So as far as I know, the technology isn't well understood as to why it works, but it works on a "sing-a-long" philosophy. When you sing along with a song or mindlessly talk along in a group, most people's studders are reduced. Now they've done their own research on certain tones and delays that are more effective than others so they put an echo box in your ear so you are your own group as far as your electrical impulses can tell