Vibrational characteristics of Saron Barong metallophones in the 1893 Field Museum Gamelan
William R. Savage, Edward L. Kottick, Sue Carole DeVale · The Journal of the Acoustical Society of America · 1979
The gongs used in Asiatic music frequently exhibit noticeable glides in pitch comprising a significant fraction of a semitone. Bar-form metallophones of the 1893 Gamelan also show a glide in pitch. This contrasts with western bar-form metallophones which are generally pitch stable. Measurements of the keys of two Saron Barong show that they have different lengths, widths, and cross sections but do not “scale” since they have nearly similar masses. The keys of lower pitch are longer and wider than those of higher pitch within a given seven note Saron. The upper surface of the keys is convex for both length and width aspects. The lower surface of the lower pitch keys is concave becoming convex for the upper keys. They are mounted with nails through holes at a distance one quarter the length from the end on resilient pads above individual air cavities. The holes are not symmetrically located and the bars are not straight. They were cast of bell metal in sand molds and roughly finished. The central part of the underside is hollowed. Torsional and flexural modes near the pitch frequency can be found by external excitation. These modes have frequencies consistent with those found by high-speed spectral analysis and pitch measurements. The pitch glide seems to be associated with a bar shape that favors excitation of both torsional and flexural modes at the initial strike with a more rapid decay of the torsional mode. This mechanism differs from that suggested for gongs where the moving mass associated with the mode decreases with decreasing amplitude of vibration.