Did you know that the Nazis believed the new world order would start with a tone? They also believed that tone was 440hzs versus the previous 432hz all orchestras used until that point. And why you ask??? because SOUND actually effects the human psyche in ways we don't even realize that it is effecting us. 

There's a whole lot more to it than that, but there is mountains of evidence that sound can change your life for the good if you use it properly. Sound therapy is a real and fantastic thing.