ガムラン楽器音の音響学的、音響心理学的比較分析

概要

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The comparative acoustical and psychoacoustical elements of the Javanese gamelan were studied with a focus on tuning, vibrational characteristics and associated perceptual effects. In addition to relating acoustical, perceptual, and musical frameworks to each other, we seek to clarify some common misconceptions about tuning modes, scales, and the assignment of pitch to metallophones which have inharmonic spectra. We found that the inharmonic modes of the spectra of the bars of the gamelan instruments saron demung, saron demung, and saron peking are described well by the standard physical theory of rectagular bars. The makers have tuned the bars by shaping so that harmonic partials also appear. The frequencies of the scale of the seven measured bars of each instrument (Low 6, middle 1, 2, 3, 5, 6, High 1) are fit perfectly by an exponential function. Results of perceptual experiments show that, although many octave mismatches occur, both Indonesian and Western subjects generally matched a pitch chroma. In judging small-cents deviations from equi-pentatonic tuning, we found one progessional Indonesian musician of four who could reliably discern them. We argue that the paradox of three different pathets (modes) for equi-pentatonic tunings can be explained by differing distributions of chroma based on Markof chains of order 0, 1, 2 or higher and other imposed formulaic and hierarchical structures, which we call chromals.