Volume 4, Issue 2 (Journal of Ergonomics 2016)                   Iran J Ergon 2016, 4(2): 17-25 | Back to browse issues page

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Biabani A, Aliabadi M, Golmohammadi R. Study of Noise Reduction Rate of Hearing Protection Devices Based on Microphone in Real Ear (MIRE) Under Laboratory Conditions. Iran J Ergon. 2016; 4 (2) :17-25
URL: http://journal.iehfs.ir/article-1-258-en.html
Department of Occupational Hygiene, Faculty of public health and Center for Health Sciences Researches, Hamadan University of Medical Sciences, Hamadan, Iran , Mohsen.aliabadi@umsha.ac.ir
Abstract:   (10073 Views)

Introduction: Nominal noise reduction rate of the earmuff manufacturers can be different compared with the actual attenuation rate. The present study aimed to determine the actual noise reduction rate of common hearing protection devices using microphone in real ear method.

Materials and Methods: In this study, five brands of common earmuffs used in Iranian industries were investigated on 30 subjects under laboratory conditions. Noise reduction rates of earmuffs were measured based on the ISO 11904 standard, microphone in real ear method, using noise dosimeter (SVANTEK, SV 102 model) equipped with a microphone SV 25 model. The earmuffs comfort was also assessed by the developed questionnaire.

Results: The results showed that the real noise reduction rates of the earmuffs were between 49% to 86% of nominal reduction rates. Moreover, the actual insertion losses were much negligible at low noise frequencies. The performances of earmuffs based on manufacturers were not statistically different (Pv> 0.05). Based on subjects’ comfort scores, comfort of ear muffs were within the acceptable range. The noise reduction rates of the different earmuffs of each model were not statistically different as well (Pv > 0.05).

Conclusions: Irregular use of earmuff can reduce the real attenuation of earmuff to lower than the minimum rate acquired in this study. Proper training and adequate supervision on proper use of earmuff can affect earmuff fitting along with increasing of real noise attenuation.

Full-Text [PDF 498 kb]   (11865 Downloads)    
Type of Study: Research | Subject: Special
Received: 2016/01/12 | Accepted: 2016/09/18 | ePublished: 2016/10/6

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