Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-14 (of 14 Records) |
Query Trace: Byrne DC[original query] |
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The Wildland Firefighter Exposure and Health Effect (WFFEHE) Study: Rationale, design, and methods of a repeated-measures study
Navarro KM , Butler CR , Fent K , Toennis C , Sammons D , Ramirez-Cardenas A , Clark KA , Byrne DC , Graydon PS , Hale CR , Wilkinson AF , Smith DL , Alexander-Scott MC , Pinkerton LE , Eisenberg J , Domitrovich JW . Ann Work Expo Health 2021 66 (6) 714-727 The wildland firefighter exposure and health effect (WFFEHE) study was a 2-year repeated-measures study to investigate occupational exposures and acute and subacute health effects among wildland firefighters. This manuscript describes the study rationale, design, methods, limitations, challenges, and lessons learned. The WFFEHE cohort included fire personnel ages 18-57 from six federal wildland firefighting crews in Colorado and Idaho during the 2018 and 2019 fire seasons. All wildland firefighters employed by the recruited crews were invited to participate in the study at preseason and postseason study intervals. In 2019, one of the crews also participated in a 3-day midseason study interval where workplace exposures and pre/postshift measurements were collected while at a wildland fire incident. Study components assessed cardiovascular health, pulmonary function and inflammation, kidney function, workplace exposures, and noise-induced hearing loss. Measurements included self-reported risk factors and symptoms collected through questionnaires; serum and urine biomarkers of exposure, effect, and inflammation; pulmonary function; platelet function and arterial stiffness; and audiometric testing. Throughout the study, 154 wildland firefighters participated in at least one study interval, while 144 participated in two or more study interval. This study was completed by the Centers for Disease Control and Prevention's National Institute for Occupational Safety and Health through a collaborative effort with the U.S. Department of Agriculture Forest Service, Department of the Interior National Park Service, and Skidmore College. Conducting research in the wildfire environment came with many challenges including collecting study data with study participants with changing work schedules and conducting study protocols safely and operating laboratory equipment in remote field locations. Forthcoming WFFEHE study results will contribute to the scientific evidence regarding occupational risk factors and exposures that can impact wildland firefighter health over a season and across two wildland fire seasons. This research is anticipated to lead to the development of preventive measures and policies aimed at reducing risk for wildland firefighters and aid in identifying future research needs for the wildland fire community. |
Population-based age adjustment tables for use in occupational hearing conservation programs
Flamme GA , Deiters KK , Stephenson MR , Themann CL , Murphy WJ , Byrne DC , Goldfarb DG , Zeig-Owens R , Hall C , Prezant DJ , Cone JE . Int J Audiol 2019 59 1-11 Objective: In occupational hearing conservation programmes, age adjustments may be used to subtract expected age effects. Adjustments used in the U.S. came from a small dataset and overlooked important demographic factors, ages, and stimulus frequencies. The present study derived a set of population-based age adjustment tables and validated them using a database of exposed workers.Design: Cross-sectional population-based study and retrospective longitudinal cohort study for validation.Study sample: Data from the U.S. National Health and Nutrition Examination Survey (unweighted n = 9937) were used to produce these tables. Male firefighters and emergency medical service workers (76,195 audiograms) were used for validation.Results: Cross-sectional trends implied less change with age than assumed in current U.S. regulations. Different trends were observed among people identifying with non-Hispanic Black race/ethnicity. Four age adjustment tables (age range: 18-85) were developed (women or men; non-Hispanic Black or other race/ethnicity). Validation outcomes showed that the population-based tables matched median longitudinal changes in hearing sensitivity well.Conclusions: These population-based tables provide a suitable replacement for those implemented in current U.S. regulations. These tables address a broader range of worker ages, account for differences in hearing sensitivity across race/ethnicity categories, and have been validated for men using longitudinal data. |
Inter-laboratory comparison of three earplug fit-test systems
