Love of musical harmony is not nature but nurture

Associate Professor Neil McLachlan from the Melbourne School of Psychological Sciences said previous theories about how we appreciate music were based on the physical properties of sound, the ear itself and an innate ability to hear harmony.


“Our study shows that musical harmony can be learnt and it is a matter of training the brain to hear the sounds,” Associate Professor McLachlan said.
 “So if you thought that the music of some exotic culture (or Jazz) sounded like the wailing of cats, it’s simply because you haven’t learnt to listen by their rules.”


The researchers used 66 volunteers with a range of musical training and tested their ability to hear combinations of notes to determine if they found the combinations familiar or pleasing.


“What we found was that people needed to be familiar with sounds created by combinations of notes before they could hear the individual notes. If they couldn’t find the notes they found the sound dissonant or unpleasant,” he said.
 “This finding overturns centuries of theories that physical properties of the ear determine what we find appealing.”


Coauthor on the study Associate Professor Sarah Wilson also from the Melbourne School of Psychological Sciences said the study found that trained musicians were much more sensitive to dissonance than non-musicians.


“When they couldn’t find the note, the musicians reported that the sounds were unpleasant, whereas non-musicians were much less sensitive,” Assoc. Prof Wilson said.
 “This highlights the importance of training the brain to like particular variations of combinations of sounds like those found in jazz or rock.” 


Depending on their training, a strange chord or a gong sound was accurately pitched and pleasant to some musicians, but impossible to pitch and very unpleasant to others. “This showed us that even the ability to hear a musical pitch (or note) is learnt,” Assoc. Prof Wilson said.


To confirm this finding they trained 19 non-musicians to find the pitches of a random selection of western chords. Not only did the participants ability to hear notes improve rapidly over ten short sessions, afterward they reported that the chords they had learnt sounded more pleasant – regardless of how the chords were tuned.

The question of why some combinations of musical notes are heard as pleasant or unpleasant has long been debated. “We have shown in this study that for music, beauty is in the brain of the beholder,” Assoc. Prof McLachlan said. The study was published in the Journal of Experimental Psychology: General.

Wired for Harmony?

Many creatures, such as human babies, chimpanzees, and chicks, react negatively to dissonance—harsh, unstable, grating sounds. Since the days of the ancient Greeks, scientists have wondered why the ear prefers harmony. Now, scientists suggest that the reason may go deeper than an aversion to the way clashing notes abrade auditory nerves; instead, it may lie in the very structure of the ear and brain, which are designed to respond to the elegantly spaced structure of a harmonious sound.

"Over the past century, researchers have tried to relate the perception of dissonance to the underlying acoustics of the signals," says psychoacoustician Marion Cousineau of the University of Montreal in Canada. In a musical chord, for example, several notes combine to produce a sound wave containing all of the individual frequencies of each tone. Specifically, the wave contains the base, or "fundamental," frequency for each note plus multiples of that frequency known as harmonics. Upon reaching the ear, these frequencies are carried by the auditory nerve to the brain. If the chord is harmonic, or "consonant," the notes are spaced neatly enough so that the individual fibers of the auditory nerve carry specific frequencies to the brain. By perceiving both the parts and the harmonious whole, the brain responds to what scientists call harmonicity.

In a dissonant chord, however, some of the notes and their harmonics are so close together that two notes will stimulate the same set of auditory nerve fibers. This clash gives the sound a rough quality known as beating, in which the almost-equal frequencies interfere to create a warbling sound. Most researchers thought that phenomenon accounted for the unpleasantness of a dissonance.

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