Efficacy of the Modifying Phonation Intervals (MPI) Stuttering Treatment Program With Adults Who Stutter.

Purpose: This study compared a new adult stuttering treatment program (Modifying Phonation Intervals, or MPI) with the standard of care for reducing stuttered speech in adults (prolonged speech).

Method: Twenty-seven adults who stutter were assigned to either MPI or prolonged speech treatment, both of which used similar infrastructures. Speech and related variables were assessed in 3 within-clinic and 3 beyond-clinic speaking situations for participants who successfully completed all treatment phases.

Results: At transfer, maintenance, and follow-up, the speech of 14 participants who successfully completed treatment was similar to that of normally fluent adults. Successful participants also showed increased self-identification as a "normal speaker," decreased self-identification as a "stutterer," reduced short intervals of phonation, and some increased use of longer duration phonation intervals. Eleven successful participants received the MPI treatment, and 3 received the prolonged speech treatment.

Conclusions: Outcomes for successful participants were very similar for the 2 treatments. The much larger proportion of successful participants in the MPI group, however, combined with the predictive value of specific changes in PI durations suggest that MPI treatment was relatively more effective at assisting clients to identify and change the specific speech behaviors that are associated with successful treatment of stuttered speech in adults.