PURPOSE:  To document and evaluate noise control technologies that are used in or applicable to the mining and construction industries and then expand this base of information to other industries. Also, to understand the noise generating mechanisms to aid in the development of new noise control technology.

RESEARCH SUMMARY:  Noise induced hearing loss is the most common occupational illness in the United States today, with over 30 million workers exposed to excessive noise levels. Engineering control of noise is the long-term solution to the nation’s occupational hearing loss problem. However, in the mining industry the application of engineered noise controls has been fraught with problems. An important enabling step for the application of existing control technology, or the development of new technology, is the identification of existing controls and their effectiveness.

The measurement of engineering noise control effectiveness is done by acquiring acoustic data with and without the control in place. The measured acoustic parameters include sound pressure level, sound intensity level, and percent noise dose. If a control cannot be removed from an application, an effort is made to find a machine of similar make, model, and age without the treatment in place. In addition to being used to evaluate the effectiveness of an engineering noise control, sound intensity measurements are applicable for noise source location. Once the primary noise sources are identified, engineering controls can be more effectively implemented.

Over the course of this study it was learned that many mine operators install noise controls without knowing how much noise reduction to expect from a control before installation, or how much noise reduction is actually achieved after the control is installed. Also, it was found that in some cases acoustical materials were improperly used. As a result of this research, increased emphasis has been placed on the installation of proven noise controls as opposed to the ‘try this, try that’ approach to noise control that was common in the past.

The majority of the outputs for this project has and will be numerous reports, presentations, and publications documenting the effective and ineffective noise controls on existing mining equipment. The ultimate outcome of this research is to educate mine operators and equipment manufacturers on not only which engineering noise controls are successful, but a basic understanding in noise control techniques which will aid them in developing their own application of controls for their future noise reduction efforts.