Abstract:

Many studies have found a mapping between the spectral center of gravity and timbre perception. In this work, a consistent relationship has been found between the main perceptual dimension of timbre and spectral distribution measures for continuant (as opposed to impulse) signals, such that it mapped strongly (ca. r(greater than or equal to)0.90) onto the spectral centroid. The present study investigates by two different psychophysical experiments the perceptual properties of the spectral centroid. Experiment 1 determines the just-noticeable difference (jnd) for spectral centroid using complexes of five harmonic components with a fundamental of 440 Hz. Results of three different standard centroid values averaged 0.153. Experiment 2 investigated the perceptual similarity of 5-component complexes which varied in shape, but not in spectral centroid. The resulting multidimensional scaling (MDS) was monotonically ordered on the principal dimension, and palendromically oriented around the second-dimensional axis. Acoustical measures of spectral irregularity map onto the second dimension. The primary dimension appears to be loudness, and one would expect such a mapping. However, it was found that correlating current measures of loudness for complex tones with the MDS solution problematical. These experiments are interpreted in terms of natural and synthetic instrument spectral and perceptual properties.