Showing papers in "Noise & Health in 2009"

Exposure-response relationship of the association between aircraft noise and the risk of hypertension

Abstract: Noise is a stressor that affects the autonomic nervous system and the endocrine system. Under conditions of chronic noise stress the cardiovascular system may adversely be affected. Epidemiological noise studies regarding the relationship between aircraft noise and cardiovascular effects have been carried out on adults and on children focussing on mean blood pressure, hypertension and ischemic heart diseases as cardiovascular endpoints. While there is evidence that road traffic noise increases the risk of ischemic heart disease, including myocardial infarction, there is less such evidence for such an association with aircraft noise. This is partly due to the fact that large scale clinical studies are missing. There is sufficient qualitative evidence, however, that aircraft noise increases the risk of hypertension in adults. Regarding aircraft noise and children's blood pressure the results are still inconsistent. The available literature was evaluated for the WHO working group on "Aircraft Noise and Health" based on the experts' comprehensive knowledge in this field. With respect to the needs of a quantitative risk assessment for burden of disease calculations an attempt was made to derive an exposure-response relationship based on a meta-analysis. This association must be viewed as preliminary due to limitations which are concerned with the pooling of studies due to methodological differences in the assessment of exposure and outcome between studies. More studies are needed to establish better estimates of the risk.

Output sound pressure levels of personal music systems and their effect on hearing.

Abstract: This study looked at output levels produced by new generation personal music systems (PMS), at the level of eardrum by placing the probe microphone in the ear canal. Further, the effect of these PMS on hearing was evaluated by comparing the distortion product otoacoustic emissions and high frequency pure tone thresholds (from 3 kHz to 12 kHz) of individuals who use PMS to that of age matched controls who did not use PMS. The relationship between output sound pressure levels and hearing measures was also evaluated. In Phase I output SPLs produced by the PMS were measured in three different conditions - a) at volume control setting that was preferred by the subjects in quiet b) at volume control setting that was preferred by the subject in presence of 65 dB SPL bus noise c) at maximum volume control settings of the instrument. In Phase II pure tone hearing thresholds and DPOAEs were measured. About 30% of individuals in a group of 70 young adults listened to music above the safety limits (80 dBA for 8 hours) prescribed by Ministry of Environment and Forests, India. Addition of bus noise did not increase the preferred volume control settings of the subjects significantly. There were no significant differences between the experimental and control groups for mean pure tone threshold and for mean DPOAE amplitude comparisons. However, a positive correlation between hearing thresholds and music levels and a negative correlation between DPOAE measures and music levels were found.

Synergistic ototoxicity due to noise exposure and aminoglycoside antibiotics

Abstract: Acoustic exposure to high intensity and/or prolonged noise causes temporary or permanent threshold shifts in auditory perception, reflected by reversible or irreversible damage in the cochlea. Aminoglycoside antibiotics, used for treating or preventing life-threatening bacterial infections, also induce cytotoxicity in the cochlea. Combined noise and aminoglycoside exposure, particularly in neonatal intensive care units, can lead to auditory threshold shifts greater than simple summation of the two insults. The synergistic toxicity of acoustic exposure and aminoglycoside antibiotics is not limited to simultaneous exposures. Prior acoustic insult which does not result in permanent threshold shifts potentiates aminoglycoside ototoxicity. In addition, exposure to subdamaging doses of aminoglycosides aggravates noise-induced cochlear damage. The mechanisms by which aminoglycosides cause auditory dysfunction are still being unraveled, but likely include the following: 1) penetration into the endolymphatic fluid of the scala media, 2) permeation of nonselective cation channels on the apical surface of hair cells, and 3) generation of toxic reactive oxygen species and interference with other cellular pathways. Here we discuss the effect of combined noise and aminoglycoside exposure to identify pivotal synergistic events that can potentiate ototoxicity, in addition to a current understanding of aminoglycoside trafficking within the cochlea. Preventing the ototoxic synergy of noise and aminoglycosides is best achieved by using non-ototoxic bactericidal drugs, and by attenuating perceived noise intensity when life-saving aminoglycoside therapy is required.

Effects of road traffic noise and irrelevant speech on children's reading and mathematical performance.

