Central Auditory Dysfunction Associated with Exposure to a Mixture of Solvents

Objective: The aim of the present research was to investigate central auditory functioning in normal-hearing, solvent-exposed subjects compared to normal-hearing subjects without solvent exposure, with a comprehensive test battery of behavioural central auditory functioning procedures.

Study Sample: Forty-six normal-hearing, solvent-exposed subjects and 46 normal-hearing, control subjects were selected to participate in the study.

Design: All subjects must present with normal hearing thresholds and absence of history of variables related to the onset of auditory dysfunction. Subjects were evaluated with a test battery comprising pure-tone audiometry (PTA), dichotic digits (DD), pitch pattern sequence (PPS), filtered speech (FS), random gap detection (RGD), masking level difference (MLD), and hearing-in-noise (HINT) tests.

Results: Analyses of covariance (ANCOVA) were performed to compare the mean values of the dependent variables (results for DD, PPS, FS, RGD, MLD, and HINT) between solvent-exposed and control subjects. Age and average hearing thresholds (500-8000 Hz) were included in the analyses as covariates. Significant differences for DD, PPS, FS, and RGD results were found between groups.

Conclusion: This study provides further evidence of the central auditory dysfunction associated with solvent exposure.