Why dissonant music strikes the wrong chord in the brain
Baku, November 17 (AZERTAC). The common aversion to clashing harmonies seems to be due to mathematical relationships of overtones.
Many people dislike the clashing dissonances of modernist composers such as Arnold Schoenberg. But what’s our problem with dissonance? It’s long been thought that dissonant musical chords contain acoustic frequencies that interfere with one another to set our nerves on edge. A new study proposes that in fact we prefer consonant chords for a different reason, connected to the mathematical relationship between the many different frequencies that make up the sound1.
Cognitive neuroscientist Marion Cousineau of the University of Montreal in Quebec and her colleagues evaluated these explanations for preferences about consonance and dissonance by comparing the responses of a control group of people with normal hearing to those of people with amusia — an inability to distinguish between different musical tones.
Consonant chords are, roughly speaking, made up of notes that ‘sound good’ together, like middle C and the G above it (an interval called a fifth). Dissonant chords are combinations that sound jarring, like middle C and the C sharp above (a minor second). The reason why we should like one but not the other has long vexed both musicians and cognitive scientists.
It has often been suggested that humans have innate preferences for consonance over dissonance, leading some to conclude that music in which dissonance features prominently is violating a natural law and is bound to sound bad. Others, including Schoenberg himself, have argued that dissonance is merely a matter of convention, and that we can learn to love it.
However, there has long been thought to be a physiological reason why at least some kinds of dissonance sound jarring. Two tones close in frequency interfere to produce 'beating': what we hear is just a single tone rising and falling in loudness. If the difference in frequency is within a certain range, rapid beats create a rattling sound called roughness. An aversion to roughness has seemed consistent with the common dislike of intervals such as minor seconds.
Yet when Cousineau and colleagues asked amusic subjects to rate the pleasantness of a whole series of intervals, they showed no distinctions between any of the intervals. In contrast, normal-hearing people rated small intervals (minor seconds and major seconds, such as C-D) and large but sub-octave intervals (minor sevenths (C-B flat) and major sevenths (C-B)) as very unpleasant.
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