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If you play a middle C on a piano and then play a high C two octaves higher, it will feel like you’re playing the “same” note.
But is that true for everyone? A study published last week in Current Biology suggests that octave equivalence may be a product of Western culture, and the results add a new layer of cultural influence to our understanding of how we perceive music.
To study people whose ears have not been molded by Western music, researchers visited the Tsimane’, a remote indigenous tribe in Bolivia. There, they asked participants to listen to a simple tune and sing it back in their own vocal register.
From a Western perspective, the Tsimane’ would sing off-key, which sounded as right to them as octave equivalents do to Westerners.
How we hear music, it seems, is as much a product of our cultural lens as our biology.
“There’s something very substantial about your experience and exposure,” says Nori Jacoby, the study’s lead author. “It’s really transforming your mind in a way that you basically hear things in a different way.”
Take a moment to find a song you know where the singer hits some ridiculously high notes and – don’t be shy – sing along. Just belt it out. If you like pop, try Ariana Grande’s “Imagine.” If you’re into Mozart, try Edda Moser’s rendition of the Queen of the Night aria from “The Magic Flute.” Or maybe Dimash Kudaibergen’s “Unforgettable Day” if Kazakh fusion is your thing. Don’t worry about everyone else on the bus. Tell them it’s for science.
Chances are that, unless you happen to be a highly trained vocalist, you’re not quite hitting those high notes. Instead, you probably had to drop down an octave or three.
But, even as you’re singing along in a lower register, you’ll know intuitively whether you’re producing the “right” notes. If Ariana sings a high C and you sing a middle C, two octaves lower, you’ll sound consonant. If you miss the mark and sing a C sharp instead, the glares from your fellow commuters will intensify.
Octave equivalence – that unshakable feeling that notes separated by an octave are really the “same” note – is such a fundamental feature of our music that it’s nearly invisible. When we think of it at all, it’s tempting to see it as natural, something encoded into the physics of acoustics and hardwired into the biology of human hearing.
Every known human culture produces music, and it’s tempting to focus only on the universal elements, to see music purely as a matter of biology. Alternatively, given the vast range of musical systems across cultures, it’s also tempting to see all music as culturally contingent.
But it might actually be more complicated than that. A study published last week in Current Biology takes aim at the taken-for-grantedness of octave equivalence. The research offers a glimpse at the perplexing and often counterintuitive ways that nature and nurture play off one another.
“When you look at human behavior, on the one hand you see commonality, on the other hand you see differences,” says Nori Jacoby, a researcher at the Max Planck Institute for Empirical Aesthetics in Frankfurt, Germany, and the study’s lead author. “The question is not whether it’s either-or. The question is within the more refined details.”
Do re mi ...
Western music is built around octaves, and it has dominated the globe to such an extent that it’s hard to find people whose musical sense hasn’t been shaped by it.
In an attempt to find ears unsullied by Western musical conventions, the researchers traveled to the Bolivian lowlands, home to the Tsimane’ (pronounced chee-MAH-nay), a remote indigenous people. There, researchers asked participants to listen to a simple tune of two or three notes – the tune could come from any octave within the range of human hearing – and to sing it back in their own vocal register.
Western participants typically reproduced the tune with the “same” notes, that is, an exact number of octaves above or below the tune they heard. The Tsimane’ did not.
“We are really getting into the question of what people hear,” says Dr. Jacoby. “There’s something very substantial about your experience and exposure, and it’s really transforming your mind in a way that you basically hear things in a different way.”
The authors point out that there is indeed an objective physical relationship between notes separated by octaves: Every note is double the frequency of the note one octave below it. The A above middle C, widely used as concert pitch, is 440 hertz. The A above it is 880 Hz and the A below it is 220. But we only become attuned to this relationship, they say, through exposure to certain kinds of music.
“There is something very special about the octave in terms of acoustics and biology,” says Josh McDermott, an associate professor in MIT’s Department of Brain and Cognitive Sciences and one of the paper’s authors. “There are these natural mathematical relationships that exist, and that probably does predispose musical systems in various ways.”
But, he says, “those relationships don’t really seem to be evident to people unless they engage with one of those musical systems.”
Music to whose ears?
Dr. McDermott is also the author of a 2016 paper in Nature that found that the Tsimane’ had different perceptions of consonance and dissonance than Westerners. To Westerners an interval of seven half steps played together (C and G, for instance) sounds pleasing, while an interval of three whole steps (say, C and F#) sounds harsh. To the Tsimane’, Dr. McDermott and his colleagues found, they sound equally pleasant.
The researchers suspect that these differences in perception arise as a result of the music that we’re exposed to. Tsimane’ music, they note, is typically performed solo. Because Tsimane’ musicians aren’t required to harmonize with each other, they may have never developed an ear for octaves.
What the researchers found most surprising, however, were not the differences, but the similarities. Even though humans can hear frequencies of up to 20,000 Hz, most Western instruments have an upper limit of about 4,000 Hz. Above that, the notes become too tinny to discern the difference.
The Tsimane’ have the same upper limit as Westerners, researchers found, even though their musical instruments tend to top out at lower frequencies.
“The most striking thing to me is how they found these incredibly clear universals across these two cultures,” says Samuel Mehr, a researcher at Harvard University who studies music from around the world.
“We’re open to the possibility that there are no strong universals, that there’s tons of variability,” he says. “But this paper [suggests] that it’s something in the middle, where there are some biological constraints, there’s some learning, there’s some culturally determined features of perception by virtue of having experience with a particular thing or no experience with that particular thing.”
But the only way to determine which aspects of music are universal and which ones are culturally specific, says Dr. McDermott, is to go into the field and listen to the notes people produce.
“You got to do the experiments, right?” says Dr. McDermott. “Reality is always a little more interesting than what you might imagine.”