I tried a prototype of one at a well-know University. Personally, I’d rather stutter than deal with the hassle it caused. Although I only used it for a few hours, I never gave it a second thought after that. For me, it amplified every sound too much for my liking. Even walking down the sidewalk hurt my ears when vehicles would drive by. I’ve always heard that when you get used to the feedback device that the effectiveness of it decreases, but I don’t know the veracity of those claims.