Semester

Spring

Date of Graduation

2008

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Industrial and Managements Systems Engineering

Committee Chair

Steven Guffey.

Abstract

Noise Reduction Rating (NRR) is a method developed by the Environmental Protection Agency (EPA) to determine the effectiveness of hearing protection devices (HPD). The limitations of NRR values have led to use of other methods, including fit-testing hearing protectors on the individuals who will use them. The fit-testing method used in this study is the Microphone in Real Ear (MIRE) method, which describes how to test earmuffs in a reverberatory chamber. A reverberatory chamber is extremely costly and not likely to be available at work-sites. If fit-testing could be completed in any room instead of in a reverberatory chamber, work-sites could save on the cost of the chamber and may be more likely to fit-test hearing protectors.;In this study, the MIRE method was used. Both Noise Reduction (NR) and Insertion Loss (IL) were determined for nine subjects, both in an ordinary room and in a reverberatory chamber. Subjects were tested while wearing earmuffs and earplugs at different times. Results showed minor deviations in values between the reverberatory chamber and ordinary room when averaged from 125 Hz to 8000 Hz for each given subject and condition. The orientation of subjects affected observed NR and IL by less than 5 dB.

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