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INTERNATIONAL JOURNAL OF OCCUPATIONAL SAFETY AND ERGONOMICS
Volume 15 Number 2, 2009
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CONTENTS:
Articles:
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Hearing Protectors: Topicality and Research Needs
Pierre Canetto
Occupational noise specialists do not generally recommend hearing protection devices (HPDs) as a preferred solution to noise risk prevention. Nevertheless, these devices are widely used and are in fact often necessary. Selection of an HPD should take into account comfort and the capacity for perceiving external signals, when they are worn. Current European regulations require that HPD attenuation be considered, when comparing noise exposure to limit values. However, HPD attenuation is effectively unknown under real-world conditions. Some methods are designed to give approximate attenuation values and these provide results within a wide statistical range. Field measurement methods and current standards have been developed to deal with this situation. The specific characteristic of impulse noise requires establishment of dedicated criteria and tools for HPD selection and testing. This paper introduces a number of avenues for research, which could be of assistance in improving HPD selection, qualification and design.
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Evaluation of the Increased Accident Risk From Workplace Noise
Esko Toppila, Ilmari Pyykkö, Rauno Pääkkönen
Directive 2003/10/EC sets the requirement for evaluating the effect of noise on accident risk. Accident risk is elevated for workers with a hearing handicap because of their reduced speech intelligibility and reduced capability to perceive the direction of incoming sound. An audiogram is not a good method for the evaluation of these functions. To reduce accident risk, organisational and personal solutions are needed. For both methods, efficiency must be evaluated through proper risk assessment. Because practical guidelines are not available, this paper presents principles for accident risk evaluation techniques.
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German Criteria for Selection of Hearing Protectors in the Interest of Good Signal Audibility
Martin Liedtke
The German transport and personal protective equipment (PPE) technical committees of the German Social Accident Insurance have laid down criteria, which have since become established, for hearing protectors to be used in railway systems and road traffic in Germany: only hearing protectors which do not significantly impair the audibility of auditory warning signals may be used. In addition, the Institute for Occupational Safety and Health of the German Social Accident Insurance (BGIA) has proposed a simple criterion for the selection of hearing protectors for workplaces outside railway systems and road traffic which perform well with regard to signal audibility (general), speech intelligibility, and perception of informative operating sound (AIP). This criterion is based upon the research carried out in the field of signal audibility in railway systems and road traffic and upon an additional study. It has been established by the German PPE technical committee and is presented here.
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Is It Reasonable to Expect Individuals to Wear Hearing Protectors for Extended Periods?
Warwick Williams
The purpose of this work is to look at the expectations and actions that exist around the use of hearing protectors. Are our expectations for the performance of hearing protectors rational and is the way we expect them to be used reasonable? Perhaps we are expecting too much of hearing protectors and their ability to effectively reduce noise exposure. Better understanding of expectations and requirements along with improvements in technology and design offer the opportunity to markedly improve on the current situation.
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Assessing Differences in Methodologies for Effective Noise Exposure Calculation
Pedro M. Arezes, Joel Geraldes
The aim of the present study was to analyse the adequacy of hearing protection devices (HPDs) by applying and comparing different methods for the estimation of effective exposure levels. This comparison involved the attenuation data of 50 HPDs (ear muffs and ear plugs), as well as 11 types of noise spectra and 4 methods. The application of the several methods considered and the comparison of the obtained estimations seem to demonstrate that there are significant differences between effective exposure levels estimated with the different methods analysed.
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Measurement of Effective Noise Exposure of Workers Wearing Ear-Muffs
Ewa Kotarbińska, Emil Kozłowski
This paper presents the methodology and the results of binaural measurements of exposure to noise for 91 industry workers wearing ear-muffs. The results revealed that 18.7% of the workers were exposed to noise of equivalent A-weighted sound pressure levels of over 80 dB(A) and 7.7% to levels of over 85 dB(A). The measured levels were compared with those calculated with the octave-band method according to Standard No. EN 458:2004. The differences ranged from – 3 dB(A) to 26.5 dB(A); their statistical distribution did not indicate any data which could suggest derating laboratory measurements. The main causes of exposure to noise higher by over 3 dB(A) than that theoretically predicted were the bad technical condition of ear-muffs (32.2% of the cases) and an incorrect way of wearing them (15.2%).
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An Educated Guess on the Workplace Attenuation Variability of Ear Muffs
Paolo Lenzuni
The attenuation variability of hearing protector devices plays a primary role in determining compliance, or lack of, with occupational noise exposure limits. This study presents an estimate of the ear muff attenuation variability, which includes several factors (biological diversity, positioning, sound field, ageing) for which specific information from laboratory studies is available. A mean value of the attenuation variability for ear muffs σFR = 4.8 dB is found. This value is about 65% larger than the typical value measured according to existing test standards. Being marginally smaller than the mean variability resulting from field measurements, and certainly within the wide range of fluctuations of the latter, it represents a robust and reliable quantity for application in any workplace environment.
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Individual Fit Testing of Hearing Protection Devices
Jérémie Voix, Lee D. Hager
While hearing protection devices (HPD) have been the last and often only line of defense against noiseinduced hearing loss in the workplace, their performance has been suspect. Laboratory evaluations have not proven to predict the actual performance of HPD in the field. Individual fit testing of HPD will allow the determination of HPD performance on individual workers, and this will improve the ability to select HPD appropriate for given noise exposures and intervene with workers to ensure sufficiency in HPD performance. A modified microphone in-real-ear (F-MIRE) has been adapted to test a variety of HPD quickly and reliably in situ. A dual-element microphone and software combination permits reliable noise reduction measurements Statistically developed compensation factors permit direct comparison of F-MIRE predicted personal attenuation ratings to traditional laboratory measures of HPD performance using real-ear-attenuation-atthreshold assessments.
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Hearing Protectors “Real-World” Performance and the European Directive 2003/10/EC
Pierre Canetto, Jérémie Voix
Reviewed by Elliott H. Berger, Jean Jacques and Martin Liedtke
Performance of Different Types of Hearing Protectors Undergoing High-Level Impulse Noise
Karl Buck
The paper describes the problems that may occur when hearing protectors, usually designed for industrial noise environments, are used for high-level impulse (weapon) noise. The military impulse noise environment is described, as are the different types of passive and active hearing protectors and the measurement procedures. The different mechanisms that may alter the effectiveness of the hearing protectors as well as their global efficiency when submitted to high-level impulse noise are presented. The paper also discusses how the performance values accessible to the user may be used in different damage risk criteria for continuous and impulse noise.
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