Abstract: Irrelevant speech in classrooms and road traffic noise adjacent to schools have a substantial impact on children's ability to learn. Comparing the effects of different noise sources on learning may help construct guidelines for noise abatement programs. Experimental studies are important to establish dose-response relationships and to expand our knowledge beyond correlation studies. This experiment examined effects of road traffic noise and irrelevant speech on children's reading speed, reading comprehension, basic mathematics, and mathematical reasoning. A total of 187 pupils (89 girls and 98 boys), 12-13 years old, were tested in their ordinary classrooms. Road traffic noise was found to impair reading speed (P<0.01) and basic mathematics (P<0.05). No effect was found on reading comprehension or on mathematical reasoning. Irrelevant speech did not disrupt performance on any task. These findings are related to previous research on noise in schools and the implications for noise abatement guidelines are discussed.

Could an underlying hearing loss be a significant factor in the handicap caused by tinnitus

Abstract: There have been several studies that have demonstrated a link between the hearing loss of subjects and tinnitus. However, there has been no systematic evaluation of the link between perceived tinnitus distress and an underlying hearing loss. The purpose of the current study is to explore this association, and ascertain whether a subject's hearing loss contributes to the handicap caused by tinnitus. A group of 96 adults were evaluated with Pure Tone Audiometry and a questionnaire that included the Tinnitus Handicap Inventory (THI). In 58% of the subjects, the side of the unilateral or worse tinnitus corresponded with the ear with poorer hearing thresholds. A subset of the THI, the Two Question Mean (TQM) that was related to questions with regard to communication, correlated significantly with the hearing thresholds in the better hearing ear ( P < 0.01). There was also a significant correlation between the THI and TQM scores ( P < 0.01). These results suggested that in tinnitus subjects with impaired hearing, the underlying hearing loss may be a significant factor in the perceived distress.

Hearing loss in veterans and the need for hearing loss prevention programs

Abstract: Currently, there are more than 445,000 veterans receiving compensation for hearing loss associated with military service, and 395,000 receiving compensation for service-related tinnitus. In addition to compensation payments, service-related hearing disorders cost the US Department of Veterans Affairs in terms of provision of hearing aids, hearing aid-related services, and clinical services at its 220 facilities nationwide. It is imperative that hearing conservation among military personnel and veterans be addressed. In this paper, we describe the rationale for and the development of a multimedia Hearing Loss Prevention Program aimed at preventing the progression of hearing loss among veterans associated with social, recreational, and nonmilitary occupational noise exposure. The program was developed based on the principles outlined in the Health Belief Model of Rosenstock (1966) and the Health Promotion Model of Pender et al. (2002).

Is there evidence that environmental noise is immunotoxic

Abstract: Noise is a stressor. Noise-induced stress can lead to release of stress hormones. Acute stress whether physical or psychological is necessary for adaptation to change. However, chronic stress can lead to the persistent elevation of hypothalamic-pituitary-adrenocortical hormones, which are detrimental to health and can lead to disease states. It has also been suggested that there may be multiple interactions between the sympathetic and the complex feedback neuroendocrine systems, which interact with the immune system, in the genesis of the observed effects. Thus noise stress may be a factor contributing to the mechanisms of noise-induced hearing loss through alterations in the cell-mediated immune response. Other than the noise stress acting directly, it may also have an impact on the immune function via noise-induced sleep deprivation. Furthermore, recent evidence indicates that the immune function may be modified by conditioning techniques, perceived control, or the individual's ability to cope with stress-inducing factors. This suggests a possible means of alleviating the stress-induced effects. This review will examine the current available data on the effects of chronic environmental noise exposure on immune function.

A field investigation of hearing protection and hearing enhancement in one device: for soldiers whose ears and lives depend upon it.

