Mack's Ultra Soft Earplugs Review: What NRR 33 Really Means

Mack's Ultra Soft foam earplugs are about as basic as gear gets: small cylinders of slow-recovery polyurethane foam, 50 pairs to a jar, made in the USA and labeled with a Noise Reduction Rating of 33 decibels. That label is why they show up in searches for "NRR 33 earplugs" and "best earplugs for sleeping", and it is also the most misunderstood number on the package.

This Mack's Ultra Soft earplugs review explains what NRR 33 means, why real-world protection is lower, how OSHA and NIOSH handle that gap, how to roll and insert foam plugs so they actually seal, how often to replace them, and how to use them for sleep and travel. Ivan, our editor, bought this 50-pair jar with his own money in 2021. His first-hand notes will be added to this page separately; the rest is based on Mack's published information, the federal rules behind the rating, and well-established hearing protection practice.

The one-line answer: these are a good, inexpensive foam plug with a top-tier rating, as long as you understand that they reduce sound rather than block it, and that fit matters more than the number on the jar.

Mack's Ultra Soft earplugs at a glance

Mack's has been making earplugs for decades and sells several foam models. The Ultra Soft is tied with the Maximum Protection for the highest Noise Reduction Rating in its current lineup and uses what Mack's calls Comfy Cush comfort foam, a soft, low-pressure polyurethane foam. The 50-pair size is Mack's item #9250 and comes in a jar.

One honest caveat about the number: Mack's own website is not perfectly consistent. The product page and Mack's main "top 5" page list the Ultra Soft at NRR 33, which matches the Amazon listing, but one of Mack's articles about earplugs for snoring lists it at 32. A single decibel makes no practical difference, but the figure printed on the package you receive is the one that counts, because federal rules require it on the label.

What NRR 33 actually means

The Noise Reduction Rating is a US requirement that dates to 1979. Under the EPA's labeling rule (40 CFR Part 211, Subpart B), hearing protectors sold in the US must show an NRR on the package so buyers can compare products. The number comes from a standardized laboratory test known as real-ear attenuation at threshold: trained subjects in a test booth listen for faint test sounds (narrow bands of noise) at several frequencies, first with open ears and then wearing the protector, and the difference is the attenuation. Those results are combined into a single decibel figure, with a statistical adjustment for variation between subjects.

Two things follow from how the test works.

First, the NRR describes performance under ideal conditions. The plugs are fitted carefully by the lab's experimenter, not by the test subjects, in a quiet lab. The EPA label itself qualifies the rating as applying when the protector is used as directed.

Second, decibels are logarithmic. A 10 dB reduction is a big change in sound energy, and people commonly perceive it as roughly halving loudness. So even the derated figures discussed below are meaningful. A plug that delivers 13 dB of real reduction turns a loud environment into a noticeably quieter one; it just does not turn it into silence.

There is also a physical ceiling on any earplug. Sound reaches the inner ear through the bones of the skull as well as through the ear canal, and no plug can stop that path. Foam plugs also tend to reduce high-pitched sounds more effectively than low rumbles, which is why engine drone, bass from a neighbor's speaker or heavy snoring often remain audible as a muffled hum.

NRR derating: OSHA's method and NIOSH's view

Because lab numbers overstate typical results, safety agencies "derate" them. The methods differ, but they are useful for anyone trying to set realistic expectations at home.

OSHA's Appendix B method. OSHA's noise standard (29 CFR 1910.95, Appendix B) explains how employers estimate the noise level under a hearing protector. When noise is measured in A-weighted decibels (dBA), which is how most sound meters and phone apps report it, you subtract 7 dB from the NRR before applying it. For NRR 33, that gives 26 dB.

OSHA's 50 percent safety factor. In a 2016 interpretation letter, OSHA described applying a further 50 percent safety factor to that figure when its inspectors evaluate whether an employer should be using engineering controls to reduce noise. The calculation becomes (NRR minus 7) divided by 2. For NRR 33:

1. 33 minus 7 = 26
2. 26 divided by 2 = 13 dB

So in an environment measured at 95 dBA, the conservative estimate under a properly inserted NRR 33 plug is about 82 dBA. OSHA calls this a conservative assessment and says fit, actual use and training still have to be considered case by case.

