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File:Swimming Earplugs.JPG
Silicone rubber earplugs for protection against water, dust etc.

An earplug is a device that is meant to be inserted in the ear canal to protect the wearer's hearing from loud noises or the intrusion of water, foreign bodies, dust or excessive wind.

Protection from water

Some earplugs are primarily designed to keep water out of the ear canal, especially during swimming. These may be made of wax or silicone which is custom-fitted to the ear canal by the wearer.

An effective and simple ear plug to block water from the ear canal is a cotton ball saturated with petroleum jelly. (Gently knead an equal volume of cotton ball and jelly together. Cut into bean sized plugs.)A 2003 study published in Clinical Otolaryngology, found that the cotton ball/petroleum jelly ear plug was more effective at keeping water out of the ear, easier to use, and more comfortable than wax plugs, foam plugs, EarGuard, Aquafit, or EarSeal. The cotton ball/petroleum jelly plugs are not intended as hearing protection.

As many have advised—from Jacques Yves Cousteau in The Silent World (New York:1953, Harper, pp. 5-6)—on down to the present, ear plugs are actually harmful to divers, especially SCUBA divers. Scuba divers breathe compressed air or other gas mixtures, at a pressure matching the water pressure. This pressure is also inside the ear, but not between the eardrum and the earplug, so the pressure behind the eardrum will often burst the eardrum. Skin divers have less pressure inside the ears, but they also have only atmospheric pressure in the outer ear canal.

Hearing protection

'Basic' type plugs

File:Disposable foam earplugs.jpg
Disposable foam earplugs: with coins for scale (top) and inserted into the wearer's ear.

Current earplug material was discovered in 1967, at National Research in the USA, by Ross Gardner and his team. As part of a project on sealing joints, they developed a resin with energy absorption properties. This E-A-R material was later developed into commercial memory foam earplugs.

This kind of earplug protection is often worn by industrial workers who work within hearing distance of loud machinery for long periods of time. Earplugs are rated with "Noise Reduction Ratings" or NRRs (Single Number Ratings, or SNR, in the European Union), which provide a guide to the noise protection, in decibels, afforded by the device. Ratings usually spread between 26 to 33 decibels.

Most earplugs are made of memory foam that is typically rolled into a tightly compressed cylinder (without creases) by the wearer's fingers and then inserted in the ear canal. Once released, the earplug expands until it seals the canal, blocking the sound vibrations that reach the eardrum. Other plugs simply push into the ear canal without being rolled first. Sometimes earplugs are connected with a cord to keep them together when not in use. Other common material bases for earplugs are wax or silicone, which is rolled into a ball and carefully molded to fit over the external portion of the ear canal, providing a snug custom fit for the wearer. The first recorded use of wax earplus is in the Odyssey, wherein Odysseus's crew used wax earplugs to avoid being distracted by the Sirens' songs.

Other devices that provide hearing protection include electronic devices worn around and/or in the ear, designed to cancel out the loud noise of a gunshot, while possibly amplifying quieter sounds to normal levels. While rich in features, these electronic devices carry a price over one hundred times their foam counterparts.

Since they reduce the sound volume, earplugs are often used to help prevent hearing loss and tinnitus (ringing of the ears), amongst other ailments.

Musicians' or 'Hi-Fi' earplugs

Some earplugs are manufactured to provide a direct decibel drop without affecting the user's perception of bass and treble levels. These are commonly used by musicians and technicians both in the studio and in concert to avoid overexposure to high volume levels whilst providing a good balance over the frequency range.

File:Musicians earplugs.jpg
Musicians' earplugs. The Grey end caps contain an acoustic transmission line with a damper (attenuator) at the end while the domed flanges form a seal in outer part of the ear canal. The output port can just be seen as a small hole at the near end of the left plug

Musicians who perform music styles noted for their loud nature, especially rock music, often wear earplugs to prevent their own performances from damaging their hearing.

Musicians' earplugs are designed to attenuate sounds evenly across the audio band thus enabling musicians to hear clearly the upper harmonics, vocals, cymbals, and other high frequencies, but at a reduced volume level. These earplugs usually give an attenuation of only about 20dB and are not intended for protection from very high noise levels (>105 dB).

File:Musicians orange plugs.jpg
Economy type musicians' earplugs made from silicone rubber. The hole seen in the left plug is the input port and extends as far as the central flange where the attenuation occurs

Some "Musicians" earplugs are custom made for the individual listener. This involves visiting an audiologist to undergo a hearing test and getting the molds made to send to a company who will then make the customer a custom set of molds into which different capsules can be inserted.

These different capsules will provide different levels of attenuation, usually 9, 15, and 25dB. These types of earplugs will provide the flattest attenuation and the truest isolation from outside noise, as they fit firmly into the individuals ears. They also provide much better protection from very high noise levels. This type of plugs is quite popular amongst audio engineers as they can listen to their loud mixes at an even and safe level for extended periods.

File:Musicians Earplugs.jpg
Custom molded musician's earplugs. Note the cylindrical noise reduction capsules.

Flight ear protection

Earplugs are available which help to protect ears from the pain caused by airplane cabin pressure changes. Some products contain a porous ceramic insert which reportedly aids equalization of air pressure between the inner and outer ear thereby preventing pain during landings and take-offs. [] error: {{lang}}: no text (help)

External links

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