Noise Exposure Measurements Research Articles

Social Inequalities in Environmental Noise Exposure: A Review of Evidence in the WHO European Region.

Environmental noise is an important public health problem, being among the top environmental risks to health. The burden of noise exposure seems to be unequally distributed in societies. Up to now there is fragmentary evidence regarding which social groups are most affected. The aim of this review was to systematically assess published evidence on social inequalities in environmental noise exposure in the WHO European Region, taking different sociodemographic and socioeconomic dimensions as well as subjective and objective measures of environmental noise exposure into account. Articles published in English in a peer reviewed journal between 2010 and 2017 were included in the review. Eight studies were finally included in the review, four of them analysed aggregated data and four analysed individual data. Though results of social inequalities in noise exposures were mixed between and within studies, there was a trend that studies using indicators of material deprivation and deprivation indices showed higher environmental noise exposures in groups with lower socioeconomic position. More research on the social distribution of environmental noise exposure on a small spatial scale is needed, taking into account aspects of vulnerability and procedural justice.

An indirect calculation method for estimating occupational sound exposure from communication headsets.

Measurement of noise exposure from communication headsets is challenging due to the need for specialized equipment, methods, and training. Canadian standard Z107.56-13 [(2013). Measurement of Noise Exposure (Canadian Standards Association, Mississauga, Canada)] introduced a calculation procedure to promote a simpler method that stakeholders in hearing loss prevention could readily apply using widely accessible sound level equipment. The original procedure specified a fixed signal-to-noise ratio (SNR) of 15 dB above the protected background noise when estimating the speech listening level through the headset communication channel. The relationship between background noise level, noise type, headset noise reduction (NR), and speech listening level is revisited in this study. In a noise simulation room, 24 participants were asked to adjust the headset volume while listening to speech and executing a visual reaction task. Results indicate that the growth in speech listening levels with noise is not adequately represented by a fixed SNR, and that one-sided listening increases speech levels by about 5-7 dB in quiet and in noise compared to two-sided listening. Moreover, use of an octave-band procedure with derating to estimate headset NR best captured the speech listening level data. A revised calculation procedure based on linear regression modeling is described with parameters adjusted separately for one-sided and two-sided headsets.

In-ear and on-body measurements of impulse-noise exposure

Accurate quantification of noise exposure in military environments is challenging due to movement of listeners and noise sources, spectral and temporal noise characteristics, and varied use of hearing protection. This study evaluates a wearable recording device designed to measure on-body and in-ear noise exposure, specifically in an environment with significant impulse noise resulting from firearms. A commercial audio recorder was augmented to obtain simultaneous measurements inside the ear canal behind an integrated hearing protector, and near the outer ear. Validation measurements, conducted with an acoustic test fixture and shock tube, indicated high impulse peak insertion loss with a proper fit of the integrated hearing protector. The recording devices were worn by five subjects during a live-fire data collection at Marine Corps Base Quantico where Marines fired semi-automatic rifles. The field test demonstrated the successful measurement of high-level impulse waveforms with the on-body and in-ear recording system. Dual channels allowed for instantaneous fit estimates for the hearing protection component, and the device worked as intended in terms of hearing protection and noise dosimetry. Accurate measurements of noise exposure and hearing protector fit should improve the ability to model and assess the risks of noise-induced hearing loss.

Measurement of hazardous personal noise exposure in spice manufacturing industry

There are many sources of hazardous noise that contributed to the hearing impairment, that resultant from over exposure noise level from workplace. This study examined the contribution of machine that used in the spice manufacturing towards to the employee. Initially, the background noise of each workstation needed to be measured using a sound level meter. Then, monitoring levels including machine noise levels and daily self-reported duration noise exposure to workers was elucidated. A total of 30 workers were identified as having workplace noise exposures. The average noise levels were between 81 and 97 dBA in high and low noise exposure areas, respectively. The average self-reported workplace noise measure time was 8 hours/day. The estimated mean daily noise exposures were calculated from machine noise were found to be higher than the Factories And Machinery (Noise Exposure) Regulations, specifically 90 dBA eight-hour time weighted average (TWA). In addition, 750% of production workers had estimated greater than TWA value exposures. It is therefore recommended that industries either limit workplace use among the production workers or require device and technological advanced to prevent occupational noise-induced hearing loss

Relationship Between Subjective Reports of Temporary Threshold Shift and the Prevalence of Hearing Problems in Military Personnel.

