RESUMEN
Workers rely on hearing protection devices to prevent occupational noise-induced hearing loss. This study aimed to evaluate changes in attenuation over time for properly fit devices when worn by workers exposed to hazardous noise. Earplug fit testing was accomplished on 30 workers at a brewery facility with three types of foam and three types of premolded earplugs. The personal attenuation ratings (PARs) were measured before and after a 2-hour work period while exposed to hazardous noise levels. The minimum acceptable initial PAR was 15 dB. Average decreases in PAR ranged from -0.7 to -2.6 dB across all six earplug types. Significant changes in PAR were observed for the Foam-1 ( p = 0.009) and Premold-3 ( p = 0.004) earplugs. A linear mixed regression model using HPD type and study year as fixed effects and subject as random effect was not significant for either fixed effect ( α = 0.05). Ninety-five percent of the final PAR measurements maintained the target attenuation of 15 dB. Properly fitting earplugs can be effective at reducing worker's noise exposures over time. The potential for a decrease in attenuation during the work shift should be considered when training workers and establishing the adequacy of protection from hazardous noise exposures.
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Ambient noise in the test environment will impact signal detection during hearing threshold measurements due to psychoacoustic masking effects. Technical standards specify the maximum permissible ambient noise levels (MPANLs) for use during audiometric testing. MPANLs are dependent on several factors, including transducer characteristics (supra-aural, circumaural, type of ear cushions or earphone enclosures, and insert earphones), the nature of the hearing test being performed (air conduction vs bone conduction and threshold test vs screen at a suprathreshold level), and measurement instrumentation. The nature of the ambient noise (spectrum and constant vs variable) at the test site must be determined and continually accounted for during the boothless hearing test procedure. Ambient noise monitoring procedures are reviewed and examples of ambient noise characteristics in real-world settings, where hearing testing might be performed outside of a sound-treated environment, are provided. Practical considerations are presented, including examples of available tools for ambient noise monitoring, selection of test locations, and transducer attenuation. These are discussed in the context of calculating MPANLs and how best to ensure that ambient noise levels are not negatively impacting the validity of hearing thresholds.
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Audiometría , Ruido , Umbral Auditivo , Ruido/efectos adversos , Audiometría/métodos , Sonido , Audición , Audiometría de Tonos PurosRESUMEN
OBJECTIVE: Distortion product otoacoustic emission (DPOAE) mapping characterises cochlear function, can include both the 2f1-2f2 and 2f2-2f1 DPOAEs, and shows promise for tracking cochlear changes. DPOAE amplitude measurements are not as repeatable longitudinally as pure-tone audiometry, likely due in part to probe placement sensitivity. We hypothesised that DPOAE level map variation over multiple testing sessions could be minimised by replacing traditional rubber tips with custom-moulded probe tips. DESIGN: Traditional rubber tips (TRT) and custom-moulded probes tips (CMPT) were used to measure DPOAE level maps repeatedly over five sessions. Probe placement was assessed using a frequency sweep in the ear canal. Repeatability of the DPOAE level maps was assessed using a Bland-Altman analysis. Overall map repeatability was assessed by measuring differences in distortion product amplitude over sessions. STUDY SAMPLE: Crossover study with a convenience sample size of six adults. RESULTS: The CMPT frequency sweeps showed reduced variability in probe placement. The repeatability coefficient for individual DPOAEs measurements improved from 6.9 dB SPL with the TRT to 5.1 dB SPL with the CMPT. Map repeatability improved for most subjects with the CMPT.
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Cóclea , Emisiones Otoacústicas Espontáneas , Estimulación Acústica , Adulto , Audiometría de Tonos Puros , Estudios Cruzados , Cultura , HumanosRESUMEN
Objective: To describe personal noise exposure measurements obtained on Guatemala sugar cane mill workers as a function of job category.Design: This is a descriptive evaluation of existing data.Sample: The data set included 51 representative noise dosimetry surveys utilising NIOSH sampling protocol, completed on workers performing 21 jobs in a Guatemalan sugar cane mill. Results: Noise doses ranged from a low of 50.9% to an extreme of 25174%. The highest observed mean noise doses were for evaporator cleaners (15761%) and juice extractors (2047%). Ninety percent of noise dosimetry samples were between 50% to 1200% dose. Annual noise exposures are also reported after considering the 7-month seasonal work schedule.Conclusions: The majority of sugar cane mill workers were exposed to hazardous occupational noise exceeding the Guatemalan permissible exposure limit (GMLSW), which is consistent with U.S. NIOSH recommended exposure limit of 100% noise dose (85 dBA time-weighted average). Consequently, the majority of workers should be enrolled in a hearing conservation programme including engineering noise control in order to prevent long-term adverse effects on workers' hearing.
