Noise is both a health and safety threat to miners. The main health effect of overexposure to loud noise is permanent hearing loss cause by damage to the sensory cells in the inner ear. Noise is also an indirect safety hazard because it can "mask" important sounds like backup alarms and spoken warnings. These hazards are well known and beyond scientific dispute. Still, noise remains a significant problem in mining. The use of heavy equipment, the drilling of rock and the confined work environment are just a few factors that contribute to high levels of noise exposure in mining. The work in this topic area is supported by the NIOSH Mining Hearing Loss Prevention program. See the NIOSH Mining Products page for software, guides, training materials or other items related to this topic.
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Data & statistics
Noise Exposure and Hearing Conservation in US. Coal Mines - A Surveillance Report (PDF, 1021 KB, 2007)
This study examines the patterns and trends in noise exposure documented in data collected by Mine Safety and Health Administration inspectors at U.S. coal mines from 1987 through 2004.
Measurement & analysis
Analysis of Nonstandard Noise Dosimeter Microphone Positions (PDF, 618 KB, 2008-03)
This study, conducted as part of a project involving the evaluation of a new type of noise exposure monitoring paradigm, showed the dffects of dosimeter microphone placement in a diffuse field were found to be minor for most of the test microphones/locations.
Application of a Microphone Phased Array to Identify Noise Sources on a Horizontal Vibrating Screen (PDF, 2397 KB, 2008)
This paper provides detailed information on the findings of NIOSH research measuring the sound power level generated by a horizontal vibrating screen with the screen either directly on the floor or on rubber isolation pads.
Application of a Microphone Phased Array to Identify Noise Sources on a Roof Bolting Machine (PDF, 3036 KB, 2007)
This paper discusses the methods NIOSH used to identify noise sources on a roof bolting machine while drilling.
Application of Phased Array Technology for Identification of Low Frequency Noise Sources (PDF, 427 KB, 2008)
NIOSH is conducting research to identify and control dominant noise sources in Continuous Miners. The objectives of the work presented in this paper were: 1) To rank the noise radiated by the different sections of the conveyor, and 2) to determine the effect of a urethane-coated tail roller on the noise radiated by the tail-section.
Assessment and Evaluation of Noise Controls on Roof Bolting Equipment and a Method for Predicting Sound Pressure Levels in Underground Coal Mining (PDF, 3609 KB, 2006)
A research program was implemented to: 1) determine, characterize and to measure sound power levels radiated by a roof bolting machine during differing drilling configurations (thrust, rotational speed, penetration rate, etc.) and utilizing differing types of drilling methods in high compressive strength rock media (>20,000 psi); 2) distinguish and correlate the empirical data into one, statistically valid, equation, in which, provided the mining industry with a tool to predict overall sound power levels of a roof bolting machine given any type of drilling configuration and drilling method utilized in industry; 3) provide the mining industry with several approaches to predict or determine sound pressure levels in an underground coal mine utilizing laboratory test results from a roof bolting machine and 4) describe a method for determining an operators' noise dosage of a roof bolting machine utilizing predicted or determined sound pressure levels.
Design and Instrumentation of a Large Reverberation Chamber (PDF, 563 KB, 2003-06)
Documents the refurbishing and instrumentation of the PRL reverberation chamber to bring it up to compliance with the ISO 3743-2 standard for engineering grade measurements for broadband noise.
Estimated Sound Power Radiated by Surfaces on a Continuous Miner Tail Section Using Vibration Measurements (PDF, 1208 KB, 2003-06)
Identifies the most significant noise radiating surfaces on a continuous miner tail section and examines the effects of three engineering noise controls.
Evaluation of Engineering Noise Controls for a Continuous Miner Conveyer System (PDF, 327 KB, 2003-06)
An analysis of extensive noise and urethane durability testing on a Joy 14CM9 continuous miner's conveyor assembly, tail roller, and bottom plate and a discussion of the initial underground testing results for the urethane-coated conveyor flights and tail roller.
Flammability of Noise Abatement Materials Used in Cabs of Mobile Mining Equipment (PDF, 207 KB, 2003)
Describes the flammability tests conducted on 15 to 20 different noise abatement materials of various chemical compositions and thickness.
Heavy Construction Equipment Noise Study Using Dosimetry and Time-Motion Studies (PDF, 1552 KB, 2007-07)
The focus of this research was to determine the noise exposures of heavy construction equipment operators while documenting the workers' tasks, (i.e. hauling, moving, and/or pushing construction material). The types of construction equipment studied included asphalt pavers, backhoes, bulldozers, compaction equipment, excavators, haul trucks, telehandlers, and wheeled loaders.
Heavy Construction Equipment Noise Study Using Dosimetry and Time-Motion Studies (PDF, 65 KB, 2005)
The focus of this research was to determine the noise exposures of heavy construction equipment operators while documenting the workers´ tasks, (i.e. hauling, moving, and/or pushing construction material).
