It probably has no effect, because stuttering is a psychological problem. It cannot be corrected by instruments. I used to be like this too. I stuttered quite badly, especially when talking to the teacher or on the phone. In fact, the reason for stuttering is very simple. It is that you are nervous when speaking. You have already thought about what to say, but the words get stuck as soon as they come to your mouth. Here's how I corrected it: first, adjust your breathing when speaking, speak slowly, and don't rush to say what you want to express as quickly as possible. Even if you just open your mouth and don't speak, don't repeat a word or word. If you're still nervous, treat your audience like a cabbage. The most important thing is to adjust your mentality. The process of correcting stuttering is relatively long. It took me nearly a year to correct it.