Wow what a thorough analysis, thanks! Admittedly, I'm not sure how to translate the numbers to audio. AI helped me find these websites:
https://hzgenerator.com/sweep-generator
https://onlinetonegenerator.com/frequency-sweep-generator.ht...
A looping 10 to 70 Hz sweep got the best result with my 20+ year old Apple sound sticks because they have a subwoofer.
With typical hearing, it sounds like almost a dozen distinct frequencies to me. Higher frequencies are just a matter of degree, they aren't qualitatively different IMHO. But I'm not musically inclined, and only have synesthesia when I sort of see color in various gray patterns on the computer screen, which look more blue or whatever sometimes, so I'm sure someone will disagree with me because they sense feelings in audio that I don't.
I'd bet that improvements in technology over the next few years (especially with the help of AI) might get the upper end to perhaps 100 Hz or more, where it begins to sound more like a tone than a hum. Loosely, a beat (like a drum) sounds like perhaps 10 to 20 Hz. A hum sounds like 60 Hz (like electricity). Also I wonder if a cochlear implant can hear below 10 Hz because it's electrical stimulation instead of physical, to maybe hear frequencies that typical hearing can't? But I don't know.
I'm fascinated by this stuff, because sometime in the next 5-10 years we'll get direct digital signal to nerve implants. That could allow people to hear above 20 kHz (like a dog) or even restore smell in people who have had it diminished due to illness or injury.
Many people can see ultraviolet light after getting cataract surgery, which supposedly looks like a blacklight but more blue because there is a little rise in the red visual receptor the overlaps blue to make violet. So technically the blue receptor ends up being a violet receptor because red isn't removed normally. Which means that violet and purple are different colors, because the visual cortex makes sense of them differently at opposite ends of the spectrum based on how much green is present. Of course all of those distinctions may go away when someday the visual nerves can be stimulated directly with an implant and make color more of a continuous spectrum like sound, rather than having distinct color bands like in a rainbow.
Subjectively, I've noticed when I wake up in the morning that the ceiling has grey and yellow splotches, because we have fewer blue receptors in the fovea at the center of the eye, and they haven't adjusted yet. Also at dusk, the rods begin to sense more, so the world fades from color to cyan and then gray. I feel like similar things might happen with audio, because I feel like I can hear better when I'm camping, especially in the morning, but I don't know why.
There are interesting experiments where they put goggles on chickens to flip the world upside down. After 2 weeks, the chickens saw normally again due to neuroplasticity. Then when they took the goggles off, the chickens walked goofy until their brains readjusted.
Also I've read that lion's mane mushrooms regrow neural connections and may even increase neuron synthesis. I've had neurological injuries due living a rough and tumble life that seemed to have healed somewhat after drinking mushroom coffee for a few weeks. Also magic mushrooms scramble nerve connections and let them reestablish themselves, sort of like starting over with a blank slate in neural networks. Mushroom medicine research has been blocked by a century of ignorant legislation, so people have missed out on spiritual healing that strays outside of what science can explain. I think of a brain or neural net as an antenna that resonates with the consciousness field, which is some sort of 5D-like field that transcends our normal 4D spacetime (otherwise it would be a frozen crystal with no observer or passage of time). When our brains get rewired after learning/trauma/injury/illness/healing, our attention shifts to different things, which alters our subjective experience. Meaning that in a very real sense we perceive the world differently and/or feel like we've shifted to a different (often better) timeline. Plant medicines and spiritual practices may allow changes to subjective experience that science can't yet talk about.
Anyway, not sure what point I'm trying to make here with these breadcrumbs, other than that the future isn't written yet, and in fact there are infinite futures, which I believe free will allows us to choose. So there is always hope and a reason to keep going.