Hemi-Sync MetaMusic "Einstein's Dream" Unopened. What is Hemi-Sync? It is an audio technology developed by the Monroe Institute in the United States. By playing different frequencies to the left and right ears, it adjusts brainwaves to guide the state of consciousness. It can lead to various states of consciousness, such as meditation, concentration, and relaxation. Effects vary from person to person. Please contact me if you wish to purchase this with other CDs. A small discount is possible. 2 for ¥3,500 3 for ¥4,000 4 for ¥4,500