Product Guides

Hearing Protection Guide: Earplugs vs Earmuffs & NRR Ratings

Noise-induced hearing loss is permanent, painless as it develops, and entirely preventable. It is also one of the most common occupational injuries in Australia. Safe Work Australia estimates around 28-37% of hearing loss in the working-age population is attributable to workplace noise, and once the hair cells in your cochlea are damaged, they do not regenerate. No surgery, no hearing aid fully restores what noise takes away. The problem is not simply the existence of loud environments. It is that most people in those environments are wearing hearing protection incorrectly, wearing the wrong class for the noise level, or making small fitting errors that eliminate the majority of the product's rated protection. A Class 5 earplug worn loosely may deliver less actual attenuation than a correctly fitted Class 3. This guide covers everything you need to select, fit, and rely on hearing protection in an Australian industrial, construction, or trade environment: the AS/NZS 1270 standard and what SLC80 classes actually mean, the difference between earplugs and earmuffs, how electronic earmuffs work, when to use double protection, and the most common fitting mistakes that negate the product you paid for. This guide is part of AIMS Industrial's curated Engineering Reference Charts library — 78 reference articles across fasteners, threading, bearings, lubrication and safety standards. AS/NZS 1270 Hearing Classes — Quick Reference Hearing protection sold for occupational use in Australia and New Zealand must comply with AS/NZS 1270:2002, Acoustics — Hearing protectors. This is the standard that governs how hearing protectors are tested, classified, and labelled. It is maintained jointly by Standards Australia and Standards New Zealand. The rating system specified in AS/NZS 1270 uses a metric called SLC80: Sound Level Conversion at the 80th percentile. This tells you the amount of noise reduction (in decibels) that can be expected for 80% of wearers when the product is fitted correctly. Expressing it at the 80th percentile accounts for real-world variability in fit between different users — it is a statistically conservative estimate designed to reflect performance in practice, not under ideal laboratory conditions. The SLC80 value is then used to assign the product to one of five classes: Class SLC80 Range Noise Level (dB(A) at ear, without PPE) Typical Use Class 1 10–13 dB Up to 90 dB(A) Light industrial, machinery rooms, low-level continuous noise Class 2 14–17 dB Up to 95 dB(A) General manufacturing, moderate mechanical noise Class 3 18–21 dB Up to 100 dB(A) Heavy manufacturing, construction, compressors, generators Class 4 22–25 dB Up to 105 dB(A) Angle grinders, jackhammers, loud power tools Class 5 26+ dB Up to 110 dB(A) Extremely loud environments: airports, mining, explosive use Why Hearing Protection Matters: Noise-Induced Hearing Loss in Australia The WHS Regulations set the exposure standard at an eight-hour equivalent continuous sound level (LAeq,8h) of 85 dB(A) and a peak sound pressure level of 140 dB(C). These are not guidelines — they are legal limits. Above these thresholds, employers must implement a hierarchy of controls: eliminate the noise source, substitute quieter equipment, engineer the noise out, isolate workers, and only then reach for personal protective equipment including hearing protection. In practice, elimination and engineering are often not possible or not sufficient, which means hearing protection is a primary control in many industrial trades. The legal trigger for mandatory hearing protection is noise exposure at or above 85 dB(A) LAeq,8h. In practical terms, if you need to raise your voice to be heard by someone one metre away, the background noise is probably at or above 85 dB(A). Noise-induced hearing loss (NIHL) develops gradually and without pain. Workers typically do not notice meaningful loss until 25-40 dB of high-frequency hearing has been destroyed, often across the 3,000–6,000 Hz range first. The result is difficulty distinguishing speech, trouble hearing in noisy environments, and progressive isolation. Tinnitus (ringing in the ears) frequently accompanies NIHL and can itself be debilitating. The occupational groups with the highest documented noise exposure in Australia include construction trades, manufacturing, mining, agriculture, aviation ground crew, live entertainment crew, and defence personnel. However, noise at injurious levels is also common in workshops, on loading docks, and during tasks as routine as grinding, cutting, drilling, or operating pneumatic tools. The key point for anyone selecting hearing protection: the protection only works if it is the right class for the noise level and fitted correctly every single time. Inconsistent use — removing protection for just a few minutes in a high-noise environment — dramatically erodes the effective protection over a full shift. Australian Standard AS/NZS 1270 and SLC80 Explained Hearing protection sold for occupational use in Australia and New Zealand must comply with AS/NZS 1270:2002, Acoustics — Hearing protectors. This is the standard that governs how hearing protectors are tested, classified, and labelled. It is maintained jointly by Standards Australia and Standards New Zealand. The rating system specified in AS/NZS 1270 uses a metric called SLC80: Sound Level Conversion at the 80th percentile. This tells you the amount of noise reduction (in decibels) that can be expected for 80% of wearers when the