How to Fit Earplugs So They Actually Work

Why this matters

A foam earplug that is pinched and pushed halfway into the ear gives a fraction of the protection printed on the box, and the wearer cannot tell, because anything in the ear makes the world sound somewhat quieter. That is the trap: the plug feels like it is working at 5 dB of protection and would have delivered 25 if it had gone in properly. Most hearing protection failures in the trades are not missing protection. They are protection worn shallow, worn loose, or taken out for the loudest ten minutes of the job.

Which tools cross the line and which limit applies are owned by the noise reference. See related: Noise: The 85 Decibel Line and Hearing Conservation. This card is about getting the protection you already own to do what the label says, or close to it.

Fitting a roll-down foam plug

Foam plugs are the commonest protector on a truck and the most sensitive to technique. Wash or at least wipe your hands first: you are about to push whatever is on your fingers into the ear canal, and grinding dust, solvent or sewage residue in the canal is an infection and irritation route.

1. Roll the plug into a thin, crease-free cylinder. Roll slowly between thumb and fingers, compressing the whole length, not just squeezing the tip. Reason: the plug has to be narrower than the canal to go in deep, and a crease becomes a leak path once the foam expands. What breaks if skipped: a half-rolled plug stops at the canal opening, which is the shallow fit that gives a few dB.

2. Pull the ear up and back with the opposite hand. Reach over the top of your head with your left hand to pull the right ear's upper rim up and back, and the reverse for the left ear. Reason: the ear canal is S-shaped, and pulling the outer ear straightens it so the plug can travel past the first bend. What breaks if skipped: the plug hits the canal wall at the bend and stays outside it, however carefully it was rolled.

3. Insert while the ear is held, until most of the plug is inside the canal. Push the rolled plug in with a fingertip so that only the outer end sits at the canal opening. Reason: attenuation comes from the length of foam sealed against the canal wall, and the deeper portion does most of it. What breaks if skipped: a plug with half its length outside the canal seals over a short length of skin and leaks around the seal.

4. Hold it in place for 20 to 30 seconds while it expands. Keep the fingertip on the end until the foam has expanded and you feel the seal. Reason: if you let go immediately, the compressed foam pushes itself back out before it grips. What breaks if skipped: the plug backs out to the shallow position you were trying to avoid, and it will look fitted to anyone glancing at you.

To remove it, twist it slowly as you pull, to break the seal gradually. A sudden pull from a well-sealed plug is uncomfortable and can be felt as pressure on the eardrum.

Premolded and flanged plugs do not roll; use steps 2 and 3, pushing until you feel the flanges seal, and pick the size that seals without pain. Banded plugs (caps on a headband) are quick for tasks you start and stop all day, and usually give less attenuation than a deep foam fit.

Checking the fit, every time

Three checks take ten seconds in a noisy space:

• Your own voice. With both plugs fitted well, your own voice sounds louder and hollow, because sound conducted through your skull can no longer escape the sealed canal. This is the occlusion effect, and it is the most reliable quick sign of a seal.
• The hand test. Cup your palms tightly over both ears with the plugs in. If the noise drops a lot, the plugs are leaking, because your hands are doing work the plugs should have done. A well-fitted pair changes little.
• The mirror or the coworker. From straight in front, a deep foam fit shows little or nothing of the plug beyond the canal opening. Half a plug visible from the front is a shallow fit.

If a check fails, take the plug out, re-roll it fresh (a plug that has expanded and been squeezed again loses some of its spring) and repeat. A plug that falls out within a minute is often the wrong size for that canal; try a smaller or larger foam or a flanged style.

Fit testing is the measured version of these checks. A fit-test system plays tones or measures sound in the canal and reports a personal attenuation rating, the protection that person actually gets with that protector. NIOSH recommends individual fit testing, and it is the only way to replace the label number with a real one for a given worker.

Why the label number overstates, and how to derate it

The noise reduction rating (NRR) on the package is required under the EPA's labeling rule at 40 CFR Part 211, Subpart B, and is measured in a laboratory on test subjects fitted under ideal conditions. Field studies consistently find that workers get much less, because they fit plugs shallower, wear them inconsistently, and use sizes that do not suit their canals. So the number is derated before anyone relies on it.

OSHA's method (from Appendix B of 29 CFR 1910.95 and the OSHA Technical Manual's noise chapter), for an exposure measured in dBA:

• Subtract 7 from the NRR (the label is referenced to C-weighted noise; the 7 converts it).
• Then take 50 percent of that, as the Technical Manual's field derating.
• For plugs and muffs worn together, compute the higher-rated protector this way and add 5 dB. Not the two ratings added together: a second protector adds far less than its own label.

