Despite years of regulation, hours of training and billions of dispensed ear plugs, the incidence of noiseinduced hearing loss (NIHL) in the workplace continues to rise worldwide.
In the European Union, NIHL is the most commonly reported occupational injury.
Determining if a worker is achieving real-world attenuation for their noise environment is therefore critical to the success of an occupational hearing conservation program.
The value of fit testing became evident in a field attenuation study conducted by the Howard Leight
Acoustical Laboratories (USA) on the performance of hearing protection devices. Conducted on over 100 workers at eight different facilities, the study showed that one-third of workers achieved attenuation higher than the published attenuation for their ear plugs, and that another third achieved attenuation within 5dB of the published rating. But the lowest one-third of workers had attenuation that was more than 5dB below published attenuation.
The study then interviewed the workers who obtained high attenuation values to determine the common factors that contribute to good earplug fit, and hence good attenuation in use. Only one factor was found to be a consistent predictor of good fit: one-on-one training. That is, the more often a worker had received individual training in the proper use of hearing protectors, the higher the probability of a good fit.
The same was not true for group training, such as watching annual training videos or passing out brochures.
The researchers highlight the importance of fit testing as a critical element of one-on-one employee
Additionally they point out that fit testing is an invaluable tool in reducing compensation claims for NIHL at the workplace. Fit testing records can help document that effective steps were taken to select appropriate hearing protectors, train workers in their proper use and to document a proper fit with a particular protection.