I didn’t even know they made devices like this but this reminds me a few times before when I am talking to friends and stuff online as we are playing games together, there is this feature where you can have your voice or any sound that goes through your mic, play back to you from you’re headphones at a slight delay exactly like you said. And a few times before I’ve had the feature turned on for a while as I was talking to friends or whatever, and had discovered this surprisingly helped with my stutter. Just thought I should say this since I’m amazing with how similar that device is with what I had discovered with some random feature on my mic setting.