https://github.com/davepinch/pinchy.cc/blob/master/content/streams/beyond-the-walls/02/down-the-hallway-you-can-see-a-million-doors.md
Next comes the technique of progressive and systematic physical relaxation while the Hemi-sync frequencies are expanded to include additional forms of “pink and white” noise designed to put the physical body at the virtual threshhold of sleep as well as to calm the left hemisphere of the mind while raising the right hemisphere to a state of heightened attentiveness.