product is fitted correctly. Expressing it at the 80th percentile accounts for real-world variability in fit between different users — it is a statistically conservative estimate designed to reflect performance in practice, not under ideal laboratory conditions. The SLC80 value is then used to assign the product to one of five classes: Class SLC80 Range Noise Level (dB(A) at ear, without PPE) Typical Use Class 1 10–13 dB Up to 90 dB(A) Light industrial, machinery rooms, low-level continuous noise Class 2 14–17 dB Up to 95 dB(A) General manufacturing, moderate mechanical noise Class 3 18–21 dB Up to 100 dB(A) Heavy manufacturing, construction, compressors, generators Class 4 22–25 dB Up to 105 dB(A) Angle grinders, jackhammers, loud power tools Class 5 26+ dB Up to 110 dB(A) Extremely loud environments: airports, mining, explosive use The class is printed on the product packaging and often moulded or stamped on the product itself. When selecting hearing protection, you first need to know the noise level at your work location — measured in dB(A) — and match it to the appropriate class. Under-protecting is a WHS compliance issue and a health risk. Over-protecting creates a different problem covered later in this guide. It is worth being clear about what "fitted correctly" means in the context of the SLC80 rating. The standard assumes the wearer has been trained in correct fit, the product is in good condition, and it is worn continuously throughout the noise exposure period. Remove a Class 5 earplug for 15 minutes in a 110 dB(A) environment and the effective protection for that eight-hour shift drops significantly. How to Calculate the Noise Level at the Ear Knowing the SLC80 value and the environmental noise level, you can calculate the approximate noise level at the ear using the formula specified in AS/NZS 1270. For Class-based selection, Safe Work Australia's simplified approach is: Effective noise level at ear = Environmental noise level (dB(A)) − SLC80 value The target is to reduce the noise level at the ear to between 75 and 80 dB(A). The lower bound matters as much as the upper: going below 70 dB(A) at the ear means you are over-protecting, which creates communication and situational awareness risks. The practical target range for most industrial environments is 75–80 dB(A) at the ear after protection is applied. Example: If the environmental noise level is 100 dB(A) and you select a Class 3 product with an SLC80 of 20 dB, the effective noise at the ear is approximately 80 dB(A) — within the target range. Selecting a Class 5 product with an SLC80 of 30 dB in the same environment would reduce the level to 70 dB(A), potentially creating situational awareness issues without providing additional health benefit. If you do not have a noise level measurement for your site, the best approach is to arrange a noise assessment with a workplace health and safety professional. Noise dosimeters and sound level meters used for compliance measurement must themselves meet Australian standards. Smartphone apps are not suitable for compliance purposes. SLC80 vs NRR: Why US Ratings Do Not Apply in Australia When purchasing hearing protection online or from international suppliers, you will often see products rated using NRR — Noise Reduction Rating — which is the system used in the United States under EPA regulations. NRR is not the same as SLC80, and the two numbers cannot be directly compared or substituted for one another. NRR is derived from laboratory testing under ideal conditions and is typically expressed as a higher number than SLC80 for equivalent products, partly because the testing methodology does not apply the same real-world correction factor. In practice, the US EPA itself recommends workers and employers derate NRR values by 50% to reflect typical real-world performance, which means an NRR 30 product in practice provides roughly 15 dB of usable protection — but this is still expressed in a different framework from SLC80. In Australia, compliance with WHS regulations requires hearing protection that meets AS/NZS 1270. A product rated only under NRR — with no AS/NZS 1270 marking — has not been tested and classified to the Australian standard. You cannot confirm its class, its SLC80 value, or whether it meets the legal requirements for use as PPE in an Australian workplace. Some products sold in Australia carry both NRR and SLC80 ratings because the manufacturer has had them tested to both standards. In that case, use only the SLC80 value for compliance purposes. When purchasing hearing protection for an Australian workplace, always check for the AS/NZS 1270 mark and the class number on the packaging. Types of Earplugs: Disposable Foam, Reusable, Corded, and Banded Earplugs are inserted directly into the ear canal to block sound. The four main types in common industrial use are disposable foam, reusable (pre-moulded or custom), corded, and banded (also called pod or canal cap earplugs). Disposable foam earplugs are the most widely used type in Australian industrial and construction environments. They are made from slow-recovery polyurethane foam that conforms to the shape of the ear canal when correctly inserted. The foam expands against the canal walls to form an acoustic seal. When new and correctly fitted, high-quality disposable foam earplugs typically achieve Class 4–5 SLC80 ratings — among the highest attenuation available from any hearing protection type. The critical word is "correctly." Disposable foam earplugs have the highest attenuation potential of any common hearing protection