Document Type


Date of Degree

Spring 2017

Degree Name

MS (Master of Science)

Degree In

Occupational and Environmental Health

First Advisor

Anthony, T Renée

First Committee Member

Nonnenmann, Matthew W

Second Committee Member

Skinstad, Anne


Despite the enactment of hearing protection laws and recommended standards over the last four decades, the prevalence of hearing loss among workers has remained unchanged. Limiting the amount of time spend in high noise areas, as well as wearing hearing protection devices, can reduce the effects of noise on hearing loss. Though research has examined the consistency of use of hearing protection devices (HPD) among workers, the importance of fit, and a real-world comparison to the marketed attenuation needed further examination.

The goal of this project is to evaluate the effectiveness of HPDs used by agricultural and industrial workers enrolled in a hearing conservation program by comparing personal attenuation rating (PAR) to the manufacturer’s reported noise reduction rating (NRR). The two study groups were selected since workplaces are required to train workers enrolled in an OSHA Hearing Conservation Program on proper insertion techniques, but farmers do not typically receive any training on using hearing protection unless they are employed elsewhere. The effectiveness of the inserted HPDs were quantified via the 3M E-A-RfitTM Dual Ear Validation System, and the results were compared to the NRR provided by the manufacturer. The fit of hearing protection was evaluated for 60 farmers (247 plug pairs) and 76 workers (275 plug pairs), using four models of earplugs (two formable and two non-formable). The results show that although formable ear plugs have higher reported NRRs, a higher percentage of participants achieved PARs greater than or equal to the A-weighted adjusted NRR-7 for the non-formable plugs.

Public Abstract

Hearing protection devices (HPD) are encouraged to be worn to reduce exposure to noise sources when elimination and engineering controls are not feasible. However, research on the fit of HPD and the ability of the HPD to achieve attenuation ratings comparable to the manufacturer’s noise reduction ratings (NRR) is limited.

This project examined the fit of HPD on agricultural and industrial workers by quantifying personal attenuation ratings (PAR) for four different types of HPD (two formable and two non-formable) via the 3M E-A-RfitTM Dual Ear Validation System.

The results of this project have found that more participants could achieve PARs greater than or equal to the A-weighted adjusted NRR-7 using non-formable HPD compared to formable HPD.


agricultural workers (farmers), hearing protection devices, industrial workers, Noise


viii, 50 pages


Includes bibliographical references.


Copyright © 2017 Christie De Vito