i used to make jet engine fan blades for the US military, they are a complicated component and usually they are not tested for frequency, but one company insisted that this be done. i was told unofficially that these were going into research aircraft, most likely the f-117 or B2, anyway whatever they were going in they had to be within a certain frequency range to pass inspection. the power of frequency can destroy and it can heal
this one seemed to have a big impact on my quality of sleep and im actually looking forward to going to bed
another i just found that i might try, its deep, lucky i just bought a subwoofer
https://youtu.be/BJ9pkEiI4OQ
this one is much higher out of our hearing range: https://youtu.be/xi_2Tz1xS70
In the video I heard reference to Yuri Grigoriev. He died in 2021 and I wrote about his contribution to our understanding of frequencies here: https://francesleader.substack.com/p/the-cold-war-of-electro-magnetic