format, but they also have the highest sensitivity to fitting technique. A poorly fitted foam earplug may achieve only 30–50% of its rated attenuation. Fitting technique is covered in detail in a later section of this guide. Disposable foam earplugs should be replaced at least daily, or more frequently in dirty environments. They are single-use in practice — re-rolling and re-inserting a used earplug that has picked up grease, dust, or sweat reduces hygiene and attenuation. Corded earplugs are disposable foam or reusable earplugs joined by a cord, typically worn around the neck when not in use. The cord prevents the earplug from being dropped or lost when removed temporarily. This is useful in environments where earplugs are put in and taken out frequently — a common scenario in intermittent-noise environments like warehouses or workshops. The cord does not affect attenuation; it is a convenience and hygiene feature. The corded format is also a useful loss-prevention measure in environments where earplugs end up in machinery or food products if dropped. Reusable earplugs are made from silicone, thermoplastic rubber, or other durable materials that can be washed and reused multiple times. Pre-moulded reusable earplugs come in one-size or multiple-size variants. They are inserted without rolling or pre-compressing. Because they do not rely on foam expansion to form a seal, correct fit depends on choosing the right size — a pre-moulded earplug that is too small will not seal adequately. Reusable earplugs are a cost-effective choice for workers who use hearing protection consistently and are trained in correct size selection. They are also more practical in environments where bare hands cannot be maintained — dirty or greasy hands contaminate a foam earplug during the rolling and insertion process in a way they do not contaminate a reusable plug that is simply inserted. Banded earplugs (canal caps / pod earplugs) consist of foam or rubber pods mounted on a flexible band that holds them at the ear canal entrance without full insertion. Because they do not seal inside the canal, they achieve lower attenuation than fully inserted earplugs — typically Class 1–3. Their advantage is convenience: they can be quickly moved from one ear to between uses without handling, making them practical for intermittent noise environments where workers move in and out of loud areas frequently. They are not appropriate as primary protection in high-noise sustained-exposure environments. Types of Earmuffs: Passive Overhead, Cap-Mounted, and Electronic Earmuffs enclose the entire outer ear in cushioned cups that press against the skull to create an acoustic seal. They do not require ear canal insertion and are therefore less dependent on individual fitting technique for their basic function — though seal integrity remains important and is affected by glasses, hair, and correct cup positioning. Passive overhead earmuffs are the standard format: two cushioned cups connected by a headband, worn over the top of the head. The cushions press against the skull around the ear and the rigid cups attenuate noise by both reflection and absorption. Passive earmuffs provide reliable, consistent protection that is straightforward to apply and remove. Most industrial-grade overhead earmuffs achieve Class 4–5 ratings. They are robust, washable (cushions are replaceable), and well suited to sustained noise exposure in fixed locations such as at machinery or on production lines. Cap-mounted earmuffs attach to the brim of a hard hat rather than sitting on a headband. They are essential in environments where both head protection and hearing protection must be worn simultaneously — construction sites, civil works, mining, and any WHS environment that mandates hard hats. Cap-mounted earmuffs fold out of the way when not needed and flip into position over the ears when entering a noise hazard zone. Their attenuation is generally comparable to overhead earmuffs, though seal pressure and consistency can vary more with cap-mounted formats depending on the specific product and hard hat combination. Electronic earmuffs (also called active noise reduction or ANR earmuffs) are covered in detail in a later section. The headline: they use microphones and speakers inside the cups to allow normal speech and situational awareness through at safe levels while automatically compressing or blocking sounds above a threshold. This makes them valuable in environments with intermittent high-noise events (nail guns, impact tools, occasional vehicle movement) and where communication remains necessary during work. Electronic earmuffs are standard in shooting sports and are increasingly used in construction, defence, and emergency services. Earplugs vs Earmuffs: How to Choose Neither earplugs nor earmuffs are universally superior. The right choice depends on the noise level, the work environment, the duration and pattern of noise exposure, other PPE being worn, and the individual worker's anatomy and task requirements. Choose earplugs when: Workers also wear hard hats (earmuffs can be worn with hard hats via cap mounts, but overhead earmuffs and hard hats create logistical friction) The environment is hot or physically demanding and earmuff cushion sweat is an issue Workers need to wear hearing protection for extended periods — earplugs are lighter and create less neck strain The noise level is very high and maximum attenuation (Class 4–5) is needed from a single device Workers wear glasses and the glasses arms may compromise earmuff seal Choose