Abstract: Operational hearing protection and maintenance of audibility of signals and speech are considered force multipliers in military operations, increasing Soldier survivability and lethality. The in-field research described in this paper was conducted to examine operational performance effects of three different hearing enhancement protection systems (HEPS) that are intended to provide both protection and audibility. The experiment utilized operationally-defined measures in full-scale, simulated combat scenarios with Army ROTC Cadet Soldiers as subjects. The Soldiers' operational performance was evaluated in two missions: reconnaissance and raid (attack on enemy camp). Both missions had substantial hearing requirements, including communications, signal detection/recognition, and distance judgments. Operational performance was measured by objective metrics of Squad performance, including the distances required to detect an enemy insurgent camp under each HEPS, and by subjective metrics, such as the Army's dimensions of combat-related mission success as evaluated by Army Officers who served as training leaders/observers. Other subjective ratings were obtained after each training exercise from both the Officers and the Soldiers, including detailed impressions about each HEPS after extended use. Two of the three HEPS were electronic sound transmission devices (comprising an ambient sound pass-through filtering and amplification circuit): a Peltor Comtac II circumaural headset (NRR=21; 16 dB maximum gain); and a Communications Enhancement Protection System (CEPS) (NRR=29; 36 dB maximum gain). One passive, level-dependent HEPS was used, the yellow end of the Combat Arms Earplug, which provides amplitude-sensitive attenuation that sharply increases when the ambient sound is above about 110 dB (e.g., due to a gunshot), but which provides an NRR of 0 and very little attenuation below 1000 Hz in lower ambient noise levels. In the military mission entailing location of and attack on an enemy camp, the CEPS device resulted in the longest (earliest) average auditory detection distance of the camp (400 feet), followed by the Peltor (233 feet) and then the Combat Arms Earplug (150 feet), in comparison to detection by the unprotected, normal ear at about 220 feet. Commanding officers' ratings of mission performance and overall success slightly favored the electronic HEPS, but these ratings were dependent upon the particular mission undertaken. Ergonomics and usability issues abounded with the electronic HEPS, and the Soldiers' subjective ratings showed variability across all three devices, with device preference depending upon the particular dimension being rated (e.g., comfort vs. hearing ability). Clearly, the results of this in-field experiment demonstrate that more development is needed to achieve the levels of hearing performance and user acceptance from the HEPS that is desirable and needed for combat conditions. In this vein, it is important to note that HEPS designs are continually evolving, and certain upgrades to the three devices evaluated in the late 2006 timeframe of this study have occurred and further evaluations are thus warranted.

Heavy metals and noise exposure: health effects.

Abstract: Heavy metals are chemical elements with a specific gravity that is atleast five times that of water which is 1 at 4°C. The commonly encountered heavy metals are lead,mercury, cadmium, and arsenic. Lead levels in children continue to be a health hazard as the current limit of 10ug/dL is considered too high with the WHO estimate of 40% of children having blood levels greater than 5ug/dL. Some authors have suggested a new limit should be set at 2ug/dL. There are substantial differences in the literature regarding the effects of lead on hearing as assessed by pure tone audiometry. Mercury causes hearing loss and neurological dysfunction in Humans and animals. Methyl mercury is considered a more toxic compound to mercuric chloride. Cadmium causes a range of health effects from lung cancer, kidney damage to hearing loss. Dose dependent effects on hearing loss have been shown in rats. Combined effect with noise exposure has been shown to be more pronounced. Arsenic is released into the environment through the smelting process of copper, zinc, and lead. It is usually found in the water supply. Hearing impairments have been noted in the low and high frequencies in conjunction with balance disturbance.

Noise sensitivity and subjective health: Questionnaire study conducted along trunk roads in Kusatsu, Japan

Abstract: A questionnaire study was conducted in a residential area along trunk roads in Kusatsu, Japan, in order to investigate the association between noise exposure, noise sensitivity, and subjective health. Subjective health of the respondents was measured by the General Health Questionnaire (GHQ-28) which yields the total score as an index of psychiatric disorder and four subscales. Noise sensitivity was measured by the improved version of the Weinstein's noise sensitivity scale named WNS-6B. The original WNS and a single question directly asking respondents' noise sensitivity were also applied to confirm the validity of the WNS-6B for investigating the effects of road traffic noise on subjective health. Respondents were also asked about disturbances of daily life due to noise exposure to find the cause of the health effects. Three hundred and twenty three answers were entered into the analysis. Applying the WNS-6B as the noise sensitivity measurement scale, a significant correlation was found between subjective health and noise exposure in the noise-sensitive group, while no significant correlation was observed in the insensitive group. These results suggest that the adverse health effects may exist especially in the sensitive group. Application of the other two noise sensitivity measurement scales showed no significant relationship either in the sensitive group or in the insensitive group. The WNS-6B would have greater advantage for detecting adverse health effects than the other scales. Furthermore, the primary cause of the adverse health effect was investigated. The results of the analysis indicated that the adverse health effects were mainly caused by the sleep disturbance and were not caused by hearing interference.

