The Critical Role of Hearing Protection Device (HPD) Fit Testing By Dr. Rivka Strom, Director of Audiology at Soundtrace

Hearing loss affects over 430 million individuals worldwide, according to the World Health Organization. This number is expected to rise, in particular due to the increased exposure to loud noise, both recreationally and occupationally. Noise induced hearing loss (NIHL) is a type of hearing loss caused by exposure to loud sounds and is the only type of hearing loss that is 100% preventable. Taking time to understand your hearing health and learning the steps necessary to protect your hearing is crucial.

A key point in understanding your risk for noise induced hearing loss (NIHL) is learning about hearing levels and duration of exposure. Hearing levels refer to the loudness of sounds, which is measured in decibels (dB), while duration of exposure refers to how long you are exposed to noise. The risk of NIHL increases with both the intensity (loudness) of the sound and the duration of exposure. Being exposed to a single extremely loud sound, such as an explosion over 120 dB, can result in sudden permanent hearing loss. In contrast, repeated or prolonged exposure to moderately loud sounds—like music, power tools, or heavy machinery—may first cause temporary hearing loss (temporary threshold shifts) that can become permanent over time (i.e., gradual hearing loss). Both sudden and gradual hearing loss damage the delicate sensory hair cells in the organ of hearing, known as the cochlea. These hair cells do not regenerate resulting in permanent damage.  

Organization such as the National Institute for Occupational Safety and Health (NIOSH) and Occupational Safety and Health Administration (OSHA) have important roles in the prevention of occupational noise induced hearing loss.  NIOSH is a U.S. federal agency responsible for conducting research and making recommendations to prevent work-related hearing loss while OSHA sets the legally enforceable safety and health standards and regulations. OSHA uses 85 dBA as the action level for its occupational noise exposure standard. Therefore, when an employee’s eight-hour time-weighted average (TWA) noise exposure reaches or exceeds 85 dBA, the employer must implement a hearing conservation program. This program requires employee notification, monitoring, training, and the provision of hearing protection and annual audiometric testing.

While most employees understand that it is the employer’s responsibility to provide them with hearing protection devices (HPD) such as earplugs, they often do not understand the critical role of the fit of HPDs in mitigating hearing loss. Earplugs are designed to attenuate the sound level that reaches the eardrum. The effectiveness of earplugs largely depends on their fit (i.e., how they are placed in the ear canal). This is why HPD fit testing is a critical component of an effective hearing conservation program. It helps to ensure that the HPDs are providing the maximum level of noise reduction.

What is involved during HPD Fit testing?

Fit testing involves measuring how well an employee’s earplug reduces noise exposure when placed in the ear canal. Historically, fit testing relied on subjective or qualitative methods, such as user feedback or visual inspection by safety officers. However, there is now a strong emphasis on implementing objective fit testing within hearing conservation programs. This includes a quantitative assessment that provides the difference in hearing thresholds for a specific employee with and without earplugs. This yields a Personal Attenuation Rating (PAR) which is a personalized score that reflects actual protection (of the earplug) for the user as opposed to the lab-tested Noise Reduction Rating (NRR) from the manufacturer. Safety professionals can then use these test results to educate the workers on the proper fit of the HPDs or to select alternate HPDs that provide a higher PAR for them. Fit testing should be performed upon initial inclusion in the hearing conservation program and at least annually thereafter.

Why Is Fit Testing So Important?

1. Each person has a unique ear canal, both in size and shape. Two workers wearing the same earplug may have different levels of noise protection as the earplug will sit differently in each ear. Fit testing helps to identify the best HPD for each person.
2. Fit testing provides a PAR reflecting the actual protection for the user as opposed to the laboratory NRRs which often overestimate real-world protection.
3. Workers often prioritize comfort over fit, often opting for earplugs that feel good but may not seal the ear canal effectively. Fit tests are excellent opportunities to educate workers on the proper insertion of HPDs. With proper training and education, workers may feel more empowered to take ownership of their hearing health and are more likely to increase usage of their HPDs.
4. Workers that experience the difference between a poorly fitted earplug and a well-fitted earplug are more likely to be consistent with their HPD usage.
5. While OSHA does not require HPD fit testing as part of a hearing conservation program, fit testing is considered best practices as it helps to demonstrate compliance and commitment to worker safety.

Most importantly, properly fitted HPDs have been proven to significantly reduce the risk of noise-induced hearing loss. Early identification of poor fit prevents long-term, irreversible damage to workers’ hearing.

Additional Benefits of FIT testing for Employers

• Fit testing adds opportunities for training and education resulting in enhanced compliance. In addition, employee satisfaction often increases as the workers appreciate when their health and comfort are prioritized.
• Workers who receive fit testing are better protected, leading to fewer cases of occupational hearing loss, thereby improving safety outcomes.
• Preventing hearing loss reduces compensation claims, medical costs, and productivity losses.

Conclusion

Hearing protection device fit testing is not just a regulatory checkbox—it is a critical component of an effective hearing conservation program. Ensuring that every worker has properly fitted hearing protection can significantly decrease the prevalence of noise induced hearing loss by improving compliance and fostering a culture of safety and care.

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