Earplugs.html



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 and watersports. These may be made of wax or silicone which is custom-fitted to the ear canal by the wearer.

A 2003 study published in Clinical Otolaryngology, found that a cotton ball saturated with petroleum jelly 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.^{citation needed}

As many have advised, including Jacques-Yves Cousteau¹, 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

There are mainly three types of earplugs for hearing protection:

• Elastic earplugs, mainly made of memory foam, which are compressed and put into the ear canal, where they expand to plug it.
• Viscous earplugs, which are 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.
• Solid earplugs, including most types of musicians' or 'Hi-Fi' earplugs, as well as custom molds once they are molded.

Furthermore, they may be either disposable or nondisposable, with elastic and viscous ones generally being disposable or for use a relatively limited number of times, while solid ones generally may be regarded as nondisposable.

History

The first recorded use of wax earplugs is in the Odyssey, wherein Odysseus's crew used wax earplugs to avoid being distracted by the Sirens' songs. 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.

'Basic' type plugs

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

This kind of earplug protection is often worn by industrial workers who work within hearing distance of loud machinery for long periods, and is used by the British Ministry of Defence (MoD) for soldiers to use when firing weapons. 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 and 33 decibels.

Most earplugs are elastic ones 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 viscous wax or silicone.

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

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. Musician earplugs are designed to attenuate sounds evenly across the audio band and thus do not affect 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.

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

They generally achieve this by incorporating a tiny diaphragm to reduce low frequencies, together with absorbant or damping material for high frequencies, and so can be quite costly, being intended for constant re-use unlike simple earplugs which are disposable. These earplugs usually give an attenuation of only about 20dB and are not intended for protection from very high noise levels (>105 dB).

Example of custom earplugs worn by professional musicians

Some musicians earplugs are custom-made for the individual listener. An audiologist administers a hearing test and makes molds of the ear. A company then makes a custom ear-piece into which different attenuator 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 plug is quite popular amongst audio engineers who can safely listen to loud mixes at for extended periods.

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

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.

Sleep

Earplugs for sleeping are made to be as comfortable as possible while blocking external sounds that may prevent or disrupt sleep. Specialized earplugs for such noises as a partner's snoring may have sound-dampening enhancements that enable the user to still hear other noises, such as an alarm clock.^{citation needed}

To determine the comfort of earplugs used for sleeping, it is important to try it on while actually lying down. The pressure on the ear between the head and pillow may cause a significant reduction in comfort. Furthermore, just tilting the head back or to the side causes significant anatomical changes in the ear canal, mostly a reduction of the ear canal diameter, which may reduce comfort if the earplug is too large.^{citation needed}

Health risks

Earplugs are generally safe, but precautions may be needed against a number of possible health risks, with additional ones appearing with long term use:

• Pushing in earplugs into the external ear canal may cause the air pressure to rise in it, in effect pushing against the eardrum and causing pain. This may be the case when completely expanded foam earplugs are pushed further into the ear. To bypass the risk, such earplugs are instead removed, compressed and inserted to the desired depth. Vice versa, when pulled out, the resultant negative pressure pulls the eardrum. Therefore, some earplugs are better carefully screwed or jiggled out rather than yanked out. Yawning does not help equalizing this air pressure difference, since it equalizes the pressures between the middle ear and the environment, while this overpressure rather is located in the outer ear, between the eardrum and the earplug.
• If pushed too far into the ear canal, they may push ear wax and debris into the canal and possibly against the ear drum. ² As a precaution, ear plugs should not be pushed further into the ear canal than that they may be grabbed and rotated.³
• There is a possibility for allergic reactions, but this is likely rare, as earplugs generally are made of immunologically inert materials.

Long-term use

Custom molded plugs are recommended, since they are more comfortable and gentle to the skin and won't go too far into the ear canal.

Nevertheless, prolonged or frequently repeated use of ear plugs have the following health risks, in addition to the short term health risks:

• They may may cause earwax to build up and plug the outer ear, since it blocks the normal flow of earwax outwards.⁴ This can result in tinnitus, hearing loss, discharge, pain or infection. ⁴ Excess earwax should be carefully removed from the ear, and earplugs should be cleaned regularly with water and mild soap. However, foam type ear plugs are usually designed to be disposable, and will expand and lose their memory property upon drying after washing with water and soap. They will become quite spongy, expand very quickly after being compressed, making them quite problematic in proper insertion into the ear canal. They also lose a large proportion of sound attenuating capability after such washing and drying.
• They may cause irritation of the temporomandibular joint, which is located very close to the ear canal, causing pain. Non-elastic earplugs are less likely to cause this irritation compared with foam ones.^{citation needed}
• Earplugs are also a possible cause of ear inflammation, otitis externa, although the short term use of earplugs when swimming and shampooing hair may actually help prevent it. Still, many pathogenic bacteria grow well on warm, moist, foam-type plugs (polyvinylchloride (PVC) or polyurethane). However, there need also be a loss of integrity of the skin for infection to occur. Hard and poorly fitting ear plugs can scratch the skin of the ear canal and set off an episode. When earplugs are used during an acute episode, disposable plugs are recommended, or used plugs must be cleaned and dried properly to avoid contaminating the healing ear canal with infected discharge. One simple method of fabricating soft waterproof disposable ear plugs is with cotton balls and petroleum jelly. These jelly coated cotton balls are NOT inserted into the ear canal, but pressed into the auricle to cover the opening of the canal.^{citation needed}

Custom molds

Noise and decibel reduction earplugs can be molded to fit an individual's ear canal. This is associated with a higher cost, but can help to reduce the discomfort typically experienced after longer use, or if the level of protection or performance is inadequate.

Pressure and flight earplug molds are less common, as they are typically not used as long as other earplugs, and are therefore less in demand.

For best results they are molded in the ear while in the position that they will be used. For instance, if they are to be used for sleeping then they should be molded in the ear while lying down, as it causes significant changes to the form of the ear canal, mostly a reduction of the diameter, which may reduce comfort if the earplug is made too large.

References

External links

Wikimedia Commons has media related to: Ear plugs

Look up earplug in Wiktionary, the free dictionary.

• Don't lose the music campaign website
• Royal National Institute for Deaf people