"Infants are good at distinguishing speech sounds, even in languages that they've never heard. When they get older, they lose that ability in languages other than the one that they learn."
Large, the Florida Atlantic University researcher, noted that the study's findings may challenge some previous theories about the innate way in which humans perceive rhythm.
"A number of us, including me, have proposed that the way we perceive these basic beats is that the brain generates oscillations that are excited by periodicity [recurrent intervals] at these different timescales," Large said.
He added, however, that the theory "doesn't explain these [irregular] rhythms from the Balkans at least not in a way we've conceived so far."
The researcher notes that numerous studies strongly suggest that humans are biased toward perceiving beats that occur twice a second.
"If you ask people to tap to a piece of music, 90 percent will tap at the beat that's closes to that pace," he said. "The thing that makes [the study's Balkan rhythms] interesting is that at that approximately [half-second] level, they are not regular. At that sweet spot [the rhythm] is not periodic."
"Theorists like myself are going to have to spend some time thinking about this, working out whether these models can explain this or not," he continued. "This study shows an example that's explicitly not like [the theory]. It showed that this may be cultural. That's a challenge."
Hannon and Sandra Trehub of the University of Toronto reported their findings in the January 2005 issue of Psychological Science, a journal of the American Psychological Society.