Glossary of custom earplugs & hearing protection

Hard acrylic is a firm, smooth plastic that many custom earplugs are made of. The material keeps its shape, lasts a long time and is easy to clean. That is why it is popular in sectors where hygiene matters, such as the food industry. A hard earplug also slides easily in and out of the ear. At Audibling, hard acrylic is the base material and soft silicone is the alternative.

An action value is a legal noise level at work above which the employer must take measures. The Dutch Working Conditions Decree (Arbobesluit) has two action values for daily noise exposure, averaged over an 8-hour working day. The lower exposure action value is 80 dB(A) and the upper exposure action value 85 dB(A). For peak noise, 135 and 137 dB(C) apply. Above 80 dB(A) the employer must provide suitable hearing protection and information. Above 85 dB(A) wearing it is mandatory and the employer must draw up a programme of measures to reduce the noise.

Attenuation is the amount of sound that a hearing protector blocks, expressed in dB. With custom earplugs, it is mainly the filter that determines how much is reduced and which tones more or less. The attenuation in practice also depends on the fit and on how consistently you wear the earplug. More attenuation is not always better. The aim is a safe level at which you can still hear your surroundings.

An audiogram is the chart that comes out of a hearing test. For each pitch, from low to high tones, it shows how soft a sound can be for you to just hear it. This shows whether, and at which tones, someone hears less well. With noise-induced hearing damage, a dip around 4000 Hz is often visible first. An audiogram is made by, for example, a hearing care professional, an ENT doctor or an occupational health service.

In the hearing world it is common to mark left and right with a colour, red for the right ear and blue for the left ear. You see this coding on hearing aids, in audiograms and often on custom earplugs too. Because a custom earplug is shaped for exactly one ear, a difference in colour helps you not to mix them up. At Audibling you choose your colour yourself.

An otoplastiek is the Dutch name for custom earplugs, made to measure from an impression of your ear. They match the shape of your outer ear and ear canal exactly and are therefore comfortable, even when worn for a long time. Custom earplugs usually contain a filter that determines how much sound is reduced. They are used as hearing protection at work, for music, on a motorcycle or for sleeping, and are made of hard acrylic or soft silicone.

The decibel (dB) is the unit in which sound level is expressed. The scale is logarithmic. Every 3 dB more means a doubling of the sound energy, and we experience 10 dB more as roughly twice as loud. So a few dB of difference is more than it seems. The attenuation of hearing protection is also expressed in dB.

dB(A) is a sound level where the measurement is adjusted to how the human ear experiences sound. Very low and very high tones count less. That is why dB(A) is used to assess noise exposure and the risk of hearing damage. The legal action values (80 and 85 dB(A)) and the exposure limit value (87 dB(A)) at work are expressed in dB(A), as an average over an 8-hour working day.

With dB(C), the low tones also count almost fully. This weighting is used for peak noise, the very highest level of a short bang or blow, such as a hammer blow or a gunshot. Separate values apply to peak noise at work. The lower exposure action value is 135 dB(C), the upper one 137 dB(C) and the exposure limit value 140 dB(C). If the difference between dB(C) and dB(A) is large, the noise contains a lot of low tones.

The Designlab is the online tool from Audibling. Step by step you choose material, colour and filter, and you can finish your custom earplugs with a logo print or jewel. You see your design and the price straight away. You get a design code and can save your design as a PDF and take it with you. You use it to have your ear impressions taken at one of our partner hearing centres, where you also pay.

A detectable custom earplug or filter contains material that a metal detector or X-ray scanner can find. If an earplug or a piece of one goes missing during production, detection on the production line can find it before it ends up in a product. That is why detectable versions are mainly used in the food and pharmaceutical industry, often with a strong cord. For food and pharma, Audibling has metal detectable and X-ray visible versions.

The DI series from Dynamic Ear Company was developed for industry and production. These filters give extra protection against high frequencies, where a lot of machine and production noise is. At Audibling they have an SNR of 22 to 26 dB. They suit mechanics, operators and staff in, for example, the food and pharmaceutical industry.