Principles and application of educational counseling used in progressive audiologic tinnitus management

Abstract: Exposure to loud sounds is a common cause and exacerbater of tinnitus - a troubling auditory symptom that affects millions of people worldwide. Clinical research at the National Center for Rehabilitative Auditory Research has resulted in a clinical model of tinnitus management referred to as Progressive Audiologic Tinnitus Management (PATM). The model involves five hierarchical levels of management: Triage, Audiologic Evaluation, Group Education, Tinnitus Evaluation, and Individualized Management. Counseling by audiologists and, as needed, mental health providers, is a key component of PATM. This style of counseling focuses less on didactic informational counseling; instead, counseling is used for facilitating patients' learning to adjust to the disturbing auditory symptom by successfully employing tools from two powerful skillsets for self-management of chronic tinnitus - the therapeutic uses of sound and techniques from cognitive-behavioral psychology. This article provides an overview of the methods of counseling used with PATM and provides details concerning the overarching principles of collaborative adult learning that are believed to be most important in facilitating self-management by patients who complain of tinnitus.

The hearing conservation amendment: 25 years later.

Abstract: It has been twenty-five years since the final version of the Hearing Conservation Amendment was issued by the Occupational Safety and Health Administration in the U.S. Department of Labor. Since that time, some things have changed and others have stayed exactly the same. Certainly the noise-exposed workforce is more knowledgeable about the hazards of noise, and the use of hearing protection devices (HPDs) has greatly increased. There have been significant strides in the technology for measuring noise and for protecting hearing through HPDs. But there is considerable room for improvement. Some of the noise regulation's provisions are embarrassingly outdated, some are in dire need of improvement, and others, such as the requirements for engineering noise control, are not being enforced. Sadly, there seems to be little progress in reducing overall noise exposure levels. What needs to be done at this point is a major overhaul of the noise regulation: recommitment to engineering noise control; reduction of the permissible exposure limit (PEL) to 85 dBA; a shift to the 3-dBA exchange rate; and a nationwide assessment of hearing loss in American workers to determine the effectiveness of current hearing conservation measures to identify and address the weaknesses in programs and regulations.

Reduction of road traffic noise and mental health: an intervention study

Abstract: Road traffic noise exposure leads to annoyance and impairment of quality of life and may impair health. If this association is causal, a reduction in noise exposure should result in a reduction in noise annoyance and improvement in quality of life. This study examines whether the reduction in road traffic noise following the introduction of a bypass leads to reduction in noise annoyance and common mental disorder and an improvement in quality of life. Repeated measures field study with intervention in three small towns in North Wales, UK. Participants were residents 16 to 90 years living in areas of high or low exposure to road traffic noise. At baseline there was no difference in annoyance, quality of life or common mental disorder between traffic noise exposed and quiet areas. There was a small reduction in noise exposure (2-4 dBA) with the opening of the bypass. There was no reduction in noise annoyance and no change in levels of common mental disorder and quality of life following the introduction of the bypass. Traffic noise reduction associated with the introduction of the bypass was not associated with measurable changes in quality of life or common mental disorder. This study suggests that reduction in traffic noise level of 3dB or less is insufficient to influence annoyance or mental health. However, the methodological difficulties of the study limit the conclusions that can be drawn on whether there is a causal effect of noise on common mental disorder.

Estimates of auditory risk from outdoor impulse noise II: Civilian firearms

Abstract: Firearm impulses are common noise exposures in the United States. This study records, describes and analyzes impulses produced outdoors by civilian firearms with respect to the amount of auditory risk they pose to the unprotected listener under various listening conditions. Risk estimates were obtained using three contemporary damage risk criteria (DRC) including a waveform parameter-based approach (peak SPL and B-duration), an energy-based criterion (A-weighted SEL and equivalent continuous level) and a physiological model (AHAAH). Results from these DRC were converted into a number of maximum permissible unprotected exposures to facilitate interpretation. Acoustic characteristics of firearm impulses differed substantially across guns, ammunition, and microphone location. The type of gun, ammunition and the microphone location all significantly affected estimates of auditory risk from firearms. Vast differences in maximum permissible exposures were observed; the rank order of the differences varied with the source of the impulse. Unprotected exposure to firearm noise is not recommended, but people electing to fire a gun without hearing protection should be advised to minimize auditory risk through careful selection of ammunition and shooting environment. Small-caliber guns with long barrels and guns loaded with the least powerful ammunition tend to be associated with the least auditory risk.

Distortion product otoacoustic emissions in an industrial setting.