earmuffs when: Workers move in and out of noise hazard zones frequently — earmuffs can be removed and replaced in seconds without hand contact with the ear Ear canal hygiene is a concern — earmuffs do not require handling of the ear canal Workers have ear canal conditions (ear infections, perforations, sensory sensitivities) that prevent earplug use Electronic/communication features are required Training and supervision make consistent correct fitting of earplugs unreliable The noise is intermittent rather than sustained — earmuffs are faster to apply for short noise events For sustained very high noise exposure (above 105 dB(A) LAeq,8h), a single device may not provide sufficient protection and double protection should be considered. For most standard industrial environments in the 85–100 dB(A) range, either a correctly fitted Class 3–4 earplug or a Class 3–4 earmuff will meet the protection requirement. Electronic Earmuffs: How Active Noise Reduction Works Electronic earmuffs look externally similar to passive earmuffs, but include microphones mounted on the outside of the cups, an electronic processing circuit, and speakers inside the cups. Sound from the external microphones is processed and replayed through the internal speakers at a safe level — typically allowing speech and environmental sounds below 82–85 dB(A) to pass through normally. When the external sound exceeds the threshold, the circuit either compresses it sharply or cuts off entirely, depending on the product design. The result is hearing protection that does not isolate the wearer from their environment. Workers can hold a normal conversation and hear radio communications, vehicle reversing alarms, and warning signals while remaining protected from impulse noise events such as gunshots, nail gun discharge, jackhammer impacts, or machinery start-up peaks. This situational awareness feature is the primary reason electronic earmuffs are preferred in certain environments. A passive Class 4 earmuff may block warning signals, reduce awareness of approaching vehicles or machinery, and create communication difficulties that lead workers to remove the protection during noise events — the worst possible outcome. An electronic earmuff at equivalent passive attenuation allows the wearer to keep the protection on continuously because normal communication is possible. Key specifications to look for in electronic earmuffs: Passive SLC80 / Class rating: This is the protection provided when the electronics are off or the batteries die. Always check this — some consumer-grade electronic earmuffs have very low passive ratings. Compression threshold: The sound level at which the circuit activates and limits the passthrough audio. Typically 82–85 dB(A). Attack time: How quickly the limiter responds to a sudden loud sound. Faster is better for impulse noise environments like shooting. Frequency response: Better-quality units amplify speech frequencies to make communication clearer, rather than simply passing through all frequencies equally. Battery life: Alkaline AA or AAA cells are common; auto-shutoff is a useful feature. AUX input / Bluetooth: Some models support radio or phone connectivity for communication-intensive environments. Cap-mounted versions of electronic earmuffs are available and are essential where hard hat use is mandatory alongside hearing protection and communication requirements — civil works, mining site supervisors, and similar roles. Double Protection: When to Combine Earplugs and Earmuffs Double protection — wearing both earplugs and earmuffs simultaneously — is appropriate when a single device cannot provide sufficient attenuation for the noise level. The relevant Australian guidance recommends double protection when the noise level exceeds 105 dB(A) LAeq,8h or when the attenuation required from a single device cannot be achieved by any product meeting AS/NZS 1270. The critical point about double protection: the combined SLC80 value is not the sum of the two individual SLC80 values. You do not add the ratings together. The combined attenuation from double protection is typically estimated as the higher SLC80 value of the two devices plus 5 dB. This reflects the fact that once attenuation exceeds a certain level, sound transmission through bone conduction and the skull itself becomes the limiting factor, and additional cup or plug attenuation yields diminishing returns. Example: Class 5 earplug (SLC80 = 30 dB) + Class 4 earmuff (SLC80 = 25 dB) = approximately 35 dB combined — not 55 dB. Environments where double protection is typically required or recommended include: airport apron operations, jet engine maintenance, blasting areas in mining and demolition, some heavy press operations, and certain power generation facilities. Defence personnel may use double protection as standard during training and operations involving firearms. Double protection also creates a communication challenge: workers wearing both earplugs and earmuffs have very limited ability to hear speech or warning signals. In these environments, electronic earmuffs (over earplugs) are strongly preferred because they restore situational awareness at the earmuff level while the earplugs provide additional attenuation of the extreme noise baseline. How to Correctly Fit Foam Earplugs Correct insertion of a foam earplug is the single biggest factor in whether the product delivers its rated protection. An improperly inserted foam earplug may attenuate 5–10 dB less than its SLC80 rating, effectively reducing a Class 5 product to Class 3 performance — or