Traditional hearing conservation programs are based on the premise that noise dose, as measured by the time-weighted average noise level, is the primary risk factor associated with occupational hearing loss and that permanent threshold shifts are the most relevant outcome measures for determining when a noise-related hearing loss has occurred. However, recent studies in animal models have suggested that significant neurological damage to the hearing system can occur from noise exposures even when they are not severe enough to result in permanent threshold shifts. This has led to a number of studies attempting to relate subjective measures of noise exposure to subjective measures of hearing difficulty and suprathreshold measures of hearing performance (e.g., speech-in-noise tests). In this study, 3,330 U.S. service members volunteered to complete a survey on noise exposure, subjective hearing complaints, and tinnitus in conjunction with their annual hearing tests. Two questions were also included about the frequency and duration of temporary hearing losses that may have been experienced by the service member. The results show that subjective reports of temporary threshold shifts were substantially more predictive of tinnitus and other hearing complaints than more traditional questions based on the frequency of noise exposure.

Noise Exposure Assessment and Estimated Excess Risk of Cabin Personnel in the Locomotive-CC205

Train is one of the most environmentally friendly mode of transportation. However, currently there are still some types of locomotive designed to be opened (such as CC201); hence, the generated noise can potentially affect the health of the workers, particularly cabin personnel (i.e. train driver and assistant of driver). The objective of this study are to analyze the noise levels exposed to cabin personnel and to estimate the excess risks of occupational noise-induced hearing loss in the locomotive. The cabin personnel were considered as exposed group while the office workers of the train station (Poncol Station) was the control group. The noise levels were measured continuously during the working hours using noise dosimeter. The audiometry test was also conducted to both case and control group. The data were analyzed using chi-square statistical test and NIOSH 1998 method of excess risk estimation. The measured noise exposure level in the locomotive-CC205 during the working hours (4-5 hours) ranged from 71.2 dBA until 123.4 dBA. However, the excess risks of the respondents were only 0.75% higher than the control group. This might be due to the short working period of the participants (no more than 10 years). The noise exposure to the case group workers were higher than time-weighted average noise level. Based on the chi-square statistical test, it is concluded that the noise levels affect the noise-induced hearing loss of the cabin personnel.

Noise Exposure on Mixed Grain and Livestock Farms in Western Australia

Noise presents an ongoing occupational health and safety issue, which despite numerous studies still presents a significant risk in agriculture with high exposures prevalent. In this study, we measured noise exposures associated with significant activities on 42 mixed grain and livestock farms in Western Australia. Employing a mixture of personal noise measurements using dosimeters, noise measurements using sound level meters, and a validated survey, we identified that 32% of farm workers were exposed to noise levels above the LAeq,8h 85 dB(A) limit, before considering extended shifts. We also noted that extended shift lengths, of up to 16 h in some cases, were possible. In addition, we found that 37% of workers were exposed to noise peak of 140 dB(C) or greater. It was further noted that hearing protection is not typically worn for the duration of an activity and is only for a small number of tasks. However we did find some evidence that farmers had begun to implement some form of noise management practice, usually in the form of buying quieter equipment or separating noisy tasks from quiet tasks. Improved education for farmer and farm workers in terms of the risks posed by noise, identifying noisy tasks, is recommended, as well as a programme to encourage better and consistent use of hearing protection.

Patterns and trends in OSHA occupational noise exposure measurements from 1979 to 2013

ObjectivesNoise is one of the most common exposures, and occupational noise-induced hearing loss (NIHL) is highly prevalent. In addition to NIHL, noise is linked to numerous non-auditory health effects. The...

The protective effect of metformin against the noise-induced hearing loss.