Byrne DC , Murphy WJ , Krieg EF , Ghent RM , Michael KL , Stefanson EW , Ahroon WA . J Occup Environ Hyg 2016 14 (4) 294-305 The National Institute for Occupational Safety and Health (NIOSH) sponsored tests of three earplug fit-test systems (NIOSH HPD Well-Fit, Michael & Associates FitCheck, and Honeywell Safety Products VeriPRO(R)). Each system was compared to laboratory-based real-ear attenuation at threshold (REAT) measurements in a sound field according to ANSI/ASA S12.6-2008 at the NIOSH, Honeywell Safety Products, and Michael & Associates testing laboratories. An identical study was conducted independently at the U.S. Army Aeromedical Research Laboratory (USAARL), which provided their data for inclusion in this report. The Howard Leight Airsoft premolded earplug was tested with twenty subjects at each of the four participating laboratories. The occluded fit of the earplug was maintained during testing with a soundfield-based laboratory REAT system as well as all three headphone-based fit-test systems. The Michael & Associates lab had highest average A-weighted attenuations and smallest standard deviations. The NIOSH lab had the lowest average attenuations and the largest standard deviations. Differences in octave-band attenuations between each fit-test system and the American National Standards Institute (ANSI) sound field method were calculated (Attenfit-test - AttenANSI). A-weighted attenuations measured with FitCheck and HPD Well-Fit systems demonstrated approximately +/-2 dB agreement with the ANSI sound field method, but A-weighted attenuations measured with the VeriPRO system underestimated the ANSI laboratory attenuations. For each of the fit-test systems, the average A-weighted attenuation across the four laboratories was not significantly greater than the average of the ANSI sound field method. Standard deviations for residual attenuation differences were about +/-2 dB for FitCheck and HPD Well-Fit compared to +/-4 dB for VeriPRO. Individual labs exhibited a range of agreement from less than a dB to as much as 9.4 dB difference with ANSI and REAT estimates. Factors such as the experience of study participants and test administrators, and the fit-test psychometric tasks are suggested as possible contributors to the observed results. |
Comment on "Concerns with amplitude variation in calibrated audiometer systems in clinical simulations"
Byrne DC , Themann CL , Stephenson MR . Noise Health 2015 17 (76) 172 Barlow and colleagues addressed the important question of variation in pure-tone audiometric thresholds within and across audiometers in their article entitled “Concerns with Amplitude Variation in Calibrated Audiometer Systems in Clinical Simulations.”[1] We agree that the reliability of thresholds obtained across test systems and individuals is a vital concern when monitoring hearing health. However, we believe that a few important details are missing, which limits the validity of this study. | The authors reported, “Each of the audiometers had recently undergone certified traceable calibration by its recommended laboratory, meaning that the tone presentation from each should theoretically be identical” [page 300]. Ideally, this would be the case; however, it is not necessarily true. An audiometer is considered “in calibration” when its output is within a certain tolerance range. The International Electrotechnical Commission (IEC) 60645-1 standard allows a deviation of ± 3.7 dB from the indicated value at test frequencies from 125 Hz through 4000 Hz, and ±6.2 dB up to and including 8000 Hz. This means, for example, that an audiometer set to generate a 50-dB HL tone at 6000 Hz could produce anywhere from 43.8 dB HL to 56.2 dB HL and be considered “in calibration.” In some cases, the ±3.7 dB calibration tolerance (i.e., 7.4 dB range) at frequencies below 6000 Hz is close to the range of variation reported for the audiometers in this study. Without verifying that all four audiometers actually produced identical outputs, the measured differences cannot be assumed to be solely due to earphone placement. (Note: The allowable deviation according to American National Standards Institute (ANSI) standard S3.6 is ±3 dB at test frequencies from 125 Hz through 5000 Hz, and ± 5 dB at 6000 Hz and higher.) |
Scientific rigor required for a re-examination of exchange rate for occupational noise measurements Re: Dobie, R.A., & Clark, W.W. (2014) Exchange rates for intermittent and fluctuating occupational noise: a systematic review of studies of human permanent threshold shift, Ear Hear, 35, 86-96
Morata TC , Themann CL , Byrne DC , Davis RR , Murphy WJ , Stephenson MR . Ear Hear 2015 36 (4) 488-91 Dobie and Clark’s recent article “Exchange rates for intermittent and fluctuating occupational noise: A systematic review of studies of human permanent threshold shift” aimed to compare the suitability of a 3-dB versus 5-dB exchange rate (ER) in predicting hearing loss from non-impulsive intermittent or fluctuating noise exposures by reviewing studies of human noise-induced permanent threshold shift. The authors concluded that 3-dB ER systematically overestimates the risk of noise-induced hearing loss for intermittent or fluctuating noise. We contend that the authors did not arrive at their conclusions through an appropriate investigation. The article used flawed methodologies in the treatment and analysis of the data/studies and drew conclusions that were not substantiated by the cited data. | The authors indicated that their review did not aim to make recommendations for regulation of occupational noise, but suggested that their review provided evidence for a re-examination of recommendations in their concluding remarks. The National Institute for Occupational Safety and Health (NIOSH) maintains its recommendation of the 3-dB ER to provide sufficient protection for the many variations of continuous, intermittent and fluctuating noise exposure scenarios encountered in the workplace. In view of the advances in noise measurement and the studies’ other weaknesses, we question the suitability of revisiting a narrow segment of the human evidence (excluding robust animal studies and temporary threshold shift studies) based on outdated methodologies to address such an important issue. |
