Introduction Many workers suffer from hearing dysfunctions, even if their exposure to noise and chemicals is within the established exposure limits. The mechanisms of action for combined exposure possible can be determined by sound perception indicators, and in this sense the appropriate health assessment can be performed.

Methods This exposure is based on the review of medical literature about the hearing process.

Result The hazardous synergistic effects of some chemicals and noise can be well understood with a deep knowledge of the hearing process. Pure-tone air-conduction audiometry is the most used method to check the state of the worker’s auditory system, but it has been proven to be insufficient when hearing loss is due to a combined exposure to noise and ototoxic agents, since it does not allow the source of the problem to be correctly identified.

Discussion The hearing system can be affected not only by the noise, but also by its combination with ototoxic chemical agents, this damage can affect from the cochlea to the higher auditory pathways. It’s important to use tools that evaluate the auditory system comprehensively, using tests that help to differentiate between the individual or the combined effects of noise and chemicals on hearing, such as the distortion product otoacoustic emissions. Furthermore, exposure limits to noise and ototoxic chemical agents lower than those set out in should be considered, taking into account their synergistic effect.