To test the protective effect of metformin against noise-induced hearing loss. 24 rats were included in the study. The first group was exposed to noise only, the second group took metformin, the third group was exposed to noise and took metformin, and the fourth group was neither exposed to noise nor took metformin as control group. After measurement of baseline DPOAE and ABR of rats, the metformin group and the metformin + noise group received 300mg/kg/day metformin via gavage for 10days. On the 11th day, group 1 and group 3 were exposured to white noise at 105dB SPL for 15h. After noise exposure, DPOAE and ABR measurements of all rats were repeated on days 1st, 7th, and 21st. At the end of the study, all animals were sacrificed and cochlear tissues were separated for immunohistochemical assessments. ABR threshold values and DPAOE measurements of groups 1 and 3 were deteriorated on the 1st day after noise, while deterioration in group 1 continued on 7th and 21st days, but normalized on 7th day in group 3. After immune staining, a significant immunoreaction was observed in the noise group, while the reaction in the noise + metformin group was close to the control group. Metformin has a protective effect on noise-induced hearing loss in rats. As a conclusion, it is determined that metformin protects from permanent threshold shift in rats. It can be considered a good alternative for protecting noise-induced hearing loss.

Occupational Noise, Job Strain and Salivary Cortisol: A Repeated-Measure Study

Background:Exposure to occupational noise and job strain have been reported to be associated with the salivary cortisol levels, but the combined effect is not clear. This study aimed to investigate individual and interactive associations between occupational noise exposure and job strain on salivary cortisol levels.Methods:We recruited 120 volunteers in an aircraft manufacturing company in Central Taiwan as study subjects. Each participant was performed 24-hour measurements of noise exposure and collected four salivary samples during different periods on the working day. The enzyme-link immunosorbent assay was applied to determine salivary cortisol levels. We also used questionnaire to obtain information related to job strain, sleep quality and other confounders. Multiple linear regression models were performed to analyze the association.Results:Workers exposed to ≥75 A-weighted decibels (dBA) had a significantly higher difference of salivary cortisol levels between 30-min waking-up and last-night sleep compared with that in workers exposed to <75 dBA and office workers, respectively. Workers exposed to high job strain (Index ≥61) had a significantly higher mean of salivary cortisol levels after 30-min waking-up and a significant difference between 30-min waking-up and last-night sleep than those with the low job strain (Index <61). Subjects co-exposed to noise levels ≥75 dBA and high job strain had a significantly higher mean of salivary cortisol levels after 30-min waking-up (0.371±0.098 mg/dL, P<0.001) and a significant difference between 30-min waking-up and last-night sleep (0.323±0.094 mg/dL, P<0.001) compared with those exposed to <75 dBA and low job strain.Conclusions:Occupational noise exposure and high job strain was associated with the increased salivary cortisol levels after 30-min waking-up. Co-exposure to noise and job strain may have a synergistic interaction with the salivary cortisol levels.

Analysis and Evaluation of Risks from Exposure to Noise in a Working Environment

This paper deals with a proposal of assessment of hearing impairment risk from the point of view of long-term exposure to noise in a selected plant in the Slovak Republic. Measurement and monitoring noise was carried out at two workshops of a mechanical engineering plant: in a Cutting Center and in a Welding Center. A Norsonic sound analyser was used to measure noise exposure. Evaluation of the noise measurement results consisted of the comparison of the measured values with the required values, which are specified, in the relevant legislative regulation (Government Regulation No. 115/2006 Coll., technical standard (STN EN ISO 9612:2010) and Directive (Council Directive 2003/10/EC). The measured results show that the normalized levels of noise exposure, extended by the uncertainty of measurement (U = ± 2,1 dB) at the all workplaces, exceed the limits stipulated by the Slovak Government, all measured professions fall within the fourth category of work activities categorized according to the noise factor. Long-term exposure of the human organism to noise pollution can cause, in addition to hearing impairment, a wide range of other diseases. Very high levels of noise cause hearing impairment, lower levels affect the control system in our body. This paper presents the results of a study aimed at assessing the risks associated with acoustic noise in connection with exposure to noise at the workplace and with its possible negative effects (a risk event) to health and hearing of workers in the engineering industry.

A Systematic Review of Full-Shift, Noise Exposure Levels Among Construction Workers: Are We Improving?

