RTRL.40: Rhythmic Perception in Babies vs. Adults (Hannon & Trehub, 2005)
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What did the researchers want to know?
Given that existing research suggests infants gradually lose the ability to discriminate speech sounds in unfamiliar languages, do we also lose the ability to discriminate rhythmic sounds in unfamiliar meters?
What did the researchers do?
Hannon and Trehub conducted three related experiments using Balkan folk music in isochronous and non-isochronous meters. Isochronous meter is one in which the beats are evenly spaced (e.g., 2/4, 3/4, 6/8), and non-isochronous meter is one in which the beats are not evenly spaced (e.g., 5/8, 7/8).
In experiment #1, they studied 52 infants (11-12 months old) with no prior exposure to Balkan folk music using two isochronous (even meter) melodies and two non-isochronous melodies (uneven meter) melodies. Each melody was accompanied by “a drum pattern that subdivided each measure into either a long-short-short or a short-short-long sequence of temporal intervals” (p. 12640), as shown below in Figure 1. Each test stimulus either preserved or disrupted the original meter.
Each infant was randomly assigned to be familiarized with either the even-meter excerpts or the uneven-meter excerpts. The infant was seated on their parent’s lap in front of two monitors, one of which would flash a red light and then show random documentary video footage while a melody was heard. “Infants were first presented with 2 min of the familiarization stimulus, consisting of four 30-s repetitions [of either the even- or uneven-meter excerpts] alternating between monitors” (p. 12640). Then the test stimuli were played six times each, “with the structure-preserving and structure-disrupting test stimuli alternating between monitors” (p. 12640). Each test ended when the infant looked away for 2 sec or when 60 sec had passed. An observer recorded the total time each infant spent looking at the monitor and not looking at the monitor for each test stimulus.
In experiment #2, parents of 26 infants (11-12 months old) with no previous exposure to Balkan music were given CDs of uneven-meter music from Macedonia, Bulgaria, or Bosnia and asked to play it for their baby twice daily for two weeks. After two weeks, each infant was tested using the same procedures as experiment #1.
In experiment #3, Hannon and Trehub studied 40 adults with no previous exposure to Balkan music. They used the same stimuli as the infants in experiments #1 and #2 and asked the adults to rate each variation according to how similar it was to the familiarization stimulus. Each adult was tested at the beginning and end of the experiment. In the interim, half of the adults were given the CD of uneven-meter music and asked to listen to it twice daily for 1 or 2 weeks.
What did the researchers find?
Results of experiment #1 showed that, for even meter, infants spent significantly more time looking at the monitor while hearing the structure-disrupting stimuli than during the structure-preserving stimuli. This indicates that they were able to perceive the structure-disrupting stimulus as novel/unexpected and thus remained interested longer, suggesting the babies were able to differentiate between the stimuli in even meter. However, looking times did not vary between structure-disrupting and structure-preserving variations in the non-even meter, suggesting that the babies were not able to perceive the differences in non-even meter variations.
Results of experiment #2 showed infants spent significantly more time looking at the monitor while hearing the structure-disrupting stimuli than during the structure-preserving variation for both meters, suggesting that the infants who had been exposed to recordings of music in an uneven meter for two weeks were able to distinguish between the stimuli in a non-isochronous meter.
Results of experiment #3 showed the adults were able to more accurately recognize music in even meters than in uneven meters. In fact, “in the [even] condition, adults tended to rate the structure-disrupting variations as more similar to the original stimulus than the structure-preserving variations” (p. 12642), suggesting that they “assimilated the original [uneven] rhythms into a Western, or isochronous, metrical framework” (p. 12643). While the adults who had listened to recordings of uneven/non-isochronous music performed slightly better on the second test, there was no statistically significant difference from those who had not listened.
“In short, adults failed to attain native-like performance after exposure to foreign musical structures, in contrast with 12-month-old infants, whose postexposure performance in the foreign musical context was equivalent to their preexposure performance in the familiar musical context” (p. 12643).
What does this mean for my classroom?
Results of this study suggest that we lose our ability to accurately perceive unfamiliar meters as we get older. Thus, it is important that infants and young children be exposed to music in a wide variety of meters, both even and uneven, as early as possible. By doing so, we will help preserve their ability to accurately perceive and make sense of rhythms in both even and uneven meters, facilitating greater understanding of music in the future.
Music teachers should be aware that older students may struggle to accurately perceive rhythms in meters beyond duple and triple. If students will be expected to perform repertoire in uneven meters (e.g., 7/8, 5/8), the music teacher should provide extensive opportunities for students to be exposed to music in such meters well in advance of being asked to perform them.
In addition to passive listening to less familiar meters, students might also be encouraged to move their bodies as they are listening. In his book Learning Sequences in Music, Gordon (2012) suggested that moving with continuous fluid movement—in a smooth and uninterrupted manner—can help us feel the space between the beats and thus prepare us to move to the beat. The music teacher might sing or play a recording of a melody in an uneven meter and ask students to move their torsos and/or various body parts in large, fluid circles as they listen. Other imagery to prompt students to move with flow includes pretending to stir a large pot of soup or pretending to smoothly paint the space around them with a paintbrush. Once students can move in a continuous fluid manner while listening to uneven-metered music, model pulsing or flicking your fingers to the big beats.
Here are some examples of music in uneven meters:
- “Niska Banja”
- “Take Five” by Dave Brubeck
- “First Circle” by Pat Metheny
- “Dulaman”