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Agricultura , Monitoreo del Ambiente/estadística & datos numéricos , Ruido en el Ambiente de Trabajo/estadística & datos numéricos , Exposición Profesional/análisis , Adulto , Productos Agrícolas , Femenino , Guatemala , Pérdida Auditiva Provocada por Ruido/etiología , Humanos , Masculino , Concentración Máxima Admisible , Persona de Mediana Edad , Ruido en el Ambiente de Trabajo/efectos adversos , Enfermedades Profesionales/etiología , Exposición Profesional/efectos adversos , Saccharum , Adulto JovenRESUMEN
To determine if conventional audiometry, EHFA, and pDPOAEs are useful as early indicators of cochlear damage from recreational firearm impulse noise exposure in youth firearm users. Quantitative cross-sectional descriptive pilot study. Descriptive statistics and MANOVA with post hoc Tukey Honestly Significant Difference test were used to compare pDPOAEs (1-10 kHz), conventional audiometry (0.25-8 kHz), and EHFA (10-16 kHz) in YFUs. 25 YFUs (n = 11 7-12 years; n = 14 13-17 years) with self-reported poor compliance with hearing protector device wear. Conventional audiometric thresholds at 2-, 3- and 4 kHz were significantly poorer than normal but did not distinguish between older and younger YFUs or between the GBE and the contralateral ear. EHFA thresholds at 14- and 16 kHz were significantly poorer than for other frequencies, and differentiate between older and younger youths, but do not distinguish the GBE from the contralateral ear. Finally, pDPOAE levels were significantly reduced at 8- and 10 kHz but did not show any differences for the younger versus older YFUs or for the GBE from the contralateral ear. Conclusion: Both EHFA and pDPOAEs provide early evidence of NIHL in YFUs, and may be useful for the early detection of NIHL in YFUs.
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Audiometría/estadística & datos numéricos , Exposición a Riesgos Ambientales/análisis , Armas de Fuego , Pérdida Auditiva Provocada por Ruido/diagnóstico , Ruido/efectos adversos , Adolescente , Audiometría/métodos , Niño , Cóclea/fisiopatología , Estudios Transversales , Diagnóstico Precoz , Femenino , Humanos , Masculino , Proyectos Piloto , Reproducibilidad de los ResultadosRESUMEN
Globally, one in three adults has some level of measurable hearing loss, and 1.1 billion young persons are at risk for hearing loss attributable to noise exposure. Although noisy occupations such as construction, mining, and manufacturing are primary causes of hearing loss in adults, nonoccupational noise also can damage hearing. Loud noises can cause permanent hearing loss through metabolic exhaustion or mechanical destruction of the sensory cells within the cochlea. Some of the sounds of daily life, including those made by lawn mowers, recreational vehicles, power tools, and music, might play a role in the decline in hearing health. Hearing loss as a disability largely depends on a person's communication needs and how hearing loss affects the ability to function in a job. The loss of critical middle and high frequencies can significantly impair communication in hearing-critical jobs (e.g., law enforcement and air traffic control).
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Promoción de la Salud/organización & administración , Pérdida Auditiva Provocada por Ruido/prevención & control , Adulto , Anciano , Centers for Disease Control and Prevention, U.S. , Femenino , Salud Global/estadística & datos numéricos , Pérdida Auditiva Provocada por Ruido/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Ruido en el Ambiente de Trabajo/efectos adversos , Enfermedades Profesionales/epidemiología , Enfermedades Profesionales/prevención & control , Estados Unidos/epidemiología , Adulto JovenRESUMEN
OBJECTIVE: This research assessed the reduction of peak levels, equivalent energy and sound power of firearm suppressors. DESIGN: The first study evaluated the effect of three suppressors at four microphone positions around four firearms. The second study assessed the suppressor-related reduction of sound power with a 3 m hemispherical microphone array for two firearms. RESULTS: The suppressors reduced exposures at the ear between 17 and 24 dB peak sound pressure level and reduced the 8 h equivalent A-weighted energy between 9 and 21 dB depending upon the firearm and ammunition. Noise reductions observed for the instructor's position about a metre behind the shooter were between 20 and 28 dB peak sound pressure level and between 11 and 26 dB LAeq,8h. Firearm suppressors reduced the measured sound power levels between 2 and 23 dB. Sound power reductions were greater for the low-velocity ammunition than for the same firearms fired with high-velocity ammunition due to the effect of N-waves produced by a supersonic bullet. CONCLUSIONS: Firearm suppressors may reduce noise exposure, and the cumulative exposures of suppressed firearms can still present a significant hearing risk. Therefore, firearm users should always wear hearing protection whenever target shooting or hunting.
