Quantitative speech production profiles and focal left hemisphere lesion

The clinical differentiation between apraxia of speech (AOS) and aphasia with phonemic paraphasia is based on impressionistic consideration of a varying list of speech properties. The diagnosing clinician is challenged with determining the presence or absence of these disorders by considering the extent to which characteristic features are evident in the speech output and by determining how much relative weight to assign to each. Predictably, the subjective nature of the diagnostic process can translate to limited agreement, even among experienced clinicians (Haley, Jacks, de Riesthal, Abou-Khalil, & Roth, 2012), and the risks of misdiagnosis and diagnostic uncertainty are substantial (Wambaugh, 2006). Additionally it is likely that the adherence to a strictly dichotomous classification system overlooks theoretically and clinically important heterogeneity. The purpose of this study was to identify a preliminary set of speech production profiles based on naturally occurring variations in individuals with acquired focal brain lesions. To avoid classification circularity, assessments were conducted without consideration of clinical speech diagnosis, and metrics were selected to represent diverse and robust observations about speech properties associated with left hemisphere lesions