Early prognosis of noise-induced hearing loss: prioritising prevention over prediction
Themann CL , Byrne DC , Davis RR , Morata TC , Murphy WJ , Stephenson MR . Occup Environ Med 2014 72 (2) 83-4 Moshammer and colleagues (1) have recommended routine implementation of a temporary threshold shift (TTS) screening test to identify workers particularly at risk of developing noise-induced hearing loss (NIHL) from occupational exposure to hazardous noise. Their work addresses an important occupational health problem. NIHL ranks among the most common work-related injuries in many countries, with an estimated global annual incidence of 1.6 million cases and accounting for approximately 16% of disabling adult hearing losses worldwide (2,3). Individuals vary in their susceptibility to the damaging effects of noise and no suitable method currently exists to predict the susceptibility of a particular worker. | In their study, Moshammer et al. measured TTS in newly-hired employees following exposure to a 20-minute, high intensity, low frequency experimental noise. They then followed the workers over time to see who ultimately developed a permanent threshold shift (PTS). The authors report that a TTS of 14 dB or more measured 2.5 minutes after the experimental exposure identifies workers at greater risk for PTS. They recommend routinely using this procedure to screen for susceptibility to noise in workplace hearing loss prevention programs. | However, this recommendation is premature in view of the study results. The TTS measure had a sensitivity of 82%, meaning that 18% of those who developed PTS were not identified by the TTS screening – a high false negative rate, particularly as we already know how to prevent PTS through reduction of noise exposures and consistent use of properly-fit hearing protection. Specificity was 70% at best, corresponding to a false positive rate 30%. If this procedure were implemented, approximately a third of the workers would be told that they are particularly at risk for NIHL when they aren’t, raising unnecessary alarm and opening the door to potential discrimination in work assignments, promotions, etc. |
Noise impacts from professional dog grooming forced-air dryers
Scheifele PM , Johnson MT , Byrne DC , Clark JG , Vandlik A , Kretschmer LW , Sonstrom KE . Noise Health 2012 14 (60) 224-6 This study was designed to measure the sound output of four commonly used brands of forced-air dryers used by dog groomers in the United States. Many dog groomers have questions about the effect of this exposure on their hearing, as well as on the hearing of the dogs that are being groomed. Readings taken from each dryer at 1 meter (the likely distance of the dryer from the groomer and the dog) showed average levels ranging from 105.5 to 108.3 dB SPL or 94.8 to 108.0 dBA. Using the 90 dBA criterion required by the US Occupational Safety and Health Administration, dog groomers/bathers are at risk if exposure to the lowest intensity dryer (94.8 dBA) exceeds 4 hours per day. If the more stringent 85 dBA criterion and 3 dB tradeoff is applied, less than one hour of exposure is permissible in an 8 hour day. Cautions are recommended for any persons exposed to noise from forced-air dryers. |
Promoting hearing loss prevention in audiology practice
Byrne DC , Themann CL , Meinke DK , Morata TC , Stephenson MR . Perspect Pub Health Iss Rel Hear Bal 2012 13 (1) 3-19 An audiologist should be the principal provider and advocate for all hearing loss prevention activities. Many audiologists equate hearing loss prevention with industrial audiology and occupational hearing conservation programs. However, an audiologist's involvement in hearing loss prevention should not be confined to that one particular practice setting. In addition to supervising occupational programs, audiologists are uniquely qualified to raise awareness of hearing risks, organize public health campaigns, promote healthy hearing, implement intervention programs, and monitor outcomes. For example, clinical audiologists can show clients how to use inexpensive sound level meters, noise dosimeters, or phone apps to measure noise levels, and recommend appropriate hearing protection. Audiologists should identify community events that may involve hazardous exposures and propose strategies to minimize risks to hearing. Audiologists can help shape the knowledge, beliefs, motivations, attitudes, and behaviors of individuals toward self-protection. An audiologist has the education, tools, opportunity, and strategic position to facilitate or promote hearing loss surveillance and prevention services and activities. This article highlights real-world examples of the various roles and substantial contributions audiologists can make toward hearing loss prevention goals. |
