A new study led by researchers from MIT and the Max Planck Institute for Empirical Aesthetics is looking at how people from different cultures interpret musical notes. To do this they have studied how a tribe living in a remote area of the Bolivian rainforest called the Tsimane perceives pitches.
The research seeks to answer the question of whether people outside of Western societies can detect the similarities between two versions of the same note played at different registers (high or low). The findings reveal that the brain only becomes attuned to note similarities after hearing music based on octaves, said Josh McDermott, an associate professor in MIT's Department of Brain and Cognitive Sciences.
"It may well be that there is a biological predisposition to favor octave relationships, but it doesn't seem to be realized unless you are exposed to music in an octave-based system," says McDermott, who is also a member of MIT's McGovern Institute for Brain Research and Center for Brains, Minds and Machines.
However, when it came to the upper limit on the frequency of notes that they can accurately distinguish, the Bolivian tribe performed the same as Westerners. This suggests that that aspect of pitch perception may be independent of musical experience and biologically determined.
In a study published in 2016, McDermott also found that Westerners and the Tsimane reacted differently to combinations of notes. Westerners found the combination of C and F# very grating, but Tsimane' listeners rated this chord as likable.
In their new study, the researchers evaluated pitch perception using an experimental test in which they play a very simple tune, only two or three notes, and then ask the listener to sing it back. Western listeners tended to reproduce the tune an exact number of octaves above or below what they heard, however, the Tsimane did not.
"The relative pitch was preserved (between notes in the series), but the absolute pitch produced by the Tsimane didn't have any relationship to the absolute pitch of the stimulus," said Nori Jacoby, a former MIT postdoc who is now a group leader at the Max Planck Institute for Empirical Aesthetics and the paper's lead author.
"That's consistent with the idea that perceptual similarity is something that we acquire from exposure to Western music, where the octave is structurally very important."
The upper limits of pitch perception
The study also shed light on the upper limits of pitch perception for humans. Both Western listeners and the Tsimane were found to not be able to accurately distinguish pitches above about 4,000 hertz.
"It looks almost exactly the same across groups, so we have some evidence for biological constraints on the limits of pitch," Jacoby says.
Jacoby and McDermott now hope to study other groups who have had little exposure to Western music.
"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. "These differences in experience can lead to dissociations of different aspects of perception, giving you clues to what the parts of the perceptual system are."
The study appears in the journal Current Biology.