Listen to this short recording:
It’s a sequence that repeats every sixth beat. But when we’re listening to music, we usually prefer to divide rhythm into two- or three-beat patterns (duple or triple rhythm). In this case, the sequence doesn’t make it obvious which pattern is correct. A traditional duple rhythm, like a march, would accent every other beat — the musicians play every other note a little louder. Similarly, a traditional triple rhythm, like a waltz, accents every third beat.
When we’re dancing (or marching), we move in time to these accented beats. Indeed, it’s often difficult to resist moving when we hear music. The Western tradition of sitting still to listen to “classical” music, which only originated in the past few hundred years, may be the only setting in which movement is not considered an integral part of experiencing music.
It may not be too much of a stretch to suggest that movement itself may also affect the sounds we perceive. Jessica Phillips-Sliver and Laurel Trainor devised a set of experiments to test that notion. While volunteers listened to the recording above, the experimenter showed them how to “bounce” along with the rhythm, either every other beat, or every third beat. After bouncing along for two minutes, the listeners heard two additional recordings, which added a minor modification to first recording.
In one recording, every other beat was accented, creating a duple rhythm:
In the other recording, every third beat was accented: a triple rhythm:
Then they were asked which recording matched the recording they had bounced along with. Here are the results:
Nearly everyone who bounced every second beat thought they actually heard a duple rhythm, while those who bounced every third beat thought they had heard a triple rhythm — even though the identical recording had been played for every listener during the bouncing phase.
In two subsequent experiments, Phillips-Silver and Trainor eliminated two potential explanations for the results. Wearing headphones had no effect on the results (thus showing that the motion of the listener relative to the sound source didn’t cause the effect). Neither did wearing a blindfold (eliminating the possibility that a visual, not a movement cue, was responsible for the effect).
In their final experiment, listeners sat still while watching the experimenter bounce at either a duple or a triple rhythm. Here are those results:
Now there was no significant difference between the different bouncing conditions. Phillips-Silver and Trainor argue that it must be the listener’s motion that causes different perceptions of the sound.
Phillips-Silver, J., Trainor, L. (2007). Hearing what the body feels: Auditory encoding of rhythmic movementâ˜†. Cognition, 105(3), 533-546. DOI: 10.1016/j.cognition.2006.11.006