Best Hearing Protectors Ever?

The best protectors are those that are worn (Aram Glorig) [...].

Field Attenuation of Foam Earplugs.

BACKGROUND: Hearing protection devices (HPDs) are often used in the workplace to prevent hearing damage caused by noise. However, a factor that can lead to hearing loss in the workplace is improper HPD fitting, and the previous literature has shown that instructing workers on how to properly insert their HPDs can make a significant difference in the degree of attenuation. METHODS: Two studies were completed on a total of 33 Hydro One workers. A FitCheck Solo field attenuation estimation system was used to measure the personal attenuation rating (PAR) before and after providing one-on-one fitting instructions. In addition, external ear canal diameters were measured, and a questionnaire with items related to frequency of use, confidence, and discomfort was administered. RESULTS: Training led to an improvement in HPD attenuation, particularly for participants with poorer PARs before training. The questionnaire results indicated that much HPD discomfort is caused by heat, humidity, and communication difficulties. External ear canal asymmetry did not appear to significantly influence the measured PAR. CONCLUSION: In accordance with the previous literature, our studies suggest that one-on-one instruction is an effective training method for HPD use. Addressing discomfort issues from heat, humidity, and communication issues could help to improve the use of HPDs in the workplace. Further research into the effects of canal asymmetry on the PAR is needed.

Audiometric Tests without Booths.

Audiometric booths are used to reduce background noise levels at testing locations to below values specified in the standards. As such, they are considered inherent parts of the audiometric testing equipment. This paper presents the results from a literature search of solutions that could ensure that background noise levels are acceptable outside booths. The technology used is especially valuable for survey tests and for locations where booths are unavailable or cannot be used for different reasons. However, its use is recommendable for only screening hearing tests but not for clinical or research applications.

Case Study in a Working Environment Highlighting the Divergence between Noise Intensity and Workers' Perception towards Noise.

Excessive noise levels are a prevalent issue in food processing operations and, although there have been numerous studies on occupational noise, no single study has used a concurrent mixed-methods approach. Employing this study design allows for an understanding of the level of convergence (similarity) between measured noise levels and workers' attitudes and perceptions towards noise. This, in turn, allows for the identification of potential challenges with respect to the implementation of hearing conservation efforts. In this study, spot noise measurements were collected using a sound level meter. One-on-one interviews were conducted with workers to determine attitudes and perceptions towards noise in their workplaces. Subsequently, the results of the noise measurements (quantitative data) were integrated with the survey responses (qualitative data) to identify convergence. The majority of the noise measurements were found to exceed 85 dBA-the criterion mandated by the local occupational health and safety legislation. Although all study participants felt that it was noisy in the workplace, a large proportion of respondents indicated that the noise was not bothersome. With workers' perception being contradictory to the measured noise levels, it is a challenge to implement hearing conservation measures unless changes are made to raise the awareness of the risks associated with excessive noise exposure.

Evaluation of smartphone sound level meter applications as a reliable tool for noise monitoring.

Noise is a constant and ongoing health hazard across many workplaces and industries worldwide. The effective management of noise-related health effects is primarily dependent on accurate measurements of sound levels. The accuracy and feasibility of smartphone sound level meter applications (apps) for noise monitoring in occupational and environmental scenarios was tested. Ten iOS and Android smartphones were used to conduct sound level measurements with five apps for each respective platform. Five different sound signals were utilized to represent the spectra present in an occupational environment, at four different reference sound levels (60, 70, 80, and 90 dBA) for a total of 1,000 tests. A calibrated Larson Davis LxT sound level meter was used as a reference. Results suggest that across all four measured sound levels the difference in smartphone app performance on the two platform is fairly nuanced. However, at the 90dBA sound level Android apps consistently underreport sound levels. This study concludes that some apps have the possibility to be appropriate for use only as screening tools and cannot be used for accurate determination of sound levels.

Noise exposure and hearing loss in classical orchestra musicians: A five-year follow-up.