NIOSH's position. NIOSH, the federal research agency for workplace safety, recommended in its 1998 noise criteria document that labeled ratings be derated by device type, with foam earplugs cut by half. In a 2025 Science Policy Update, NIOSH went further and recommended individual, quantitative fit testing in place of derating schemes, noting that a formula cannot assess whether a particular person has a proper fit.

The practical lesson for a home user is simple. Expect somewhere between the conservative estimate and the label, depending almost entirely on how well you insert the plug. A careless half-insertion can deliver far less than either number.

How to insert foam earplugs properly

Fit is everything with foam. These steps follow Mack's published directions, with practical notes added.

1. Clean hands. Mack's says to roll the plug with clean hands. Dirt and skin oil on the foam end up in your ear canal.
2. Roll it down. Roll the plug between your thumb and fingers into a thin, tight cylinder with no creases. Take your time; a crease becomes a leak path for sound.
3. Open the canal. Reach over your head with the opposite hand and pull the top of your outer ear up and back. This straightens the ear canal, which is naturally curved.
4. Insert quickly. Slide the rolled plug well into the canal before it starts to expand.
5. Hold it. Keep a fingertip on the end for several seconds while the foam expands and seals. Slow-recovery foam is designed to give you time to do this.
6. Check the fit. Mack's says a properly seated plug should still be easy to grip with your thumb and forefinger. Another sign of a good seal is that your own voice sounds louder and more internal than usual.

If the plug pops back out as it expands, it was not inserted far enough or it was not rolled thin enough. If more than half the plug is sticking out, the seal is probably shallow and the protection will be well below the label.

Removal matters too. Mack's advises twisting the plug slowly to break the seal gradually and warns that fast removal may damage the eardrum. Do not yank a fully expanded plug straight out.

Hygiene, reuse and when to replace

Mack's is direct about this: the plugs cannot be cleaned. Its guidance is to discard them after several uses, or sooner if dirt or earwax builds up. Washing foam with soap and water usually leaves it slow to dry and changes how it expands, so it is not a workaround.

Signs that a pair is done:

• The foam expands quickly instead of slowly, which means it has lost its slow-recovery behavior.
• Creases stay in the plug after rolling.
• The surface looks discolored or feels tacky.
• The plug no longer fills your canal the way a fresh one does.

The 50-pair jar makes frequent replacement easy. If you change pairs every few nights, the jar covers several months of nightly use; if you use them only on trips and at loud events, it lasts much longer.

Some sensible habits:

• Store the pair you are currently using in a small clean case, not loose in a pocket or bag.
• Keep the jar closed so the spares stay clean.
• Never share earplugs.
• Keep plugs away from infants and small children. Mack's warns that they can interfere with breathing if caught in the windpipe, which could lead to serious injury or death.

Earplugs for sleeping: what to expect

Sleep is one of the uses Mack's lists for the Ultra Soft, and soft foam plugs are the most common choice for light sleepers dealing with traffic, neighbors, hotel corridors or a partner who snores. We are not going to make claims about sleep quality, which depends on far more than noise. What we can describe is how the plugs behave in that setting.

What they do well. Foam plugs take the edge off higher-pitched, intermittent noises: voices in a hallway, a door closing, a dog barking down the street. Those are often the sounds that cut through, and they are the frequencies foam handles best.

What remains. Low-frequency noise, such as a bass line through a wall or deep snoring, is harder for any earplug to cut. Expect it to sound duller and further away, not to disappear.

Comfort lying down. Side sleepers press one ear into the pillow, which pushes on the end of the plug. A fully inserted plug sits deeper and causes less pressure than one sticking halfway out, which is another reason to get the insertion right.

Safety. Plugs that reduce noise also reduce your ability to hear a smoke alarm, an alarm clock or a child. If that matters in your household, plan around it: a vibrating alarm, a partner who sleeps without plugs, or skipping plugs on nights when you are responsible for someone.

Earwax. If you wear earplugs every night, something sits in your ear canals for hours at a time, night after night. If you start to feel fullness or blocked hearing that does not clear, see a doctor rather than trying to dig wax out yourself.

Earplugs for travel: flights, trains and hotels

Travel is where a jar of foam plugs earns its keep. Cabin noise on a jet is a constant broadband roar, and trains, buses and ferries add their own rumble. Foam plugs reduce the overall level and take the hiss off the top of that sound, which makes it easier to read, rest, or listen to something at a lower volume through headphones.