worse. The insertion process has four steps and takes around 20–30 seconds per ear. Step 1: Roll Using clean, dry hands, take the earplug and roll it between your fingers into a thin, smooth cylinder. The aim is to compress the foam as evenly as possible into the smallest diameter that allows insertion. Do not simply pinch or squeeze — roll it. The cylinder should be no more than 4–5mm in diameter when fully rolled. If the foam springs back quickly, keep rolling or pinch the tip to hold compression while inserting. Step 2: Pull Reach over your head with the opposite hand and pull the outer ear (pinna) up and back. For the right ear, use your left hand; for the left ear, use your right hand. Pulling the pinna up and back straightens the ear canal, which is slightly curved in its natural state. Without this step, the earplug meets the curve of the canal rather than seating fully within it. Step 3: Insert While still holding the pinna up and back, use your other hand to insert the rolled earplug into the ear canal with a gentle forward and slightly downward pressure. The earplug should go in deeply enough that it is almost flush with or slightly proud of the canal entrance. If the earplug is still substantially protruding from the ear, it is not inserted far enough and will not seal effectively. Step 4: Hold Keep your finger gently pressed against the earplug for 20–30 seconds while the foam expands to fill the canal. Do not release pressure too early — the foam needs time to expand against the canal walls and form a complete acoustic seal. Once you release, the earplug should sit securely in the canal without being pushed out by the foam's expansion. Check your fit: A correctly fitted foam earplug produces a noticeable reduction in environmental sound when you speak — your own voice should sound hollow or "plugged." This is a practical field check. You can also try a gentle tug on the earplug — it should resist removal slightly, indicating the seal is engaged. If it comes out easily, re-roll and re-insert. How to Correctly Fit Earmuffs Earmuffs are simpler to fit than foam earplugs but are not fail-safe. Seal integrity is the critical variable — anything that breaks the seal between the cushion and the skull reduces attenuation substantially. Position the cups correctly: Each cup should fully enclose the outer ear with the cushion making even contact with the skull around the entire circumference of the ear. The headband should sit over the top of the head — not at an angle. Tilted or off-centre cups reduce attenuation. Some earmuffs have an adjustable headband; adjust it until the cups sit evenly without needing to hold them in place. Adjust headband tension: The cushions need enough pressure against the skull to maintain the seal, but not so much that wearing becomes uncomfortable over a shift. Most overhead earmuffs allow headband adjustment. If the cushions are barely in contact with the skull, the seal is compromised. If the headband pressure is causing headache or soreness, adjust or consider a different product with a softer headband. Account for glasses: Glasses arms (temples) pass between the earmuff cushion and the skull, breaking the seal at two points. This is one of the most common and least understood sources of earmuff attenuation loss. The thicker the temple arm, the greater the breach. Solutions include using thin-profile safety glasses, wearing safety glasses over the earmuffs (where the design allows), choosing earmuffs with softer, more conformable cushions that adapt around the temple arm, or switching to safety goggles that do not use temple arms. Account for hair: Long hair, high buns, or hair clips caught under the cushion all compromise the seal. Hair should be moved clear of the cushion contact area before fitting earmuffs. This is particularly important with ear-covering hairstyles that may seem out of the way but create a pathway for sound at the cushion edge. Cap-mounted earmuffs: Ensure the cups are correctly adjusted to the wearer's head width and that the hard hat is sitting correctly on the head before flipping the ear cups into position. An incorrectly positioned hard hat will cause the cup attachment mechanism to push the cups out of position relative to the ears. Common Fitting Mistakes That Eliminate Protection Understanding what goes wrong is as important as knowing the correct technique. These are the most common errors observed in workplace hearing protection use: Not rolling foam earplugs fully before insertion. Workers who are unfamiliar with the technique or in a hurry often insert a foam earplug that has been only lightly compressed. The earplug does not seat deeply in the canal and does not form an adequate seal. The earplug is visibly prominent in the ear — a quick visual check supervisors can use. Not pulling the pinna back before insertion. Without straightening the ear canal, the earplug meets the curve of the canal and sits in the outer portion only. Full depth insertion requires the pinna pull — always. Not holding the earplug while it expands. Releasing before expansion is complete allows the foam's expansion force to push the earplug back toward the canal entrance. Workers who insert and immediately remove their finger get a shallower seal than the product is capable of. Using a dirty or contaminated earplug. A used foam earplug that has absorbed sweat or picked up oil or dust should be discarded. Contamination stiffens the foam, reduces its ability to conform to the canal, and creates hygiene risks. Disposable earplugs are designed