Register impacts perceptual consonance through roughness and sharpness.

The perception of consonance and dissonance in intervals and chords is influenced by psychoacoustic and cultural factors. Past research has provided conflicting observations about the role of frequency in assessing musical consonance that may stem from comparisons of limited frequency bands without much theorizing or modeling. Here we examine the effect of register on perceptual consonance of chords. Based on two acoustic principles, we predict a decrease in consonance at low frequencies (roughness) and a decrease of consonance at high frequencies (sharpness). Due to these two separate principles, we hypothesize that frequency will have a curvilinear impact on consonance. A selection of tetrads varying in consonance were presented in seven registers spanning 30 to 2600 Hz. Fifty-five participants rated the stimuli in an online experiment. The effect of register on consonance ratings was clear and largely according to the predictions; The low registers impacted consonance negatively and the highest two registers also received significantly lower consonance ratings than the middle registers. The impact of register on consonance could be accurately described with a cubic relationship. Overall, the influence of roughness was more pronounced on consonance ratings than sharpness. Together, these findings clarify previous empirical efforts to model the effect of frequency on consonance through basic acoustic principles. They further suggest that a credible account of consonance and dissonance in music needs to incorporate register.