

By Emma Young

All human cultures feature music. But the majority of studies of perceptions of music have been conducted on Western university students. This can make it hard to know whether the findings are biologically-driven, and common to all people, or the result of cultural influences.

To disentangle these two possibilities, you need a society that hasn’t really been exposed to Western music, for comparison. They’re not easy to find. But in 2016, a team led by Josh McDermott at MIT reported that the Tsimane’, a group of people living in the remote Bolivian rainforest, showed some unexpected differences in their musical perceptions compared to Western listeners. For example, while a chord comprised of an A and an F sharp sounded horribly grating to Western ears, for the Tsimane’ it was just as pleasant as a C with a G, which Westerners also enjoyed. Culture had to explain these differences.

Now a new study, led by Nori Jacoby at the Max Planck Institute for Empirical Aesthetics, Germany, has found that the Tsimane’ don’t perceive pitch in the same way as Americans, either. This work adds to other research finding cultural variations in perceptions that had once been assumed to be universal, such as colour perception.

The new study, published in Current Biology, involved trained musicians and non-musicians from the US as well as members of the Tsimane’ society. The participants were played very simple tunes of only two or three notes, and were asked to “copy” them, by singing them back. Though each tune fell within one of eight octaves, the listeners had to sing within their own vocal range.

Unlike Tsimane’ music, Western music (as well as some other musical traditions) is based around octaves. The pitch of a note doubles with each ascending octave. So tones with the frequencies of 27.5 Hz, 55 Hz, 110 Hz, and so on, are all ‘As’, just in different octaves.

The team found that the US participants — and the trained musicians, especially — accurately reproduced the tunes, within their own vocal range. So if the tune had been A-C-A, for example, they tended to sing back A-C-A, just in a different octave appropriate to their own range, higher or lower than the original.

The Tsimane’ preserved the relative pitch between the notes. So, if the tune was A-C-A, they sang back a middle note that was appropriately different in pitch, compared with the other two. “But the absolute pitch produced by the Tsimane’ didn’t have any relationship to the absolute pitch of the stimulus,” reports Jacoby. So, while they might have heard an A as the first note, they didn’t start singing back with an A. This suggests that it’s our exposure to Western music that makes us hear various As (and Cs, etc) as being similar, rather than anything to do with which parts of the cochlea in the inner ear are being stimulated.

Some cross-cultural similarities did emerge, however. The highest pitched note on the piano is just over 4,000 Hz, and it’s long been known that Westerners struggle to distinguish between different pitches above that frequency. Is that because of a biological constraint, the team wondered, to do with the inner ear or the nervous system? Or is it a cultural constraint, due to the fact that few musical instruments go any higher and we are rarely exposed to such notes, so haven’t learned to perceive differences between them?

Most Tsimane’ instruments are restricted to a pitch that is far lower than 4,000 Hz. So if culture plays a key role in pitch discrimination, you’d expect the performance of the Tsimane’ to deteriorate at a lower frequency than it does for Westerners. But they too only had trouble above about 4,000Hz. “It looks almost exactly the same across groups, so we have some evidence for biological constraints on the limits of pitch,” Jacoby notes.

The team would now like to see more work done to further explore the cultural vs the biological impacts on pitch perception, including the perception of harmony, for example. “We’re finding that there are some cross-cultural similarities, but there also seems to be really striking variation in things that a lot of people would have presumed would be common across cultures and listeners,” McDermott says.

– Universal and Non-universal Features of Musical Pitch Perception Revealed by Singing

Emma Young (@EmmaELYoung) is a staff writer at BPS Research Digest