Efficacy Research in Stuttering Therapy: A Longitudinal Observation of the Effects of Three Treatment Programs

Wendy J. Huinck and Herman F.M. Peters

In this study we evaluated the effect of three speech therapy programs on the speech of adult stuttering persons (N=65). Speech characteristics were assessed pre-therapy, post-therapy, and at one and two years follow-up on three levels of dysfluency: a) speech quality (e.g. perceptual evaluation of speech fragments; percentages stuttered syllables); b) speech physiological processes; c) emotions and cognitions that are related to stuttering (self-evaluation questionnaires). We found substantial progress immediately after therapy but also some relapse at the long term. Based on these results participants were classified into groups. Short- and long-term differences between these groups are discussed.