No devices helped me. Only turning on headphones with white noise. Then I can read without stuttering. But only read. I still can't hold a conversation. On a forum, I read a review from someone who got rid of their stuttering. He enrolled in a humanities university and wanted to become a teacher. It was impossible with his speech. So, he earned some money and hired three speech therapists, each of whom worked with him twice a week. He got rid of his stuttering in two years, but it cost him a lot. I think if you repeat this approach and also take mild antipsychotics, your speech could become perfect.