Words, music, our body, indeed the entire universe is nothing more than vibration of energy. The rate this energy vibrates is called the frequency. Emotions, people and even planets differ from each other, and everything else, because of their unique vibrational frequency.
Therefore by 'tuning' your brain to certain frequencies using BWE and other techniques, it is possible to experience different states of consciousness, as well as stimulating certain brain functions such as creativity or mood enhancement. There are also other 'sacred' frequencies which are said to contain the power of creation and transformation.
Learn more about frequencies and transformation here.