Since the Theta level is associated with sleep, the subject concerned may progress from a fully awake to a sleep state (provided that he does not consciously resist) as the brain strives to entrain its wave frequency output with the one which the person hears.
This is the famous NGC 884 “Double Star Cluster” in Perseus, one of the truly classic examples of a galactic cluster, and a wonderfully beautiful object for moderate telescopes. Among the all-time favorites for amateur observers, it may be seen without optical aid as a hazy patch of light about midway between the stars of Perseus and the familiar “WwW” figure of Cassiopeia. A small telescope reveals that this luminous spot consists of two fine open star clusters together in the field, the pair forming one of the most impressive and spectacular objects in the entire heavens. In the mythological outline of the constellation it marks the “Sword Handle” of Perseus and is often identified on star atlases by the inconsistent designation “h - x” Persei. The cluster called “h” is NGC 869, and “y” is NGC 884.