Published in the May 2005 American Longwall Magazine

“Health issues like hearing loss are becoming more prominent now that the fatality rate has come way down in mining, so other quality of life issues are becoming more important,” said NIOSH’s audiology team leader Robert F Randolph.

The program has been distributed in CD-ROM form to various interest groups including educators, audiologists and trainers. Randolph remarked that many of his more than 200 requests so far for the program have come from referrals from the National Hearing Conservation Association.

A self-contained program that runs in Windows, the hearing loss simulator gives the user a first-hand experience of what hearing loss he will have in a specified amount of time and decibel level. The program can also incorporate pre-recorded background noises such as construction equipment into the effect, making the result even more realistic.

A 55-year-old male with no noise exposure, for example, would experience only age-related hearing loss measures on the simulator. That same individual’s years of exposure and decibel level can then be adjusted to show the consequences of noise exposure over periods of time in different scenarios.

The long-term effects for miners, in particular, are significant, something that NIOSH hopes the simulator will help increase awareness of in the industry. “Noise becomes more hazardous as it exceeds about 85 decibels,” said Randolph.

“A typical worker who is exposed to a noise at 95 decibels (dB) over an eight-hour day will probably develop a hearing loss over time. After working 25 years at that level of noise, their hearing will be significantly worse, especially around 4000Hz. This effect looks like a dip in the noise-exposed person’s hearing test graph, and is commonly called the noise notch.”

For safety, Randolph continued, NIOSH recommends limiting exposure times in excess of 85dB over eight hours. For noise levels above 85dB, it recommends cutting exposure time for every additional three decibels – four hours at 88dB, two hours at 91dB, and so forth. The simulator illustrates an individual’s hearing loss as a result of exposure exceeding those recommendations, and can be tailored for many different scenarios.

In addition to age, years of exposure and level of background noise, the simulator can be adjusted for both male and female workers. The program’s standard is based on substantial population studies, which = found females to be slightly less susceptible to hearing loss in general and experience loss in a slightly different span of frequencies to males.

Randolph noted, however, that higher frequencies are the most disturbing for both genders. “Low frequency hearing loss does happen, but it tends to be caused by mechanical issues when you damage the eardrum and middle ear,” Randolph said. “Noise and aging have an effect on the higher frequencies.”

The foundation for the project was awareness, Randolph said, a hope that miners and other individuals exposed to noise regularly would take the necessary steps to protect themselves before actual impairment.

“By helping them visualize life in 20, 30 years, when they can’t understand people as well, where it’s embarrassing to be in social situations, when they can’t enjoy their music as much, we hope it will motivate a change in behavior now.”

The free software will be released on the NIOSH web site (www.cdc.gov/ niosh/homepage.html) in the near future; in the meantime, Randolph is accepting requests via e-mail at rgr4@cdc.gov.