To get protected from loud noises such as snoring, or for blocking intrusion of foreign bodies, water, excessive wind or dust, earplugs are used, as they have been designed to be set into the ear canals for protecting the wearer from these intrusions.
How it protects from water?
There are earplugs that have been designed specifically to avoid water getting into the ear canal, particularly when activities like swimming or water sports are carried out.
These earplugs are made from moldable silicone or wax, which gets custom-fitted as when the wearer sets it into his ear canal. As per the study that was conducted in the year 2003 and which got published in Clinical Otolaryngology, an effective, comfortable and easier way to avoid water from entering into the ear canal as when compared to the wax plugs happen to be that of a cotton ball that gets saturated with that of petroleum jelly.
Many have propounded the view, which includes Jacques-Yves-Cousteau that advocates the harmful effects of the earplugs caused to divers, particularly to scuba divers.
The source of breathing for scuba divers happen to be the compressed air or gas mixtures of other kinds, which gets done at a pressure that matches the water pressure.
This pressure can only be found inside the ear, and not between the earplug and the eardrum, which causes the pressure found behind the eardrum to moot the bursting of the eardrum. Skin divers are known to experience less pressure in the ears, but their outer ear canal also has only that of the atmospheric pressure.
The earplugs that can be put to use by the divers happen to be the vented earplugs, as this is the only type that can be used by them.
Main Earplugs and Hearing Protection
There are three main earplug types for hearing protection, which include the Foam earplugs, Flanged earplugs and the Silicone earplugs.
Foam earplugs are one among the three main earplugs, which are made from memory foam that primarily get compressed and are inserted into that of the ear canal, where the expansion then helps in the plugging in of the earplug.
Silicone earplugs are the earplugs that get rolled in the form of a ball that are molded carefully as in a way to fit on top of the external section pertaining to the ear canal, which enables the wearer to enjoy a comfortable fitting.
Flanged earplugs are the earplugs that include most types belonging to the ‘Hi-Fi’ or musicians’ earplugs and that of custom molds, as when they are molded.
Memory Foam earplugs – Method to use
In the case of earplugs for snoring, the Mining Safety and Health Research at NIOSH advocate the usage of the roll, pull and that of the hold method pertaining to the usage of these earplugs.
The process unfolds with the rolling of the earplug by the user, as it gets rolled to take the shape of thin rod so as to get pulled back on that of the ear, and to be followed by the holding of the earplug with the finger to make the earplug get deep into the canal. Twenty seconds must be left to elapse for the expanding inside the canal in the case of the need for getting a complete seal.
Disposable and Non-Disposable Earplugs
Earplugs encompass non-disposable or disposable types, with silicone and foam being disposable earplugs or that get used on fewer occasions, as the solid earplugs usually take the form of the non-disposable type.
No-roll foam ear plugs happens to be the variation pertaining to the foam, in which a central stem that is built-in is used for pushing the foam plugs as in a way to get inserted in the ears, for that of a clean, simple, inexpensive and a helpful option as when compared to the traditional form of the roll down foam earplugs.
History of Earplugs
The history of earplugs can be traced back to the times of Odyssey. Odyssey has recorded the usage of wax earplugs for the first time, where the wax earplugs were used by Odyssey’s crew to avoid distraction caused by Siren’s songs. It was in the year 1967 that the current earplug material got discovered through the efforts of Ross Gardner along with his team, which got accomplished at the National Research found in the USA.
Earplugs Types and Use
Earplugs have been put to use for various purposes. Concerning the use of earplugs, industrial workers wear this type of earplugs to avoid the sounds from loud machinery that lie within hearing distance as while working for longer periods. The earplug is also put to use by that of MoD, or the British Ministry of Defence, where soldiers make use of this type of earplug when firing weapons. Earplugs get rated according to their ability to bring down noise levels.
