Individual Fit Testing of Hearing Protection Devices

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-at-threshold assessments

Le misanthrope / Molière, aut. ; Jean-Louis Barrault (Alceste), Madeleine Renaud (Célimène), Pierre Bertin (Oronte), Jean Desailly (Philinte)... [et al.], voix

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Power capacity from earcanal dynamic motion

In-ear devices, such as a hearing aids, electronic earplugs, and wearables, need electrical power to operate. Batteries are the current solution, but unfortunately they also create other problems. For example, several hundred million users, mostly elderly, must change their hearing aid batteries on a weekly basis, which represents not only significant financial costs but a negative environmental impact. A promising alternative involves harvesting energy by converting the dynamic jaw movements into electrical energy via the earcanal. The extent that jaw movements distort the earcanal is still unknown, making it difficult to design the appropriate energy harvesting system for the earplug. Moreover, the finite element methods are barely capable to model the behavior of the earcanal distortion because of the complexity of mechanisms that deform the earcanal. However, this paper presents an alternative method, based on analytical considerations, to understand in-ear mechanical quasi-static deformations using earcanal point clouds. This model quantifies the bending and compressive movements of the earcanal. It can therefore be used to select an appropriate deformation mode for harvesting energy from the earcanal’s dynamic motion. The value of this approach was illustrated by calculating the obtainable mechanical energy from 12 human subjects. On average, the bending energy in a human earcanal was found to be three times greater than the radial compression energy. This key finding will need to be considered in the design of future in-ear energy harvesting devices. Such an energy harvesting device has the potential to revolutionize the market for in-ear wearable devices and hearing aids by complementing or replacing battery technology

Development and validation of a field microphone-in-real-ear approach for measuring hearing protector attenuation

Numerous studies have shown that the reliability of using laboratory measurements to predict individual or even group hearing protector attenuation for occupationally exposed workers is quite poor. This makes it difficult to properly assign hearing protectors when one wishes to closely match attenuation to actual exposure. An alternative is the use of field-measurement methods, a number of which have been proposed and are beginning to be implemented. We examine one of those methods, namely the field microphone-in-real-ear (F-MIRE) approach in which a dual-element microphone probe is used to measure noise reduction by quickly sampling the difference in noise levels outside and under an earplug, with appropriate adjustments to predict real-ear attenuation at threshold (REAT). We report on experiments that validate the ability of one commercially available F-MIRE device to predict the REAT of an earplug fitted identically for two tests. Results are reported on a representative roll-down foam earplug, stemmed-style pod plug, and pre-molded earplug, demonstrating that the 95% confidence level of the Personal Attenuation Rating (PAR) as a function of the number of fits varies from ±4.4 dB to ±6.3 dB, depending on the plug type, which can be reduced to ±3.1 dB to ±4.5 dB with a single repeat measurement. The added measurement improves precision substantially. However, the largest portion of the error is due to the user′s fitting variability and not the uncertainty of the measurement system. Further we evaluated the inherent uncertainty of F-MIRE vs. the putative "gold standard" REAT procedures finding, that F-MIRE measurement uncertainty is less than one-half that of REAT at most test frequencies. An American National Standards Institute (ANSI) working group (S12/WG11) is currently involved in developing methods similar to those in this paper so that procedures for evaluating and reporting uncertainty on all types of field attenuation measurement systems can be standardized. We conclude that the hearing conservationist now has available a portable, convenient, quick, and easy-to-use system that can improve training and motivation of employees, assign hearing protection devices based on noise exposures, and address other management and compliance issues

JOHANN STRAUSS - Sa vie - Sa musique / Texte de Jeannine DAUBANNAY ; sur des extraits musicaux de Josef STRAUSS et de Johann STRAUSS ; Pierre GARIN (le Récitant) et P. PERRIN - N. HUSSENOT - J.P. CONSTANT - H. VIRLOJEUX - H. POIRIER - J. BERGER

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