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Armas de Fuego , Pérdida Auditiva Provocada por Ruido/prevención & control , Ruido/prevención & control , Exposición Profesional/prevención & control , Salud Laboral , Acústica/instrumentación , Amplificadores Electrónicos , Umbral Auditivo , Dispositivos de Protección de los Oídos , Audición , Pérdida Auditiva Provocada por Ruido/etiología , Pérdida Auditiva Provocada por Ruido/fisiopatología , Pérdida Auditiva Provocada por Ruido/psicología , Humanos , Movimiento (Física) , Ruido/efectos adversos , Exposición Profesional/efectos adversos , Presión , Factores Protectores , Medición de Riesgo , Factores de RiesgoRESUMEN
In the United States and other parts of the world, recreational firearm shooting is a popular sport that puts the hearing of the shooter at risk. Peak sound pressure levels (SPLs) from firearms range from â¼140 to 175 dB. The majority of recreational firearms (excluding small-caliber 0.17 and 0.22 rifles and air rifles) generate between 150 and 165 dB peak SPLs. High-intensity impulse sounds will permanently damage delicate cochlear structures, and thus individuals who shoot firearms are at a higher risk of bilateral, high-frequency, noise-induced hearing loss (NIHL) than peer groups who do not shoot. In this article, we describe several factors that influence the risk of NIHL including the use of a muzzle brake, the number of shots fired, the distance between shooters, the shooting environment, the choice of ammunition, the use of a suppressor, and hearing protection fit and use. Prevention strategies that address these factors and recommendations for specialized hearing protectors designed for shooting sports are offered. Partnerships are needed between the hearing health community, shooting sport groups, and wildlife conservation organizations to develop and disseminate accurate information and promote organizational resources that support hearing loss prevention efforts.
RESUMEN
OBJECTIVE: To assess the test-retest variability of hearing thresholds obtained with an innovative, mobile wireless automated hearing-test system (WAHTS) with enhanced sound attenuation to test industrial workers at a worksite as compared to standardised automated hearing thresholds obtained in a mobile trailer sound booth. DESIGN: A within-subject repeated-measures design was used to compare air-conducted threshold tests (500-8000 Hz) measured with the WAHTS in six workplace locations, and a third test using computer-controlled audiometry obtained in a mobile trailer sound booth. Ambient noise levels were measured in all test environments. STUDY SAMPLE: Twenty workers served as listeners and 20 workers served as operators. RESULTS: On average, the WAHTS resulted in equivalent thresholds as the mobile trailer audiometry at 1000, 2000, 3000 and 8000 Hz and thresholds were within ±5 dB at 500, 4000 and 6000 Hz. CONCLUSIONS: Comparable performance may be obtained with the WAHTS in occupational audiometry and valid thresholds may be obtained in diverse test locations without the use of sound-attenuating enclosures.
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Estimulación Acústica/instrumentación , Acústica/instrumentación , Audiometría/instrumentación , Umbral Auditivo , Pérdida Auditiva Provocada por Ruido/diagnóstico , Audición , Industria Manufacturera , Ruido en el Ambiente de Trabajo/efectos adversos , Enfermedades Profesionales/diagnóstico , Exposición Profesional/efectos adversos , Salud Laboral , Tecnología Inalámbrica/instrumentación , Adulto , Automatización , Diseño de Equipo , Femenino , Pérdida Auditiva Provocada por Ruido/etiología , Pérdida Auditiva Provocada por Ruido/fisiopatología , Pérdida Auditiva Provocada por Ruido/psicología , Humanos , Masculino , Persona de Mediana Edad , Enfermedades Profesionales/etiología , Enfermedades Profesionales/fisiopatología , Enfermedades Profesionales/psicología , Valor Predictivo de las Pruebas , Reproducibilidad de los ResultadosRESUMEN
OBJECTIVE: To characterize the impulse noise exposure and auditory risk for air rifle users for both youth and adults. DESIGN: Acoustic characteristics were examined and the auditory risk estimates were evaluated using contemporary damage-risk criteria for unprotected adult listeners and the 120-dB peak limit and LAeq75 exposure limit suggested by the World Health Organization (1999) for children. STUDY SAMPLE: Impulses were generated by nine pellet air rifles and one BB air rifle. RESULTS: None of the air rifles generated peak levels that exceeded the 140 dB peak limit for adults, and eight (80%) exceeded the 120 dB peak SPL limit for youth. In general, for both adults and youth, there is minimal auditory risk when shooting fewer than 100 unprotected shots with pellet air rifles. Air rifles with suppressors were less hazardous than those without suppressors, and the pellet air rifles with higher velocities were generally more hazardous than those with lower velocities. CONCLUSION: To minimize auditory risk, youth should utilize air rifles with an integrated suppressor and lower velocity ratings. Air rifle shooters are advised to wear hearing protection whenever engaging in shooting activities in order to gain self-efficacy and model appropriate hearing health behaviors necessary for recreational firearm use.
