The influence of the tambura drone on the perception of proximity among scale types in North Indian classical music
Kathryn Vaughn · Contemporary Music Review · 1993
The unique character of the tambura drone is the result of a nonlinear interaction of the strings with the bridge of the instrument. The placement of juari, or “life giving” threads at the curved bridge causes the energy to spread into the higher partials. Experimental evidence indicates that the perception of timbre resulting from this acoustical property alters similarity judgments of pitches within the three most commonly used tambura tunings. The rags of North Indian classical music can be grouped into a system known as the Circle of Thats, based on 32 possible scales, of which 10 are the most commonly used. The perceptual relation among the ten scales and the three tambura drone tunings was investigated using multidimensional scaling and cluster analysis of experimental data from both North Indian and Western musicians. It was found that the perceptual relation among the ten scale types in the absence of the drone is very close to the theoretical Circle of Thats. In the presence of the PA-SA drone the scales tend to cluster on the basis of common tones, placement of gaps and tetrachord symmetry. Correlation between subjects was unrelated to original culture background but significantly related to length of time spent studying this musical tradition.