Earplug

« Back to Terms Index

Earplugs are devices inserted into the ear canal to protect the user’s ears from loud noises, water, foreign bodies, dust, or excessive wind. They help in reducing sound volume and can prevent hearing loss and tinnitus in some cases. The U.S. Occupational Safety and Health Administration (OSHA) mandates hearing conservation programs that include hearing protection devices (HPDs), although the effectiveness of these devices can vary.

History

The use of earplugs dates back to ancient times. In Homer’s Odyssey, Odysseus’s crew uses earplugs made from beeswax to avoid the Sirens’ bewitching songs. Modern earplugs began with the German company Ohropax in 1907, which produced wax earplugs. The first moldable pure silicone earplug was invented by Ray and Cecilia Benner in 1962, valued for its waterproof qualities. In 1967, Ross Gardner Jr. and his team at National Research Corporation (NRC) developed a resin with energy absorption properties, leading to the creation of memory foam earplugs.

Types of Earplugs

Foam Earplugs

• Made from polyvinyl chloride (PVC) or polyurethane (PU) (memory foam).
• Compressed and inserted into the ear canal, where they expand to fit.

Wax Earplugs

• Rolled into a ball and molded to fit over the external portion of the ear canal.

Flanged Silicone Earplugs

• Universal fit with multiple flanges to seal the ear canal.

Custom Molded Earplugs

• Made from a mold of the wearer’s ear for a precise fit.
• Can be laboratory-made or formed in place.

Musicians’ Earplugs

• Designed to attenuate sounds evenly across all frequencies.
• Commonly used by musicians and technicians to avoid hearing damage while maintaining sound quality.

Electronic Earplugs

• Combine passive earplugs with a microphone and speaker to allow transmission of sound.
• Reduce loud noises more than soft noises and can even amplify soft sounds.

Usage and Training

Proper training on the use and insertion of earplugs is crucial. This includes:

• Insertion techniques, such as the roll, pull, and hold method for foam earplugs.
• Seal and depth checks to ensure proper attenuation.
• Instructions on removal, cleaning, and replacement to prevent infections and maintain effectiveness.

Noise Attenuation and Fit Testing

Noise attenuation can be measured using methods like real-ear attenuation at threshold (REAT) or microphone in the real ear (MIRE). Fit-testing systems, such as NIOSH HPD Well-Fit and Honeywell Howard Leight VeriPRO, ensure earplugs fit properly and limit sound exposure effectively.

Permissible Noise Levels

Different countries have varying permissible noise levels and time limits for exposure:

Country	TWA, dBA	Level increase corresponding to doubling the dose
Argentina	90	3
Australia	85	3
Brazil	85	5
Canada	85 & 82	3
Chile	85	5
China	70-90	3
European Union countries	85	3
USA	90 (100)*	5

Noise Exposure Limits

Noise, dBA	Time reaching maximum daily dose, hours : minutes
80	8:00
85	2:31
90	0:48
95	0:15
100	0:04

Applications

Earplugs are used in various settings:

• Industrial workers exposed to loud machinery.
• Soldiers using firearms.
• Musicians and audio engineers.
• Motorcyclists and skiers to reduce wind noise.

Custom Molds

Custom molded earplugs offer a better fit for users with unique ear anatomies. They are made from impressions of the ear canal and can be laboratory-made or formed in place. Proper fitting and verification using real-ear methods are essential for effective attenuation.

Conclusion

Earplugs are versatile devices essential for protecting hearing in noisy environments. Their effectiveness depends on proper selection, fitting, and usage training. Various types of earplugs cater to different needs, from industrial use to musical applications.

[glossary_wikipedia] « Back to Terms Index