Hearing Protection Technologies for the Future

Self-fitting technology will enhance communication and eventually incorporate intelligent filtering that will adapt to your noise environment.

• By Anthony Di Giovanni, Nick Laperle
• Sep 01, 2013

Hearing loss continues to be among the top preventable occupationally related illnesses. Hearing loss is often neglected because it progresses slowly with age and is typically self-diagnosed as "normal." But for the most part, hearing loss is noise induced, and we have the technology to prevent it.

Workers today are exposed to much higher levels of noise than ever before. While we would like to believe that improvements to equipment have made the work environment quieter, it is not significant enough to show a decrease in hearing loss. Thanks to computers and sensors, we have more machinery in less square footage and we do more, faster. Demographics, technology, and economic conditions have combined to leave workers in at their jobs for much longer careers. Added to this is the fact that workers at home or leisure expose their ears to other sources of loud noise, such as recreational machines, tools, and personal entertainment devices.

Protecting your hearing is more in focus today than it was 30 years ago. However, when we look at the technology advancement, we see that there have not been quantum leap developments. Workers continue to use what has been around for the last few decades and in most cases, despite massive training efforts, continue to misuse the products.

Ear Plugs and Muffs: Challenges for End Users
Foam plugs, the most commonly used hearing protection product, are available in more types today than 20 years ago. However, most variations are related to preference. Softer plugs are more comfortable yet harder to insert consistently and correctly. If you consider how many times workers will pull out plugs in a day, it is not difficult to extrapolate that a significant number are not reinserted correctly. How many variations in plug exposure at the ear do we see when we walk into a plant? Some have them inserted so deeply that they are hardly visible. Others are barely hanging on.

Much of this is not a function of insertion capability or dexterity. It is usually a function of ear canal size. We all know that our ear canals are uniquely distinctive -- pretty much like fingerprints. Inserting plugs can be challenging when people have smaller ear canals. The same constraints exist when we consider the shape of the ear canal. Oval-shaped canals are less compatible with ridged, tree-shaped plugs.

When considering all variations of product and ear shapes, it takes plug technology from a simple-looking item to a hyper-complex dynamic. And even if one finds the best technology suited to the shape the ear canal, there is still the issue of over-protecting. When a plug fits too snugly and deeply, the attenuation may be too much and may hamper him or her from hearing warning signals and rolling equipment.

Foam ear plugs are convenient. They are disposable and therefore innately hygienic, and they have a low profile so that they minimally interfere with worker movements. Foam plugs also serve a purpose for third-party workers or visitors. They are relatively inexpensive, easy to dispense, and do provide a level of hearing protection. The expectation is that improvements in materials and design will ameliorate user operability and therefore, likely, the performance. Another traditional technology that has withstood the test of effectiveness is the ear muff style hearing protector. An over-the-ear style is much more adaptable to the individual user and can offer consistent attenuation. The major issue with muffs has always been related to bulkiness or heat. In long-term wear they can become uncomfortable. Improvements over the years have been related to lighter-weight materials, sound insulation, and the incorporation of communication equipment.

Custom-molded ear plugs are very popular in Europe but much less so in the Americas. This technology has been around for more than 30 years and has become better, but for the most part it still requires a technician to fit them. The traditional process involves the insertion of a corded damming pad, followed by the filling of the ear canal with a fluid putty material to take an impression. This impression is sent to a lab that will make a mold and shape your personal ear plugs. The technology produces plugs that fit one’s ears perfectly and thus attenuate closely to what is required. The drawback with this technology is that it is expensive and requires a lengthy procurement process. Over the years, others have developed putty materials that take shape within the ear. While this seems to be an obvious answer, not many people are willing to push putty-like material into their ears and expect consistent attenuation.

The Future is Bright
More than 10 years ago, a group of medical researchers set out to find an alternative technology that grabbed the best of all worlds. They knew that for anything to be effective it had to shape to the individual’s ear canal. It had to be easy to insert and remove. Most of all, it had to provide consistent attenuation at the optimal safe zone.

They knew that it was not about the highest NRR; it was about getting a personal attenuation rating that put the worker in the safe zone. And to make matters even more challenging for them, they required that the product effectiveness be verifiable with an interior/exterior microphone. This meant that sound would be induced on the outside and premeasured on the inside for a true differential that would be known as a PAR (Personal Attenuation Rating).

The patented technology they developed consisted of filling a canal-shaped, hypoallergenic silicone bladder with a fluid silicone and having it instantly set within the ear for a perfect shape. The first iterations of this product required a technician to carefully fill the bladder. While the process was painless, quick, and rendered an excellent ear plug, it was difficult to scale on a mass level and expensive when compared to foam.

Three years ago, this technology was pushed further with the development of a self-fit system whereby the technician is eliminated. The unfilled ear plug bladders are bought pre-docked onto a headband that contains two silicone-filled side cartridges. All the worker does is put on the headband and fit the bladders snuggly onto the ears. He then presses a button on each side, releasing the silicone fluid into each bladder and expanding them to the exact shape of the ear canal. Instantly the worker has personal ear plugs that are shaped to the ear canal and offer optimized noise attenuation. Different filters-faceplates can be put on to achieve the precise attenuation level that allows the filtering out of dangerous noise but maintains conversation and allows the worker to hear warning signals.

While this seems to be the future of hearing protection, it is only the beginning. This self-fitting technology will incorporate more than just passive filters. It will enhance communication and eventually incorporate intelligent filtering that will adapt to your noise environment.

This article originally appeared in the September 2013 issue of Occupational Health & Safety.