Speech motor control, so speech production seems to be tightly coupled to auditory feedback. A disruption in the integration of this feedback to motor control is proposed to play an important role in speech fluency. This also links to the temporary fluency effects stutterers experience with altered auditory feedback, such as Delayed Auditory Feedback. Here is a good review to dive in deeper: https://direct.mit.edu/nol/article/2/2/308/98521/The-Role-of-Sensory-Feedback-in-Developmental