Comparison of speech intelligibility measures for an electronic amplifying earmuff and an identical passive attenuation device
Byrne DC , Palmer CV . Audiol Res 2012 2 (1) 17-24 The purpose of this study was to identify any differences between speech intelligibility measures obtained with MineEars electronic earmuffs (ProEars, Westcliffe, CO, USA) and the Bilsom model 847 (Sperian Hearing Protection, San Diego, CA, USA), which is a conventional passive-attenuation earmuff. These two devices are closely related, since the MineEars device consisted of a Bilsom 847 earmuff with the addition of electronic amplification circuits. Intelligibility scores were obtained by conducting listening tests with 15 normalhearing human subject volunteers wearing the earmuffs. The primary research objective was to determine whether speech understanding differs between the passive earmuffs and the electronic earmuffs (with the volume control set at three different positions) in a background of 90 dB(A) continuous noise. As expected, results showed that speech intelligibility increased with higher speech-to-noise ratios; however, the electronic earmuff with the volume control set at full-on performed worse than when it was set to off or the lowest on setting. This finding suggests that the maximum volume control setting for these electronic earmuffs may not provide any benefits in terms of increased speech intelligibility in the background noise condition that was tested. Other volume control settings would need to be evaluated for their ability to produce higher speech intelligibility scores. Additionally, since an extensive electro-acoustic evaluation of the electronic earmuff was not performed as a part of this study, the exact cause of the reduced intelligibility scores at full volume remains unknown. | |
Acceptance of a semi-custom hearing protector by manufacturing workers
Davis RR , Murphy WJ , Byrne DC , Shaw PB . J Occup Environ Hyg 2011 8 (12) D125-30 Workers complain about wearing hearing protection for two primary reasons: comfort and communication.(1) Employers are concerned about hearing protection costs. Recent advances in hearing protector technology seemed to address those issues through a semi-custom earplug. This new device was designed to prevent overprotection by incorporating only enough attenuation to bring the worker down into the safe exposure zone. Although initially more expensive than disposable hearing protection devices (HPDs), the semi-custom hearing protector would be expected to last several years. | The Hearing Loss Prevention Team of the National Institute for Occupational Safety and Health (NIOSH) was invited by a major auto manufacturing company and the union (UAW) to supervise a longitudinal trial of a semi-custom hearing protector (SonoCustom by Sonomax Technologies, Inc.,Montreal, Canada). This protectorwas advertised as (1) being more comfortable since each plug was custom molded for each worker, and (2) more effective because each plug’s noise reduction rating was tuned to that worker’s particular job. The company’s hearing conservation contractor partnered with NIOSH by recruiting volunteers for the study and providing follow-up usage reports. The study was conducted over the course of 1 year with NIOSH site visits at the start, at 1 month, at 4 months, and at 1-year time intervals. The goal of this trial was to determine worker acceptance of the semi-custom earplug. | Compared with the non-custom earplugs used in this study, the SonoCustom ear plugs were relatively new to the market and have not been extensively investigated in the literature. Initial studies have focused on a new way to measure and model the acoustical performance.(2–4) Wagoner et al.(5) studied speech intelligibility and attenuation while subjects wore the SonoCustom earplugs or two other non-custom, commercially available hearing protectors in laboratory tests and in the field. In the laboratory they were not able to find any statistically significant difference, between the three earplugs, for speech intelligibility or attenuation. Regarding comfort issues, they briefly mentioned that the two non-custom HPDs were judged by the workers to be more comfortable and easier to use than the SonoCustom earplug. |
Comparison of the HPDLab and REATMaster software/hardware systems for ANSI S12.6 testing