Abstract: Distortion product otoacoustic emissions (DPOAEs) is an objective sensitive test of cochlear function. The aim of this study was the evaluation of noise-induced hearing loss in a group of industrial workers, using this method in conjunction with standard puretone audiometry (PTA). One hundred and five subjects (210 ears) were included in the study. PTA, tympanometry, and DPOAEs were performed. Results were analyzed using a mixed analysis of variance model, and compared with the data of 34 normal persons of similar age and sex. We found statistically significant lower DPOAE levels in the noise-exposed group than in the control group. Additionally, the effect of frequency was significant, indicating that amplitude varied across frequency, with lower responses observed at 4 and 6 kHz, and maximum response found at 2 kHz. PTA showed a statistically significant effect of Group, owed to elevated puretone thresholds in the noise-exposed subjects, but a Frequency main effect was not found, although the interaction between Frequency and Group was statistically significant, as well as the interaction between Frequency and Ear. A main effect for Ear was found only in puretone thresholds, due to better thresholds in the left ears of the subjects, and not in DPOAE measurements. DPOAE levels were selectively affected at the higher frequencies, whereas puretone thresholds were affected at all frequencies. Direct comparison of the number of significantly affected ears between the two methods at 1, 2, and 4 kHz showed statistically significant differences at all comparisons, with more ears affected in PTA in comparison with DPOAEs at 4 kHz, whereas more ears were affected in DPOAEs at the lower frequencies (1 and 2 kHz). Therefore, it may be concluded that DPOAEs and PTA are both sensitive methods in detecting noise-induced hearing loss, with DPOAEs tending to be more sensitive at lower frequencies.

Self-reported noise exposure as a risk factor for long-term sickness absence.

Abstract: Self-reported noise exposure is on the rise in Denmark. Little is known, however, about the social consequences, including sickness absence, of noise exposure. The aim of this paper was to investigate the association between self-reported noise exposure and long-term sickness absence. The association was investigated using the Cox proportional hazards model to analyze outcomes in Danish register data on the basis of Danish survey data (5357 employees aged 18-69 in 2000). The analyses showed that self-reported noise exposure was significantly associated with long-term sickness absence for both men and women when adjusting for demographic factors and health behavior. After further adjustment for physical workload at work the association between noise exposure and sickness absence disappeared for women, but not for men. Men that reported to be exposed to loud noise between one-quarter and three-quarters of their time at work had an increased risk of 43% (CI: 10-85%) for sickness absence of two weeks or longer compared to men that reported never to be exposed to loud noise. Men that reported to be little/rarely exposed to loud noise had an increased risk of 37% (CI: 7-76%). Men that reported to be exposed to loud noise more than three-quarters of their time at work did not have an increased risk of sickness absence. This latter result might be due a healthy worker effect and/or more frequent use of hearing protection in this group. Along with evidence from previous studies these results provide further support for an association between occupational noise exposure and sickness absence.

Chronic exposure of rats to occupational textile noise causes cytological changes in adrenal cortex.

Abstract: Chronic exposure to industrial noise and its effects on biological systems. Occupational exposure to noise may result in health disorders. Our aim was to evaluate the effects of chronic exposure to high-intensity noise of textile industry cotton rooms on the adrenal morphology. The environmental noise of a cotton-mill room from a large textile factory of Northern Portugal was recorded and reproduced by an adopted electroacoustic setup in a sound-insulated animal room where the rats were housed. The sounds were reproduced at the original levels of approximately 92 dB, which was achieved by equalization and distribution of sound output in the room. Wistar rats were submitted to noise exposure, in the same time schedule as employed in textile plants. After one, three, five, and seven months, the adrenals were collected and analyzed by light microscopy. Analyzed by multivariate analysis of variance and post hoc Bonferroni correction for multiple comparisons of the means between the groups. Noise exposure induced time-dependent changes in adrenal cortex, with decrease of zona fasciculata (ZF) and increase of zona reticularis volumes, together with a significant depletion of lipid droplet density in ZF cells of exposed rats, in comparison to control rats. Chronic exposure of rats to textile industry noise triggers cytological changes in the adrenals that suggest the existence of a sustained stress response.

Estimates of the auditory risk from outdoor impulse noise. I: Firecrackers.

