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NORA Manufacturing Sector Strategic Goals

927ZJHNa - Hearing Protector Performance for Impulse Noise

Start Date: 10/1/2009
End Date: 9/30/2013

Principal Investigator (PI)
Name: Amir Khan
Phone: 513-841-4363
Organization: NIOSH
Sub-Unit: DART
Funded By: NIOSH

Primary Goal Addressed

Secondary Goal Addressed


Attributed to Manufacturing


Project Description

Short Summary

This project will develop a laboratory method to measure the impulse noise reduction for hearing-protection devices, will validate of the method through real-world assessment, and will develop an electro-acoustic model impulse noise reduction performance of hearing protection devices. This project will help in the implementation of the standards NIOSH and EPA are currently planning to recommend. This research will validate the new EPA labeling regulations that have been proposed as a revision of the hearing protector labeling regulation. Research findings of this project will be used to develop new acoustic measurement standards and will be used to establish hearing-protection testing methods and recommendations for protection from impulsive noise exposure.


The primary goal of this study is to develop and optimize a method for accurately measuring the performances of a wide range of hearing-protection devices in research laboratories using a mannequin and several different impulse sources. The second objective is to validate the laboratory performances of the hearing-protection devices in real-world settings. The third objective of this study is to develop and design an electro-acoustic model for hearing-protection devices that can be used by manufacturers in developing noise rating reduction for their products in impulse noise exposures.

The study will be executed in three phases as follows: In the first phase of this study the performances of the hearing protectors will be measured at three impulse exposures ranging from 150 to 170dB in at least two different research laboratories. In the second phase of this study the new methodology developed in the first phase will be validated in a wide range of workplaces, which will include manufacturing, construction, and law-enforcement and military environments. In the third phase of this study the performance data collected on a wide range data of hearing-protection devices will be used in the development of an electro-acoustic hearing-protection model. This research effort will be contracted outside NIOSH to a company with extensive experience and resources in working with electro-acoustic system.

The goal of this research is to disseminate the scientific information to the public through presentations in leading national meetings and conferences and also through publications on the efficacy of the new method. NIOSH researchers will also work with the American National Standards Institute (ANSI) and other standards bodies to transfer the methodology developed and refined in this project to establish hearing-protection-testing methods for impulse noise. This project will also help in the implementation of the standards NIOSH and EPA are currently planning to recommend. This research will confirm the new EPA labeling regulations, which will take effect in the near future. A NIOSH technical guidance document on the measurement of hearing-protection effectiveness will be developed and disseminated to occupational safety and health specialists and industrial hygienists who work in this area.


Stakeholders' roles are identified as collaborators and evaluators. Stakeholders from the occupational safety and health community as well as law enforcement and military partners will assist in the evaluation of the new methodology for evaluating the performances of their hearing-protection devices developed by this project. The U.S. military, represented by the U.S. Air Force at Wright-Patterson and the U.S. Army Aeromedical Research Laboratory, has sought NIOSH input into the assessment of exposures of soldiers.

Several technology transfer mechanisms will result from the successful execution of this project. The first involves information dissemination—along with scientific presentations and publications on the efficacy of the new methodology and the hearing-protection model, we will work with the American National Standards Institute and other standards bodies to transfer the technology and the methodology developed and refined in this project to establish hearing-damage-risk criteria for impulse noise. This could take the form of a new ANSI standard or a revision to ANSI S3.44 Occupational Noise Exposure. Additionally, NIOSH will develop an impulse-noise-reduction calculator, which will be submitted for U.S. and international patent protection by the CDC technology transfer office. The technology can be licensed to hearing-protection devices manufacturers. The methodology used to develop the measurement platform and the various metrics will be published and shared with our partners in academia, industry, and the U.S. military. Finally, technology to generate, test and measure the performance of hearing protectors will be shared with microphone manufacturers and testing laboratories.

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