for single-shift use. Wearing earmuffs over-ear rather than fully enclosing the ear. The cup must surround the outer ear entirely, with the cushion on the skull — not resting on the cartilage of the outer ear. Earmuffs worn with the cup partially on the ear rather than around it achieve dramatically reduced attenuation. Allowing glasses arms to breach the earmuff seal without compensation. As noted above, uncorrected glasses-cushion interference can reduce earmuff attenuation by 5–15 dB — enough to shift a Class 4 product into Class 2 effective performance. Removing protection for short periods in noise. This is the most consequential error. During a 30-minute grinding session at 105 dB(A), removing protection for just two minutes reduces the effective protection for that entire session from the rated SLC80 value to almost nothing, because the accumulated dose during those unprotected two minutes dominates the overall exposure calculation. Using hearing protection rated too low for the environment. Class 1 earmuffs in a 105 dB(A) grinding environment provide compliance theatre, not actual protection. The class must be matched to the noise level. Hearing Protection for Specific Environments Different work environments create different noise profiles, different coexisting PPE requirements, and different communication demands. Here is a practical breakdown of the most common industrial contexts: Construction and civil works: Noise levels vary widely by task — concrete cutting at 105+ dB(A) (see the Diamond Blade Guide for the cutting tool side), general site noise at 85–95 dB(A). Hard hat mandates make cap-mounted earmuffs the practical default. Where precision task-switching is frequent (workers regularly entering and exiting noise zones), corded earplugs in a neck cord wallet or banded earplugs for easy access are useful. Communication with other workers and with vehicles/plant makes electronic earmuffs highly valuable for supervisors and workers who need to communicate while protected. Manufacturing and production lines: Sustained, consistent noise from machinery typically in the 90–100 dB(A) range. Full-shift protection requirements favour foam earplugs (comfortable for long wear) or overhead earmuffs where workers are not mobile. Cap-mounted earmuffs are generally not needed unless the facility also mandates hard hats. Corded earplugs reduce the replacement frequency from workers dropping and losing earplugs. Grinding, cutting, and angle grinding: Angle grinders and cutting tools typically generate 100–108 dB(A) at the operator position. Class 4–5 protection is required. A Class 5 foam earplug correctly fitted is appropriate. Workers often also need face shields or safety glasses, which makes earmuffs less convenient — foam earplugs avoid the glasses-seal interference issue. Shooting sports and range use: Firearms generate impulse noise events of 140–165 dB(C) peak — well above the peak pressure exposure standard of 140 dB(C). This is a category where electronic earmuffs are strongly preferred: they allow normal communication between shooters, permit range commands to be heard clearly, and compress the impulse noise event instantaneously. Class 5 passive earmuffs are also effective for sustained firing but eliminate the ability to communicate. For high-intensity competition or military training, double protection (Class 5 earplugs + Class 4–5 electronic earmuffs) is recommended. Aviation and airports: Ground crew on airport aprons are exposed to jet engine noise at 140+ dB(A) depending on proximity. Double protection is standard — Class 5 earplugs under Class 5 earmuffs, with the combined effective attenuation of approximately 35 dB. Communication headsets integrated into earmuff cups are used for air traffic communication. Maintenance personnel working inside engine bays or near auxiliary power units face similar requirements. Warehousing and logistics: Forklift operations, pallet jack use, and loading dock activity typically generate 85–95 dB(A). The intermittent nature of the noise and the frequent need to communicate with other workers makes electronic earmuffs or banded earplugs practical for noise zones, with corded foam earplugs as a lower-cost alternative for sustained-exposure areas. Woodworking and cabinet making: Table saws, routers, and planers produce 90–105 dB(A). The sawdust-laden environment makes earmuff cushion hygiene a consideration — cushions must be wiped down and replaced regularly. Foam earplugs avoid this issue but become impractical for workers who are also wearing dust masks, as the breathing exertion from intensive physical work makes the ear canal area humid and fitting more difficult. How to Choose the Right Hearing Protection: A Decision Guide Use this framework to select appropriate hearing protection for a given task or environment: Step 1: Establish the noise level. If you do not have a measured noise level, arrange a noise assessment. In the meantime, use the conservative approach: if you need to raise your voice for normal conversation at one metre distance, assume 85 dB(A) or above. Step 2: Determine the required SLC80 class. Use the table earlier in this guide to match the environmental noise level to the appropriate class. Remember the target: effective noise at the ear should be 75–80 dB(A). Selecting a higher class than needed creates over-protection and situational awareness risk. Step 3: Consider coexisting PPE. If a hard hat is mandatory, either cap-mounted earmuffs or earplugs are the practical choices. If safety glasses or goggles