Effect of noise and organic solvents on acoustic stapedial reflex

Abstract

Objective

Noise and solvents are two occupational exposures with possible hearing effects. We aimed to assess the effect of exposure to noise and organic solvents on acoustic reflex.

Methods

This cross-sectional study was conducted on three groups: 80 workers exposed to impermissible amounts of organic solvents (mainly styrene), 78 workers exposed to loud noise and 67 subjects as a control group. The hearing status of the subjects was assessed by pure tone audiometry and acoustic reflex. Data were analysed by SPSS (ver. 20) (SPSS Inc., Chicago, IL) using Student’s t-test, chi-square test and ANOVA.

Results

The mean hearing threshold at high frequencies was significantly higher in the noise group, followed by the solvent group, compared to the control group (p<.0001). Mean acoustic reflex was higher in the solvent group, followed by the noise group (p<.05). The frequency of absent acoustic reflex was also significantly higher in noise and solvent groups than in controls (p<.05).

Conclusion

This study suggests that exposure to organic solvents alone without simultaneous noise, despite a normal hearing threshold, can affect acoustic reflex, so conducting preventive hearing tests such as acoustic reflex test, in workers exposed to organic solvents, may be one of the effective ways to prevent occupational hearing loss in these workers.

Keywords:

• Acoustic reflex
• noise
• solvent
• audiometry

Acknowledgements

The authors would like to acknowledge Mr. Abolfazl Mollasadeghi, Master of Audiometry, for his contribution to this study.

Disclosure statement

This article summarizes a residency thesis at Shahid Sadoughi University of Medical Sciences. There is no conflict of interest relevant to this study.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.