I looked it up and found that "leonard Horowitz, along with Joseph Puleo, proposed a set of musical pitches in 1999, which they call "solfeggio frequencies." These pitches, claimed to originate in centuries-old Gregorian chant, are not based in any practical musical tuning, but come from a numerological manipulation of decimal representations of frequencies in cycles per second, or Hertz.

There are many unverifiable claims made regarding spiritual and/or scientific properties of the frequencies. The six "original" frequencies are: 396 Hz, 417 Hz, 528 Hz, 639 Hz, 741 Hz, 852 Hz.[25] The number of pitches has been expanded to nine, then twelve, but the numerical system used to formulate the numbers could be extended further."

Here is a sampling:

http://www.youtube.com/watch?v=wSa7plNbocU

I've not heard of this exact thing before, but I have heard of the Tibetan singing bowls

http://www.youtube.com/watch?v=-V0IMYlYVZQ

and I've also heard about some special sounds like of the didgeridoo

http://www.youtube.com/watch?v=hjOk3Zg1N6I

also, there is some controvery now about classic tuning... where in most orchestras the key of A is at 440 hz, and some are saying that this is actually not good and that using 432 hz is more harmonious and so more calm.

I have practiced overtone singing and it can be very relaxing.

while exploring I found this.. chakra music.. that is very nice

http://www.youtube.com/watch?v=r3hLmrJMHco

I think music, as qualities and combinations of sound, affects us in a primitive and preverbal very basic way. Both discords,, like heavy dark metal music,, and harmonies,, affect us differently.

I was admitted to a psych unit a few months ago, because I told a crisis counselor that I wanted to,, not be here any more, and I was crying.. I had had it.. so, anyway.. it was night and somebody got admitted that was making sounds,, low kind of angry sounds.. like metal music.. and I thought,, he is being preverbal,, and I'm going to sing back to him, in the Spirit.. and so I vocalized some harmonies,, and he actually responded,, and we were singing.. not in words, back and forth.. and a nurse came in and told me to shutup. She didn't understand. But I kept singing,, and each time he sang back it was less discordant, and then there was a smoother sound, and then began harmonies,, and we were harmonizing. I found out later that he had taken some kind of drug that wrecked him.

Whatever the science about it, music helps me. Not just listening to it, but making it, which is why 2 guitars are on stands in my living room at all times for me to play and sing.

Loved what x shared about Gregorian chant. It goes with what was said about Eastern Asian chanting, too. Made me thing of Tibetan chanting.

I've got some healing chants on my iPod I carry around with me at work for when I get stressed.

My two cents.