are required, consider the glasses-seal interference issue with earmuffs and whether earplugs would be more appropriate. Step 4: Assess communication requirements. If workers need to communicate, hear warning signals, or operate radios while protected, electronic earmuffs are worth the investment. In environments where communication is not critical and workers are in sustained noise, passive earplugs or earmuffs are appropriate. Step 5: Consider exposure pattern. For intermittent noise exposure with frequent entry and exit from noise zones, earmuffs (faster to apply and remove) or banded earplugs are more practical than foam earplugs. For sustained full-shift exposure in a fixed location, foam earplugs offer the best attenuation and comfort for extended wear. Step 6: Verify AS/NZS 1270 compliance. Check that the product carries the AS/NZS 1270 mark and the SLC80 class on its packaging. Products rated only under NRR or lacking Australian standard compliance cannot be used for WHS compliance in an Australian workplace. Step 7: Train workers in correct fit. The product class only delivers its rated protection when worn correctly. Fitting training — especially for foam earplugs — is not optional. Build it into induction and safety refreshers. AIMS Industrial stocks a range of hearing protection compliant with AS/NZS 1270, from Class 5 foam earplugs in corded and uncorded formats through to electronic earmuffs with active noise reduction and cap-mount capability. View the full range at AIMS ear protection. Frequently Asked Questions What is SLC80 and how does it differ from NRR? SLC80 (Sound Level Conversion at the 80th percentile) is the Australian hearing protection rating system specified in AS/NZS 1270:2002. It represents the noise reduction achievable for 80% of wearers with correct fit. NRR (Noise Reduction Rating) is the US system used under EPA regulations. The two values are not interchangeable. NRR figures are typically higher than SLC80 for equivalent products because of different testing methodology. For Australian workplaces, only the SLC80 class — not NRR — is valid for WHS compliance purposes. What SLC80 class do I need for working with an angle grinder? Angle grinders typically generate 100–108 dB(A) at the operator position. For this range, you need at minimum a Class 4 product (SLC80 22–25 dB) and ideally Class 5 (SLC80 26+ dB). A correctly fitted Class 5 disposable foam earplug is the most common choice for grinding work, as foam earplugs avoid the seal-interference issues that arise when wearing earmuffs with safety glasses. Can I use US NRR-rated hearing protection in an Australian workplace? No. Australian WHS regulations require hearing protection that complies with AS/NZS 1270. A product rated only under NRR has not been tested or classified to the Australian standard. Its SLC80 class cannot be confirmed, and it cannot be used to demonstrate WHS compliance. Some products carry both NRR and SLC80 ratings — in that case, use only the SLC80 value for Australian compliance purposes. What is the difference between Class 3 and Class 5 hearing protection? Class 3 hearing protection has an SLC80 of 18–21 dB and is appropriate for noise levels up to approximately 100 dB(A). Class 5 has an SLC80 of 26+ dB and is appropriate for noise levels up to approximately 110 dB(A). The practical difference is the amount of attenuation provided — Class 5 products reduce the noise level at the ear by roughly 26–30 dB, compared to 18–21 dB for Class 3. Selecting too low a class for the actual noise level means insufficient protection; selecting too high a class can over-protect and create situational awareness risks. How do I correctly fit foam earplugs? Correctly fitting a foam earplug requires four steps: (1) Roll the earplug into a thin cylinder using clean, dry fingers; (2) Pull the outer ear up and back with the opposite hand to straighten the ear canal; (3) Insert the rolled earplug deeply into the canal while maintaining the ear pull; (4) Hold it in place for 20–30 seconds while the foam expands to fill the canal. A correctly fitted earplug should sit almost flush with the canal entrance. Missing any of these steps — especially the pull and hold — significantly reduces the attenuation achieved. When should I use double hearing protection (earplugs and earmuffs together)? Double protection is recommended when the noise level exceeds 105 dB(A) LAeq,8h, or when no single device provides sufficient attenuation for the noise level. Note that the combined SLC80 value is not the sum of both ratings. The combined protection is typically estimated as the higher SLC80 value plus 5 dB, because bone conduction through the skull limits the additional benefit of stacking two devices. Electronic earmuffs worn over earplugs are preferable for double protection in environments where communication and situational awareness are also required. Do glasses affect earmuff protection? Yes. Glasses temple arms (the arms that pass over the ears) break the seal between the earmuff cushion and the skull. This can reduce earmuff attenuation by 5–15 dB depending on the thickness of the temple arm — enough to reduce effective performance by one or two classes. Solutions include using thin-profile safety glasses, selecting earmuffs with soft conformable cushions that adapt around the temple, wearing safety goggles that do not use temple arms, or switching to earplugs in environments where both hearing and eye protection are required. What are electronic earmuffs and when should I use them? Electronic earmuffs use