Method for measurement of insertion loss of ear-muff type hearing protectors (simplified method for quality inspection purposes)

1990 ◽  
2011 ◽  
Vol 129 (4) ◽  
pp. 2651-2651
Author(s):  
William J. Murphy ◽  
Gregory A. Flamme ◽  
Amir Khan ◽  
Joseph Echt ◽  
Belinda C. Johnson

Author(s):  
Daniel W. Mauney

A field-implementable measure is needed to estimate the attenuation workers achieve with their hearing protectors in the field. Manufacturer-supplied values overestimate in-field attenuation and reliance on these values could result in greater noise exposure, thus contributing to hearing loss. Alternative measures for assessing a hearing protector's effectiveness were evaluated through comparison to the standardized real-ear attenuation at threshold (1/3-REAT) method (ANSI S3.19-1974). These measures, termed microphone in real ear (MIRE), used miniature microphones underneath and outside of the hearing protector to physically measure the attenuation of the protector using both insertion loss (IL-MIRE) and noise reduction (NR-MIRE) techniques. Results indicate that the MIRE measures differ significantly from the 1/3-REAT method (a psychophysical technique) for attenuation collapsed across protectors, with absolute differences as great as 6.6 dB and the direction of the difference changing due to frequency. At 125 Hz, the MIRE metrics yielded lower attenuation, while from 500 to 8000 Hz, the 1/3-REAT method generally yielded lower attenuation. These differences may be due in part to the occlusion effect and the bone conduction of sound. The size and consistency of these differences across HPDs suggest that these measures hold promise for providing quick and relatively accurate estimations of an HPD's attenuation in the field.


2012 ◽  
Vol 131 (4) ◽  
pp. 3532-3532
Author(s):  
Richard McKinley ◽  
Hilary Gallagher ◽  
William Murphy

Author(s):  
K. Yoshida ◽  
F. Murata ◽  
S. Ohno ◽  
T. Nagata

IntroductionSeveral methods of mounting emulsion for radioautography at the electron microscopic level have been reported. From the viewpoint of quantitative radioautography, however, there are many critical problems in the procedure to produce radioautographs. For example, it is necessary to apply and develop emulsions in several experimental groups under an identical condition. Moreover, it is necessary to treat a lot of grids at the same time in the dark room for statistical analysis. Since the complicated process and technical difficulties in these procedures are inadequate to conduct a quantitative analysis of many radioautographs at once, many factors may bring about unexpected results. In order to improve these complicated procedures, a simplified dropping method for mass production of radioautographs under an identical condition was previously reported. However, this procedure was not completely satisfactory from the viewpoint of emulsion homogeneity. This paper reports another improved procedure employing wire loops.


Author(s):  
Yeshayahu Talmon

To bring out details in the fractured surface of a frozen sample in the freeze fracture/freeze-etch technique,the sample or part of it is warmed to enhance water sublimation.One way to do this is to raise the temperature of the entire sample to about -100°C to -90°C. In this case sublimation rates can be calculated by using plots such as Fig.1 (Talmon and Thomas),or by simplified formulae such as that given by Menold and Liittge. To achieve higher rates of sublimation without heating the entire sample a radiative heater can be used (Echlin et al.). In the present paper a simplified method for the calculation of the rates of sublimation under a constant heat flux F [W/m2] at the surface of the sample from a heater placed directly above the sample is described.


2005 ◽  
Vol 173 (4S) ◽  
pp. 140-141
Author(s):  
Mariana Lima ◽  
Celso D. Ramos ◽  
Sérgio Q. Brunetto ◽  
Marcelo Lopes de Lima ◽  
Carla R.M. Sansana ◽  
...  

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