Methods for measurement and manipulation of timbral physical correlates

Abstract

Multidimensional scaling calculations based on the results of listening tests comparing musical sounds almost always identify one perceptual dimension which is strongly correlated with a measure of the spectral centroid, whereas other dimensions are less obviously correlated to particular physical parameters. Some parameters which have been suggested as good correlates are attack time, spectral flux, and spectral irregularity [J. Krimphoff et al., J. Phys. IV (C5), 625–628 (1994)]. Also, spectral rolloff, preattack noise, general noisiness, and inharmonicity have been proposed as important factors. Based on time-variant spectral analysis with custom software [J. Beauchamp, Audio Eng. Soc. Preprint No. 3479], these parameters and others can be quantified and manipulated, leading to various applications. For example, synthesis using simplified parameter contours provides stimuli for discrimination testing to reveal listeners’ sensitivities to these parameters. Measurement of spectral differences can be correlated to discrimination results. Equalization of parameters common to two instrument sounds allows listeners to focus on those timbral aspects which are different. Finally, hybrid musical sounds created by interchanging parameter contours between instruments can shed light on timbral perception.