Not to rain on the parade, but in Fig. 1-D I see by comparing the two graphs that the VLF is almost always turned on in sync with a bass drop or with the start

Not to rain on the parade, but in Fig. 1-D I see by comparing the two graphs that the VLF is almost always turned on in sync with a bass drop or with the start of a new section of the song, which I think is correlated with people suddenly dancing more vigorously. I didn't read the main text, does anyone know if they address this?