CFTraveler,

I think the one machine that I linked does take you to delta waves.

Speaking of sound producing altered states, I once was in a trance techno club in Germany, and being there for more than a hour I started to see strange things. Every time someone would walk to one side of the room I would then see them back at the other side of the room without them having walked back to that side. Weird. So from this experience I think that sound can produce altered states.

Thanks for your help.

Superluminal