Directional characteristics of two gamelan gongs.

This article focuses on the acoustic radiation characteristics and directivity patterns of two types of Balinese gamelan gongs: the ageng lanang and the bebende. Using high-resolution spherical microphone array measurements and scanning laser Doppler vibrometry (SLDV), the study reveals that the gongs exhibit dipole-like sound radiation at low frequencies and increasingly complex, multi-lobed directivity patterns at higher frequencies, which correspond to their structural mode shapes and the number of anti-nodal regions on the gong edges. Differences in geometry, modal frequency ordering, and structural features such as the boss and side walls lead to distinct radiation behaviors between the two gongs, including the presence of the ombak beating phenomenon in the ageng lanang but not in the bebende. The research highlights the influence of the gongs' unique construction on their acoustic output and notes the limitations of existing theoretical models in fully capturing their radiation, suggesting the need for improved modeling approaches.