Study examines why humans don’t like dissonant sounds

Science : Dissonant chords are combinations of musical notes that people find jarring, though no one is sure why they aren’t liked. A new study suggests that for some dissonant chords, the reason is the way that the notes’ frequencies interfere with each other. Marion Cousineau of the University of Montreal in Quebec and her colleagues played both consonant and dissonant chords for a group of hearing people and a group of people suffering from amusia, an inability to distinguish musical tones. Cousineau’s team examined the role of beating and of harmonicity in dissonant chords. Beating is a pattern of rapid, repeated rises and falls in tones that occurs when the difference in the frequencies of a chord’s notes is within a certain range. Harmonicity is when the overtones of the notes have the same frequency multiplier. To get a baseline comparison, the researchers chose an amusic group that did not share the normal hearing group’s preference for the consonant chords. Chords in which beating occurred were equally disliked by both groups, suggesting that the dislike for dissonance was not rooted in beating. However, the amusic group could not distinguish the dissonant chords in which harmonicity was lacking. Cousineau’s group believes that the frequency ratios that define harmonicity are part of what defines a chord as dissonant.