The DIM filter (DIM Impulse) from Dynamic Ear Company is level-dependent. At normal sound levels it lets relatively much sound through, so you can still hear your colleagues and your surroundings well. With sudden loud bangs and blows (impulse noise) the filter attenuates extra. That makes it suitable for sudden bangs, such as in hunting, shooting sports and fireworks, and for heavy industry with loud blows. For construction, the DI filter is the standard. At Audibling the SNR is between 15 and 19 dB.

The DM series from Dynamic Ear Company is made for music and communication. These filters reduce all tones as evenly as possible (flat attenuation), so music and speech sound natural, only quieter. That is why they are popular with musicians, festival-goers, hospitality staff and motorcyclists. At Audibling the SNR is between 10 and 20 dB.

The DR series from Dynamic Ear Company consists of all-round filters for general use, such as sleeping, travel, the office or a busy place. They reduce sound fairly evenly and come in several strengths, with an SNR of 7 to 19 dB. At Audibling the DR filter is included as standard in the price of your custom earplugs.

The ear canal is the channel that runs from the outer ear to the eardrum. In adults it is about 2.5 centimetres long and has an S-shaped bend. That shape is different for everyone, even between your left and right ear. That is why custom earplugs, made from an impression of your ear canal, fit better than a standard earplug.

An ear impression is an exact mould of your outer ear and ear canal and is the basis for all custom earplugs. The hearing care professional first places a small protective plug (otostop) in your ear canal to protect your eardrum, and then injects a soft silicone paste into your ear. After a few minutes it has set and the impression is carefully removed.

The eardrum is a thin membrane at the end of the ear canal, on the border between the outer ear and the middle ear. Sound waves make the eardrum vibrate, and those vibrations are passed on to the inner ear by the small bones of the middle ear. When an ear impression is taken, the eardrum is protected with a small plug (otostop) in the ear canal.

EN 352 is the European series of standards for hearing protectors. Each part covers one type. EN 352-1 covers earmuffs, EN 352-2 earplugs (including custom earplugs), and other parts cover, for example, helmet-mounted earmuffs and level-dependent or electronic versions. The standard sets requirements for construction, materials, comfort and attenuation, among other things, and prescribes which attenuation values, such as SNR and HML, the manufacturer must state.

An ENT doctor (ear, nose and throat specialist) is a medical specialist for the throat, nose and ears. With ongoing ear complaints, such as sudden hearing loss, earache, ringing in the ears or dizziness, your GP can refer you to an ENT doctor. They investigate the cause and discuss any treatment. For an ear impression for hearing protection, you usually go to a hearing care professional.

The exposure limit value is the noise level that must never be exceeded at work. That is a daily exposure of 87 dB(A) or a peak noise of 140 dB(C). Unlike the action values, the attenuation of the hearing protection worn counts here. It is about the sound that actually reaches the ear. If the limit value is exceeded anyway, the employer must take measures immediately.

A fit check tests whether custom earplugs seal the ear canal properly. If there is a gap between the earplug and the ear canal, sound leaks past the filter and the attenuation in practice is lower than on paper. There are different methods, for example with air pressure or by measuring the attenuation in the ear. Especially for use at work, it is sensible to have the fit checked regularly.

The fit is how well an earplug matches the shape of your ear. A good fit is needed for protection. If sound leaks past the earplug, the attenuation drops. The fit also determines comfort, because an earplug that presses or is loose is worn for less time. With custom earplugs, the fit is based on an impression of your ear. Because ears and materials change over the years, they can fit less well over time.

A hearing care professional (audicien) is a specialist in hearing and hearing aids. They do hearing tests, give advice on hearing aids and hearing protection and take ear impressions for custom earplugs. For Audibling custom earplugs, you have your ear impressions taken by one of our partner hearing care professionals. The ear impressions are included in the price and you pay at the hearing centre. With your design code from the Designlab, the hearing care professional knows exactly what you have chosen.

