Listen Up! From the NHCA Experts…

July 30, 2024|Hearing/Noise, Industrial Hygiene in the Workplace

Hearing Protector Fit-Testing: Beyond the NRR

Selecting and fitting hearing protectors is not as simple as checking the manufacturer-labeled noise reduction rating (NRR). The NRR, a laboratory measure based on the amount of noise reduction obtained by a group of individuals under ideal conditions, serves as a reference point to determine hearing protector suitability. However, the NRR does not directly translate to real-world attenuation and does not tell you how much noise reduction an individual worker is obtaining.

Using the NRR is just one step in choosing hearing protectors. Factors like fit, comfort, seal and individual variability affect real-world attenuation. Federal regulations require employers to ensure selected hearing protectors have proper initial fit and workers are trained. Hearing protector fit-testing (HPFT) is the best way to do this.

HPFT enables employers and safety professionals to identify workers at risk for either overprotection or under protection. Overprotection provides too much attenuation for the noise environment that might interfere with communication or situational awareness, such as hearing safety signals. This might be especially important for workers with hearing loss. Underprotection leaves the worker exposed to high noise and vulnerable to auditory injury. A general guide aims for protected exposures between about 70–85 dBA (see chart).

Noise level hazards combined with hearing protector fit testing. When hearing protection is worn, a balance must be achieved between the underprotection that leads to noise-induced hearing loss and overprotection which could lead to communication difficulties. The appropriate protected level is between 70 and 85 dB(A). (Figure from NORA [2023])

HPFT can also be used to improve training outcomes by providing real-time feedback. If the attenuation is not appropriate, the worker can adjust how the hearing protector fits and, in real-time, be retested. Coaching and retraining are key during this retesting process. If the desired attenuation cannot be achieved with the first hearing protector, select a different type, model or size, and repeat the process.

HPFT systems provide an attenuation estimate for individual workers and are more accurate than relying on derating schemes. Individuals who fail to achieve targeted attenuation can be given immediate feedback through training to ensure that their hearing is adequately protected. IHW

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