Newborns pick up the beat

Sonny and Cher once crooned that the beat goes on, but little did they know that the beat starts up within days of birth. A new study indicates that the brains of 2- to 3-day-old babies recognize when a rhythmic drum sequence lacks its initial beat, or downbeat. The downbeat corresponds to the downstroke of a conductor’s baton at the beginning of a musical measure.

Newborns automatically perceive the downbeat of a sequence of sounds, thankfully without having to snap their fingers or tap their toes, says psychologist and study director István Winkler of the Hungarian Academy of Sciences in Budapest, who reports the work with colleagues online January 26 in Proceedings of the National Academy of Sciences.

It’s unclear to what extent this ability depends on innate biology versus hearing rhythmic sounds, such as a mother’s heartbeat, in the womb, Winkler notes.

“Although the ability to sense a regular pulse in an auditory sequence has been thought of as learned sometime late in infancy at the earliest, this is the first evidence of beat induction in newborns,” says musicologist and study coauthor Henkjan Honing of the University of Amsterdam.

Newborns’ knack for perceiving rhythmic beats may lie at the core of not only musical ability, but also the unique communication, including baby talk, between a caretaker and a baby that sets the stage for language learning, Winkler hypothesizes.

“Infants’ ability to extract a regular beat is probably very important for music learning, but it is not clear that it’s helpful in learning language,” remarks psychologist Laurel Trainor of McMaster University in Hamilton, Canada. Speech rhythms tend to consist of irregular beats unlike the one that Winkler’s team presented to newborns, she notes.

In the new study, 14 sleeping newborns were exposed to repeated recordings of a rock drum accompaniment pattern and to four variations of that pattern. Babies were usually exposed to patterns with a downbeat. On rare occasions, the downbeat was missing.

Of the 306 consecutive drum sequences presented to newborns, one in 10 lacked a downbeat.

Each newborn wore scalp electrodes during the study. Drum sequences missing a downbeat elicited a signature, split-second brain response that has been linked in adults to the violation of one’s expectations.

Earlier studies conducted by Winkler had indicated that infants’ brains respond to sounds as the babies contentedly snooze. “We don’t know what sleeping babies actually experience as sound reaches their brains,” Winkler says.

Questions remain about whether newborns can detect musical beats, comments psychologist Glenn Schellenberg of the University of Toronto at Mississauga. Critically, in the new study the downbeat consisted of a bass drum and cymbal sound simultaneously. The babies either heard this simultaneous sound, or a pause. Only the cymbal sounds were omitted at other times. The newborns, Schellenberg says, showed a larger brain response to omissions of a pair of sounds than to omissions of single sounds.

“These results do not tell us that babies were detecting the beat, but simply that a larger change in the sound pattern elicited a greater neurological response,” Schellenberg says.

Still, newborns’ brains had to remember a standard sound sequence in order to respond to variations, he holds. Winkler’s findings thus indicate that newborns remember rhythm sequences, in Schellenberg’s view.

Memory for rhythmic sequences is actually a more complex process than beat detection, responds Honing. Beat detection requires only that the brain discern the length of a sound sequence and its onset.