Hearing Protection Tests in the U.S. and the European Union
There are hearing protection tests carried out to testify the noise reduction ratings. The U.S. Environmental protection Agency in the U.S. has made it mandatory, wherein the hearing protection has to go through tests for providing NRR or the Noise Reduction Rating, in which a panel comprising of ten subjects get tested in that of a laboratory for determining the attenuation that gets tested over various frequency ranges.
The hearing protectors also go through strenuous testing methodologies in other parts of the globe, and as per the European Union, earplugs are required to go through tests that fall in accordance with the acoustical testing standard of the ISO or International Organization for Standardization, which happens to be the 4869 Part I, with the SNR or the Single Number Rating or HML, High/Middle/Low getting calculated as per the ISO 4869 Part 2.
Hearing Protection Tests in Brazil, Australia, New Zealand, Canada
With regards to the hearing protection tests, many countries follow their norms to testify the noise reduction ratings of the earplugs. The ANSI S12.6-1997 of the American National Standards Institute is used in Brazil for testing hearing protectors and the NRR (SF) or the Noise Reduction Rating Subject Fit is used for ratings of the hearing protectors. In Australia and New Zealand they follow different standards as for protector ratings, which in turn yield a quantity in Sound Level Class for that of the 80th percentile or SCL80. A class system is implemented in Canada for rating the protectors’ performance.
Having reviewed the merits related to different ratings methods, a rating system has been developed by Gauger and Berger, which forms the basis to pave way for an American National Standard that is new, which is recognized as ANSI S12.68-2007.
Different Rating Methods
The different methods provide different interpretations, nevertheless, each of the methods carry an effective percentile that gets associated with that of the rating, as the rated attenuation has to be achieved by that percent pertaining to the users. The NRR for instance is arrived when the difference between that of mean attenuation and two standard deviations get calculated, and in turn gets translated into that of a 98% statistic, which means that the level of attenuation should be achieved by 98% of users.
The HML and SNR happen to be the difference between a mean minus and standard deviation static. In effect, the level pertaining to protection should be achieved by 86% related to the users, on an approximate basis. In the same breath, the difference between mean and one standard deviation paves way for the NRR (SF), which in turn is the representation related to 86% of the users, as this level of protection is expected to be achieved by the users.
The differences that get noted between that of the ratings depend upon the way through which the protectors get tested. An experimenter-fit protocol gets used for testing the NRR. A subject-fit protocol that is experienced is used for testing the SNR/HML. A subject-fit protocol that is naïve is used in testing NRR (SF).
As per Murphy and others (2004), different amounts related to attenuation gets yielded through these three protocols, with the NRR (SF) happening to be the least and the NRR, the greatest.
The National institute for Occupational Safety and Health provides guidelines for adjusting the experimenter-fit NRR, where the NRR ratings that are required differ greatly from that of lab tests to that of field tests.
Derating of Labeled Noise Reduction
For compensating the known differences between that of attenuation values that are laboratory-driven and that of the protection that gets obtained by the worker belonging to the real world, the derating of labeled noise reduction ratings gets done as follows:
Earmuffs – Subtracting 25% from that of the labeled NRR of the manufacturer; earplugs that are slow recovery formable type by subtracting 50%; and all for other types of earplugs, by subtracting 70% from that of the labeled NRR of the manufacturer. These derating values are proposed to be put to use until such time, where the manufacturers test as well as label their products that fall in line with that of a subject-fit method as that of Method B pertaining to ANSI S12.6-1997.
Derating is not required for the NRR (SF) that is put to use in Brazil as it takes a resemblance to the manner through which the hearing protection is worn by a typical user.
Most earplugs happen to be elastic earplugs that are made from memory foam, which get rolled typically into that of a tightly compressed cylinder, without creases, as it gets done by that of the wearer’s fingers and is then put into the ear canal.
As when it is released, the expansion of the earplug takes place until the sealing of canal is done, which blocks the sound vibrations from reaching the ear drum.
