Earplug

Since they reduce the sound volume, earplugs may prevent hearing loss and tinnitus (ringing of the ears), in some cases.

[3] The first recorded mention of the use of earplugs is in the Greek tale Odyssey, wherein Odysseus's crew is warned about the Sirens that sing from an island they will sail past.

Circe, their hostess, tells them of the Sirens' bewitching song that makes men drive their boats ashore and perish.

[citation needed] Present-day earplug material was discovered in 1967, at National Research Corporation (NRC) in the US by Ross Gardner Jr. and his team.

Once the plugs have been worn down from repeated use, they will no longer seal correctly or provide the proper attenuation level, and the device will need to be replaced.

Earplugs and other hearing protection devices can be tested to ensure that they fit properly and are successfully limiting sound exposure, which is called fit-testing.

These use large headphones or specialized (surrogate) earplugs to transmit the test sounds and measure the attenuation provided by the hearing protector.

But in practice, the Compliance Safety and Health Officer must record the excess of these values with a margin, in order to take into account the potential measurement error.

Basic foam style earplug protection is often worn by industrial workers who work within hearing distance of loud machinery for long periods of time, and is used by the British Ministry of Defence (MoD) for soldiers to use when firing weapons.

Most disposable earplugs are elastic ones made of memory foam, that is typically rolled into a tightly compressed cylinder (without creases) by the user's fingers and then inserted in the ear canal.

In other activities, hobby motorcyclists and skiers may also choose to use decibel reduction earplugs, to compensate for the ongoing noise of the wind against their head or helmet.

Musicians are exposed to potentially harmful levels of sound, which can lead to hearing loss, tinnitus, and other auditory symptoms.

Musician's earplugs generally achieve a more natural frequency response by incorporating a small diaphragm or membrane together with acoustic channels and damping materials.

[22][23] The review results (which include attenuation measures and user ratings of comfort, fit and sound quality) are available at What Plug?.

These earplugs are typically made out of silicone or vinyl materials and come with a vent and a variety of filters that can change the amount of attenuation provided.

[25] This type of plug is quite popular among audio engineers who can safely listen to loud mixes for extended periods of time.

These types of earplugs do not provide the flat attenuation that is characteristic of a musician's plug, but may still be useful for some, due to their lower price points.

Real-ear attentuation at threshold (REAT) measurements test how narrowband noises of varying frequency are attenuated with and without the custom mold in place.

[21] These changes can be felt by feeling with a finger just at the entrance to the ear canal while moving the jaws sideways, up and down or anterior and posterior.

When external sounds exceed an established threshold (typically 82 dBA SPL), the amplification of the electronic circuit is reduced.

They are designed with a thin diaphragm which allows the amount of noise reduction to increase in proportion to the sound level to which the wearer is exposed.

Exostosis, or surfer's ear, is a condition which affects people who spend large amounts of time in water in cold climates.

Some products contain a porous ceramic insert which reportedly aids equalization of air pressure between the middle and outer ear thereby preventing pain during landings and take-offs.

Some airlines distribute regular foam earplugs as part of their amenity kits for passengers to aid their comfort during landings and takeoffs as well as to reduce exposure to the aircraft's noise during the flight.

Australia and New Zealand have different standards for protector ratings yielding a quantity SLC80 (Sound Level Class for the 80th percentile).

Similarly, the NRR (SF) is a mean minus one standard deviation and represents an 86% of users should achieve that level of protection.

The NRR(SF) used in Brazil, Australia, and New Zealand does not require derating as it resembles the manner in which the typical user will wear hearing protection.

[8] Due to the discrepancy between how protectors are fit in the testing laboratory and how users wear protectors in the real world, the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) have developed derating formulas to reduce the effective NRR.

Such custom molded earplugs with low pass filter and mechanical valve typically have a +85 dB(A) mechanical clamp, in addition to having a lowpass filter response, thereby providing typically 30-31 dB attenuation to loud impulse noises, with only a 21 dB reduction under low noise conditions across the human voice audible frequency range (300–4000 Hz) (thereby providing low attenuation between shots being fired), to permit hearing range commands.

[48][failed verification] The wide variation in recommendations[2] may be due in part to the very large inter-individual variability in results that cannot be predicted; but can be taken into account by individual measurements.