Ear Plugs: A Field Guide

Today's protective options offer a plug for all occasions.

• By Bill Sokol
• Mar 01, 2005

ACCORDING to OSHA 1910.95(b)(1), when harmful workplace noise cannot be controlled by other means, "personal protective equipment shall be provided and used . . . ." This may seem like an easy task, but it's not. With a plethora of product options available and new technologies offering improved capabilities, safety professionals are often at a loss to understand which product is best in which application.

Following is a brief "field guide" to recent product developments that should help ease the selection process. We'll start with ear plugs and then examine ear muffs in the June issue.

There are four categories of ear plugs: single use, which are worn once and then replaced when workers reenter a noise area; multiple use, which can be used repeatedly and cleaned with soap and water; banded ear plugs, which essentially are two foam ear plugs held together by a plastic or metal band; and detectable ear plugs, which can be used in environments where you need to be able to screen for foreign substances in the finished product. These are particularly useful in the food processing, tobacco, and paper industries.

Single-Use Ear Plugs
Single-use, or disposable, ear plugs are the most common type used today. They are popular because of their low cost, ease of use, and high level of comfort. There are different styles, ranging from the 35-year-old yellow PVC barrel ear plugs to the latest contoured polyurethane (PU) foam ear plugs.

PU ear plugs were introduced in the 1980s and have taken over a significant share of the world ear plug market. PU plugs are soft, comfortable, easy to roll down for insertion, and available in a variety of different shapes, sizes, and colors. PU foam is also made in different densities, which means you can get a heavier ear plug that blocks out the maximum amount of noise (NRR 33 is the current max) or a lower density in a smaller shape that exerts less pressure on the ear canal. These are particularly useful for people who wear ear plugs for extended periods of time or have smaller ear canals.

A recent advance in single-use ear plugs is the use of thermoplastic elastomer (TPE) foam. These products are very comfortable and do not require rolling prior to insertion. By using dual foam densities in which a stiffer core is surrounded by a softer, less dense outer layer, these ear plugs can be inserted simply by sliding them into the ear canal.

These new ear plugs also offer improved acoustic performance through uniform attenuation. Simply, these foam materials block sound more evenly across all frequency levels, or octave bands, thereby not only blocking harmful noise but also allowing users to hear other sounds, such as speech and warning signals, more naturally and without the distortion typical of a high-NRR ear plug. For workers who need to communicate on the job or who complain of isolation when wearing hearing protection, TPE foam ear plugs with uniform attenuation offer a new alternative.

Single-use ear plugs are available in corded or uncorded styles. Corded ear plugs are convenient if you have a process that generates noise intermittently--they can be taken out and hung around your neck, then reinserted as needed.

Multiple-Use Ear Plugs
Reusable ear plugs appeal to different types of users and companies. While they are significantly more expensive than disposable foam ear plugs, over time they can actually be more economical. If wearers take proper care and maintain their multiple-use ear plugs, the dollar spent on a pair can go a lot further than the pennies spent on each pair of single-use ear plugs.

Multiple-use ear plugs are typically molded with a semi-rigid stem and pliable flanges, so they don't require rolling prior to insertion. They insert easily and can be quite comfortable for extended periods. Like disposables, most reusable ear plugs used to be made of PVC, which has gotten bad press. It's not a particularly environmentally friendly product, and many of these HPDs end up in a landfill.

Some more forward-thinking manufacturers are now making products out of either PU or TPE materials. These have less environmental impact than PVC, while offering other characteristics that make them more useful in ear plug construction.

One new ear plug is made of a special TPE formulation that actually responds to body heat. As the ear plug warms up to body temperature inside the ear canal, it takes on the shape of the surrounding canal for a more personalized fit. These ear plugs are extremely comfortable for long periods of time, compared to traditionally molded ear plugs that try to return to their original shape, causing pressure when they're in your ear.

Multiple-use ear plugs are typically provided in a corded format, although uncorded styles are also available. Because people tend to use them repeatedly, it's easier to hang them around their necks. One handy new feature is a detachable cord that allows them to be worn corded or uncorded, according to preference or usage.

Detectable Ear Plugs
Detectable ear plugs fill a unique niche in a growing market. These ear plugs are made to be detectable, either visually or by automated means, when a product is screened for final inspection. This is particularly appropriate in food processing, pulp and paper, and tobacco industries, where contamination of the process or the final product is unacceptable or poses a safety risk.

Detectable ear plugs are available in single-use and multiple-use styles and are virtually all corded. Typically, detectable ear plugs involve the introduction of a metal material into their construction that can be located by X-ray machines or magnetometers. Most detectable ear plugs have a small piece of metal attached to the ear plug itself, a ring around the stem of a multiple-use ear plug, or a piece inserted into the end of a single-use ear plug. Some also have a ferrous substance built into the cord, providing additional detectability. In the event the cord is chopped or ground up during the manufacturing process, screeners can still locate every piece. On the bottom end of the spectrum are visually detectable ear plugs. These are typically made blue in color for food processing, as there are not a lot of blue foods and it's easy to spot them floating around in the tomato soup.

Banded Ear Plugs
Another multiple-use option are banded ear plugs--a pair of ear plugs held together by a plastic band. These are useful for people who are in and out of noisy areas. Some people find it difficult to insert a regular ear plug properly, and if they need to go into an area for just two or three minutes, they simply don't want to bother. Ear muffs, on the other hand, are very easy to don and doff but tend to be rather large and bulky. If you're walking around a lot or need to have this device on you at all times, ear muffs may not be the ideal solution.

Banded ear plugs cross this gap. A kind of hybrid between an ear muff and an ear plug, they provide the portability and convenience of ear plugs with the ease of use of ear muffs. The pressure of the band facilitates insertion, and users can just pop them on, walk into a noisy area, and then take them off when they exit. Most can be carried in a pocket or hung around the neck. They are also an alternative in hot temperatures where ear muffs can become uncomfortable.

Selection Tips
The thing you should not do in selecting ear plugs is choose for other people. No two people are alike, and no two ear canals are alike. It's very important that you enlist a group that can test the products in your workplace. People will support your hearing conservation efforts more enthusiastically if they feel they've had a voice in the process. It's best to work with a small group whose opinions you can trust and have them wear different types and styles over a period of time. Ask your hearing protection salesperson for samples your employee group can try.

It is also very important to offer more than one type of protection, particularly with ear plugs because the choice is so broad. At the end of the day, it's the employees who are going to have to wear these products, and if the protection is comfortable and well fitted, chances are greater they will actually wear them.

This article appeared in the March 2005 issue of Occupational Health & Safety.

This article originally appeared in the March 2005 issue of Occupational Health & Safety.