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Had to look up what you were talking about. Then listened to some of this on YouTube. And frankly, having those frequencies, no matter how artfully combined, playing throughout my house would drive me crazy in short order. It's anything but soothing, to me. It feels like an attempt to hypnotize, and since I'm incapable of being hypnotized, it's annoying instead.
What I find much more relaxing (and gently mentally stimulating at the same time) from this musician's standpoint is listening to the breeze playing through my 4 harmonized sets of tuned windchimes.
Oh, and it's also sorta annoying that these people have hijacked the perfectly good word Solfeggio from its original usage and definition. Seems rather pretentious of them, IMHO.
Tune your instruments to 432Hz for “A” rather than 440hz. That’s what is happening in these YouTube videos. I have my Uke tuned that way.