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Estimulación Acústica/efectos adversos , Acústica , Armas de Fuego , Pérdida Auditiva Provocada por Ruido/etiología , Ruido/efectos adversos , Adulto , Umbral Auditivo , Niño , Dispositivos de Protección de los Oídos , Pérdida Auditiva Provocada por Ruido/fisiopatología , Pérdida Auditiva Provocada por Ruido/prevención & control , Humanos , Recreación , Medición de Riesgo , Factores de Riesgo , Espectrografía del SonidoRESUMEN
Distortion product otoacoustic emission (DPOAE) level mapping provides a comprehensive picture of cochlear responses over a range of DP frequencies and f2/f1ratios. We hypothesized that individuals exposed to high-level sound would show changes detectable by DPOAE mapping, but not apparent on a standard DP-gram. Thirteen normal hearing subjects were studied before and after attending music concerts. Pure-tone audiometry (500-8,000 Hz), DP-grams (0.3-10 kHz) at 1.22 ratio, and DPOAE level maps were collected prior to, as soon as possible after, and the day after the concerts. All maps covered the range of 2,000-6,000 Hz in DP frequency and from 1.3 to -1.3 in ratio using equi-level primary tone stimuli. Changes in the pure-tone audiogram were significant (P ≤ 0.01) immediately after the concert at 1,000 Hz, 4,000 Hz, and 6,000 Hz. The DP-gram showed significant differences only at f2= 4,066 (P = 0.01) and f2= 4,348 (P = 0.04). The postconcert changes were readily apparent both visually and statistically (P ≤ 0.01) on the mean DP level maps, and remained statistically significantly different from baseline the day after noise exposure although no significant changes from baseline were seen on the DP-gram or audiogram the day after exposure. Although both the DP-gram and audiogram showed recovery by the next day, the average DPOAE level maps remained significantly different from baseline. The mapping data showed changes in the cochlea that were not detected from the DP-gram obtained at a single ratio. DPOAE level mapping provides comprehensive information on subtle cochlear responses, which may offer advantages for studying and tracking noise-induced hearing loss (NIHL).
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Cóclea/fisiopatología , Exposición a Riesgos Ambientales/efectos adversos , Pérdida Auditiva Provocada por Ruido , Ruido/efectos adversos , Adulto , Audiometría de Tonos Puros/métodos , Femenino , Voluntarios Sanos , Pérdida Auditiva Provocada por Ruido/diagnóstico , Pérdida Auditiva Provocada por Ruido/etiología , Pérdida Auditiva Provocada por Ruido/fisiopatología , Pérdida Auditiva Provocada por Ruido/terapia , Humanos , Masculino , Música , Emisiones Otoacústicas Espontáneas/fisiología , Reproducibilidad de los Resultados , Factores de TiempoRESUMEN
OBJECTIVE: To characterize the impulse noise exposure and auditory risk for youth recreational firearm users engaged in outdoor target shooting events. The youth shooting positions are typically standing or sitting at a table, which places the firearm closer to the ground or reflective surface when compared to adult shooters. DESIGN: Acoustic characteristics were examined and the auditory risk estimates were evaluated using contemporary damage-risk criteria for unprotected adult listeners and the 120-dB peak limit suggested by the World Health Organization (1999) for children. STUDY SAMPLE: Impulses were generated by 26 firearm/ammunition configurations representing rifles, shotguns, and pistols used by youth. Measurements were obtained relative to a youth shooter's left ear. RESULTS: All firearms generated peak levels that exceeded the 120 dB peak limit suggested by the WHO for children. In general, shooting from the seated position over a tabletop increases the peak levels, LAeq8 and reduces the unprotected maximum permissible exposures (MPEs) for both rifles and pistols. Pistols pose the greatest auditory risk when fired over a tabletop. CONCLUSION: Youth should utilize smaller caliber weapons, preferably from the standing position, and always wear hearing protection whenever engaging in shooting activities to reduce the risk for auditory damage.
