Interactive effects of presentation mode and pitch register on simultaneous consonance

In this study, we tested for interactive effects of presentation mode (diotic vs. dichotic), pitch register, and both harmonicity and spectral interference on simultaneous consonance, the tendency to perceive some combinations of simultaneously sounded musical tones as more pleasant than others. In two experiments, participants were asked to rate the pleasantness of synthetic dyads (i.e., two-note chords) generated from an unconventional musical system, the Bohlen–Pierce chromatic just scale. Consistent with earlier findings, analyses of these ratings showed that diotic presentation bolsters the positive association between harmonicity and consonance. Analyses also newly revealed that diotic presentation bolsters the negative association between spectral interference and consonance, presumably reflecting the reduction in interference between close-frequency partials engendered by channeling chord tones to different ears. However, the results also showed that these interactive effects were no longer reliable when dyads were presented in a relatively high pitch register (centered at C 7 vs. C 4 ), even when controlling for potential confounds between register and loudness. This appears to reflect the marked aversion to dyads presented in a high-frequency range, a tendency that may have overwhelmed the relatively subtle contribution of presentation mode. In sum, our results point to the importance of taking pitch register into account when modeling the combined effects of presentation mode, harmonicity, and spectral interference on simultaneous consonance judgments.