Other types of earplugs get pushed into that of the ear canal without getting rolled initially. A cord is used to connect earplugs at times, for keeping them together when it is not put to use. Vicious wax or that of silicone happens to be the other material bases that are commonly used for the making of earplugs.
Hearing protection provided by other devices includes the electronic devices that get worn around or/and in that of the ear, for keeping the loud noise pertaining to gunshot at bay , while the quieter sounds get amplified to that of normal levels. Though rich in features the price related to the electronic devices happen to be nearly one hundred times that of their foam counterparts. Since the earplugs bring about the reduction in the sound volume they are used in preventing tinnitus and hearing loss, among the other ailments.
Importance of Noise Reduction Ratings
Noise Reduction ratings of the earplugs is an important criteria that helps deduct the noise reducing capacity of the earplugs. The EPA or the Environmental Protection Agency in the U.S. necessitates hearing protectors that get sold in the U.S.to possess NRR or the Noise Reduction Rating, which happens to be an estimate related to the reduction in noise experienced at the ear in case of protectors getting worn in a proper fashion. Owing to the discrepancies arising out of procedures for the fitness of protectors that get done in the testing laboratory and about the way users wear protectors, the OSHA or the Occupational Safety and Health Administration, and the NIOSH or the National Institute for Occupational Safety and Health have brought forth the derating formulae for reducing the effective NRR.
While Single Number Rating or SNR and the NRR get designed as in a way to be used with that of C-weighted noise to make sure that lower frequencies don’t get de-emphasized, the other ratings as that of NRSA and NRR (SF) get determined to be used with that of A-weighted noise levels, where the lower frequencies get de-emphasized. The NIOSH along with the U.S. EPA have brought in the mandatory requirement of 7-dB compensation between that of C and A weighting, which needs to be applied as when NRR gets used along with that of the A-weighted noise levels.
Derating by OSHA
In the training manual catering to the inspectors, OSHA has defined the adequacy related to hearing protection that is to be put to use for a hazardous noise environment, which in effect should get derated as in a way to account for the way the ear protection is worn by the workers relative to the way by which the attenuation of the protector gets tested in the laboratory by the manufacturer.
The derating factor set by OSHA for hearing protection provided by all types is 50%. In case of putting it to use with that of C-weighted noise, the derated NRR becomes NRR/2. In case of putting it to use with A-weighted noise, 7-dB adjustment for that of C-A weighting gets applied by OSHA first, and then the derating of the reminder happens.
To take a closer look, if 33-dB is the attenuation of a protector, the derating would be:
Derated NRR = (33-7)/2
Derating by NIOSH
A different scheme has been proposed by NIOSH for derating, where the protector type forms the basis upon which the derating is done. The NRR for the earmuffs should get derated by 25%, and the derating for slow-recovery foam earplugs is 50%, and it is 70% for other protection types. The C-A spectral compensation is applied differently by NIOSH as when compared to OSHA. Where the 7-dB factor gets subtracted first by OSHA followed by the derating of the result, the NRR gets derated first to compensate the C-A difference later through the means of NIOSH.
To know how it works, a 33-dB slow recovery foam earplug for instance would possess the NIOSH derating as:
Derated NRR= (33/2)-7
For the many hearing protection types, NIOSH has derating percentages that are different. In the current scenario, the derating factor for premolded plugs is 70%, and it is 25% for muffs and the fast expansion foam plugs carry a derating factor of 50%. For an earmuff, the procedure related to finding the derated NRR by making use of NIOSH derating system would be as following:
Derated NRR= (Original NRR x (1-.25)-7
Noise Reduction Ratings –Expected Updates
A new standard was published by the American National Standards Institute in 2007 for noise reduction ratings related to hearing protectors, which was ANSI S12.68-2007.
Collecting threshold data by that of a laboratory test and making use of the real ear attenuation at that of threshold data prescribed as per ANSI S12.6-2008, a set pertaining to 100 noises as per listings in the standard is used to compute the noise reduction statistic concerning the A-weighted noise or NRSA.
