No abstract

Composers often pick specific instruments to convey a given emotional tone in their music, partly due to their expressive possibilities, but also due to their timbres in specific registers and at given dynamic markings. Of interest to both music psychology and music informatics from a computational point of view is the relation between the acoustic properties that give rise to the timbre at a given pitch and the perceived emotional quality of the tone. Musician and nonmusician listeners were presented with 137 tones produced at a fixed dynamic marking (forte) playing tones at pitch class D# across each instrument's entire pitch range and with different playing techniques for standard orchestral instruments drawn from the brass, woodwind, string, and pitched percussion families. They rated each tone on six analogical-categorical scales in terms of emotional valence (positive/negative and pleasant/unpleasant), energy arousal (awake/tired), tension arousal (excited/calm), preference (like/dislike), and familiarity. Linear mixed models revealed interactive effects of musical training, instrument family, and pitch register, with non-linear relations between pitch register and several dependent variables. Twenty-three audio descriptors from the Timbre Toolbox were computed for each sound and analyzed in two ways: linear partial least squares regression (PLSR) and nonlinear artificial neural net modeling. These two analyses converged in terms of the importance of various spectral, temporal, and spectrotemporal audio descriptors in explaining the emotion ratings, but some differences also emerged. Different combinations of audio descriptors make major contributions to the three emotion dimensions, suggesting that they are carried by distinct acoustic properties. Valence is more positive with lower spectral slopes, a greater emergence of strong partials, and an amplitude envelope with a sharper attack and earlier decay. Higher tension arousal is carried by brighter sounds, more spectral variation and more gentle attacks. Greater energy arousal is associated with brighter sounds, with higher spectral centroids and slower decrease of the spectral slope, as well as with greater spectral emergence. The divergences between linear and nonlinear approaches are discussed.

Sound mass has been an influential trend in music since the 1950’s and yet many questions about its perception remain unanswered. Approaching sound mass from the perspective of auditory scene analysis, we define it as a type of auditory grouping that retains an impression of multiplicity even as it is perceived as a perceptual unit. Sound mass requires all markers of the individual identities of sounds to be deemphasized to prevent them from splitting off into separate streams. Seeking to determine how consistent listeners are in their perception of sound mass, and whether it is possible to determine sound parameters and threshold values that predict sound mass perception, we conducted two perceptual studies on Ligeti’s Continuum. This piece consists of an extremely rapid, steady stream of eighth-note dyads with no tempo changes. We addressed the claim by Ligeti and others that the fusion into a continuous texture or sound mass occurs at ca. 20 attacks/s, hypothesizing that other factors such as pitch organization, emergent rhythm, timbre, and register would affect this value. A variety of factors were found to affect sound mass perception, suggesting that the threshold value is not absolute but varies according to principles of auditory scene analysis.