Construction industry workers are at high risk of occupational noise exposure. Although regulations and guidelines for this industry specify the use of noise controls, workers continue to be exposed to hazardous noise levels. The objectives of this study were (i) to collate and describe full-shift noise exposure experienced by construction workers; (ii) to review trends in full-shift exposure over time and between countries; and (iii) to identify any occupational categories within the construction industries that have higher levels of exposure. Of the 1171 studies found using key terms, 25 contained noise exposure measurements that met our inclusion criteria. Sample populations were predominantly from large construction sites and primarily comprised occupations known to engage in noisy workplace activities. Studies spanned over 36 years with all having average full-shift noise exposure over 85 A-weighted decibels (dBA). No time trend in full-shift noise exposure levels for construction workers was observed. Construction workers in the subgroup occupations of mason, sheet metal workers, carpenters, concrete workers, and operating engineers consistently had mean LAeq,8h over the 85 dBA limit. Studies spanning 36 years in 10 countries consistently show construction workers have been exposed to hazardous noise levels. There has been no significant change over time of the average full-shift exposure levels of construction workers, including in all occupational subgroups except iron-workers. Some variability in full-shift measures is due to sampling methods and population characteristics and to a lesser extent, methods used to derive exposure levels.

A study of the performance of a generalized exceedance algorithm for detecting noise events caused by road traffic

A key question for road traffic noise management is whether prediction of human response to road traffic noise could be improved by accounting for noise events instead of, or in addition to, energy equivalent or percentile measures of noise exposure. However, there is a critical prior question: how should noise events in road traffic be measured? Even at moderate traffic flow rates, detecting and counting noise events caused by road traffic is not a trivial exercise, and as yet there is no generally accepted noise event detection algorithm. This paper investigates the performance of a generalized exceedance algorithm for detecting noise events, constructed on the basis of the literature on noise events caused by road traffic. For this purpose, a microscopic traffic simulation model, coupled to an emission model that accounts for distributions of sound power levels of individual vehicles, is used to simulate one-hour time histories of the noise level in the proximity of a roadway, for an exhaustive set of traffic flow/composition and propagation distance conditions in unshielded locations. The validity and reliability of the number of noise events detected by the generalized algorithm in these one-hour time histories is then evaluated for a range of algorithm parameter sets. By discarding parameter sets that do not result in an algorithm that returns valid or reliable counts, and by examining redundancy in the remaining ones, a small number of representative parameter sets is identified, which may prove useful in the construction of event-based indicators supplementary to energy-equivalent measures of road traffic noise.

Noise-induced hearing loss: what South African mineworkers know

Purpose. The current study aimed to investigate the knowledge of mineworkers regarding noise-induced hearing loss in the South African gold and non-ferrous mining subsectors. Method. A descriptive research design was adopted. Semi-structured interviews were conducted with 90 participants who comprised managers, supervisors and miners. Data were analysed qualitatively. Results. The majority of participants (97%) acknowledged working in a noisy environment and demonstrated knowledge of the consequences of this exposure on their hearing function. Although all but one participant indicated having known the importance of using hearing protection devices (HPDs), less than 50% reported consistent use of HPDs. This highlights gaps in education and training, as well as implementation monitoring. All participants reported knowledge regarding the importance of hearing monitoring, but a lack of understanding of their test results. Conclusions. Current findings contribute towards evidence regarding internal barriers to effective application of best practice in hearing conservation programmes (HCPs). Findings highlight the important role of occupational audiologists in South African mines and the need for individualized education during medical surveillance to enhance efficacy of HCPs. Comprehensive education and training programmes regarding noise exposure and exposure measurements with consistent HPD efficiency assessments are recommendations emanating from these findings.

