I n a recent article , B onin , T rainor , B elyk , and Andrews (2016) proposed a novel way in which basic processes of auditory perception may influence affective responses to music. According to their source dilemma hypothesis (SDH), the relative fluency of a particular aspect of musical processing—the parsing of the music into distinct audio streams—is hedonically marked: Efficient stream segregation elicits pleasant affective experience whereas inefficient segregation results in unpleasant affective experience, thereby contributing to (dis)preference for a musical stimulus. Bonin et al. (2016) conducted two experiments, the results of which were ostensibly consistent with the SDH. However, their research designs introduced major confounds that undermined the ability of these initial studies to offer unequivocal evidence for their hypothesis. To address this, we conducted a large-scale ( N = 311) constructive replication of Bonin et al. (2016 ; Experiment 2), significantly modifying the design to rectify these methodological shortfalls and thereby better assess the validity of the SDH. Results successfully replicated those of Bonin et al. (2016) , although they indicated that source dilemma effects on music preference may be more modest than their original findings would suggest. Unresolved issues and directions for future investigation of the SDH are discussed.

Two experiments examined whether discrimination of component pitches in a harmonic interval is affected by the consonance or dissonance of the interval. A single probe pitch (B or C) was followed by a two note harmonic interval including that pitch (e.g., C then C-F# or C-G) or not including it (e.g., C then B-F# or B-G). On each trial, subjects indicated by key press whether the probe note was repeated in the following interval. The target note in the interval either matched the probe or differed by one semitone (B or C). The other note produced a consonant (e.g., perfect fifth) or dissonant (e.g., tritone) context for the target. Pitch discrimination was faster and more accurate in consonant intervals than dissonant, when the context note was higher than the target (Experiment 1), but there was no effect of consonance when the target was higher (Experiment 2). We conclude that the perception of the lower but not the upper pitch in a two note harmonic interval is affected by the interval’s consonance or dissonance. We discuss the results in terms of the theoretical framework of processing fluency and aesthetics proposed by Winkielman, Schwarz, Fazendeiro, and Reber (2003).

psychoacoustic theories of dissonance often follow Helmholtz and attribute it to partials (fundamental frequencies or overtones) near enough in frequency to affect the same region of the basilar membrane and therefore to cause roughness, i.e., rapid beating. In contrast, tonal theories attribute dissonance to violations of harmonic principles embodied in Western music. We propose a dual-process theory that embeds roughness within tonal principles. The theory predicts the robust increasing trend in the dissonance of triads: major < minor < diminished < augmented. Previous experiments used too few chords for a comprehensive test of the theory, and so Experiment 1 examined the rated dissonance of all 55 possible three-note chords, and Experiment 2 examined a representative sample of 48 of the possible four-note chords. The participants' ratings concurred reliably and corroborated the dual-process theory. Experiment 3 showed that, as the theory predicts, consonant chords are rated as less dissonant when they occur in a tonal sequence (the cycle of fifths) than in a random sequence, whereas this manipulation has no reliable effect on dissonant chords outside common musical practice.

ATTEMPTS TO EXPLAIN HARMONY PERCEPTION SINCE Helmholtz (1877/1954) have relied primarily on psychoacoustical models of the dissonance among the partials of chord tones. Those models are successful in explaining interval perception and the interval structure of common scales, but do not account for even the basics of triadic harmony. By introducing a 3-tone "tension" factor, I show how the sonority of the triads of diatonic music can be explained.Moreover, the relative size of the intervals among the partials in triads determines the major/minor modality of chords: major chords have a predominance of larger lower intervals, while minor chords have a predominance of smaller lower intervals. Finally, by invoking the "frequency code" known from linguistics and ethology, the positive/negative valence of the major/minor chords is shown to have an acoustical basis. I conclude that the perception of harmony can be explained by the acoustical structure of triads, without invoking cultural factors.