Cumulative Noise Levels Research Articles

Assessment of noise complaints as an indicator of long-term effects of aircraft noise on communities surrounding aerodromes

Aircraft noise is considered by many as the most burdensome part of aircraft operations. Communities neighbouring airports often express concerns about the possible health effects of chronic exposure to noise. To quantify the long-term effects of environmental noise exposure, researchers often use the metric of annoyance. Annoyance is widely considered to be the most well-corroborated health effect of aircraft noise and a moderating factor for other suspected health effects. Annoyance can also be correlated to average cumulative noise levels, such that higher levels of chronic noise likely evoke higher levels of annoyance within the population. Annoyance data is typically collected using extensive surveys and/or interviews, which are costly and time-consuming. In the absence of annoyance data, complaints are often used as a proxy for annoyance. This research used complaint, noise and annoyance data to demonstrate that complaints do not equate to annoyance, nor do they correlate to cumulative noise metrics. Thus, while complaint data may prove useful in analyzing short-term response to operations, it should not be relied upon for the assessment of long-term impacts from aircraft noise exposure, nor should it be used to direct noise and annoyance mitigation initiatives.

Association between occupational noise and obesity: a retrospective cohort study in China.

To determine the relationship between occupational noise, and obesity and body mass index (BMI) changes. Baseline data were collected from participants (n = 1264) who were followed for 6years in a retrospective study. The noise exposure level (LAeq,8h) was determined by equivalent continuous weighted sound pressure levels using the fixed-point surveillance method for noise monitoring. The cumulative noise exposure (CNE) level was determined using the equal energy formula, which is based on exposure history and level. The incidence of obesity at low (RR = 2.364, 95% CI 1.123-4.739]), medium (RR = 3.921, 95% CI 1.946-7.347]), high (RR = 5.242, 95% CI 2.642-9.208]), and severe noise levels (RR = 9.322, 95% CI 5.341-14.428]) was higher risk than the LAeq,8h control level. The risk of obesity among participants exposed to low (RR = 2.957, 95% CI 1.441-6.068]) and high cumulative noise levels (RR = 7.226, 95% CI 3.623-14.415]) was greater than the CNE control level. For every 1dB(A) increase in LAeq,8h, the BMI increased by 0.063kg/m2 (95% CI 0.055-0.071], SE = 0.004). For every 1dB(A) increase in the CNE, the BMI increased by 0.102kg/m2 (95% CI 0.090-0.113], SE = 0.006). Occupational noise is related to the incidence of obesity. The occupational noise level and occupational noise cumulative level were shown to be positively correlated with an increase in BMI.

Cumulative Noise Exposure and Perceived Effects: A Comparative Study Among Different Occupational Groups in Kolkata.

Adverse short-term and long-term health effects following a high level of noise have been established. The current study aims to find the relationship of these effects with an environment-specific level of noise exposure. A comparative cross-sectional study was conducted among 50 auto-rickshaw drivers and 51 age-matched service-sector employees. The peak average noise exposure in decibels (dB) was measured. The duration of exposure and response regarding perceptions following noise exposure was assessed through a pre-designed pre-tested semi-structured questionnaire. The mean age of the participants was 42.24 (±13.72) years. Among the auto-rickshaw drivers, 82% perceived stress, 64% had hearing difficulty, and 74% complained of lack of sleep following exposure to a high level of noise. However, the perceptions were comparable among the comparison group and the differences were not statistically significant. The mean average peak level of noise exposure among drivers and their comparison group was 91.64 (±7.37) dB and 91.98 (± 8.06) dB, respectively, but were not different statistically. Around 52.94% of the service-sector respondents and 48% of the drivers were exposed to the lower cumulative noise levels. Those having a higher level of cumulative noise exposure, had a higher odds of feeling irritated (Odds ratio [OR]: 2.182, 95% confidence interval [CI]: 0.845-5.636), feeling stressed (OR: 5.805, 95% CI: 1.552-21.708), having palpitation (OR: 3.694, 95% CI: 1.264-10.793), and lack of sleep (OR: 3.020, 95% CI: 1.006-9.066). Stress and lack of sleep were the most important perceived effects of noise exposure. The exposures to the higher cumulative noise level in specified groups were more important in relation to quantifying perceived symptoms than the average peak noise level.

