Hosted by the National Institute for Occupational Safety and Health, and sponsored by the Bituminous Coal Operators' Association, the US Mine Safety and Health Administration, the National Mining Association and the United Mine Workers of America, the focus was not only on research already done, but the future of research endeavours and overviews of some field studies conducted all over the nation.

RJ Matetic, chief of NIOSH’s Hearing Loss Prevention Branch, offered an overview of the subject of hearing loss as it related to noise, the very danger miners encounter underground and which through years of exposure can be degenerative.

Noise exposure underground, according to Matetic, is permanent and irreversible. Additionally, as we grow older, our percentage of hearing impairment grows.

Matetic outlined two kinds of hearing loss: conductive and sensori-neural. It is the latter, which often occurs in the inner ear and affects higher frequencies, that is found in mine workers. While this same type of hearing loss is found in ageing individuals, most of the resulting hearing loss is as a result of noise.

He then outlined the features of NIOSH’s Hearing Loss Simulator, released in 2005 by the NIOSH Pittsburgh Research Laboratory (PRL) Hearing Loss Prevention Branch. A software program downloadable to a user’s computer or available in CD-ROM form, the simulator allows the user to hear “with another person’s ear”

The variables of the program, such as age, decibel exposure and gender can all be customised for a particular result. For example, users of the software can hear the effect that 20 years of exposure to noise at 100dB has on a 45-year-old man and see what frequencies that person would no longer be able to hear.

Matetic said he and his colleagues within the branch have heard a lot of comments from workers, especially miners, over the years, such as: “My dad worked at [a company] for 30-something years and I hope I don’t end up like him. You got to scream for him to hear you” and “It’s almost like you’re mad at yourself because why can he hear? He works in the same atmosphere – why can he hear and I can’t?”

It is those feelings of frustration which the researchers want to eliminate for the future of mine workers by preserving their hearing ability.

To help in that effort, Matetic outlined some of the areas where hearing can be most affected through extended exposure, such as high-powered motorised equipment, the process of digging, drilling and striking, and the use of air-powered tools.

He also said that every worker must be aware of their surroundings and when a noise is too loud. “Risk of damage starts at 85dB or higher,” he noted, and said that your risk of hearing loss increases as your exposure time lengthens.

To stay a step ahead of the problem, the department encourages regular hearing tests and reminds workers to watch for the “warning signs” of loss: ringing, a “dull” sound to one’s surroundings and speaking loudly.

Matetic then outlined how operations can institute the “hierarchy of controls”, a three-step process for preventing hearing loss among a workforce at a mine. Each step involves the institution of engineering controls, administrative controls and the use of personal prevention equipment.

First, the noise must be eliminated. Some adjustments to machinery have been made and continue to be made in this area to reduce the decibel level of working machinery underground. Other suggestions include shutting doors, cab seal maintenance, muffler and control maintenance, and the reporting of non-operational controls.

Secondly, stay away from the noise. If a worker is able to relocate to another area where the decibel level is lower, they will benefit. Also, Matetic said, if a noisy task must be done, a worker should try to break up the exposure into smaller time intervals.

Lastly, the team recommends the use of protective equipment. This includes headphones, earplugs and canal caps. He described the process of “roll, pull and hold” for inserting plugs that form to the shape of one’s ear.

Not only should every miner own these items, but they should also learn how to use them by wearing them correctly and learning how to hear through them by practising. “[It is] hard, but easier than listening through damaged ears,” he said.