As a speech pathologist I have never known any stutterer whose stuttering was not affected by stress. The Valsalva response is triggered by stress which is the causal factor in stuttering. When I gained voluntary control over my Valsalva response I was able to achieve fluency. I rewired my brain from a stuttering brain to a fluent brain. After a lifetime of stuttering I am now fluent. I sometimes don’t even remember I used to stutter.