https://www.youtube.com/watch?v=ZXCZ3OyklrE
I am still processing this. I wasn’t aware that acoustic pollution was such a thing. Just because you can’t hear it, doesn’t mean it isn’t affecting you.
I am not clicking on that. Is this a test?! 
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Haha, nope. It’s a ~60 minute lecture that is both riveting and terrifying in it’s content.
Interesting Infrasound - Wikipedia – anything below 20Hz, including one human singing. I haven’t watched the lecture, but I’ll guess it is about windmills.