Phonetic Processes and Their Influence on Speech Intelligibility in Dysarthric Speech after Traumatic Brain Injury: A Longitudinal Case Study

Significant changes in dysarthric speech can be achieved many years post-onset of traumatic brain injury (TBI). Individuals with TBI dysarthria frequently apply phonetic processes (PPs) that are viewed as speech errors. This study reports the results of two Examinations (E1, E2) of PPs and their influence on the speech intelligibility rate at 12 (E1) and 50 (E2) months post-coma in ML, a 26-year-old Polish individual with TBI dysarthria. ML performed the Polish Dysarthria Test for TBI Patients. The recordings were transcribed phonetically and analysed acoustically. We also carried out a perception study in which 48 naïve native Polish listeners judged ML’s speech intelligibility based on recordings from E1 and E2. The results show a significant improvement in ML’s intelligibility. The frequency of occurrence of PPs in E1 and E2 was nearly the same, as was the number of types of PPs. However, in E2 ML applied more types of PPs that had a higher communicative force [16], and were less radical [9]. To conclude, considerable speech improvements in TBI dysarthria may still be achieved several years post-trauma.