The mantra OM chanted out loud is very useful
the Oh sound is the alpha state
the M sound is a bit deeper,
one can balance rations, 50 % oh 50 % m
or play around, and they learn how to enter into good states of being
http://www.swamij.com/om.htm
Here is an indepth yogic perspective on why and how OM works, and the 7 levels of consciousness it tunes one into being.