A few travel-specific points:

• Pressure changes. Foam plugs are not designed to relieve ear pressure during climb and descent. Mack's sells separate products for flying discomfort. If you have a cold or a history of ear trouble, ask your doctor about flying, with or without plugs.
• Hearing announcements. You will still hear the cabin crew if they speak to you directly, but you may miss announcements. Take one plug out when the seat-belt sign changes or before landing.
• Pack a case. The jar is for home. Carry the pair you are using in a small case, and a spare pair in another pocket.
• Hotel rooms. Ice machines, elevators and corridor traffic are classic higher-pitched disturbances that foam handles well.

A sleep setup for travel usually has three parts: something for noise, something for light and something for your neck. Ivan bought all three, and we review the others separately:

See the Dream Essentials Escape sleep mask review, the Trtl Pillow review, and the rest of the Travel Gear hub.

Mack's Ultra Soft vs other earplugs

We compared these on paper using published ratings and descriptions. The figures for other Mack's models come from Mack's own site; we have not bought or tested any of the alternatives.

Within Mack's range. The Ultra Soft is tied for the highest rating, so it is a natural choice if you want the top label figure and your ear canals tolerate a standard-size foam plug. If full-size foam feels too big, Mack's own smaller options trade a few decibels of rated reduction for comfort. Remember that a plug you can insert fully and comfortably will usually outperform a higher-rated plug you can only push halfway in.

Silicone putty. Moldable silicone plugs sit over the canal opening rather than inside it. They feel different and suit people who dislike anything in the canal, and they can be used for water, but the rating is far lower.

Other foam brands. Disposable foam plugs from the big industrial safety brands typically carry ratings from the high 20s to the low 30s. Between plugs in that band, foam softness, shape and size usually matter more for comfort and fit than a couple of decibels on the label.

Reusable and custom options. Flanged silicone plugs and the newer reusable "lifestyle" plugs can be washed and kept for months, but most carry lower ratings than top foam plugs. Custom-molded plugs made from an impression of your ears, usually through an audiologist, are the premium route for people who wear plugs every day.

Who should buy them

• Light sleepers in noisy places. City apartments, thin walls, roommates or a partner who snores.
• Frequent travelers. Flights, trains, buses and hotels all benefit from a small, cheap noise reducer you can replace freely.
• People exposed to loud short sessions. Concerts, motorsports, shooting sports and power tools are all on Mack's list of intended uses.
• Anyone who wants a stockpile. Fifty pairs means you can keep a few in the car, a gym bag, a travel kit and the nightstand.

Who should skip them

• Small ear canals. If standard foam feels painful even when rolled thin, try a smaller foam plug or silicone putty instead.
• People who must hear alarms or children. Use a backup alarm or skip plugs when you are on duty.
• Swimmers. Mack's does not recommend these foam plugs for water.
• People with ear conditions. Ear tubes, a perforated eardrum, a current infection or chronic ear problems mean a conversation with your doctor first.
• Heavy daily industrial use. For work in loud environments, follow your employer's hearing conservation program, which may include fit testing.

Tips and common mistakes

• Not rolling thin enough. A plug that is too thick never gets deep enough to seal.
• Skipping the ear pull. Pulling the outer ear up and back makes insertion much easier and deeper.
• Letting it expand outside the ear. Insert within a few seconds of rolling.
• Reusing past their life. Once the foam springs back fast or stays creased, swap it.
• Pulling them out fast. Twist slowly to break the seal, as Mack's advises.
• Trusting the number blindly. Use the derated estimate when thinking about how loud an environment will still be.
• Forgetting hygiene. Clean hands, a clean case and no sharing.

Final verdict

As this Mack's Ultra Soft earplugs review shows, the product itself is simple; the value is in understanding it. You get 50 pairs of soft, slow-recovery polyurethane foam plugs, made in the USA, carrying an NRR of 33, tied for the highest rating in Mack's lineup. That makes them a strong, low-cost default for sleep, travel and loud events.

The limits are the limits of all foam earplugs. The lab rating overstates what most people achieve, and OSHA's conservative derating puts NRR 33 at roughly 13 dB of real reduction in dBA terms. Low rumbles still come through, the plugs are disposable, and full-size foam does not suit every ear canal. They reduce sound; they do not block it.

If you roll them thin, seat them properly, replace them often and plan around alarms you need to hear, they do exactly what a foam earplug should. Ivan bought this jar in 2021; his own notes will be added here, and until then this is our reasoned assessment from the specs and the rules behind the rating.