Brainwave Entrainment History
The truth is that human beings have been replicating their brainwaves to desired states of mind for thousands of years. The music they played allowed them to enter these states of mind naturally. Specific drumbeats per second would usually enter them into the delta state of mind.
The higher pitched stringed instruments such as the harp, guitar and violin entrain the brain in another state of mind. Therefore, each instrument is truly unique in how it affects your mind and life.
I know you are familiar with the fact that classical music helps you think more clearly and do better on tests. Has it occurred to you that it is because of the frequencies? Well that is exactly why it works.
Now in the era of technology, you can do this too and know exactly how it will effect you.