Rather than using single noise spectrum for computing noise reduction rating, variability pertaining to spectral effects and subject is incorporated by NRSA. A method is also defined by ANSI S12.68 for estimating the performance related to a protector in noise environment that is atypical.
For protectors that possess significant differences between that of low as well as high frequency attenuation, the derating might be severe as that of 10-15 decibels.
The effect related to C-A is less for that of ‘flat’ attenuation protectors. The need pertaining to calculators get eliminated by the new system as it relies on databases related to empirical data and graphs, as it is also considered to embrace more accuracy for determining NRRs.
Hi-Fi earplugs or Musicians’ earplugs
Earplugs also serve other purposes as the musicians also put earplugs to use. Musicians performing music styles that embrace loud noises as that of rock music wear earplugs at often times to avoid damage to their
hearing by their own performances. Musicians’ earplugs are made with the focus proffered in attenuating sounds evenly across that of the audio band for minimizing the effect concerning the user’s perception of treble and bass levels. Technicians and musicians use them commonly in concert and in studio for avoiding overexposure to that of high volume levels.
Generally this is achieved as when a tiny diaphragm gets incorporated for reducing low frequencies, along with that of damping or absorbent material used for high frequencies. Differing form the simple earplugs that are disposable, these earplugs are designed for constant re-use and carry a costly tag. Near about 20dB is the attenuation given by these earplugs as these earplugs get designed for protection from noise levels that are very high.
Custom-made musicians’ earplugs
There are custom-made musicians’ earplugs for individual listeners. A hearing test gets administered by an audiologist and the molds pertaining to the ear is then made. A custom ear-piece is then made by a company as in a way that different attenuation capsules can get inserted into the earplugs.
Different levels pertaining to attenuation gets provided by the different capsules, usually in the likes of 9, 15 as well as 25 dB. Flattest attenuation gets provided by these earplugs as also truest isolation for avoiding from outside noise is made possible, as the earplugs fit firmly into that of the individual’s ears.
Better protection also gets provided from noise levels that are very high. This earplug type is a popular stuff with audio engineers as these earplugs can be worn for listening to loud mixes, as they can also be done for longer and extended time periods.
Concerning other activities as that of skiers and hobby motorcyclists, decibel reduction earplugs happen to be the preferred choice, for compensating the noise related to wind against that of the helmet or head.
Flight ear protection
Earplugs assume more importance as they also provide protection during the travel undertaken in a flight. For protecting ears from pain that get caused by cabin pressure changes in airplane, earplugs are available. Some of the products unveil porous ceramic insert that reportedly helps to equalize the air pressure found between that of middle and outer ear, which helps is avoiding pain while take-offs and landings are experienced.
Earplugs for Sleep
Earplugs, which get worn while sleeping, are designed as in a way to block external sounds, which might disturb the sleep.
Specialized earplugs designed to prevent such noises as that of partner’s snoring sound might come with sound-dampening enhancements, which enables the hearing of other noises for the user, as with the case of an alarm clock.
For determining the comfort levels related to best earplugs for snoring that get used while sleeping, trying it while lying down is the idyllic way.
The pressure caused on the ear as experienced between that of head and pillow might bring down the comfort levels.
Moreover, while the head gets tilted back or to the side, it produces considerable anatomical changes in that of the ear canal, as in most cases it is the reduction related to the diameter of the ear canal, which might bring down the comfort levels in cases of earplugs being too large.
Earplugs and Health Risks
Though earplugs are considered safe, precautions will have to be exercised to overcome possible health risks, as additional ones may also appear with the usage becoming a long-term affair.
