sound. We propose a suitable array layout and directivity encoding scheme. Further, we develop a model of a total powerspectrogram which contains all spectral information present in the array signals. Based on this spectral descriptor, we are able to find temporal evolutions of the directivity patterns associated with each partial within the instrumental sound. Finally, we illustrate some examples regarding the bonang barung.