Impact of Aircraft Delays on Population Noise Exposure in Airport's Surroundings.

The motivation behind this research was to analyse the consequences of aircraft operations’ delays on cumulative noise levels produced upon the neighbouring communities and to estimate the relative change in the number of people annoyed by aircraft noise. Many studies showed that residents’ reactions to abrupt changes in noise exposure were more intense compared to the anticipated ones. Aircraft delays may cause such abrupt changes in noise exposure by increasing the traffic in some periods compared to the scheduled traffic. The methodology applied includes noise contour development for two different scenarios for intervals where aircraft delays occur. Only delays connected with the Total Airport Management (TAM) were analysed, since such delays can be influenced by airports. The first scenario considered the influence of aircraft operations on population noise exposure without TAM delays, whereas the second one included all delayed flights (actual traffic). The proposed method was tested through case studies of three southeast European airports. The results showed that the highest potential of decrease in the number of people annoyed by the noise was recorded at Niš Airport (59%), followed by Zadar Airport (49%) and Sarajevo Airport (25%). Similar results were obtained in the context of highly annoyed people.

System Noise Assessment and Uncertainty Analysis of a Conceptual Supersonic Aircraft

This paper describes a system noise assessment of a conceptual supersonic aircraft called the NASA 55t Supersonic Technology Concept Aeroplane (STCA), its prediction uncertainty, and related validation tests. A landing and takeoff noise (LTO) standard for supersonic aircraft is needed to realize future supersonic aircraft, and the noise impact due to the introduction of future supersonic aircraft should be analyzed to develop the standard. System noise assessments and uncertainty analyses using Monte Carlo simulation (MCS) were performed. The predicted noise levels showed good agreement with the prior study for both the benchmark case and statistics of the predictions. The predicted cumulative noise level satisfied the ICAO Chapter 4 noise standard, and its standard deviation was approximately 2 EPNdB. Moreover, sensitivity analysis using the obtained datasets revealed strong correlations with the takeoff noise for jet noise, fan exhaust noise at the flyover measurement point, and airframe trailing edge noise. Further understanding of these extracted factors, which were estimated to have a significant impact on the LTO noise, will be beneficial for the development of LTO noise standards and the design of supersonic aircraft.

Investigation and prediction of noise pollution levels from wind turbines: A case study of Nexif Energy Ben Tre wind power plant, South Vietnam

In recent years, the demand for electric power in Vietnam has increased at annual growth rates of 10% to 12%, and the challenge is to promote renewable energy sector. One of these sustainable energy sources is to harness energy from the wind through wind turbines (WTs). In fact, more wind power plants in Vietnam are continuously to be built due to the rapidly growing demand of country's industrialization and modernization process. However, a significant hindrance preventing the widespread use of WTs in Vietnam is the noise they produce, which significantly contributes to the annoyance experienced by residents living near wind farms. The prediction of noise impacts for new wind farms is one of the many aspects of the environmental impact assessment process in Vietnam as well as in the world. In addition, the determination of the 45 dBA noise contour-line is very important because it is the basis for determining the scope of the project impact according to the IFC/WB performance standards and the number of households to be relocated from the project site. The article’s main focus is therefore on the estimation and simulation of the acoustical noise produced by 18 WTs during the operation phase of Nexif Energy Ben Tre wind power plant and the background noise levels at the project site have been performed by using a combination of specific study methods such as environmental modeling (iNoise Pro modeling software), mapping and geographic information systems. The obtained results show the importance of using modeling method in quantifying the noise levels generated from 18 wind turbines of the Nexif Energy Ben Tre wind power plant met IFC standard and Vietnamese regulation on noise during day-time, but did not meet IFC standard on noise during night-time. The level of background noise measured during night-time in the project area also did not meet IFC standard. Therefore, the overall cumulative noise level exceeds the IFC standard for residential area (45 dBA only). In addition, the appropriate solutions to reduce noise levels from WTs are also proposed.

How loud is the underwater noise from operating offshore wind turbines?