NIOSH's older derating scheme (its 1998 criteria document) reduces the label by type before applying the 7: earmuffs by 25 percent, formable (foam) plugs by 50 percent, and all other plugs by 70 percent. NIOSH now prefers fit testing to any fixed derating.

A worked derating: the cut-off saw crew

A hardscape crew cuts concrete pavers with a gas cut-off saw. The saw reads about 108 dBA at the operator's ear while cutting, and a shift dosimeter on the operator returned an 8-hour TWA of 97 dBA. The crew carries foam plugs labeled NRR 32 and earmuffs labeled NRR 25. The question under 29 CFR 1910.95(j) is whether the protection brings the TWA to 90 dBA or below (85 for a worker who has had a standard threshold shift), and the shop has chosen to aim for 85 for everyone.

• Foam plugs, OSHA method: 32 minus 7 is 25; half of 25 is 12.5. 97 minus 12.5 is 84.5 dBA. Passes 90, and just passes the shop's 85.
• Earmuffs, OSHA method: 25 minus 7 is 18; half is 9. 97 minus 9 is 88 dBA. Passes 90, fails the shop's 85.
• Both together, OSHA method: the higher rating is the plug's 12.5, plus 5, gives 17.5. 97 minus 17.5 is 79.5 dBA. Passes both.
• Foam plugs, NIOSH scheme: 32 reduced by 50 percent is 16, minus 7 is 9. 97 minus 9 is 88 dBA. Fails the shop's 85.
• Earmuffs, NIOSH scheme: 25 reduced by 25 percent is 18.75, minus 7 is 11.75. 97 minus 11.75 is 85.25 dBA. Just fails the shop's 85.

Read the two methods together and the decision makes itself: foam plugs alone pass by 0.5 dB on OSHA's method and fail by 3 dB on NIOSH's, so neither protector alone is a comfortable answer for the saw operator. The crew wears both for cutting. The helper, who stacks pavers 20 feet away and whose own dosimeter read a lower TWA, wears plugs.

The ten-minute gap. The saw operator likes to pull the muffs and plugs out to talk to the crew lead between cuts and sometimes forgets to refit before the next cut. Take one hour of cutting at 108 dBA in which the operator wears both protectors for 50 minutes (108 minus 17.5 leaves 90.5 dBA at the ear) and neither for 10 minutes. On an energy basis, that hour averages about 100.6 dBA at the ear: the 10 unprotected minutes carry roughly 11 times the energy of the 50 protected ones. Five unprotected minutes still average about 98 dBA. The pair was worth 17.5 dB on OSHA's method and delivered about 7.4 (108 minus 100.6) for that hour. A protector is only worth what it is worth for the minutes it is in.

What changes the answer. A battery saw with water feed that reads 98 dBA at the ear would bring a comparable day down far enough that plugs alone would carry it on either method, and it controls the silica dust in the same move (see related: Respirable Crystalline Silica and the Construction Standard). Pavers cut on a commercial job site would put the work under the construction standard, where 29 CFR 1926.101 requires protection whenever Table D-2 is exceeded, and the same derating logic applies to choosing it.

When the answer is muffs, not plugs, and when it is less protection

• Muffs over plugs for the loudest group (cut-off saws, chainsaws, jackhammers, powder-actuated tools), and for any impulse tool fired indoors.
• Muffs alone for a task you start and stop all day where plugs would be pulled and pushed with dirty hands each time, provided the derated muff value is enough.
• Plugs alone where a muff cannot seal: thick glasses temples and respirator straps break a muff's seal and cut its protection noticeably, so a tech wearing a half-face respirator often does better with deep foam plugs.
• Less, not more, where the crew needs to hear. NIOSH suggests aiming for roughly 70 to 80 dBA under the protector; far below that, a tech cannot hear a backup alarm, a coworker's shout or a failing bearing, and starts pulling protection out to listen, which is the ten-minute gap above. Level-dependent protectors and plugs with flat attenuation help here.

References

• 29 CFR 1910.95, Occupational Noise Exposure, (i) hearing protectors, (j) attenuation adequacy, and Appendix B methods for estimating attenuation
• 29 CFR 1926.101, Hearing Protection (construction)
• 40 CFR Part 211, Subpart B, the EPA labeling rule that requires the noise reduction rating
• OSHA Technical Manual, Section III, Chapter 5, Noise, for the 50 percent field derating and the dual-protection method; NIOSH 1998 criteria document for its derating scheme and its fit-testing recommendation
• See related: Noise: The 85 Decibel Line and Hearing Conservation; How to Measure Noise on Your Own Jobs; What Hearing Conservation Actually Requires