Provided by bass instruments, the low-frequency parts of music tend to contribute the beat we actually dance to. Songs with lower-frequency baselines tend to have higher perceived "groove" ratings, but what if the frequency is so low that it falls outside humans' audible range?
from McMaster University, Fitchburg State University and the Rotman Research Institute set out to test just that. Utilizing so-called very-low frequency (VLF) sound, participants with motion capture headbands at a live concert for electronic music duo Orphx and had them fill in pre- and post-concert questionnaires. VLF speakers were turned on and off every 2.5 minutes throughout the 55-minute performance, and the recorded mo-cap data was used to calculate participants' head movement speeds in the presence or absence of VLF.
The resulting data showed that audience participants moved an average of 11.8% more when the VLF sound was on versus off. The researchers also performed additional experiments to confirm that the VLF was inaudible.
If it can’t be heard, how can VLF sounds contribute to a sense of groove or make people dance more? The researchers suggest that VLF sounds lead to changes in behaviour through subconscious processes involving our brains’ vestibular, vibrotactile, motor and reward systems. Sounds are mainly processed through our auditory pathways; however, low-frequency sounds are additionally processed via the vibrotactile and vestibular pathways.
While known for controlling our balance and proprioception (sense of where our bodies are), the vestibular system has previously been in perceptions of rhythm. In addition, both the vestibular and vibrotactile pathways have close links to our motor systems. The researchers believe that one, or more, of these pathways, are responsible for the dance-inducing effects of VLF sound.
