Speaker
Description
The NExpo study investigates how noise exposure, aging, and noise-induced hearing loss affect the human auditory nervous system. 200 healthy participants were recruited into four groups (n=50 each) based on age, pure tone audiometry (PTA), and Noise Exposure Structured Interview (NESI) score. Group 1 (G1): 18-19 years, low noise exposure, normal hearing; Group 2 (G2): 30-50 years, low noise exposure, normal hearing; Groups 3 and 4 (G3/G4) same age range as G2, high noise exposure, normal hearing (G3); high noise exposure, elevated 3-8 kHz PTA (G4). Participants underwent audiological assessments and MRI to measure auditory nerve structure (cross-sectional area; CSA) and microstructure (diffusion fractional anisotropy; FA), along with whole-brain structural measures and resting-state functional MRI of the auditory pathways.Tinnitus Functional Index (TFI) scores differed across groups, with significantly higher scores in noise-exposed participants. Audiological differences were driven by G4, with no significant G2-G3 differences. While CSA showed no significant overall group or age effects, post-hoc t-tests revealed differences between G1 and other groups (G1-G2: p=0.007, G1-G3: p=310-6; G1-G4: p=0.0003) and between G2 and G3 (p=0.01). FA differed significantly across groups (H(3)=11.96, p=0.008) with post-hoc Mann-Whitney U tests (Bonferroni-Holm-corrected across comparisons) revealing that G1 had significantly higher FA than G4 (p<0.001). Further MRI analyses of the cortical brain measures are ongoing. Early findings from this study suggest that the effect of noise exposure on the auditory pathway is likely much smaller than the effect of ageing or noise-induced hearing loss.