Identification of Noise Sources on Longwall Panels Using Multiple Time-Synchronized Dosimeters (PDF, 501 KB, 2007)
This paper describes research designed to develop guidelines and test procedures for identifying all noise sources that are major contributors to the underground noise exposure of longwall coal mining system workers.
Limestone Mining - Is It Noisy or Not? (PDF, 385 KB, 2006)
Presents the results of noise research conducted in both underground and surface limestone mines, detailing the equipment likely to cause worker overexposures and the occupations experiencing overexposures. Implications for worker noise exposure reduction are also reported.
Lower Respirable Dust and Noise Exposure with an Open Structure Design (PDF, 988 KB, 2006-11)
NIOSH performed an evaluation to determine to what extent building types could impact respirable dust and noise levels. This report discusses the evaluation of three different types of product sizing silica sand structures: a masonry design, a steel-sided design, and an open structure design. The data obtained in this study indicate that the open structure design (no walls) was superior from both a dust and noise (health) standpoint compared to the other two structures.
Measurement Method for Determining Absorption Coefficients for Underground Mines (PDF, 230 KB, 2007-11)
Mine workers are exposed to additional noise levels underground due to the reflection of machine generated noise that would otherwise dissipate in an above ground setting. This paper presents a method using a ray-tracing technique to determine absorption coefficients, for octave bands from 63 Hz to 8 kHz, for underground mines.
A Measurement Method for Determining Absorption Coefficients for Underground Mines (PDF, 162 KB, 2006)
This paper will present a method using a ray-tracing technique to determine absorption coefficients for underground mines. Absorption coefficients are determined and presented for octave bands from 63 Hz to 8 kHz. The absorption coefficients will be essential for determining and predicting potential noise overexposure to machine operators in different mine environments.
Noise Assessment of Stone/Aggregate Mines: Six Case Studies (PDF, 1694 KB, 2007-08)
NIOSH is conducting a cross-sectional survey of equipment sound levels and worker noise exposures in the stone/aggregate mining industry. Six stone/aggregate mines (three surface and three underground) were recently surveyed. The findings identify the equipment and machinery that are likely to cause worker overexposures and the workers found to be experiencing overexposures. In addition, the benefit of cabs in reducing mobile equipmeent operator noise exposure is discussed.
Noise Source Identification on a Continuous Mining Machine (PDF, 759 KB, 2008)
In the Hemi-anechoic chamber of the Pittsburgh Research Laboratory noise source identification on a continuous miner was performed using phased array measurements and a frequency domain beamforming algorithm with Diagonal Removal.
Results of Noise Measurements from Underground Testing of a Roof Bolting Machine Duty Cycle (PDF, 353 KB, 2007)
This paper presents the results of an evaluation of the duty cycle of a typical roof bolting machine operation at two coal mines. The evaluation entails a time motion study of an operators´ shift, logging each activity for time and the noise levels associated with each task. The results provide insight into which portion of the operators´ duty cycle is the most prominent contributor to noise exposure.
Snapshot of Noise and Worker Exposures in Sand and Gravel Operations (PDF, 951 KB, 2008-03)
This paper presents research examining noise on dredges used in several surface mine sand and gravel operations and in the processing facilities.
Sound Power Level Study of a Roof Bolter (PDF, 1717 KB, 2006)
NIOSH initiated a study of a roof bolter to reduce noise exposure to mine roof-bolter operators. An important segment of this research entails determining the affect of various drilling configurations on the performance (penetration rate) and sound power emissions when drilling into granite.This paper details the effects of each of these variables on the performance and sound power level emission. When drilling into granite, it was found that wet drilling generated lower sound power levels and performed better than vacuum drilling.
Sound Restoration Hearing Protection: Genesis of a Standard Test Method (PDF, 75 KB, 2008)
Issues related to testing the performance of sound restoration hearing protectors are outlined within this paper, and possible solutions are discussed.
Survey of Noise in Coal Preparation Plants (PDF, 545 KB, 2007)
Noise surveys were conducted in eight coal preparation plants. The research consisted of worker dose monitoring, task observations, and equipment noise profiling. Results indicate that only workers who routinely spend a significant portion of their shift in the plants (away from the control rooms) are susceptible to overexposure from noise. Certain pieces of equipment (screens, centrifuges, sieve bends) are the loudest primary noise sources responsible for the worker noise exposures.
Engineering controls
An Assessment of Engineering Noise Controls at a Talc Processing Plant (PDF, 800 KB, 2008)
This report describes an investigation by NIOSH researchers to quantify sound levels and to determine the amount of sound reduction provided by engineering noise controls installed in a talc processing plant.
Assessment of Noise Controls Commonly Used on Jumbo Drills and Bolters in Western United States Underground Metal Mines (PDF, 1102 KB, 2005-01)
The noise-control treatments most commonly observed on drills and bolters during this study were evaluated on machines at underground metal mines to determine the amount of noise reduction achieved by each control.
Development and Evaluation of a Urethane Jacketed Tail Roller for Continuous Mining Machines (PDF, 549 KB, 2007)
This paper details the Laboratory noise testing results of a continuous mining machine conveyor system which uses a coating for the tail roller component designed to help bring the continuous mining machine into compliance with federal noise regulations.
