https://medicalxpress.com/news/2024-08-reveals-ways-40hz-sensory-brain.html
here’s some
https://onlinesound.net/download/audio/subbass-tone-freq-40hz
https://www.youtube.com/watch?v=Ld0SoozrBBw
https://www.thegatewaypundit.com/2024/08/kamala-harris-holds-rally-cracker-box-maybe-250/