Offshore wind turbines are increasingly abundant sources of underwater low frequency noise. This increase raises concern for the cumulative contribution of wind farms to the underwater soundscape and possible impact on marine ecosystems. Here, available measurements of underwater noise from different wind turbines during operation are reviewed to show that source levels are at least 10-20 dB lower than ship noise in the same frequency range. The most important factor explaining the measured sound pressure levels from wind turbines is distance to the turbines with smaller effects of wind speed and turbine size. A simple multi-turbine model demonstrates that cumulative noise levels could be elevated up to a few kilometres from a wind farm under very low ambient noise conditions. In contrast, the noise is well below ambient levels unless it is very close to the individual turbines in locations with high ambient noise from shipping or high wind speeds. The rapid increase in the number and size of offshore wind farms means that the cumulative contribution from the many turbines may be considerable and should be included in assessments for maritime spatial planning purposes as well and environmental impact assessments of individual projects.

System Noise Prediction Uncertainty Quantification for a Hybrid Wing–Body Transport Concept

Aircraft system noise prediction for advanced, unconventional concepts has undergone significant improvement over the past two decades. Prediction model uncertainty quantification is necessary to reliably assess the potential benefits of unconventional configurations, which can be outside the range of empirical models. This paper builds on previous work to improve estimates of element prediction uncertainties where the model has improved, or new validation data are available. These element-level uncertainties are propagated via a Monte Carlo method to the system level for predictions at each of the three certification points. Although the quantitative uncertainty values contained here are specific to the hybrid wing–body configuration presented, the underlying process is the same regardless of configuration. Comparisons with previous work show a reduction of 1.1 EPNdB in the 95% coverage interval of the cumulative noise level. The largest impediment for continued uncertainty reduction is the need for validation experiments and improved modeling of fan source noise, propulsion airframe aeroacoustic effects, and the Krueger flap source noise, which comprise the bulk of the uncertainty in the cumulative certification noise level.

Numerical analysis of fan noise for the NOVA boundary-layer ingestion configuration

Aim of this paper is to investigate the effects of the turbulent flow developing over a fuselage on fan noise for BLI embedded propulsion systems. Such configurations can suffer from inlet flow distortions and ingestion of turbulence at the fan plane with consequent impact on both broadband and tonal fan noise. The analysis is performed on a modified version of the Low-Noise NASA SDT fan-stage integrated into the ONERA NOVA fuselage in order to reproduce the NOVA BLI configuration. The numerical flow solution is obtained by solving the explicit, transient and compressible lattice-Boltzmann equation implemented in the high-fidelity CFD/CAA solver Simulia PowerFLOW®. The acoustic far-field is computed by using the Ffowcs-Williams & Hawkings integral solution applied to a permeable surface. All simulations are performed for an operating condition representative of a take-off with power cut-back. Installation effects due to the BLI configuration are quantified by comparison with an isolated configuration of the modified Low-Noise SDT fan-stage at the same operating condition. It is found that the BLI fan-stage, which is not optimal, is characterized by strong azimuthal fan blade loading unsteadiness, less axisymmetric and coherent rotor wake tangential velocity variations and higher levels of in-plane velocity fluctuations compared to the isolated engine. This resulted in no distinct tonal components and higher broadband levels in the far-field noise spectra, as well as in an increment of cumulative noise levels up to 18 EPNdB. This study, which represents the first high-fidelity CFD/CAA simulation of a full-scale aircraft geometry comprehensive of a BLI fan/OGV, provides with a clear understanding of the change of the noise sources in BLI integrated configurations.

Marine Noise Budgets in Practice

AbstractMany countries have made statutory commitments to ensure that underwater noise pollution is at levels which do not harm marine ecosystems. Nevertheless, coordinated action to manage cumulative noise levels is lacking, despite broad recognition of the risks to ecosystem health. We attribute this impasse to a lack of quantitative management targets—or “noise budgets”—which regulatory decision‐makers can work toward, and propose a framework of risk‐based noise exposure indicators which make such targets possible. These indicators employ novel noise exposure curves to quantify the proportion of a population or habitat exposed, and the associated exposure duration. This methodology facilitates both place‐based and ecosystem‐based approaches, enabling the integration of noise management into marine spatial planning, risk assessment of population‐level consequences, and cumulative effects assessment. Using data from the first international assessment of impulsive noise activity, we apply this approach to herring spawning and harbor porpoise in the North Sea.

