OBJECTIVES: This study had two objectives: to examine associations between extended high-frequency (EHF) thresholds, demographic factors (age, sex, race/ethnicity), risk factors (cardiovascular, smoking, noise exposure, occupation), and cognitive abilities; and to determine variance explained by EHF thresholds for speech perception in noise, self-rated workload/effort, and self-reported hearing difficulties.
DESIGN: This study was a retrospective analysis of a data set from the MUSC Longitudinal Cohort Study of Age-related Hearing Loss. Data from 347 middle-aged adults (45 to 64 years) and 694 older adults (≥ 65 years) were analyzed for this study. Speech perception was quantified using low-context Speech Perception In Noise (SPIN) sentences. Self-rated workload/effort was measured using the effort prompt from the National Aeronautics and Space Administration-Task Load Index. Self-reported hearing difficulty was assessed using the Hearing Handicap Inventory for the Elderly/Adults. The Wisconsin Card Sorting Task and the Stroop Neuropsychological Screening Test were used to assess selected cognitive abilities. Pure-tone averages representing conventional and EHF thresholds between 9 and 12 kHz (PTA (9 - 12 kHz) ) were utilized in simple linear regression analyses to examine relationships between thresholds and demographic and risk factors or in linear regression models to assess the contributions of PTA (9 - 12 kHz) to the variance among the three outcomes of interest. Further analyses were performed on a subset of individuals with thresholds ≤ 25 dB HL at all conventional frequencies to control for the influence of hearing loss on the association between PTA (9 - 12 kHz) and outcome measures.
RESULTS: PTA (9 - 12 kHz) was higher in males than females, and was higher in White participants than in racial Minority participants. Linear regression models showed the associations between cardiovascular risk factors and PTA (9 - 12 kHz) were not statistically significant. Older adults who reported a history of noise exposure had higher PTA (9 - 12 kHz) than those without a history, while associations between noise history and PTA (9 - 12 kHz) did not reach statistical significance for middle-aged participants. Linear models adjusting for age, sex, race and noise history showed that higher PTA (9 - 12 kHz) was associated with greater self-perceived hearing difficulty and poorer speech recognition scores in noise for both middle-aged and older participants. Workload/effort was significantly related to PTA (9 - 12 kHz) for middle-aged, but not older, participants, while cognitive task performance was correlated with PTA (9 - 12 kHz) only for older participants. In general, PTA (9 - 12 kHz) did not account for additional variance in outcome measures as compared to conventional pure-tone thresholds, with the exception of self-reported hearing difficulties in older participants. Linear models adjusting for age and accounting for subject-level correlations in the subset analyses revealed no association between PTA (9 - 12 kHz) and outcomes of interest.
CONCLUSIONS: EHF thresholds show age-, sex-, and race-related patterns of elevation that are similar to what is observed for conventional thresholds. The current results support the need for more research to determine the utility of adding EHF thresholds to routine audiometric assessment with middle-aged and older adults.