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Armas de Fuego , Pérdida Auditiva Provocada por Ruido/etiología , Ruido/efectos adversos , Estimulación Acústica , Acústica , Adolescente , Factores de Edad , Audiometría , Umbral Auditivo , Estatura , Dispositivos de Protección de los Oídos , Pérdida Auditiva Provocada por Ruido/diagnóstico , Pérdida Auditiva Provocada por Ruido/prevención & control , Pérdida Auditiva Provocada por Ruido/psicología , Humanos , Ruido/prevención & control , Postura , Valor Predictivo de las Pruebas , Recreación , Medición de Riesgo , Factores de Riesgo , Espectrografía del SonidoRESUMEN
OBJECTIVE: This study surveyed youth recreational firearm users (YRFUs) regarding shooting habits, reported use of hearing protection devices (HPDs), self-assessed auditory status, and attitudes about firearm noise and hearing loss. DESIGN: A descriptive study using a 28-item survey administered by personal interview. STUDY SAMPLE: Two-hundred and ten youth aged 10 to 17 years responded. RESULTS: Seventy-eight percent of those surveyed began shooting before the age of ten. The majority reported using large caliber firearms capable of rapid fire for both hunting and target practice. Most youths in this study were not aware of, and therefore, were not utilizing HPDs specifically designed for the shooting sports. Ten percent of subjects reported constant tinnitus and 45% notice tinnitus occurred or worsened after shooting. Although the majority of YRFUs reported good or perfect hearing, a small percentage (4-5%) of youth reported having only 'fair" hearing. CONCLUSION: YRFUs are putting themselves at risk beginning at a young age for noise-induced hearing loss (NIHL) and tinnitus based on self-reported shooting habits and inconsistent use of HPDs during both target practice and hunting activities. This research highlights the need for early education and intervention efforts to minimize the risk of NIHL in youth.
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Dispositivos de Protección de los Oídos , Armas de Fuego , Hábitos , Conductas Relacionadas con la Salud , Conocimientos, Actitudes y Práctica en Salud , Pérdida Auditiva Provocada por Ruido/prevención & control , Ruido/prevención & control , Recreación , Acúfeno/prevención & control , Adolescente , Conducta del Adolescente , Factores de Edad , Niño , Conducta Infantil , Preescolar , Colorado , Femenino , Encuestas Epidemiológicas , Pérdida Auditiva Provocada por Ruido/diagnóstico , Pérdida Auditiva Provocada por Ruido/etiología , Humanos , Masculino , Michigan , Ruido/efectos adversos , Medición de Riesgo , Factores de Riesgo , Encuestas y Cuestionarios , Acúfeno/diagnóstico , Acúfeno/etiologíaRESUMEN
Distortion product otoacoustic emission (DPOAE) level mapping may be useful for detecting noise-induced hearing loss (NIHL) early. Employing DPOAE mapping effectively requires knowledge of the optimal mapping parameters to use for detecting noise-induced changes. The goal of this project was to show the map regions that differ most between normal and noise-damaged cochlea to determine the optimal mapping parameters for detecting NIHL. DPOAE level maps were generated for the 2f 1 -f 2 and the 2f 2 -f 1 DPOAEs for 17 normal hearing male subjects and 19 male subjects with NIHL. DPOAEs were measured in DPOAE frequency steps of approximately 44 Hz from 0.5 kHz to 6 kHz using constant f 2 /f 1 ratios incremented in 0.025 steps from 1.025 to 1.5 using both unequal-level (L1,L2 = 65,55 dB sound pressure level (SPL)) and equi-level (L1,L2 = 75,75 dB SPL) stimulus paradigms. Maximal responses for the 2f 2 -f 1 emission at L1,L2 = 65,55 dB SPL were found at lower ratios compared to previous studies. The map regions where NIHL eliminated or reduced DPOAE magnitude were identified. DPOAE level mapping using higher-level, equi-level primaries produced significantly more detectable emissions particularly for the 2f 2 -f 1 emission. The data from this study can be used to optimize DPOAE level mapping parameters for tracking noise-exposed subjects longitudinally.