Spatial interpolation of noise monitor levels

Continuously recording noise monitoring stations provide feedback of the noise environment at monitor locations. While this feedback is useful, it only provides information at a few point locations, and in many cases it is of interest to know the noise level(s) at the locations between and beyond noise monitoring locations. In this study, we test the accuracy of several spatial interpolation models with experimental data collected during the Strategic Environmental Research and Development Program (SERDP) Community Attitudes Towards Military Blast Noise study. These datasets include 9 months of blast noise events captured at two different study locations. In both cases, a small number of monitors (e.g., 3–9) were located over a large region of interest (e.g., 1–8 km2), thus providing realistic operational conditions. The utility of deterministic (e.g., nearest neighbor, Delaunay triangulation, thin plate splines, etc.) and stochastic (e.g., geostistical or kriging) interpolation models for estimating single-event and cumulative noise levels is examined using leave-one-out cross validation. The accuracy of each approach is assessed with the root-mean-square-error (RMSE), and we discuss the practical implications of implementing such approaches in real-time systems.

Cumulative Industrial Noise Impact on the Environment

Abstract The paper presents basic legal conditions, applicable to the calculation of cumulative noise levels in the environment with indication mainly on lack of detailed regulations both in formal and methodological approach for evaluating those levels. The paper is focused on methodological approach with the emphasison analysis of existing case studies in the industry. The main subject of the analysis is the cumulation of industrial noise sources: newly designed and existing ones, together with a proposal of accumulate other types of the noise. Evaluation of cumulative noise levels for new (designed) objects is realised by computational methods, and for existing objects, by measurements or by combination of measurement and computational methods. It is assumed that the cumulative level is an energetic sum of the rating levels for all installations and it will not exceed the limit value in a given place. For the cumulation of different noise sources, the weighting for criterion values of these sources will be applied in aggregation.

Asymmetric Hearing Loss in Chinese Workers Exposed to Complex Noise.

Evaluate the audiometric asymmetry in Chinese industrial workers and investigate the effects of noise exposure, sex, and binaural average thresholds on audiometric asymmetry. Data collected from Chinese industrial workers during a cross-sectional study were reanalyzed. Of the 1388 workers, 266 met the inclusion criteria for this study. Each subject underwent a physical examination and an otologic examination and completed a health-related questionnaire. χ and t tests were used to examine the differences between the asymmetric and symmetric hearing loss groups. One hundred thirty-one subjects (49.2%) had a binaural hearing threshold difference of 15 dB or more for at least one frequency, and there was no statistically significant difference between the left and right ears. The asymmetric hearing loss group was not exposed to higher cumulative noise levels (t = 0.522, p = 0.602), and there was no dose-response relation between asymmetry and cumulative noise levels (χ = 6.502, p = 0.165). Men were 1.849 times more likely to have asymmetry than women were (95% confidence interval, 1.051 to 3.253). Among the workers with higher high-frequency hearing thresholds, audiometric asymmetry was 1.024 times more prevalent than that among those with lower high-frequency hearing thresholds (95% confidence interval, 1.004 to 1.044). The results indicated that occupational noise exposure contributed minimally to asymmetry, whereas sex and binaural average thresholds significantly affected audiometric asymmetry. There was no evidence that the left ears were worse than the right ears.

Noise exposure and serious injury to active sawmill workers in British Columbia

BackgroundOccupational noise might increase the risk of workplace injury through a variety of mechanisms, including interference with communication and increased stress.ObjectivesThe purpose of this study was to assess the effect...

Ambient noise levels in the chemotherapy clinic

Many of the drugs used for chemotherapy treatments are known to be ototoxic, and can result in permanent hearing threshold shifts. The degree of ototoxic damage can be influenced by many factors including dosage, duration of exposure, genetics, and coadministration with other ototoxic agents. Cisplatin is known for its ototoxic effects on hearing thresholds, particularly in the high frequencies. Recent studies have indicated a synergistic relationship between Cisplatin administration and moderate to high noise level exposure starting between 70-85 dB SPL. This study measured the noise levels in the Portland Veteran's Affairs Medical Center's outpatient chemotherapy clinic. Average (LAeq) and peak (LCpeak) noise measures were recorded every minute from 7 am until 6 pm on the two busiest clinic days. Patients, visitors, and staff members filled out anonymous surveys regarding their reactions to noise levels. Cumulative noise levels were not at levels known to interact with Cisplatin for a significant period of time. Noise measurement analysis indicated that levels were at or above 70 dB SPL for less than ten minutes during the 11-hour recording window. The patient and visitor surveys indicated that both groups were unbothered by noise in the clinic. However, most staff members were bothered by or concerned about noise levels, and many felt that it caused stress and difficulty communicating on the phone.