Abstract: Firecrackers are common impulse noise exposures in the United States. In this study, impulses produced outdoors by consumer firecrackers were recorded, described, and analyzed with respect to the amount of the auditory risk they pose to the unprotected listener under various listening conditions. Risk estimates were obtained using three contemporary damage risk criteria (DRC), including a waveform parameter-based approach (peak SPL and B duration), an energy-based criterion (A-weighted sound exposure level and equivalent continuous level), and a physiological model (the AHAAH model developed by Price and Kalb). Results from these DRC were converted into numbers of maximum permissible unprotected exposures to facilitate comparison. Acoustic characteristics of firecracker impulses varied with the distance, but only subtle differences were observed across firecrackers. Typical peak levels ranged between 171 dB SPL at 0.5 m and 142 dB SPL at 8 m. Estimates of the auditory risk did not differ significantly across firecrackers, but varied with the distance. Vast differences in maximum permissible exposures were observed, and the directions of the differences varied with the level of the impulse. Typical estimates of maximum permissible exposures ranged between 0 and 2 at 0.5 m and between 31 and 227,000 at 8 m. Unprotected exposures to firecracker impulses should be limited or avoided entirely if the firecrackers are ignited in batches within 8 m of the listener. Differences across DRC are inconsequential at 0.5 m, but have substantial implications at distances of 1 m and more.

Sound localization with an army helmet worn in combination with an in-ear advanced communications system.

Abstract: Conventional hearing protection devices result in decrements mainly in the ability to distinguish front from rearward sound sources. The aim of this study was to investigate the effect of wearing an earplug with advanced communications capability, in combination with an army helmet, on horizontal plane speaker identification. Ten normal-hearing male subjects were tested in a semi-reverberant sound proof booth under eight conditions defined by combinations of two levels of ear occlusion (unoccluded and occluded by the earplug) and four levels of the helmet (head bare and fitted with the helmet modified to give no, partial and full ear coverage). Percent correct speaker identification was assessed using a horizontal array of eight loudspeakers surrounding the subject at one meter. These were positioned close to the midline and interaural axes of the head, at ear level. The stimulus was a 75-dB SPL, 300-ms broadband white noise. Both degree of ear coverage and ear occlusion significantly determined outcome. Overall percent correct ranged from 93.6% (bareheaded) to 79.7% (full ear coverage) with the ears unoccluded, and from 83.4%-77.5% with ear occlusion. Both variables affected the prevalence of mirror image confusions for positions 30° apart in front and back of the interaural axis. With ear occlusion, front given back errors were more likely than back given front errors, increasing with degree of ear coverage to 49% and 25.4%, respectively. These errors also increased with ear coverage with the ears unoccluded, but were similar. Both degree of ear coverage and ear occlusion significantly impacted horizontal plane speaker identification, particularly for sources close to the interaural axis. However, overall percent correct was higher than observed in a previous study with conventional and level-dependent hearing protection devices, using the same array.

Attitudes of college music students towards noise in youth culture.

Abstract: The effectiveness of a hearing loss prevention program within a college may be dependent on attitudes among students majoring in music. The purpose of this study was to assess the attitudes of music majors toward noise and to compare them to students not majoring in music. Participants ( N = 467) filled out a questionnaire designed to assess attitudes toward noise in youth culture and attitudes toward influencing their sound environment. Results showed that students majoring in music have a healthier attitude toward sound compared to students not majoring in music. Findings also showed that music majors are more aware and attentive to noise in general, likely to perceive sound that may be risky to hearing as something negative, and are more likely to carry out behaviors to decrease personal exposure to loud sounds. Due to these differences, music majors may be more likely than other students to respond to and benefit from a hearing loss prevention program.

A national project to evaluate and reduce high sound pressure levels from music.

Abstract: The highest recommended sound pressure levels for leisure sounds (music) in Sweden are 100 dB LAeq and 115 dB LAFmax for adults, and 97 dB LAeq and 110 dB LAFmax where children under the age of 13 have access. For arrangements intended for children, levels should be consistently less than 90 dB LAeq. In 2005, a national project was carried out with the aim of improving environments with high sound pressure levels from music, such as concert halls, restaurants, and cinemas. The project covered both live and recorded music. Of Sweden's 290 municipalities, 134 took part in the project, and 93 of these carried out sound measurements. Four hundred and seventy one establishments were investigated, 24% of which exceeded the highest recommended sound pressure levels for leisure sounds in Sweden. Of festival and concert events, 42% exceeded the recommended levels. Those who visit music events/establishments thus run a relatively high risk of exposure to harmful sound levels. Continued supervision in this field is therefore crucial.

