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Earplugs are the most widely used hearing protection device in industrial settings—and the most consistently misused. Foam earplugs with NRR ratings of 29–33 dB often provide only 10–15 dB of real-world attenuation when improperly inserted. This guide covers earplug types, insertion technique, fit testing, and the OSHA requirements that apply to earplug selection and use in occupational hearing conservation programs.
Soundtrace provides on-site and in-house quantitative earplug fit testing, with personal attenuation ratings (PARs) recorded per employee in a cloud compliance platform.
| Type | NRR Range | Best For | Fit Testing Need |
|---|---|---|---|
| Formable foam (roll-down) | 29–33 | High-noise environments; single use | High — technique-dependent |
| Pre-molded (reusable) | 24–30 | Intermittent exposures; multiple removals/day | Medium — size selection critical |
| Banded/canal caps | 14–22 | Frequent on/off; moderate exposures | Low — but limited attenuation |
| Custom-molded | 25–30 | Long-duration wear; comfort-sensitive workers | Built-in to manufacturing process |
Foam earplugs require a three-step insertion technique: roll the plug into a thin cylinder, reach over the head to pull the ear canal straight, and hold the plug in place until it fully expands. Workers who skip any step consistently achieve 10–20 dB less attenuation than the labeled NRR.
Providing foam earplugs with no insertion training and no fit verification. Studies show that without training and fit testing, the average worker achieves approximately half the labeled NRR. At facilities where workers are exposed at 100+ dBA TWA, this gap means workers who believe they are protected are actually exposed above the PEL during every shift.
Quantitative earplug fit testing measures the actual attenuation an individual achieves with a specific earplug using their own insertion technique. The result is a personal attenuation rating (PAR) expressed in dB. The PAR replaces the labeled NRR for that individual and determines whether their HPD is adequate for their actual exposure level.
A foam earplug with NRR 33 inserted incorrectly may provide as little as 8–12 dB of real-world attenuation. Training and fit testing are what close that gap.
See: Hearing Protection & Fit Testing: The Complete Employer Guide
Soundtrace fit testing services measure each worker's actual earplug attenuation and flag anyone falling short of their required protection level.
Book a DemoGet a quote →Formable foam earplugs have the highest NRR ratings at 29 to 33 dB, but effectiveness depends entirely on correct insertion technique. Custom-molded earplugs offer the best combination of comfort and consistent attenuation for workers with long wear durations.
Roll the plug into a thin cylinder, reach over the top of the head to pull the ear canal straight, then insert the compressed plug deep into the canal while holding it for 20 to 30 seconds until it fully expands. Skipping the ear canal straightening step is the most common cause of inadequate attenuation.
A PAR is the actual noise reduction measured for an individual worker with a specific HPD using their own technique. It replaces the labeled NRR and is the most defensible measure of HPD adequacy in an OSHA compliance program.