Complexity-Based Analysis of the Difference Between Normal Subjects and Subjects with Stuttering in Speech Evoked Auditory Brainstem Response

Deficits in auditory processing are an assumed underlying mechanism in stuttering. Previous studies have demonstrated that speech evoked auditory brainstem response (s-ABR) is a reliable method to evaluate brainstem timing in clinical populations with persistent developmental stuttering (PDS). The examination of s-ABR signals to quantify differential complexities between PDS and normal subjects using linear analysis is unreliable. This prompted us to evaluate non-linear methods, which are more effective for conveying complex dynamics. The aim of the current study is to apply fractal dimension and the Hurst exponent to s-ABR signals in order to identify complexity differences between PDS and normal subjects who were stimulated with the synthetic/da/stimulus. Analysis of scaling exponents showed a statistically significant difference between the two groups. The s-ABR signal in subjects with stuttering becomes more complex due to stimulation. These findings are discussed in terms of dysfunctional sub-cortical activation in PDS populations.