Techniques and confidence estimates for uncertainty analysis of measuring sound power of power tools.
NOISE-CON 2007: Proceedings of the 2007 National Conference on Noise Control Engineering, Reno, Nevada, October 22-24, 2007. Burroughs C; Hambric S; Conlon S; Maling G; eds., Ames, IA: Institute of Noise Control Engineering of the USA, 2008 Feb; 3:1305-1316
To realistically characterize the noise emissions of powered hand tools as the tool is used in the field, the National Institute for Occupational Safety and Health (NIOSH) began measuring the sound power levels of various powered hand tools in the loaded condition. Testing in the loaded condition can introduce many factors affecting uncertainty of the measurement. Two techniques to reduce uncertainty are to allow the time for the tool to come to full speed before cutting the workpiece and to acquire data only when the tool is cutting the workpiece. Measurements in conformance with ISO 3744 must have a standard deviation less than 1.5 dB. There are additional requirements for labeling in accordance with ISO 7574-1,2, the sound power level is prorated by the measurement expanded uncertainty, resulting in a labeled sound power level that is nominally 3 dB or more greater than the measured sound power level. Since it is desirable to report the labeled sound power level as close to the measured sound power level as possible. It is desirable to minimize the confidence interval of the estimated sound power level. This paper presents techniques to reduce the confidence interval of the measured sound power level for several types of powered hand tools.
Noise-exposure; Noise-induced-hearing-loss; Hearing-loss; Hearing-impairment; Hearing-disorders; Hearing-conservation; Engineering-controls; Control-technology; Power-tools; Sound; Noise-levels
Edward Zechmann, NIOSH Robert A. Taft Building, 4676 Columbia Parkway C-27, Cincinnati, OH 45226
Burroughs-C; Hambric-S; Conlon-S; Maling-G
NOISE-CON 2007: Proceedings of the 2007 National Conference on Noise Control Engineering, Reno, Nevada, October 22-24, 2007