Byrne DC , Perry CC , Murphy WJ . J Acoust Soc Am 2011 130 (4) 2434 The American National Standard Methods for Measuring the Real-Ear Attenuation of Hearing Protectors (ANSI S12.6-2008) requires a Bekesy procedure for testing occluded and unoccluded thresholds. Since 2002, the National Institute for Occupational Safety and Health (NIOSH) has used the custom-designed HPDLab software operating Tucker-Davis Technologies System 3 hardware. ViAcoustics, Nelson Acoustics, NASA, and NIOSH researchers recently developed REATMaster which runs on National Instruments hardware in the LabVIEW environment. Ten subjects were trained by the experimenter on how to fit a passive earmuff and were qualified according to the requirements of ANSI S12.6-2008. The laboratory was configured such that diffuse sound field thresholds were tested with either the HPDLab or REATmaster hardware by flipping a toggle switch. The earmuff was not touched or re-positioned between test trials with the two different hardware/software systems. The test sequence for the order of open and occluded measurements was counterbalanced across occluded conditions and hardware system. Results from this testing were used to validate the REATMaster system for its ability to produce accurate threshold data. Preliminary results indicate no significant differences between the two systems. |
Measuring, rating, and comparing the real ear attenuation at threshold of four earplugs
Murphy WJ , Stephenson MR , Byrne DC . J Acoust Soc Am 2011 130 (4) 2435 The effect of training instruction, whether presented as the manufacturer's printed instructions, a short video training session, specific to the product, or as a one-on-one training session, was evaluated using four hearing protection devices with eight groups of subjects. The Howard Leight Fusion and Airsoft premolded earplugs and the Moldex PuraFit and EAR Classic foam earplugs were tested. Naive subjects were recruited and tested using three different forms of training: written, video, and individual training. The differences between group averages for A-weighted attenuation were not statistically significant when compared between the video or the written instruction conditions, regardless of presentation order. The experimenter- trained A-weighted attenuations were significantly greater than the written and video instruction for most of the protectors and groups. For each earplug, the noise reduction statistic for A-weighting (NRSA) and the associated confidence intervals were calculated for the 90th and 10th percentiles of protection. Across subject groups for each protector, the differences between NRSA ratings were found to be not statistically significant. Several comparisons evaluating the order of testing, the type of testing, and statistical tests of the performance across the groups are presented. [Portions of this work were supported by the U.S. EPA Interagency Agreement DW75921973-01-0.]. |
Effects of training on hearing protector attenuation
Murphy WJ , Stephenson MR , Byrne DC , Witt B , Duran J . Noise Health 2011 13 (51) 132-41 The effect of training instruction, whether presented as the manufacturer's printed instructions, a short video training session specific to the product, or as a one-on-one training session was evaluated using four hearing protection devices with eight groups of subjects. Naive subjects were recruited and tested using three different forms of training: written, video, and individual training. The group averages for A-weighted attenuation were not statistically significant when compared between the video or the written instruction conditions, regardless of presentation order. The experimenter-trained A-weighted attenuations were significantly greater than the written and video instruction for most of the protectors and groups. For each earplug, the noise reduction statistic for A-weighting (NRS A ) and the associated confidence intervals were calculated for the 80 th and 20 th percentiles of protection. Across subject groups for each protector, the differences between NRS A ratings were found to be not statistically significant. Several comparisons evaluating the order of testing, the type of testing, and statistical tests of the performance across the groups are presented. |
Relationship between comfort and attenuation measurements for two types of earplugs
Byrne DC , Davis RR , Shaw PB , Specht BM , Holland AN . Noise Health 2011 13 (51) 86-92 Noise-induced hearing loss is almost always preventable if properly fitted hearing protectors are worn to reduce exposure. Many individuals choose not to wear hearing protection because it may interfere with effective communication in the workplace or it may be uncomfortable. Hearing protector comfort has not received the same amount of attention as noise reduction capability. The present study was conducted to evaluate the comfort level of two different types of insert earplugs as well as the attenuation levels achieved by the earplugs. Attenuation levels were obtained with a commercially available earplug fit-test system, and the comfort ratings were obtained by questionnaire. The primary research objective was to determine whether hearing protector comfort was related to measured attenuation values. A linear mixed effects model provided evidence for an inverse relationship between comfort and attenuation. |
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