I've always wondered about this...

In the Gateway Wave 1 CD, part of the process of moving into Focus 10 is resonant tuning, where the listener sings or hums in resonance with voices on the CD. I'm just wondering-- why? I don't have a problem doing the resonant tuning, but it just doesn't seem to fit in the with the rest of the CD. The Gateway Manual states that resonant tuning is important.

The only theory I have is that singing and chanting have been known to increase CO2 levels in the blood, resulting in more spiritual states of consciousness. But I think this is a bit far-fetched.