Analysis of the physical discomfort of earplugs experienced by a group of workers in Canadian companies and identification of the influencing variables

Earplugs are widely used to prevent noise induced hearing loss. However, the discomforts they induce negatively impacts their effectiveness by influencing their consistent and correct use. The physical earplugs discomfort is related to the user perception resulting from biomechanical and thermal interactions between the earplug and the earcanal. Its main attributes are “physical annoyance”, “pain”, “pressure” and “irritation". The (dis)comfort results from the complex interactions between the wearer, his/her earplug, and his/her work environment, which form the concept of triad. This study aims at improving our understanding of the physical discomfort of earplugs by identifying the triad characteristics that have a significant influence on the main attributes of the physical discomfort. The (dis)comfort of earplugs was assessed in the field with 173 participants who tested 7 different earplugs models over 7 weeks and answered comprehensive comfort questionnaires. Triad characteristics were assessed both with questionnaires and in laboratory using comfort testers. Statistical analyses enabled to identify main characteristics of the triad that influence physical comfort attribute including the earplug radial force, extraction force and friction coefficient. Characteristics of the work environment (work duration) and of the person (i.e., ear morphology, past experience with earplugs), were shown to influence physical discomfort. Results of this study could provide tools to manufacturers so that they can design earplugs taking into account comfort aspects and to preventionists so that they can propose to workers the earplugs that are the most adapted to them and to their work environment.