Summary

Noise remains very present in the work environment. As a result, many workers live every day with occupational deafness. Others may present with deafness of non-work-related origins and, as well, the aging workforce has a higher risk of suffering from hearing loss. Hearing loss can compromise the effective accomplishment of tasks and the safety of the worker and of others when it is accompanied by difficulties in perceiving audible signals, including speech, in the presence of noise and being able to identify where sounds are coming from. In order to maintain an accurate perception of ambient sound and to do their jobs safely, efficiently and autonomously, a viable solution for deaf workers may be to wear hearing aids. However, this option raises important questions as to whether hearing aids can actually optimize the hearing ability necessary for workers to carry out their tasks and amplify useful sounds to levels that remain safe, so as not to exacerbate the hearing loss.

Few scientific studies have dealt with the issue of wearing hearing aids in noisy workplaces. We therefore know very little about the extent of their use in the workplace and the associated risks and benefits. This study involves seeking information from health professionals, workers and manufacturers, and a review of the scientific literature in order to (1) explore the frequency of hearing aid use in noisy workplaces; (2) examine the risk of aggravating hearing loss in workers who wear hearing aids in noisy workplaces and to establish valid measurement methods to assess the risks of over-amplification; (3) determine whether hearing aids can be used to assist hearing and communication needs without aggravating hearing loss or compromising safety; and (4) establish whether other amplification and protection technologies (e.g., sound restoration hearing protection devices) could help improve hearing performance at work, or at least not make it worse.

While this study did not enable us to precisely determine the number of workers who use hearing aids in noisy workplaces, many health professionals report having seen a worker using them in noisy environments, or a worker who was considering the possibility of wearing them, at least once in the last five years. Among the obstacles to an adequate management of these cases, valid measurement methods of the risk of over-amplification, clear guidelines, and consultative and collaborative processes among the various professionals involved are reported to be lacking. Sharing of information among professionals, with respect to context and sound levels, the demands of the workstation and viable solutions, is especially limited. The role of each professional is not well understood, which does not encourage interdisciplinarity. In most cases, professionals attempt to preserve workers’ residual hearing by discouraging hearing aid use in noisy work environments, but in so doing they may be underestimating workers’ need to hear for reasons of effectiveness, safety and communication.

A review of the literature, including that of current technologies, did not enable clear conclusions to be drawn about the risk of aggravating hearing loss by the use of hearing aids, or to determine a valid, reliable and standardized method to document or predict this risk.

In addition, recommendations for workers are inadequate and are not generally supported by evidence.

Along with over-amplification, health professionals are concerned that hearing aids could compromise the safety of workers by reducing certain hearing abilities necessary for the autonomous and safe execution of tasks in the workplace. Depending on how the parameters are adjusted, there may sometimes be a decrease in speech comprehension in the presence of noise when wearing hearing aids compared to without them. Specific adjustments could, however, contribute to improving this ability in some situations. Examples include the use of directional microphones that amplify the sources of sound directly in front of an individual more than those behind him or her, while other devices, known as noise reducers, contribute to improving the comfort of hearing and the sound quality, while reducing the effort required to hear. The scientific literature is less conclusive on how well hearing aids help the wearer localize where sounds are coming from, but, in general, performance is better without them. Current scientific data do not enable us to demonstrate beyond a doubt that hearing aids contribute to improving the required hearing abilities, both for autonomous execution of work tasks and for ensuring the safety of workers with hearing loss. On the other hand, the data do not enable us to say with certainty that hearing aid use represents a risk for the safety of workers.

A review of alternative or additional options to wearing hearing aids is therefore necessary. Despite some remarkable technological advances in the area of active hearing protection and their generally positive reception by workers, it does not appear that a device to systematically improve hearing capacity exists. As well, there are fewer possibilities of adapting and personalizing the adjustment of hearing protectors compared to hearing aids. It is also difficult to select a product adapted to the needs of workers with hearing disorders and to the workplace because manufacturers’ accessibility is limited in terms of parameters and operation of their products. One possible explanation for this is the absence of standards for test conditions, the parameters to be assessed and the information that must be included in the technical specifications for active hearing protectors. These elements, in addition to the safety aspect, require further study before systematically suggesting their use for workers with hearing loss.

For this study, the research team follows the precautionary principle and therefore recommends that hearing aids only be worn as a last resort, after first looking into reducing noise at the workstation. Afterward, other avenues could be investigated, such as modifying the hearing, communication and localization requirements at the workstation and adapting it, including by using another sensory modality (e.g., vibrating or visual cues). It is essential that the risk of over-amplification and worker safety be taken into account and managed by all of the professionals concerned. In the absence of clear evidence-based guidelines, it is all the more important for professionals to consult, coordinate and work together in order to identify the most appropriate recommendations to respond to the objective of not compromising the health and safety of the worker and others.