3D Laser Ear Scanning

Project ID: 8479
Principal Investigator: Theresa Gallagher
Research Topic: Public and Employee Safety
Funded Fiscal Years: 2016 and 2017
Keywords: None

Research Question

Is there a statistically significant difference in performance between custom hearing protectors created using the
new 3D laser scanner and whatever traditional hearing protective earplug that is currently used in the workplace?
Is there a difference in Personal Attenuation Ratings (PARs)obtained using two fit-check systems: 3M and NIOSH
HPD Well-Fit?

Need and Benefit

Noise is a pervasive workplace hazard. Engineering or administrative control of high level noise is always the first
line of defense. However, due to technological and/or economic reasons, noise levels cannot always be adequately
controlled, creating situations where individuals must work in areas or perform operations that are loud enough
to cause permanent hearing loss. Despite active and robust hearing conservation programs, occupational hearing
loss remains Reclamation's #1 workman's compensation issue. Over the past 10 years, Reclamation paid
approximately $5M in hearing loss claims. HPDs do not always work as advertised. Three major issues combine to
determine the effectiveness of a HPD—attenuation, comfort, and compliance. Studies have shown repeatedly that
there is a wide variability in the level of attenuation achieved by different individuals using the same device. This
is dependent not only on the physical characteristics of the device, but also by user-driven factors such as
anatomical differences or depth of insertion (in the case of an earplug). Comfort is also key. Deep insertion past
the cartilaginous-bony junction at the second bend of the external auditory canal can result in greater attenuation,
but can result in a plug that can be extremely uncomfortable and even painful for some users (Tufts, et.al, 2013);
thus, the employees do not wear them which results in hearing loss and hearing loss claims. Decreasing canal
girth can improve comfort, but will also result in decreased attenuation. Discomfort is the most common
complaint of earplug users, and the most frequent reason that earplugs are not fitted "correctly" by the user.
Finally, compliance is an issue. An industry adage is "the best earplug is the one the patient will wear." Hearing
protection that remains on the shelf does nobody any good, no matter how sophisticated, expensive, or
appropriate for the environment. A 2005 study by the US Navy showed that not only is usage compliance
poor-47% of those flight deck personnel surveyed indicated that they NEVER wore the required double HPD—but
that even for those who have the equipment and are willing to wear it, there is still a failure of compliance. In fact,
only 7% of those surveyed were inserting foam plugs deeply enough to achieve at least 22dB of attenuation. A new
technology involving a 3-D laser scanner that can be used to create a custom-made earplug may have a positive
impact on all of these issues. 1) Attenuation: Custom-fit hearing protectors have been shown to provide adequate
attenuation with increased comfort, particularly for long periods of use. A custom-fit earplug may result in a
snugger fit, resulting in greater attenuation. In addition, if the laser scanning procedure results in a more accurate
model of an individual's unique ear geometry than the traditional silicone ear-impression method, the resulting
plugs may show greater attenuation, as well decreased variability in terms of level of attenuation achieved
amongst individuals. 2) Comfort: A plug that is custom-fit to an individual's ear may allow a greater insertion
depth while maintaining comfort. The chances of a poorly fit or improperly inserted plug are greatly reduced
when the plug is individually custom-fit. 3) Compliance: Individuals are more likely to wear a plug that feels
comfortable. They are also less likely to remove the device, even for brief time periods. Furthermore, individuals
may be more motivated to use a device that is custom-made for their ears. This saves their hearing and reduces
hearing loss claims; thus- saving Reclamation's most valuable asset - the employees-reducing potential
compensation costs.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Please contact research@usbr.gov about research products related to this project.


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Last Updated: 4/4/17