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Cóclea/fisiopatología , Pérdida Auditiva Provocada por Ruido/fisiopatología , Emisiones Otoacústicas Espontáneas/fisiología , Adolescente , Adulto , Análisis de Varianza , Audiometría de Tonos Puros , Estudios de Casos y Controles , Pérdida Auditiva Provocada por Ruido/diagnóstico , Humanos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
OBJECTIVE: This study describes signals generated by .22 and .32 caliber starter pistols in the context of noise-induced hearing loss risk for sports officials and athletes. DESIGN: Acoustic comparison of impulses generated from typical .22 and .32 caliber starter pistols firing blanks were made to impulses generated from comparable firearms firing both blanks and live rounds. Acoustic characteristics are described in terms of directionality and distance from the shooter in a simulated outdoor running track. Metrics include peak sound pressure levels (SPL), A-weighted equivalent 8-hour level (L(eqA8)), and maximum permissible number of individual shots, or maximum permissible exposures (MPE) for the unprotected ear. RESULTS: Starter pistols produce peak SPLs above 140 dB. The numbers of MPEs are as few as five for the .22-caliber starter pistol, and somewhat higher (≤ 25) for the .32-caliber pistol. CONCLUSION: The impulsive sounds produced by starter pistols correspond to MPE numbers that are unacceptably small for unprotected officials and others in the immediate vicinity of the shooter. At the distances included in this study, the risk to athletes appears to be low (when referencing exposure criteria for adults), but the sound associated with the starter pistol will contribute to the athlete's overall noise exposure.
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Acústica , Armas de Fuego , Pérdida Auditiva Provocada por Ruido/prevención & control , Ruido en el Ambiente de Trabajo/prevención & control , Exposición Profesional/prevención & control , Atletismo/estadística & datos numéricos , Adulto , Femenino , Pérdida Auditiva Provocada por Ruido/epidemiología , Humanos , Masculino , Modelos Teóricos , Exposición Profesional/estadística & datos numéricos , Salud Laboral , Factores de Riesgo , Carrera , Adulto JovenRESUMEN
OBJECTIVE: To describe the rationale and creation of a national award to recognize and promote hearing loss prevention. DESIGN: In 2007, the National Institute for Occupational Safety and Health partnered with the National Hearing Conservation Association to create the Safe-in-Sound Excellence in Hearing Loss Prevention Award™ ( www.safeinsound.us ). The objectives of this initiative were to recognize organizations that document measurable achievements and to share leading edge information to a broader community. RESULTS: An expert committee developed specific and explicit award evaluation criteria of excellence in hearing loss prevention for organizations in different industrial sectors. The general approach toward award criteria was to incorporate current 'best practices' and familiar benchmarks of hearing loss prevention programs. This approach was reviewed publicly. In addition, mechanisms were identified to measure the impact of the award itself. Interest in the award was recorded through the monitoring of the visitor traffic registered by the award web site and is increasing yearly. Specific values and strategies common across award winners are presented. CONCLUSION: The Safe-in-Sound Award™ has obtained high quality field data; identified practical solutions, disseminated successful strategies to minimize the risk of hearing loss, generated new partnerships, and shared practical solutions with others in the field.
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Distinciones y Premios , Pérdida Auditiva Provocada por Ruido/prevención & control , HumanosRESUMEN
OBJECTIVE: In 2009, the U.S. Environmental Protection Agency (EPA) proposed an impulse noise reduction rating (NRR) for hearing protection devices based upon the impulse peak insertion loss (IPIL) methods in the ANSI S12.42-2010 standard. This study tests the ANSI S12.42 methods with a range of hearing protection devices measured in field conditions. DESIGN: The method utilizes an acoustic test fixture and three ranges for impulse levels: 130-134, 148-152, and 166-170 dB peak SPL. For this study, four different models of hearing protectors were tested: Bilsom 707 Impact II electronic earmuff, E·A·R Pod Express, E·A·R Combat Arms version 4, and the Etymotic Research, Inc. Electronic BlastPLG™ EB1. STUDY SAMPLE: Five samples of each protector were fitted on the fixture or inserted in the fixture's ear canal five times for each impulse level. Impulses were generated by a 0.223 caliber rifle. RESULTS: The average IPILs increased with peak pressure and ranged between 20 and 38 dB. For some protectors, significant differences were observed across protector examples of the same model, and across insertions. CONCLUSIONS: The EPA's proposed methods provide consistent and reproducible results. The proposed impulse NRR rating should utilize the minimum and maximum protection percentiles as determined by the ANSI S12.42-2010 methods.