F2 transitions during sound/syllable repetitions of children who stutter and predictions of stuttering chronicity.

The purpose of the present study was to examine the relationships between second formant (F2) transitions during the sound/syllable repetitions (SSRs) of young children who stutter and their predicted chronicity of stuttering. Subjects were 13 youngsters who stutter, who were divided into two groups based on their predicted chronicity of stuttering as measured by the Stuttering Prediction Instrument (SPI; Riley, 1984): a high-risk group, consisting of 7 boys (mean age = 50.6 months), and a low-risk group, consisting of 5 boys and 1 girl (mean age = 48.5 months). Each child was audio/videotape-recorded during a 30-minute conversational interaction with his or her mother. Ten SSRs per child were acoustically analyzed to identify differences in F2 transitions between the repeated (stuttered) and fluent (nonstuttered) portions of the words. Present findings are consistent with those of Stromsta (1965, 1986), who reported that children who stutter produce F2 transitions during stuttering that are nonmeasurable or missing or that differ in direction of movement from fluent transitions. However, there were no significant between-group differences in the frequency of occurrence of these "abnormal" F2 transitions, findings that are apparently inconsistent with Stromsta's results. The remaining measurable F2 transitions showed no significant between-group differences in the mean differences between stuttered and fluent F2 transitions for onset and offset frequencies, transition extents, and transition rates. Within both groups, significant positive correlations were found between stuttered and fluent F2 transitions for all acoustic measures except for transition durations, which were not significantly correlated for either high-risk or low-risk subjects. Within the low-risk group, stuttered F2 transitions were typically shorter than fluent transitions. Findings were taken to suggest that some elements of sound or segment prolongation may be present within the SSRs of children who stutter and who are considered to be at high risk for continuing to stutter, indicating that further study of selected aspects of F2 transitions during stuttering may provide useful clinical information for predicting the likelihood that a child will continue to stutter.