Effects of shift work on noise-induced hearing loss.

Abstract: Evidence has accumulated concerning the adverse effects of noise on hearing acuity, but it is not clear whether working shifts may decelerate the effects of hearing loss. The objective of this study is to assess the effects of shift work on hearing loss in a noisy work environment. A sample of 218 male workers recruited at a semiconductor factory with no known occupational hazards that affected hearing acuity other than noise was chosen. The subjects worked either in an eight-hour or 12-hour shift. A standardized audiometric procedure was performed by a qualified audiologist to measure pure-tone hearing thresholds at 0.5kHz, 1kHz, 2kHz, 3kHz, 4kHz, 6kHz and 8kHz in both ears. Using multiple linear regression adjusted for age, smoking habits, and work duration, the results showed that the severity of hearing loss in both ears was significantly lower in subjects who worked a 12-hour shift. In conclusion, working a 12-hour shift followed by a day off is best for workers and hearing protection should be provided in high noise areas.

Noise characteristics of grass-trimming machine engines and their effect on operators.

Abstract: Over the last few years, interaction of humans with noisy power-driven agricultural tools and its possible adverse after effects have been realized. Grass-trimmer engine is the primary source of noise and the use of motorized cutter, spinning at high speed, is the secondary source of noise to which operators are exposed. In the present study, investigation was carried out to determine the effect of two types of grass-trimming machine engines (SUM 328 SE and BG 328) noise on the operators in real working environment. It was found that BG-328 and SUM-328 SE produced high levels of noise, of the order of 100 and 105 dB(A), respectively, to which operators are exposed while working. It was also observed that situation aggravates when a number of operators simultaneously operate resulting in still higher levels of noise. Operators should be separated 15 meters from each other in order to avoid the combined level of noise exposure while working with these machines. It was found that SPL, of the grass-trimmer machine engines (BG-328 and SUM-328 SE), were higher than the limit of noise recommended by ISO, NIOSH, and OSHA for an 8-hour workday. Such a high level of noise exposure may cause physiological and psychological problems to the operators in long run.

Shooting habits of U.S. waterfowl hunters

Abstract: Exposure to high-intensity impulse noise from the recreational use of firearms is a common cause of noise-induced hearing loss (NIHL). Although recreational firearm users who shoot firearms without proper hearing protection are at risk for NIHL, a specific subgroup involved in hunting waterfowl may also be at risk due to their particular shooting habits. The goal of the present study was to investigate the shooting habits of this particular group of U.S. recreational firearm users. A 23-item written survey was sent to waterfowl hunting club members regarding their shooting behaviors, use of hearing protective devices (HPDs), and auditory status. Results indicated that waterfowl hunters in this study typically used large bore semiautomatic shotguns, did not consistently utilize HPDs during target practice or hunting and were exposed to multiple, unprotected shots during the past waterfowl season. Most subjects reported hunting in reverberant acoustic environments (hunting blinds). This group of recreational firearm users also reported high incidences of hearing loss and tinnitus. Information provided by this study may help hearing conservationists and hearing healthcare providers understand and better educate these shooters regarding the risk of acquiring NIHL.

Assessment of noise exposure in a hospital kitchen

Abstract: In March 2007, the National Institute for Occupational Safety and Health (NIOSH) was asked to evaluate the noise exposure of employees in the Nutrition and Food Services Department of a large hospital, because of noise concerns raised after the installation of the PowerSoak® dishwashing system. Eleven employees (two cooks, eight food service workers, and a materials handler) contributed 13 full-shift and two task-based personal noise dosimetry measures over two days. The noise levels for two food service workers assigned to the pots and pans room (85.1 and 85.2dBA), a cook working in the food preparation area (85.9 dBA), and a food service worker assigned to the dishwashing room (89.5 dBA) exceeded the NIOSH Recommended Exposure Limit (REL); however, none of the measures exceeded the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL). The noise level from the PowerSoak® dishwashing system alone was not excessive, but additional noise from the food preparation area (primarily from blenders and utensils), and from metal-to-metal contact between stainless steel pots and pans and metal racks, may explain exposures above the NIOSH REL for employees in the pots and pans room. The cooks were exposed to many intermittent impact noise sources, such as, metal-to-metal contact between utensils and the use of industrial-size blenders. We recommended that metal-to-metal contact be reduced as much as possible throughout the Nutrition and Food Services Department, and hearing protectors be provided to employees in the dishwashing room until engineering controls were in place.

