@MyView @decryption Depends on your sensitivity to low-frequency sounds (which is... complicated and hard to predict) and your propensity to anxiety. And probably your background knowledge as well.
(While a lot of the neuroscience is focused on infrasound causing stress and anxiety - which it can - I'm not sure that I buy that it's a hardwired or default reaction, though that's based entirely on my own limited experiences with it.)
It can also be really uncomfortable at close range for people with certain anatomical quirks to do with their auditory and vestibular system, and people who've had acoustic shock injuries as well. But you'll know pretty quickly if that's you, and I'm not sure if tours would actually let you get that close to them anymore (for me and my Dad, it's at around the 20-30m range that it gets a bit uncomfortable, it's just a feeling of slight pressure inside my ear as I hear the 'whoosh' from the blade).
I should also add that while 20Hz is usually cited as the low threshold of human hearing, that's kind of an average - individually, human hearing can range as low as 12Hz, so there are definitely people who can actually hear infrasound frequencies. (Infrasound is usually defined as anything below 20Hz as well; 17-18Hz seems to be used the most in experiments.)
Yeah ... as somebody once said, perception is everything ...
I have a tall tower near my house that is as ugly as sin ... but with the arthritis in my neck I can't look up so ... :)
one real reality, we are all living with is the global economy has largely exhausted the kinds of mineral inputs that needs to function. Conventional oil, production peak in 2005. Nonconventional sources are basically running out quickly, but the other mineral inputs needed are largely done.