When earplugs get pushed into that of the ear canal, the air pressure might go up as a result, this in turn pushes it against that of the eardrum and causes pain. The pressure on the ear may get caused as when lying down on a particular side and this is the same when expanded foam earplugs get pushed completely into the ear. The latter risk gets bypassed through the means of removing, compressing as well as inserting the earplug to the desired depth. Vice versa as when pulled out, the eardrum gets pulled by the resultant negative pressure. In effect, it is better to screw or jiggle out some earplugs carefully rather than getting the earplugs yanked out. Yawning is of no help to equalize the air pressure difference, as it gets the pressure between that of the environment and middle ear equalized, while it is in the outer ear that this overpressure gets located, as between the earplug and the eardrum.
Ear wax as well as debris may get pushed into that of the canal if inserted too deep into the ear canal as well as when the earplug gets pushed against the eardrum. As a precautionary measure, pushing of ear plugs to reach deeper portions of ear canal must be avoided than getting grabbed as well as rotated. When earplugs produce impact on the ear wax, the earplug can get removed by irrigation or through other remedies, as that gets described.
Allergic reactions are also a possibility, though it is rare, as immunologically inert materials make up for the earplugs generally.
Earplugs for Long-term use
There are earplugs that are fit to be used on a long-term basis. For long-term use, custom molded plugs are the idyllic choice, as they are comparatively gentler and comfortable to the skin and wouldn’t get too deep into that of the ear canal. However, frequent or prolonged usage of earplugs may bring about the health risks denoted here, apart from the health risks on a short term basis.
Earplugs might cause the building up of the ear wax and in plugging the outer ear, as the normal flow pertaining to the ear wax to go outwards gets blocked. Tinnitus can be the result, as also the discharge, hearing loss, infection or pain can also be caused by the usage of earplugs. Ear wax in excess should also get carefully removed as from the ear, as water as well as mild soap should be used to clean the earplugs regularly. Nevertheless, the foam type earplugs are the disposable types and have a tendency to expand as well as lose memory property when these earplugs are left for drying after the process of washing through water and soap gets carried out. These earplugs possess the tendency to become spongy, and when compressed these earplugs expand quickly, increasing the problematic nature as when these earplugs are inserted to get into the ear canal. Sound attenuating property on a large scale is also lost as when these earplugs get washed and dried.
Irritation might get caused to the temporomandibular joint by the earplugs, which can be found near the ear canal, which ultimately leads to pain. Non-elastic earplugs that are individually fitted might be a good alternate as when it comes to causing of irritation as when they get compared to the foam ones, which get subjected to expanding inside that of the ear canal.
Ear inflammation, otitis externa can also be caused by earplugs, although using the earplugs on a short term basis as when shampooing of hair or swimming helps in preventing it. The growth of pathogenic bacteria on the warm foam type earplugs cannot be ruled out. But only the loss of integrity pertaining to the skin leads to infection. The hard as well as the poorly fitting earplugs can pave way for scratches of the skin pertaining to the ear canal, which might lead to an episode. During acute episode, disposable earplugs are the idyllic ones to be used, or cleaning of used earplugs and proper drying must be done as in a way that the healing ear canal doesn’t get contaminated with that of infected discharge.
Earplugs – Custom molds
Custom mold earplugs come in with many advantages as they are made to overcome the negative aspects concerning the usage of earplugs. The molding of noise as well as decibel reduction earplugs can be done as in a way to make it a correct fit that suits the individual’s ear canal.
Though it gets done at a higher cost, the discomfort can be reduced that gets typically experienced when the earplug is put to use on a longer term, or in case of performance or protection being inadequate. Pressure molds as well as the flight earplug molds are the types that are not the most common ones, as these earplugs are not put to use quite often as the other earplugs get used, and hence the demand is lesser.
To enable best results, these earplugs get molded in the ear as in a way that these earplugs get positioned in the right way that meets the position for the usage.
In case of earplugs used while sleeping, the earplugs should get molded so as to suit the lying-down mode, as the positioning of jaws in different ways leads to significant changes concerning the form related to the ear canal, where reduction related to the diameter is the most common, risking in making the sleeping earplug too large otherwise. Silicon is used to make the molded earplugs mostly, but there are other materials that get used as in the case of thermoplastics.