I actually had a hearing aid-like device that did that for me in high school. I believe it was called the Speech Easy. In a quiet room it was wonderful and I wouldnt stutter at all. But the problem is it amplifies and delays EVERYTHING it hears, not just your voice. So at lunch or in a space with many people there it was unbearable to wear. I haven’t checked in on this technology in more than a decade but I hope they worked on that aspect of its flaws.