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.
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Lu Zhi (painter) (Wikipedia)Lù Zhì, formerly romanized as Lu Chih (simplified Chinese: 陆治; traditional Chinese: 陸治; ca. 1496–1576), was a Chinese landscape painter, calligrapher, and poet during the Ming dynasty (1368–1644).