Extended High-Frequency Hearing Thresholds and Categorical Loudness Scaling in Parkinson's Disease

PURPOSE: Sensory difficulties are increasingly recognized as part of the pathology of Parkinson's disease (PD). The present study examined hearing in people with PD to further advance understanding of audition in the disease process. A PD group was compared to an age-matched control group to build a nuanced understanding of hearing in PD at standard and extended high frequencies and the relationship of intensity to perceived loudness. METHOD: Two participant groups (with 30 paired members) were recruited: a PD group and an age-matched control group. At the between-groups level, pure-tone audiometric hearing thresholds across standard and extended high frequencies were measured. Categorical loudness scaling (CLS) also was assessed. At the within-group level, relationships of auditory measures to PD motor symptom severity were tested. RESULTS: Pure-tone audiometric metrics did not differ for the PD and control groups. One CLS parameter differed between the groups and was correlated with symptom severity. Linear modeling indicated that PD motor symptom severity in the Movement Disorder Society-Unified Parkinson's Disease Rating Scale was predicted from average hearing thresholds at frequencies most important for speech perception (500, 1000, and 2000 Hz). CONCLUSIONS: The relative lack of differences between the PD and control groups in their hearing abilities may reflect the relatively mild severity of the disease in this sample. However, the observed relationship between motor symptom severity and hearing thresholds suggests that PD severity may be associated with a decline in hearing ability that warrants further investigation and clinical monitoring in conjunction with other PD symptoms.