Completely anecdotal. Works for some people, doesn’t for others. Same with devices like the speech easy or tricks like soft starts. It’s a huge bummer that people try to pass of techniques and stuff like they are a cure all if you practice. I am firmly in the belief that some of us will just be stuck with the worst speech of our lives. I was in speech therapy from 4th grade till college. I’m 30 now and it did absolutely nothing for me. All the techniques were a complete waste of time. I purchased a speech easy at one point and it’s the most expensive paper weight I’ve ever purchased