Measurement of low-frequency noise during CNC machining and its assessment

The aim of the paper is to point out the necessity to measure noise exposure by means of weighting filter Z, not only weighting filter A, which is prescribed by the standard. The measurement in the paper confirms the various acoustic pressure levels using weighting filter A and weighting filter Z at a low-frequency from 16 Hz to a frequency of 100 Hz. Such measurements suggest that the way in which this noise is evaluated must be adjusted. Due to the risks of exposure to excessive noise, the legislation prescribes regular measurement of permissible noise levels. European legislation and technical standards (e.g. ISO 1996) prescribe “weighting A” in case of such noise. However, this does not respect the energetic effect of sound on the auditory organ, as well as the neuropsychic and cardiovascular system of humans and sensory-motor functions. Experiments and research show that when evaluating low-frequency sounds with strong acoustic energy, the evaluation procedures should be adjusted to the impact of real acoustic energy affecting humans.The noise exposure measurement described in the paper was carried out during production of cars parts that were machined by a CNC machine. The measurement results showed that when weighting filter Z was used, the acoustic pressure levels were higher than those measured by weighting filter A by 22.8 dB. The measured equivalent LZeq values for the given work activity were 73.4 dB(Z) and LAeq was 50.6 dB(A). At low frequencies, this difference was the most pronounced, up to several times higher.

Evidence of noise-induced subclinical hearing loss using auditory brainstem responses and objective measures of noise exposure in humans

Exposure to loud sound places the auditory system at considerable risk, especially when the exposure is routine. The current study examined the impact of routine auditory overexposure in young human adults with clinically-normal audiometric thresholds by measuring the auditory brainstem response (ABR), an electrophysiological measure of peripheral and central auditory processing. Sound exposure was measured objectively with body-worn noise dosimeters over a week. Participants were divided into low-exposure and high-exposure groups, with the low-exposure group having an average daily noise exposure dose of ∼11% of the recommended exposure limit compared to the high-exposure group average of nearly 500%. Compared to the low-exposure group, the high-exposure group had delayed ABRs to suprathreshold click stimuli and this prolongation was evident at ABR waves I and III but strongest for V. When peripheral differences were corrected using the I-V interpeak latency, the high-exposure group showed greater taxation at faster stimulus presentation rates than the low-exposure group, suggestive of neural conduction inefficiencies within central auditory structures. Our findings are consistent with the hypothesis that auditory overexposure affects peripheral and central auditory structures even before changes are evident on standard audiometry. We discuss our findings within the context of the larger debate on the mechanisms and manifestations of subclinical hearing loss.

The Noise Exposure Structured Interview (NESI): An Instrument for the Comprehensive Estimation of Lifetime Noise Exposure.

Lifetime noise exposure is generally quantified by self-report. The accuracy of retrospective self-report is limited by respondent recall but is also bound to be influenced by reporting procedures. Such procedures are of variable quality in current measures of lifetime noise exposure, and off-the-shelf instruments are not readily available. The Noise Exposure Structured Interview (NESI) represents an attempt to draw together some of the stronger elements of existing procedures and to provide solutions to their outstanding limitations. Reporting is not restricted to prespecified exposure activities and instead encompasses all activities that the respondent has experienced as noisy (defined based on sound level estimated from vocal effort). Changing exposure habits over time are reported by dividing the lifespan into discrete periods in which exposure habits were approximately stable, with life milestones used to aid recall. Exposure duration, sound level, and use of hearing protection are reported for each life period separately. Simple-to-follow methods are provided for the estimation of free-field sound level, the sound level emitted by personal listening devices, and the attenuation provided by hearing protective equipment. An energy-based means of combining the resulting data is supplied, along with a primarily energy-based method for incorporating firearm-noise exposure. Finally, the NESI acknowledges the need of some users to tailor the procedures; this flexibility is afforded, and reasonable modifications are described. Competency needs of new users are addressed through detailed interview instructions (including troubleshooting tips) and a demonstration video. Limited evaluation data are available, and future efforts at evaluation are proposed.

Development of a Job Exposure Matrix for Noise in the Swedish Soft Tissue Paper Industry.

Noise exposure is a common occupational hazard, but has not been sufficiently characterized in paper mills. We developed a job-exposure matrix (JEM) for noise exposure for use in estimating exposures among Swedish soft tissue paper mill workers. We used a combination of area and personal dosimetry noise exposure measurements made at four soft tissue paper mills by industry and research staff between 1977 and 2013 to estimate noise exposures by department, location, and job title. We then utilized these estimates, in conjunction with information on process and facility changes and use of hearing protection collected via focus groups, to create a seven-category, semi-quantitative JEM for all departments, locations, and job titles spanning the years 1940-2010. The results of the 1157 area and personal dosimetry noise measurements indicated that noise levels have generally declined in Swedish paper mills over time, though these changes have been neither uniform nor monotonic within or across the four mills. Focus group results indicated that use of hearing protection has generally increased over time. The noise JEM totals 1917 cells, with each cell representing a unique combination of operation, job title, and single year. We estimated that ~50% of workers at the four mills assessed were exposed at or above the Swedish 8-h average noise exposure limit of an 85 dBA at the conclusion of the study period in 2010. Our results highlight the continuing need for hearing loss prevention and noise control efforts at these and similar mills, and the completed JEM now represents a tool for use in epidemiological studies of noise-related health outcomes.

