科学美国人60秒:音符感知可能取决于文化

This is Scientific American — 60-Second Science, I'm Susanne Bard.
Every culture around the world creates music. But what shapes our perception of music? Two candidates are the limits of the human brain and the exposure we've already had to music during our lives.
"If you only test participants with experience with Western music, then we really can't know whether these features comes from the experience or from the biological constraint."
Psychologist Nori Jacoby of the Max Planck Institute for Empirical Aesthetics. During the past few years, he and his colleagues have visited a remote area of Bolivia to investigate this question.
"And so we traveled there by taking a canoe ride or taking a Cessna plane or a couple of hours on a truck to communities that don't have running water or electricity."
The Tsimane' are an indigenous people who live in the Amazon basin.
"We specifically recruited participants from the Bolivian Amazon because these participants have relatively little exposure to Western music."
For example, octaves are a staple of Western music, but Tsimane' musical instruments don't feature them. As an acoustical phenomenon, an octave is defined as the interval in which the vibrational frequency of the bottom note is half that of the top note. They're considered the same note, an octave apart. For example, middle C...
(CLIP: Middle C tone)
... and high C.
(CLIP: High C tone)

For the study, Tsimane' participants were asked to listen to simple melodies and sing them back to the researchers. This exercise revealed that the Tsimane' don't perceive tones that are an octave apart as the same note. On the other hand, participants from the U.S. did recognize octaves—although musically trained Westerners were better at it than those with no musical training.
"And so what is exciting here is that it highlights the importance of experience and exposure on the human mind."
The research is in the journal Current Biology.
In an earlier study, Jacoby's colleague Josh McDermott and his team from M.I.T. found that the Tsimane' don't find it unpleasant to hear notes like C and F# played together.
(CLIP: C and F# notes)
But they're a dissonant combo that's particularly grating to many Western ears.
Despite the evidence that experience influences pitch perception, biology is also a factor. Jacoby says the new study also revealed that both Westerners and the Tsimane' have trouble distinguishing between really high notes above 4,000 hertz...
(CLIP: 4,000 hertz tone)
... even though human hearing goes all the way up to 20,000 hertz.
And that may be because, no matter where we're from, we hit the limits of our brains before we reach the limits of our ears.
Thanks for listening for Scientific American — 60-Second Science. I'm Susanne Bard.