Robust Optimization of Integrated Aircraft-Propulsion System Control to Meet Takeoff Noise Requirements of Supersonic Business Jet

The integrated aircraft-propulsion system control is considered from the point of view of the probability of meeting stringent market takeoff noise requirements to supersonic business jet (SSBJ). The probability of meeting requirements to the SSBJ cumulative noise level was considered, by taking into account the accuracy of SSBJ noise prediction models and real-life accuracy of optimal control realization. The robust optimization of integrated aircraft-propulsion system control was used to achieve maximum probability of meeting SSBJ takeoff noise requirements. For robust optimization the IOSO technology (new generation multidimensional nonlinear optimization technology) was used. The results of this paper show the Pareto set probability statement, which allows us to find the set of compromise control laws for different levels of preset probabilities. The paper presents the comparison of conventional deterministic and stochastic approaches to assess maximum probability of meeting of market noise requirements. The proposed stochastic approach to noise reduction allows us to considerably decrease the risk level in meeting future stringent noise requirements.

Community Noise Reduction of Supersonic Business Jet

The “low noise” aircraft-propulsion system control is defined in such a way as to achieve community noise reduction during takeoff and initial climb of supersonic business jet (SSBJ). The conducted low noise aircraft-propulsion system control contains special low noise propulsion system control to obtain a minimum of cumulative noise level and low noise aircraft control to obtain low noise initial flight path. The low noise control must take into account all airworthiness standards restrictions and provide the market demand requirements to SSBJ. The efficiency comparison of conventional aircraft-engine control, which is used for subsonic passenger jet and the low noise aircraft-propulsion system control is understood from the perspective of minimum noise in the community. The integrated aircraft-propulsion system control is applied to the SSBJ project with 6–10 passengers. Research has shown the technical feasibility of satisfaction of new stringent market demands on a community noise level of SSBJ.

Measurements of personal aircraft noise exposure of outdoor recreationists

The at-ear noise exposure of hikers created by sporadic aircraft overflights in an outdoor recreational setting was measured on public lands underlying an active military operations area. Cumulative noise levels for entire hikes and for shorter time intervals were compared with conventional (place-oriented) noise monitoring records. Variability in personal aircraft noise exposure, even of hikers on the same itinerary but at different times of day, was so great as to call into question the adequacy of conventional noise exposure measurement and aircraft noise exposure modeling as representations of the actual aircraft noise experience of outdoor recreationists. Distributions of closest points of approach of aircraft to hikers (derived from radar flight track information and time-stamped geo-coding of hikers’ paths) were examined as an explanatory mechanism for the variability. [Work supported by U.S. Air Force Air Combat Command.]

Precision noise dosimeter with alarm

In noise dosimeters which have been developed, either the frequency weighting networks are preselected manually or only one is incorporated. This can result in loss of precision since the noise level may increase beyond or decrease below the selected range. Secondly, most noise dosimeters need visual attendance which can result in the permissible noise dose being exceded without warning. This paper describes a new design in which the A, B, C frequency weighting networks are selected automatically depending on the noise level. Moreover, an audio alarm system included in the design can be triggered whenever the noise dose limit is reached. It has also visual displays of the cumulative noise level in decibels and the noise exposure factor so that the approach to the critical level can be observed. The dosimeter is lightweight, can be battery operated and can be worn by an industrial worker.

Physical modeling of a computer installation

Some results of a two-phase study of the physical modeling of a portion of a large data processing installation are presented. A physical model, as opposed to graphical or computational techniques, was used because of the complex diffraction and reflection effects among the small machines and surfaces that form a computer installation. During the first phase of the study, an installation was selected and a model was constructed and assessed for its adequacy. It was concluded at the end of the first phase that the model simulated the installation to within about 2 dB. This was considered adequate in evaluating changes that could affect installation noise levels. During the second phase of the study, the modeling technique was used to determine the cumulative noise levels of the data processing equipment. Emission data acquired on individual machines in a controlled acoustical environment was used to “calibrate” the model. Immission data for the multiple machine installation could then be determined at any selected position in the installation. The results obtained for several machine configurations are presented. Additional results relative to barrier effects and the prediction of individual machine noise levels will also be shown.