Development of field methods for assessing auditory situational awareness when using hearing protective equipment in the noisy workplace

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In many occupational settings, workers are exposed to high levels of noise from machinery and equipment that can adversely impact on hearing health and job safety. While engineering control of noise at the source is the preferred solution, it is not always feasible to reduce noise to safe levels in this way and the use of personal hearing protectors (such as earmuffs and earplugs) often becomes necessary. Current standards on the selection, fit and use of hearing protectors focus on methods to determine the noise attenuation that these devices must provide to satisfy regulatory limits on the maximum daily sound exposure. In focus group meetings, however, concerns are often raised by workers about the lack of auditory situational awareness when working with hearing protectors as these devices can reduce their ability to respond to important sounds from the surrounding environment and interfere with verbal communication. Current standards only provide general guidance regarding communication requirements that is not specific to the individual worker's needs, hearing profile, job requirements or workplace noise. The goal of this research program is to develop auditory tests that can be used by occupational stakeholders to measure the effects of hearing protectors on situational awareness in their own workplaces. The two main objectives are to (1) develop tools to assess speech perception when a given worker wears his/her assigned hearing protector in workplace noise, and to (2) develop a test module to assess the audibility and recognition of critical workplace sounds (e.g., alarms, approaching vehicle sound, acoustic cue from machine malfunction) that are important to ensure safety and efficient operations in the workplace while wearing hearing protectors. Key design requirements for these tests are they could be administered quickly (e.g., <10 min.) in workplace environments and possess good psychometric properties (e.g., test-retest reliability). Experiments with human participants are planned to evaluate the proposed tests. Validation will be conducted over a wide range of adult test participants in terms of age, gender, language proficiency and hearing profile. Overall, this research program will contribute to our basic understanding of the complex interaction between noise, hearing protection and hearing status on auditory perception as well as to the development of practical tools to assist in the selection of hearing protectors that considers both protection and communication needs. This, in turn, will support the development or revision of national and international occupational standard procedures for the optimal selection of hearing protectors.