Dial Down Dust and Noise Exposure (PDF, 1541 KB, 2007-07)
Although structure type and building material were not viewed as significant factors affecting the health of employees in mineral processing facilities when they were built, NIOSH has found that building type can impact respirable dust and noise levels. NIOSH performed a study in which it evaluated three building types: masonry, an open-structure design, and a steel-sided design.
A Dual Sprocket Chain as a Noise Control for a Continuous Mining Machine (PDF, 371 KB, 2007)
This paper describes a noise control for reducing the noise overexposures of continuous mining machine operators.
In-Cab Noise Reduction on an Air-Rotary Drill Rig (PDF, 3828 KB, 2007-05)
The National Institute for Occupational Safety and Health (NIOSH) has investigated engineering noise controls to reduce sound levels in cabs on air-rotary drill rigs. A recent investigation revealed that some drillers are exposed to A-weighted sound levels exceeding 85 dB even though a cab is used. NIOSH studied the in-cab sound levels of one such rig. Next, field tests were performed in a production environment to evaluate noise controls to reduce in-cab sound levels.
Mining Haul Truck Cab Noise: An Evaluation of Three Acoustical Environments (PDF, 234 KB, 2008)
This study examines the contribution of cab acoustics, operator performance, and maintenance to noise reduction for each of three cab styles.
A Noise Control for A Roof Bolting Machine: Collapsible Drill Steel Enclosure (PDF, 459 KB, 2008)
This paper describes and evaluates an engineering noise control for the roof bolting machine, namely the collapsible drill steel enclosure.
Technology News 527 - The Partial Cab: A New Noise Engineering Control for Surface Drill Rigs (PDF, 1411 KB, 2007-08)
NIOSH, in partnership with stakeholders in the mining and surface drilling industries, conducted research to develop engineering control technologies that reduce workplace noise exposure. The result of this research partnership is the development of a partial cab.
Technology News 531 - Engineering Controls for Reducing Continuous Mining Machine Noise (PDF, 175 KB, 2008-09)
Research conducted by NIOSH, with stakeholder involvement, has focused on producing noise treatments to reduce noise generated by the CMM conveyor system. Two engineering noise controls have been developed: the urethane-coated flight bar chain and the dual-sprocket chain.
Technology News 532 - Collapsible Drill Steel Enclosure for Reducing Roof Bolting Machine Drilling Noise (PDF, 318 KB, 2008-09)
Research conducted by NIOSH has focused on producing noise treatments to reduce noise generated by the Roof Bolting Machine. A drill steel enclosure for reducing roof bolting machine drilling noise has been developed as an engineering control.
Underground Evaluation of Coated Flight Bars for a Continuous Mining Machine (PDF, 371 KB, 2006)
Continuous mining machines rank first among all equipment in underground coal mining whose operators exceed 100% noise dosage. The conveying system is one of the principal noise sources. A highly durable polyurethane coating has been developed for the chain flights to decrease noise generated by these impacts. This paper evaluates the effectiveness of this engineering noise control in reducing the noise exposure of continuous mining machine operators in an underground coal mine environment.
Personal protective equipment
The Effect of an Insertion Lubricant on the Noise Attenuation of Foam Earplugs (PDF, 117 KB, 2008)
This study examines the use of a commercially-available lubricant for hearing aids to determine whether it would facilitate improved fit and attenuation for earplugs.
Equipment
Practical Application of a Partial Cab to Reduce the A-Weighted Sound Level at the Operator's Station on Surface Drill Rigs (PDF, 1191 KB, 2007-12)
This paper discusses the preliminary cab design, the testing of materials for construction of the prototype, and the field test method and results of a collaboration with a local drilling company to design and install a partial cab between the operator and the drill steel in an effort to reduce the sound level at the operator station of a surface drill rig.
Training
Noise Exposure and Overhead Power Line (OPL) Safety Hazards at Surface Drilling Sites (PDF, 2968 KB, 2005-11)
This is a series of 5 separate double sided sheets designed to educate workers about noise exposure and overhead power line safety at surface drilling sites.
Training theory & methodology
An Examination of Antecedents to Coal Miners' Hearing Protection Behaviors: A Test of the Theory of Planned Behavior (PDF, 847 KB, 2008-02)
The motivation behind this investigation was to apply an established theory to better understand three potential antecedents to intentions toward wearing hearing protection among coal miners.
Laboratories
Anechoic Chamber
Provides a reflection free environment for acoustic testing.
Information gateways
MSHA noise information (http://www.msha.gov/1999noise/noise.htm)
Health Standards for Occupational Noise Exposure Noise and Hearing Loss Prevention
NIOSH topic page on Noise and Hearing Loss Prevention OSHA noise and hearing conservation (http://www.osha.gov/SLTC/noisehearingconservation/)
Safety and Health Topics - An OSHA Cooperative Program - Noise and Hearing Conservation
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