Earplug

Earplug

Device to protect ears from loud noises

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Pre-molded earplugs (left), formable earplugs (center), and roll-down foam earplugs (right)

An earplug is a device placed in the ear canal to safeguard ears from loud noises, water, foreign bodies, dust, or wind. By lowering the volume of sounds, earplugs help prevent hearing loss and tinnitus (ear ringing) in some instances.

The U.S. Occupational Safety and Health Administration (OSHA) mandates hearing conservation programs that include providing hearing protection devices (HPDs). However, OSHA does not necessarily regard HPDs as completely effective.

History

The earliest known use of earplugs is mentioned in the Greek story Odyssey. Odysseus made earplugs from beeswax for his crew to block out the Sirens' enchanting songs, preventing their boats from crashing ashore.

In 1907, German inventor Max Negwer founded Ohropax, a company specializing in wax earplugs. Ray and Cecilia Benner developed the first moldable pure silicone earplugs in 1962, which were waterproof and noise-reducing. This improvement led to the popular Mack's Pillow Soft Earplugs.

Modern earplug materials were discovered in 1967 by Ross Gardner Jr. and his team at the National Research Corporation (NRC) in the U.S. This led to the creation of E-A-R (Energy Absorption Resin) memory foam earplugs, refined in 1972 to the commercial foam earplugs we know today.

Hearing Protection

Four main types of earplugs are used for hearing protection:

• Foam earplugs: Made of memory foam (PVC or PU) and inserted into the ear canal to expand and seal off noise.
• Wax earplugs: Rolled into a ball and molded over the outer ear canal.
• Flanged silicone earplugs: Universal-fit earplugs.
• Custom molded earplugs: Tailored to fit the wearer's ear through a precise mold.

NIOSH Mining Safety and Health Research suggests using the roll, pull, and hold method for memory foam earplugs. This involves rolling the earplug, pulling back the ear, and holding the earplug inside the ear canal until it expands.

Proper training in earplug use is crucial for effectiveness. This includes instruction on insertion, seal and depth checks, removal, cleaning, and replacement.

Noises above 80 dB can be harmful. For shooting or other high-noise activities, specialized hearing protection should be used. Explore What Decibel Ear Protection for Shooting for specific options.

Types and Use Cases

Simple Earplugs

Disposable foam earplugs are common in industrial settings and among soldiers. These plugs are rolled and inserted into the ear canal, where they expand to block noise.

For more advanced needs, electronic earplugs can cancel out gunshots while amplifying quieter sounds. These high-tech options are more expensive than foam plugs.

Motorcyclists and skiers also use earplugs to reduce wind noise.

Musicians' Earplugs

Musicians face high risks of hearing damage from loud performances. Musician's earplugs attenuate sounds evenly across all frequencies, preserving the natural tone of music. These earplugs often use diaphragms and acoustic channels for high-fidelity sound reduction.

Preformed earplugs like ER-20 offer around 12 dB noise reduction. Custom-molded options provide more tailored protection and include filters that vary the level of attenuation.

Some musicians use in-ear monitors that double as earplugs, allowing clear sound monitoring while attenuating external noise. The effectiveness depends on the listening levels set by the musician.

Custom Molds

Custom molded earplugs offer better fit and protection, especially for unusual ear anatomies. These molds can last several years and must be checked and fitted by a professional.

The process involves taking an ear canal impression and turning it into a protector. Custom molds need to be verified for proper fit and attenuation using real-ear methods.

Electronic Earplugs

Electronic earplugs reduce loud noises more effectively while allowing softer sounds to be heard. They use a combination of passive earplugs and microphones/speakers to transmit sound. High-level sounds trigger a reduction in amplification, offering dynamic range compression.

Nonlinear Earplugs

Nonlinear earplugs amplify soft sounds while reducing loud noises, often using a thin diaphragm. They're useful in environments where situational awareness and noise protection are essential, like in the military.

Sleep

Earplugs for sleeping are designed for comfort and noise dampening. Adjusting the earplugs while lying down helps ensure proper fit and comfort. Specialized plugs are available for snoring and other specific noise disruptions.

Protection from Water

Earplugs for water protection are mainly used during swimming and water sports. These plugs prevent conditions like exostosis (surfer's ear) by blocking cold water and wind.

To prevent otitis externa (outer ear infection), ears should be dried thoroughly after water exposure, and ear plugs or swim molds can be used for protection.

For divers, special vented earplugs are recommended to avoid pressure issues underwater.

Flight Ear Protection

Earplugs designed for air travel help alleviate the pain caused by pressure changes during take-off and landing. Some products include porous ceramic inserts to balance middle and outer ear pressure, reducing discomfort.

Noise Attenuation, Labeled (NRR, SNR, HML, SLC80) and Real-World

Noise attenuation for earplugs is determined through lab tests and various rating methods (NRR, SNR, HML). However, real-world attenuation can vary significantly due to individual differences.

Various methods have been developed to predict workplace noise attenuation based on lab data. The newest standards offer more accurate predictions, considering individual variability.

Rating

The U.S. EPA requires hearing protection devices to have a Noise Reduction Rating (NRR) based on tests. The European Union uses SNR and HML ratings, while other countries have their own standards and ratings.

The NRR is determined by lab testing, with adjustments for real-world use. NIOSH offers derating methods based on the type of protector, recommending adjustments for more accurate real-world estimates.

Noise Reduction Rating (NRR)

In the U.S., NRR is mandated by the EPA to estimate the noise reduction provided by hearing protection. Ratings may be adjusted by OSHA and NIOSH to reflect differences between lab and real-world usage.

Active electronic ear muffs provide noise cancellation, varying in effectiveness across different frequencies.

Double Protection

Using both ear muffs and earplugs concurrently offers the best protection but presents challenges in accurately estimating noise reduction. Combining ear muffs and earplugs can provide a higher level of protection but may still be limited by individual variability.

Derating in Several Countries

Different countries have varied derating recommendations for hearing protectors. These variations may reflect the individual differences in how earplugs fit and function.

Personal Attenuation Rating (PAR)

PAR is a more personalized measure of noise reduction achieved with specific hearing protection devices. Unlike the generalized NRR, PAR accounts for individual fitting differences, providing a more accurate estimate of noise exposure reduction.

Health Risks

While earplugs are generally safe, there are some health risks to consider, especially with long-term use:

• Increased air pressure in the ear canal can cause discomfort.
• Earplugs can push earwax deeper into the canal, potentially leading to blockages.
• Allergic reactions to earplug materials are rare but possible.

Long-Term Use

Prolonged use of earplugs can lead to earwax buildup, irritation, and infections. Custom-shaped plugs are recommended for long-term comfort and hygiene.

References

For detailed questions about hearing protection, explore additional resources like the EAR-Log series, scientific papers, and online databases.

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