A research team led by neuroscientists Drs. Daniel Levitin and Vinod Menon, from McGill and Stanford Universities, analyzed the scores of close to 2,000 musical compositions written by more than 40 composers over the last 400 years in a large variety of Western musical genres. They discovered a mathematical formula governing the rhythmic patterns to which every single piece of music conformed.
Researchers uncover mathematical formula for rhythm and
suggest our brains may be hardwired to respond to it
Whether it’s Bach or Brubeck, a new study shows that composers
repeat rhythmic patterns in their works in such a way that the part
is a copy of the larger whole. A research team led by
neuroscientists Drs. Daniel Levitin and Vinod Menon, from McGill
and Stanford Universities, respectively, analyzed the scores of
close to 2,000 musical compositions written by more than 40
composers over the last 400 years in a large variety of Western
musical genres.
They discovered a mathematical formula governing the rhythmic
patterns to which every single piece of music conformed. “One of
the things that we’ve known about music for a couple of decades is
that the distribution of pitches and loudness in music follow
predictable mathematical patterns,” says Levitin. “Rhythm is even
more fundamental to our enjoyment of music: it’s rhythm that
infants respond to first, it’s rhythm that makes you want to get
out of your chair and move, and so it’s not really a surprise to
discover that rhythm, too, is governed by a similar mathematical
formula.”
The researchers found that all the musical compositions they
studied shared the same "fractal" quality, where the part is a more
limited repetition of the whole. That is the larger temporal
structure of well-formed musical pieces is composed of repeating
motifs of their own short-term temporal structure. At the
same time, researchers also discovered that each composer had his
or her own highly individual rhythmic signature. “This was one of
the most unanticipated and exciting findings of our research,”
asserts Levitin. “Mozart's notated rhythms were the least
predictable, Beethoven's were the most, and Monteverdi and Joplin
had nearly identical, overlapping rhythm distributions. But they
each have their own distinctive rhythmic signature that you can
capture. Our findings also suggest that rhythm may play an even
greater role than pitch in conveying a composer’s distinctive
style.”
From snowflakes to fern fronds and broccoli florets, fractal
patterns are to be found throughout the natural world. The
discovery that four centuries of musical compositions obey this
same mathematical rule strongly suggests that composers’ own brains
may have incorporated certain regularities of the physical world,
to recreate self-similarity in works of musical art. Indeed, the
authors suggest, building on work begun in the 1970s that our
sensory and motor systems may have a fundamental propensity to both
perceive and produce fractal patterns not just across the three
dimensions of space, but also across time.
For Levitin, whose undergraduate supervisor persuaded him to do
a PhD in psychology rather than mathematics by telling him he would
be able to do math while studying psychology, but not reverse, the
study provides a perfect balance between his two interests.
The research was funded by: Natural Sciences and Engineering
Research Council of Canada (NSERC), the Canada Foundation for
Innovation (CFI) and the National Science Foundation (NSF).
To read the original paper: http://www.pnas.org/