The main objective of this study was to investigate developmental aspects of disfluencies over time as stuttering persists or ameliorates for 2 groups of preschool age children who stutter. Results indicated that the frequency, type, and duration of disfluencies remained relatively constant instead of increasing as expected in the persistent group over a 3-year period. In contrast, the recovered group's initially higher frequency of disfluency decreased over time, as did their number of repetition units and proportion of disrhythmic phonations, while the duration of silent intervals between repetition units and proportion of monosyllabic word repetitions increased.
Throneburg, Rebecca and Yairi, Ehud, "DURATIONAL, PROPORTIONATE, AND ABSOLUTE FREQUENCY CHARACTERISTICS OF DISFLUENCIES: A LONGITUDINAL STUDY REGARDING PERSISTENCE AND RECOVERY" (2001). Faculty Research and Creative Activity. Paper 7.