Noise-induced hearing damage occurs when the ear is exposed to loud sound for a long time or repeatedly, or to a single very loud bang. This damages the hair cells in the inner ear, and they do not recover. The damage is permanent. It often starts unnoticed, for example with difficulty following conversations in noisy places or with ringing in the ears. Hearing loss caused by noise at work is a common occupational disease.

Hearing protection is the collective name for products that reduce the sound reaching your ear, such as earmuffs, foam earplugs, universal earplugs and custom earplugs. At work, hearing protection is personal protective equipment (PPE). Under the occupational hygiene strategy, hearing protection only comes into play when the noise cannot be reduced enough at the source or with organisational measures.

Besides the SNR, manufacturers of hearing protection state three separate attenuation values. H stands for noise with a lot of high tones, M for middle tones and L for noise with a lot of low tones. This shows whether a filter reduces all tones evenly (H, M and L are close together) or mainly the high ones. With the HML values you can match hearing protection more precisely to the type of noise, such as the high whine of machines or the low hum of engines.

Hyperacusis is oversensitivity to sound. Everyday sounds such as rattling crockery, a vacuum cleaner or voices feel too loud or even painful. It often occurs together with tinnitus. Hearing protection can be pleasant in loud situations, but with hyperacusis people are often advised not to block their ears all day. If you have complaints, ask your GP (huisarts), an ENT doctor or an audiology centre for advice.

Impulse noise is a very short, powerful sound, such as a gunshot, a hammer blow on metal, a nail gun or fireworks. It lasts only a fraction of a second, but the peak can be so high that a single bang can cause permanent hearing damage. Impulse noise is measured as a peak level in dB(C). For varying noise with loud bangs, a level-dependent filter such as the DIM filter is suitable.

An interchangeable filter can be taken out of the custom earplug and replaced with another one. This lets you use a different level of attenuation with the same fit, or replace a dirty filter. The filters from Dynamic Ear Company in the DR, DM, DI and DIM series have the same dimensions and are therefore interchangeable.

A jewel is a small decorative stone that Audibling can set in custom earplugs, in silver, gold or rose gold. This turns your hearing protection into an accessory you enjoy wearing, at a festival, at a party or simply every day. You choose the jewel when you design your earplugs. For each design you choose either a logo print or a jewel. You choose the filter separately, to suit your situation.

The Audibling logo print is a technique for printing a logo on custom earplugs. Our logo print is patent pending. From 10 pairs this can be your own logo, such as a company logo, club badge or your own design. For smaller numbers we use our standard logo. You supply your own logo as PNG, JPG, SVG or PDF. We make a print-ready version of it and email you a proof. A logo makes earplugs recognisable, so they find their way back to their owner more quickly. It does not change the protection.

A membrane filter reduces sound with a thin membrane in the filter. This lets the tones be reduced more evenly than with a simple channel, so sound is more natural. Audibling works with membrane filters from Dynamic Ear Company. According to the manufacturer, they are made of breathable acoustic materials that keep your ear ventilated.

The occlusion effect is the hollow, booming feeling you get when your ear canal is blocked. Your own voice, chewing and footsteps then sound louder and duller, because the vibrations that travel through your skull stay trapped in the closed ear canal. Ventilation (venting) and well-fitting custom earplugs can reduce this effect.

The outer ear is the visible part of your ear. It catches sound and guides it to the ear canal. Custom earplugs rest in the hollow just in front of the entrance to the ear canal (the concha). That is why they stay in place well and are easy to hold. The shape of the outer ear is also unique for everyone.

Overprotection means that hearing protection blocks more sound than necessary. That sounds safe, but you then hear colleagues, warning signals and your surroundings less well. Many people take their earplugs out now and then because of this, which leaves them unprotected. So match the attenuation to the actual noise level instead of simply choosing the strongest filter.

The European PPE Regulation (EU) 2016/425 divides protective equipment into three categories, according to the seriousness of the risk. Category III is the highest. It covers equipment against risks that can cause very serious or permanent damage to health. Protection against harmful noise is one of them. Such products are assessed by a notified body, which also supervises production. The product then carries a CE marking with the number of that body.