external microphones and internal speakers to pass through ambient sound and speech at a safe level (typically below 82–85 dB(A)) while compressing or blocking sounds above that threshold. This allows normal communication and situational awareness while protecting against noise peaks and impulse events. Use electronic earmuffs when: workers need to communicate while protected; the environment has intermittent impulse noise (gunshots, nail guns, impact tools); or warning signals and vehicle alarms must be heard. Check both the passive SLC80 class and the compression threshold when selecting. How often should I replace disposable foam earplugs? Disposable foam earplugs should be replaced at least once per shift, or more frequently in dirty, dusty, or high-humidity environments. A used earplug that has absorbed sweat, grease, or dust has reduced foam compliance and cannot conform to the ear canal as effectively as a new plug. Re-rolling and re-inserting a contaminated earplug also creates a hygiene risk. Treat disposable earplugs as single-shift consumables. Is it possible to wear hearing protection that is rated too high? Yes. Over-protection — using a higher class than the noise level requires — reduces the noise level at the ear below 70 dB(A), which impairs the ability to hear speech, warning signals, vehicle reversing alarms, and other situational cues. Workers who cannot hear warnings may be at greater risk of injury from other causes than noise itself. The target noise level at the ear after protection is 75–80 dB(A). Selecting the appropriate class — not the highest available class — is correct practice. What hearing protection is best for construction sites? Construction sites typically mandate hard hats, which makes cap-mounted earmuffs or earplugs the practical options. For supervisors and workers who communicate frequently, cap-mounted electronic earmuffs offer the best combination of hearing protection and situational awareness. For workers in sustained-noise zones such as near generators or compressors, corded Class 4–5 foam earplugs are a cost-effective and comfortable choice. Match the class to the specific noise level at each work zone — not all areas of a construction site are at the same noise level. How do I know if my hearing protection is adequate for my workplace? Adequate hearing protection reduces the noise level at your ear to 75–80 dB(A). To verify this: measure or obtain the measured noise level at your work location (in dB(A) LAeq,8h); confirm your product's SLC80 value from the packaging; subtract the SLC80 from the noise level. If the result is between 75 and 80 dB(A), the product class is appropriate and correctly fitted protection is adequate. If it is above 80 dB(A), upgrade to a higher class or consider double protection. If it is below 70 dB(A), consider a lower class to restore situational awareness. People Also Ask — Hearing Protection Q: What is the difference between SLC80 and NRR ratings on hearing protection? SLC80 (Sound Level Conversion at 80th percentile) is the Australian and New Zealand rating method under AS/NZS 1270, indicating the protection level achieved by 80% of wearers. NRR (Noise Reduction Rating) is the US-based ANSI rating. When selecting hearing protection in Australia, use SLC80-rated products and compare ratings under the same standard. Importing products rated only in NRR requires conversion to ensure compliance with local requirements. Q: What class of hearing protection do I need for my work environment? Australian Standard AS/NZS 1270 classifies hearing protectors into five classes based on the noise level they attenuate. Class 1 provides the least attenuation for mildly noisy environments, while Class 5 provides the highest protection for extreme noise levels. Select the class appropriate to your workplace noise exposure — over-protecting in lower-noise environments can reduce situational awareness and communication, creating other safety risks. Q: Are earmuffs or earplugs better for hearing protection? Neither is universally better — each suits different situations. Earmuffs are easier to fit correctly, more comfortable for intermittent use, and easier to inspect. Earplugs generally achieve higher SLC80 ratings, are more compact, and work better under helmets or when wearing other head PPE. For sustained high-noise environments, some workers use both simultaneously. Proper fitting of either type is critical to achieving the rated protection level. Q: How do I know if I need hearing protection in my workplace? Under Australian WHS legislation, hearing protection is required when noise exposure reaches or exceeds 85 dB(A) as an eight-hour time-weighted average (TWA), or when peak sound pressure exceeds 140 dB(C). A noise assessment should be conducted by a competent person to measure actual exposure levels. Until formal assessment is completed, if you need to raise your voice to be heard at arm's length, assume hearing protection is required. Q: How often should hearing protection be replaced? Earplugs designed for single use must be discarded after each use. Reusable earplugs should be inspected before each use and replaced when they become stiff, cracked, or no longer spring back after rolling. Earmuffs should have the foam cushions replaced at least annually or when they harden, crack, or no longer seal effectively against the head. Damaged or poorly fitting hearing protection provides substantially less protection than its rated SLC80 value. Need retaining ring pliers? Browse the AIMS range at retaining ring pliers.