Development of a comfort evaluation protocol for earplugs in the workplace

In France, many workers are exposed daily to noise levels that are potentially dangerous for hearing. For prevention purposes, individual hearing protectors are in widespread use. The comfort of the earplugs directly affects the effective protection by influencing their consistent and correct use. Based on this observation, the INRS started, in collaboration with the IRSST and the TS (Canada), a study dedicated to the comfort of earplugs. First, a review of the literature enabled to identify the parameters that can impact the feeling of comfort. On this basis, a multidimensional definition (physical, acoustic, functional and psychological) of comfort was proposed. A comfort evaluation questionnaire was then developed. This questionnaire was deployed in four companies with 118 participants who tested nine models of earplugs (belonging to three families: roll-down foam, premolded and custom molded). The analyses validated the structure of the questionnaire and confirmed its relevance. These analyses were also used to rank the families and models tested. It made it possible to identify and explain the preferences of these participants (the custom molded models being the most popular) and to progress in understanding the parameters that can influence the feeling of comfort. In the end, the questionnaire proves to be an appropriate tool for the (subjective) evaluation of comfort, making it possible to assess the importance of each dimension, while involving the workers in the choice of their hearing protection and making them aware of the noise risk