INTRODUCTION: This study is a follow-up to prior research from our group that attempts to relate noise exposure and hearing thresholds in active performing musicians of the National Ballet of Canada Orchestra. MATERIALS AND METHODS: Exposures obtained in early 2010 were compared to exposures obtained in early 2017 (the present study). In addition, audiometric thresholds obtained in early 2012 were compared to thresholds obtained in early 2017 (the present study). This collection of measurements presents an opportunity to observe the regularities in the patterns of exposure as well as threshold changes that may be expected in active orchestra musicians over a 5-year span. RESULTS: The pattern of noise exposure across instrument groups, which was consistent over the two time points, reveals highest exposures among brass, percussion/basses, and woodwinds. However, the average noise exposure across groups and time was consistently below 85 dBA, which suggests no occupational hazard. These observations were corroborated by audiometric thresholds, which were generally (a) in the normal range and (b) unchanged in the 5-year period between measurements. CONCLUSION: Because exposure levels were consistently below 85 dBA and changes in audiometric thresholds were minimal, we conclude that musicians experienced little-to-no risk of noise-induced hearing loss.

Direct measurements of meltwater runoff on the Greenland ice sheet surface.

Meltwater runoff from the Greenland ice sheet surface influences surface mass balance (SMB), ice dynamics, and global sea level rise, but is estimated with climate models and thus difficult to validate. We present a way to measure ice surface runoff directly, from hourly in situ supraglacial river discharge measurements and simultaneous high-resolution satellite/drone remote sensing of upstream fluvial catchment area. A first 72-h trial for a 63.1-km2 moulin-terminating internally drained catchment (IDC) on Greenland's midelevation (1,207-1,381 m above sea level) ablation zone is compared with melt and runoff simulations from HIRHAM5, MAR3.6, RACMO2.3, MERRA-2, and SEB climate/SMB models. Current models cannot reproduce peak discharges or timing of runoff entering moulins but are improved using synthetic unit hydrograph (SUH) theory. Retroactive SUH applications to two older field studies reproduce their findings, signifying that remotely sensed IDC area, shape, and supraglacial river length are useful for predicting delays in peak runoff delivery to moulins. Applying SUH to HIRHAM5, MAR3.6, and RACMO2.3 gridded melt products for 799 surrounding IDCs suggests their terminal moulins receive lower peak discharges, less diurnal variability, and asynchronous runoff timing relative to climate/SMB model output alone. Conversely, large IDCs produce high moulin discharges, even at high elevations where melt rates are low. During this particular field experiment, models overestimated runoff by +21 to +58%, linked to overestimated surface ablation and possible meltwater retention in bare, porous, low-density ice. Direct measurements of ice surface runoff will improve climate/SMB models, and incorporating remotely sensed IDCs will aid coupling of SMB with ice dynamics and subglacial systems.

Efficient meltwater drainage through supraglacial streams and rivers on the southwest Greenland ice sheet.

Thermally incised meltwater channels that flow each summer across melt-prone surfaces of the Greenland ice sheet have received little direct study. We use high-resolution WorldView-1/2 satellite mapping and in situ measurements to characterize supraglacial water storage, drainage pattern, and discharge across 6,812 km(2) of southwest Greenland in July 2012, after a record melt event. Efficient surface drainage was routed through 523 high-order stream/river channel networks, all of which terminated in moulins before reaching the ice edge. Low surface water storage (3.6 ± 0.9 cm), negligible impoundment by supraglacial lakes or topographic depressions, and high discharge to moulins (2.54-2.81 cm⋅d(-1)) indicate that the surface drainage system conveyed its own storage volume every <2 d to the bed. Moulin discharges mapped inside ∼52% of the source ice watershed for Isortoq, a major proglacial river, totaled ∼41-98% of observed proglacial discharge, highlighting the importance of supraglacial river drainage to true outflow from the ice edge. However, Isortoq discharges tended lower than runoff simulations from the Modèle Atmosphérique Régional (MAR) regional climate model (0.056-0.112 km(3)⋅d(-1) vs. ∼0.103 km(3)⋅d(-1)), and when integrated over the melt season, totaled just 37-75% of MAR, suggesting nontrivial subglacial water storage even in this melt-prone region of the ice sheet. We conclude that (i) the interior surface of the ice sheet can be efficiently drained under optimal conditions, (ii) that digital elevation models alone cannot fully describe supraglacial drainage and its connection to subglacial systems, and (iii) that predicting outflow from climate models alone, without recognition of subglacial processes, may overestimate true meltwater export from the ice sheet to the ocean.

