Brightness perception for musical instrument sounds: Relation to timbre dissimilarity and source-cause categories

Abstract

Timbre dissimilarity of orchestral sounds is well-known to be multidimensional, with attack time and spectral centroid representing its two most robust acoustical correlates. The centroid dimension is traditionally considered as reflecting timbral brightness. However, the question of whether multiple continuous acoustical and/or categorical cues influence brightness perception has not been addressed comprehensively. A triangulation approach was used to examine the dimensionality of timbral brightness, its robustness across different psychoacoustical contexts, and relation to perception of the sounds' source-cause. Listeners compared 14 acoustic instrument sounds in three distinct tasks that collected general dissimilarity, brightness dissimilarity, and direct multi-stimulus brightness ratings. Results confirmed that brightness is a robust unitary auditory dimension, with direct ratings recovering the centroid dimension of general dissimilarity. When a two-dimensional space of brightness dissimilarity was considered, its second dimension correlated with the attack-time dimension of general dissimilarity, which was interpreted as reflecting a potential infiltration of the latter into brightness dissimilarity. Dissimilarity data were further modeled using partial least-squares regression with audio descriptors as predictors. Adding predictors derived from instrument family and the type of resonator and excitation did not improve the model fit, indicating that brightness perception is underpinned primarily by acoustical rather than source-cause cues. V

Adaptive auditory brightness perception

“…In order to further explicate the observed effects, we constructed simple models of task performance. We followed the literature that has used the spectral centroid (SC; center of gravity of the spectral energy distribution of the sound signal) as a feature for quantifying auditory brightness perception 3 , 26 , 27 , 36 . We focus on modelling an adaptive response criterion, which bears similarity to previous work on pitch content effects 19 .…”

“…The attribute of auditory brightness has commonly been considered as a critical contributor to timbre perception and has been considered as being determined by the instantaneous spectrum 3 , 35 , 36 processed in auditory cortex 37 , 38 . Yet, relatively little is known about neural underpinnings of spectral adaptation effects.…”

“…The averaged results for the model with minimal error are plotted as dotted lines in the results figures. The model was based on the spectral centroid (SC), which corresponds to the center of gravity of the spectral energy distribution and has been shown to reliably correlate with brightness ratings of isolated musical instrument sounds 3 , 26 , 27 . SCs were computed via the magnitudes of a Fast Fourier Transform (FFT) of the signal; all magnitudes below the threshold of -90 dB full scale were set to zero 50 .…”

A Normative Survey on Auditory Perception and Semantic Descriptors of Musical Timbres

“…However, such use will be restricted to western instruments as the model relies on human identification of descriptors that was limited to western musical instruments. A recent study suggested that timbre brightness perception is primarily perceived by acoustical cues (Saitis & Siedenburg, 2020). Prompting us to observe the potential of using semantic descriptors for identification of timbral qualities commonly used in music production.…”

The Timbre Explorer: A Synthesizer Interface for Educational Purposes and Perceptual Studies

“…Traversing spectrum values largely follows a transition from a sine wave to a square wave to a sawtooth; starting with the fundamental frequency, gradually adding oddharmonics, and then adding even ones. Brightness, experimentally correlated to spectral centroid [7], is recreated as a frequency filter. The filter is either low-pass or high-pass, depending on whether the parameter is low or high respectively.…”