Development of a noise prediction model under interrupted traffic flow conditions: a case study for Jaipur city.

Abstract: The objective of this study is to develop an empirical noise prediction model for the evaluation of equivalent noise levels (Leq) under interrupted traffic flow conditions. A new factor tendency to blow horn (AH) was introduced in the conventional federal highway administrative noise prediction (FHWA) model and a comparative study was made between FHWA and modified FHWA models to evaluate the best suitability of the model. Monitoring and modeling of Leq were carried out at four selected intersections of Jaipur city. After comparison of the results, it was found that the modified FHWA model could be satisfactorily applied for Indian conditions as it gives acceptable results with a deviation of +/-3 dB (A). In addition, statistical analysis of the data comprising measured and estimated values shows a good agreement. Hence, the modified FHWA traffic noise prediction model can be applied to the cities having similar traffic conditions as in Jaipur city.

Reliability of audiometric thresholds obtained with insert earphones when used by certified audiometric technicians.

Abstract: Clinical audiologists and audiometric equipment manufacturers have embraced the clinical use of insert earphones; however, their use in audiometric testing in occupational hearing loss prevention programs has been limited. This study was undertaken to research whether certified audiometric technicians without practical hands-on training could reliably use insert earphones when compared to a clinically experienced audiologist. Hearing thresholds were obtained on 60 human ears by six certified audiometric technicians using insert earphones for the first time. Technician-acquired audiometric thresholds were compared to thresholds obtained under the same conditions by a clinical audiologist experienced in the use of the insert earphones. Statistical analyses of audiometric thresholds were performed to investigate the relationships between audiometric threshold values at each frequency obtained by certified technicians vs. the audiologist. These relationships were examined for the group as a whole as well as when ear tip size and earphone insertion depth varied between the audiologist and the technicians. No significant differences (p > .01) were found between mean group thresholds at any of the test frequencies (500-8000 Hz). Mean group thresholds differed by .01) even when the audiologist and technicians varied in their selection of ear tip size or in the amount of insertion depth achieved. This study suggests that CAOHC-certified audiometric technicians can reliably use insert earphones without practical training when testing in quiet environments by reading the earphone package directions provided by the manufacturer.

Non-auditory health effects among air force crew chiefs exposed to high level sound

Abstract: The possibility of non-auditory health effects in connection with occupational exposure to high level sound is supposed by some researchers, but is still debated. Crew chiefs on airfields are exposed to high-level aircraft sound when working close to aircraft with running engines. We compared their health status with a similar control group who were not subject to this specific sound exposure. Health records of 42 crew chiefs were compared to health records of 42 aircraft mechanics and 17 former crew chiefs. The specific sound exposure of crew chiefs was assessed. The number of reported disease cases was generally small, but generally slightly higher among mechanics than among crew chiefs. Diseases of the ear were more frequent among crew chiefs (not significant). Former crew chiefs reported fewer diseases of the ear and more airways infections (both significant). The sound exposure during launch was up to 144 dB (peak) and 124 dB (L eq ), but for limited time. The study did not reveal a higher disease frequency in general among crew chiefs. However, it did reveal a tendency to ear diseases, possibly due to their exposure to high-level sound.

Effects of shift work and intermittent noise exposure on hearing: mechanisms and prophylactic potential.

Abstract: It is well established that intermittent noise exposure characteristically produces less hearing loss than equal energy/intensity continuous noise in animal models. Ongoing different shift work regimes open for direct studies on hearing effects of intermittent noise exposure in man without ethical concern. Amazingly, few such studies are reported. In one recent study in the present volume, noise-exposed employees working 12 hours a day for two consecutive days followed by two days off, the cycle then repeated, had significantly lower permanent hearing loss than employees working nine-hour shifts from 8 am to 5 pm Monday to Friday. This commentary refers to the few studies reported, gives a short overview of the mechanisms behind noise-induced hearing loss and the protective effect of intermittent exposure, and concludes that direct studies in man on the effects of different shift work regimes on occupational hearing loss under specified noise conditions represent a prophylactic potential that calls for increased research activity. Such studies might pave the way for direct use of more optimal intermittent noise exposure regimes in future design of the noise exposure workday/-week and make future hearing conservation programs more effective.