pears to be too small for some power tool measurements or to measure certain tools under load. That chamber is not NVLAP-accredited, which would be appropriate for the nature of the work being performed (where outputs would be expected to be used as the basis of third-party product noise declarations and purchase specifications, etc.). The committee has concerns about the conduct of operations at the University of Cincinnati laboratory that extend beyond accreditation, however. Data generated for the purposes of consensus standards, comparison of commercial equipment, or publicly available references for decision making should be carried out according to standardized documented procedures, with a professional level of accuracy and repeatability that can be quantified and guaranteed. It was not clear to the committee that the work met these standards.
Projects to reduce noise on continuous mining machines and noise generated by roof bolting machines using wet and mist drilling are well under way and have generated outputs in the form of new technologies that have been described in trade journals and conference proceedings (e.g., “Noise Controls for Continuous Miners” [Kovalchik et al., 2002]). The necessary next steps to validate these technologies with full-shift noise exposure monitoring (not merely sound emission measurements) under mining conditions in a working mine are very important and highly relevant to the reduction of hearing loss in mines where they might be implemented. Should these technologies qualify as “technically achievable” according to MSHA, they are much more likely to be used, as discussed later in this chapter.
Collection of baseline power tool noise emission measurements is a necessary precursor to any product noise control design project. However, the Hearing Loss Research Program’s current online power tool database is of limited value because of uncertainty in how the measurements were made (the database contains results that were obtained in accordance with a test standard that specifies unloaded conditions for some tools and loaded conditions for others, and the operating conditions are not indicated in the database) and limitations of the laboratory facility and operations where the measurements were acquired. Expert, experienced professionals should carry out this work in an NVLAP-accredited laboratory facility to ensure its quality and credibility.
NIOSH has used small contracts to involve engineering students at five universities in designing acoustical engineering controls to reduce noise from small construction tools (Hayden, 2004). Student research projects are worthwhile and important activities, but they are not a substitute for focused research by experienced professionals, whether on the NIOSH staff, at universities, or in the private