i hated my stutter so much that i did psychology as an extra degree in college and i specifically took as many classes related to stuttering as possible to have a better understanding of stuttering and what i concluded is that it stems from both human neurology and psychology. there are specific areas of the brain like wernicke's and brocas area where speech is recognized and speech produced. when speaking variables like the context, setting and person(s) being spoken to largely has a big effect on your psychology and in turn your body reacts by producing specific hormones to regulate "you" but even in this example your brain is working in concert with your body through complex mechanism of biochemistry. i have done a lot of different experiments on myself chemically and non-chemically and what i have found to work noticeably are 3 things. small dosage of modafinil by increasing your histamine levels causing you to feel more awake and "focused", hence the quotes there. applying small amounts(<2 mil amp) of electricity to the brocas area while reading out loud for 25-30 minutes. finding an appropriate place(concert, empty structure) to yell. your probably thinking the 3rd one is a bit strange and i would agree with that but what i think happens during yelling is that your brocas area become charged with neurons and your vocal chords become activated and even these things are not a permanent fix. ​ ​