Hidden Hearing Injury: The Emerging Science and Military Relevance of Cochlear Synaptopathy.

The phenomenon recently described as "hidden hearing loss" was the subject of a meeting co-hosted by the Department of Defense Hearing Center of Excellence and MIT Lincoln Laboratory to consider the potential relevance of noise-related synaptopathic injury to military settings and performance, service-related injury scenarios, and military medical priorities. Participants included approximately 50 researchers and subject matter experts from academic, federal, and military laboratories. Here we present a synthesis of discussion topics and concerns, as well as specific research objectives identified to develop militarily relevant knowledge. We consider findings from studies to date that have demonstrated cochlear synaptopathy and neurodegenerative processes apparently linked to noise exposure in animal models. We explore the potential relevance of these findings to the prediction and prevention of military hearing injuries, and to comorbid injuries in the neurological domain. Noise-induced cochlear synaptopathic injury is not detected by conventional audiometric assessment of threshold sensitivity. Animal studies suggest there may be a generous window of opportunity for intervention to mitigate or prevent cochlear neurodegenerative processes, e.g., by administration of neurotrophins or antioxidants. However, it is not yet known if the mechanisms that underlie "hidden hearing loss" also occur in human beings or, if so, how to identify them early, and how and when to intervene. Neurological injuries resulting from noise exposures via the auditory system have potentially significant implications for military Service Member performance, long-term Veteran health, and noise exposure standards. Mediated via auditory pathways, such injuries have possible relationship to clinical impairments including speech perception, and may be a largely overlooked contributor to cognitive symptoms associated with other military service-related injuries such as blast exposure and brain trauma. The potential health and performance consequences of noise-induced cochlear synaptopathic injury are easily overlooked, especially if it is assumed that hearing threshold sensitivity loss is the major concern. There should be a renewed impetus to further characterize and model synaptopathic mechanisms of auditory injury; study its potential impact on human auditory function, cognition, and performance metrics of military relevance; and develop solutions for auditory protection (including noise dosimetry) and treatment if appropriate following noise or blast exposure in military scenarios. We identify specific problems, solution objectives, and research objectives. Recommended research calls for a multidisciplinary approach to address cochlear nerve synaptopathy, central (brain) dysfunction, noise exposure measurement and metrics, and clinical assessment.

Community response to construction noise in three central cities of Zhejiang province, China

As a common source of environmental noise in China and many developing countries worldwide, construction work provokes many complaints and deterioration in acoustic climate quality. This paper describes research to obtain an improved understanding of people's community response to, and evaluation of, construction noise in three central cities of Zhejiang province, China. This involved carrying out a social survey using standard questionnaires developed by the International Commission on Biological Effects of Noise (ICBEN). A dose-response relationship model is established using a quadratic polynomial regression analysis based on construction noise exposure measurements from 40 construction sites in Hangzhou, Ningbo and Wenzhou.The results of the study indicate that the majority of people have a negative attitude to construction noise; the noise ranges between 60 dB and 80 dB (compared with 50 dB–70 dB traffic noise in Tianjin), with the percentage of highly annoyed people affected increasing from 15%-20% to 30%–40% over the range. There also different levels of annoyance depending on the time of day, and the location and activities of those affected. Other cultural differences are also apparent both between Ningbo/Wenzhou and the more urbane citizens of Hangzhou, and the Chinese people and their more noise-tolerant EU and Vietnam counterparts.The findings of this study provide a new perspective for the study of construction noise that can help local governments have an improved understanding of how residents react to construction noise for the purpose of selecting construction noise-mitigation projects and introducing construction noise-control regulations.