Chance, music, and the ear of the beholder
Feb 6, 2006 - 5:00:00 AM
|
|
|
In the 1970s, the American scientists Voss and Clarke noticed that even music, speech, and natural soundscapes appear to behave according to the 1/f rule. Large, abrupt changes in loudness or in musical pitch are proportionally less frequent than small, gradual ones, and when human volunteers are asked to rate computer-generated random melodies, they instinctively prefer those melodies that obey the 1/f rule to those that do not. Melodies that change more abruptly than the 1/f rule would sound unpleasantly erratic. In contrast, melodies that change more slowly sound boring.
|
By Cell Press,
[RxPG] The work is reported by a team of scientists led by Dr. Jan Schnupp at the Oxford University Auditory Neuroscience group.
The world we inhabit is constantly subjected to countless random influences that may occasionally conspire to bring about large and abrupt changes in our environment, but that more often will cancel each other out, and thus provoke only little or no change. Imagine a boy playing a game where, on every round, he tosses twenty coins, and for every head he will take a step to the left, while for every tail he will take a step to the right. In most rounds, the number of heads will be very similar to that of the tails, and the boy's net position will change only a little, but occasionally it might be almost all heads or all tails and the boy will make a sudden large leap to the left or right. Many things in nature are pushed around, much like the boy in this game, by a combination of random influences, from dust grains in a drop of water pushed about by the collision with water molecules to flocks of animals roaming across a pasture. Scientists would say that their movement is approximately 1/f-distributed, which means simply that there is an inverse relationship between the size of a change and the likelihood of a change. Small changes occur often (at a large frequency), while large, abrupt changes occur with a proportionately smaller frequency.
In the 1970s, the American scientists Voss and Clarke noticed that even music, speech, and natural soundscapes appear to behave according to the 1/f rule. Large, abrupt changes in loudness or in musical pitch are proportionally less frequent than small, gradual ones, and when human volunteers are asked to rate computer-generated random melodies, they instinctively prefer those melodies that obey the 1/f rule to those that do not. Melodies that change more abruptly than the 1/f rule would sound unpleasantly erratic. In contrast, melodies that change more slowly sound boring.
Now, in the new study, the researchers have discovered that this preference for 1/f-distributed soundscapes appears to be hard-wired into the mammalian brain. Individual neurons in the auditory cortex of ferrets were found to respond more strongly and more reproducibly to stimuli with random pitch and loudness fluctuations that conformed to the 1/f rule than to other stimuli that did not. This selective sensitivity results in a more accurate representation of the 1/f-distributed sounds within the brain. 1/f-distributed behavior has a strong random element, but is nevertheless not entirely unpredictable, and it appears that our sensory systems have evolved to expect this partial predictability as natural, and to exploit it to become particularly efficient at processing sensory inputs that exhibit just the right amount of randomness.
Advertise in this space for $10 per month.
Contact us today.
|
 |
Related Latest Research News
|
|
Subscribe to Latest Research Newsletter
|
|
|
|
Feedback
|
For any corrections of factual information, to contact the editors or to send
any medical news or health news press releases, use
feedback form
|
Top of Page
|