Isotope ratios of H, C, and O in CO2 and H2O of the martian atmosphere.

Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation. We report in situ measurements of the isotopic ratios of D/H and (18)O/(16)O in water and (13)C/(12)C, (18)O/(16)O, (17)O/(16)O, and (13)C(18)O/(12)C(16)O in carbon dioxide, made in the martian atmosphere at Gale Crater from the Curiosity rover using the Sample Analysis at Mars (SAM)'s tunable laser spectrometer (TLS). Comparison between our measurements in the modern atmosphere and those of martian meteorites such as ALH 84001 implies that the martian reservoirs of CO2 and H2O were largely established ~4 billion years ago, but that atmospheric loss or surface interaction may be still ongoing.

Noise exposure of musicians of a ballet orchestra.

With over 70 dancers and its own orchestra, The National Ballet of Canada ranks amongst the world's top dance companies. It performs three seasons annually: fall, winter and summer, plus many shows of Tchaikovsky's Nutcracker. The 70-strong orchestra plays an average of 360 hours/year including rehearsals and performances. Rehearsals are held at two locations: one in a ballet rehearsal room with little or no absorption, and the other in an acoustically treated location. Performances are held in the Four Seasons Centre for the Performing Arts in Toronto. The present survey was done at the request of the National Ballet, since the musicians complained of excessive sound levels and were concerned about possible hearing losses. The survey was performed using five dosimeters Quest Mod 300 during 10 performances of the ballet Romeo and Juliet by Sergei Prokofiev, deemed as the noisiest in the whole repertoire. Results of the survey indicate that the noise exposure levels from only the orchestra's activities do not present risk of hearing loss. Exposure due to other musical activities was, however, not included.

Noise exposure of music teachers.

A noise exposure survey was performed to assess the risk of hearing loss to school music teachers during the course of their activities. Noise exposure of 18 teachers from 15 schools was measured using noise dosimeters. The equivalent continuous noise level (L(eq)) of each teacher was recorded during single activities (classes) as well as for the entire day, and a normalized 8-hour exposure, termed the noise exposure level (L(ex)) was also computed. The measured L(eq) exceeded the 85-dBA limit for 78% of the teachers. L(ex) exceeded 85 dBA for 39% of the teachers. Limited recommendations on how to reduce the noise exposures are provided. The need for a hearing conservation program has also been emphasized.

Development of a new standard laboratory protocol for estimation of the field attenuation of hearing protection devices: sample size necessary to provide acceptable reproducibility.

The mandate of ASA Working Group S12/WG11 has been to develop "laboratory and/or field procedure(s) that yield useful estimates of field performance" of hearing protection devices (HPDs). A real-ear attenuation at threshold procedure was selected, devised, tested for one earmuff and three earplugs via an interlaboratory study involving five laboratories and 147 subjects, and incorporated into a new standard that was approved in 1997 [Royster et al., "Development of a new standard laboratory protocol for estimating the field attenuation of hearing protection devices. Part I. Research of Working Group 11, Accredited Standards Committee S 12, Noise," J. Acoust. Soc. Am. 99, 1506-1526; ANSI, S12.6-1997, "American National Standard method for measuring real-ear attenuation of hearing protectors" (American National Standards Institute, New York, 1997)]. The subject-fit methodology of ANSI S12.6-1997 relies upon listeners who are audiometrically proficient, but inexperienced in the use of HPDs. Whenever a new method is adopted, it is important to know the effects of variability on the power of the measurements. In evaluation of protector noise reduction determined by experimenter-fit, informed-user-fit, and subject-fit methods, interlaboratory reproducibility was found to be best for the subject-fit method. Formulas were derived for determining the minimum detectable difference between attenuation measurements and for determining the number of subjects necessary to achieve a selected level of precision. For a precision of 6 dB, the study found that the minimum number of subjects was 4 for the Bilsom UF-1 earmuff, 10 for the E.A.R Classic earplug, 31 for the Willson EP100 earplug, and 22 for the PlasMed V-51R earplug.