PPE stands for personal protective equipment, in Dutch PBM (persoonlijke beschermingsmiddelen). It is equipment that an employee wears to protect themselves against risks, such as a helmet, safety glasses or hearing protection. Under Dutch occupational health and safety rules, the employer must provide suitable PPE free of charge and explain how to use it correctly. In the European Union, PPE must meet the requirements of the PPE Regulation (EU) 2016/425.

The RI&E (risk inventory and evaluation) is a mandatory inventory of the occupational risks in a company. Every employer with staff in the Netherlands must have an RI&E, with an action plan for the measures. If employees work in noise, the RI&E should describe the noise risks, based on noise measurements where necessary. This shows whether hearing protection is needed and which kind.

With sensory overload, more sensory input comes in than someone can process at that moment, for example in a busy office, at school or on public transport. Sound often plays a big part in this. Many people who are highly sensitive (HSP) or have autism or AD(H)D recognise it, but it can happen to anyone after a busy day. Earplugs with light, flat attenuation make sound quieter without shutting you off completely from your surroundings.

Silicone is a soft, flexible material for custom earplugs. Silicone earplugs feel supple and give a little with small movements of the ear canal, for example when talking or chewing. That is why people who wear their earplugs for long periods often choose them. Hard acrylic is smoother and keeps its shape better. At Audibling, silicone has an extra cost.

SNR stands for Single Number Rating. It is a single number that shows how much a hearing protector attenuates on average across all tones, in dB. The value is determined in a laboratory with measurements on a group of test subjects and is stated in the product specifications. As a rule of thumb, the sound level minus the SNR gives an indication of what reaches your ear. At 95 dB and an SNR of 20 dB you end up at around 75 dB. In practice the attenuation is often somewhat lower, for example because of the fit or because the earplug is not worn all the time.

Speech intelligibility is how well you can understand spoken words. Many sounds in speech, especially consonants such as s, f and t, are in the higher tones. Hearing protection that mainly reduces the high tones therefore makes speech duller and harder to follow. A filter with flat attenuation, such as the DM series, keeps speech more natural. This is useful in places where you need to keep communicating.

A swim plug keeps water out of your ear canal, for example when swimming, showering or doing water sports. Custom swim plugs seal the ear canal completely and therefore usually have no filter. They are used, among others, by people who have been advised by their doctor to keep water out of their ears. A swim plug is meant to keep out water, not as hearing protection against noise.

Tinnitus is hearing sounds that do not come from outside, such as beeping, ringing, hissing or humming. It can be temporary, for example after a concert, or permanent. Exposure to loud sound is a well-known cause, but there are other causes too. Tinnitus is not a disease but a symptom. If you have ongoing ringing in your ears, see your GP (huisarts), who can refer you to an ENT doctor or audiology centre if needed.

In a tube filter, sound passes through a narrow channel (tube) in the earplug. The length and diameter of the channel determine how much is reduced. Tube filters often mainly reduce the high tones, which can make sound a little duller. The alternative is a membrane filter.

Universal earplugs are earplugs in one standard size or a few sizes, such as foam earplugs or plugs with silicone flanges. They are cheap and ready to use, but do not fit everyone equally well. As a result they can start to press, slide out of the ear or reduce less than expected if they are not inserted properly. Custom earplugs, on the other hand, are made for your ear and are reusable.

Venting is ventilation in an earplug, through a small opening or air passage that lets air flow between your ear canal and the outside world. This reduces the blocked, pressing feeling and the occlusion effect, and feels more comfortable during long wear. A large opening also lets more sound through, especially low tones. So the ventilation has to match the attenuation you need. According to the manufacturer, the membrane filters that Audibling uses are breathable themselves and so provide ventilation.

The Working Conditions Decree (Arbobesluit) sets out the Dutch Working Conditions Act (Arbowet) in concrete rules. Chapter 6, section 3 is about noise at work. Among other things it contains the action values of 80 and 85 dB(A), the exposure limit value of 87 dB(A) and the duty to tackle noise at the source first. Hearing protection only comes into play when the noise cannot be reduced enough in another way.