Actual Noise Level Research Articles

Directional wind turbine noise prediction plots and prevalence histograms for community consultation

In Australia, wind turbine noise is predicted using international standards and guidelines with a set of conservative assumptions. For example, wind turbine noise predictions using the ISO 9613-2 method are based on a scenario in which each receiver is simultaneously downwind of every wind turbine. As such, winds that are outside of the downwind direction range will result in lower wind turbine noise levels than predicted using ISO 9613-2. These predictions are also based on the assumption that each turbine is simultaneously generating their maximum noise emissions, whereas variations in winds speeds across the site will frequently result in individual turbines producing lower noise levels than assumed in the modelling. The net effect of these conservative assessment choices is that actual wind turbine noise levels would be lower than presented in noise assessments in many cases. Providing an indication of how frequently predicted noise levels would likely occur can assist community consultation and provide useful context to noise modelling data. This paper presents analysis utilising directional noise modelling to assess the effect of wind direction, combined with an analysis of historic wind records, to determine the range of predicted noise levels and how frequently they may occur.

Comparing acoustic models with measured noise levels in a Polypropylene production industrial complex

This paper presents a detailed comparison between the final noise source data, as documented in the Project Report, produced noise map during design phase, and the field-measured noise values, along with the empirically generated noise map during the plant's operational phase. The study investigates into the accuracy and reliability of the assessed noise map, evaluating its alignment with actual noise levels recorded on-site, identifies discrepancies between both the noise maps, pinpointing areas for improvement in predictive modelling. The goal is to see how well the predicted noise levels match up with the real-world situation, helping improve noise control strategies, specifically focus on noisy equipment, checking if the expected or calculated noise levels are the same with field measured values. By shedding light on these disparities, this study contributes to refining noise prediction models and improving the effectiveness of noise control measures in industrial settings.

Actual versus perceived noise levels among critical care nurses and their related adverse effects: A cross-sectional study.

Critical care nurses should help in reducing noise to improve the well-being of patients and health care providers. To measure actual noise levels in intensive care units, identify nurses' perceived irritation levels of noise sources and examine the impact of noise on nurses' work performance and well-being. This cross-sectional study was conducted from January to April 2023 at a teaching hospital's six intensive care units. It involved three phases: mapping locations for noise measurement, actual noise measurements in decibels and a cross-sectional survey to identify nurses' perceptions and the adverse effects of noise. Actual noise was measured between patients' beds, nursing stations and beside 16 noise sources for 7 days 24 h a day. For nurse perceptions, the mean of perceived irritation levels by a Likert scale for each noise source was calculated to present perceived noise levels. Ranking of noise sources according to the actual measured and perceived irritation by nurses was done based on mean values. Curve estimation regression test was used to predict the relationship between actual and perceived noise and stepwise multiple linear regression identified factors associated with noise adverse effects. The mean noise level in the intensive care units was 65.55 dB. Nurses perceived mechanical ventilator alarms as the most irritating noise. However, the mean noise measurements showed that conversations among colleagues were the primary source of noise. There was no significant predictive relationship between the actual and perceived noise. Nurses reported feeling distressed, irritable, fatigued and less productive due to noise. There was a discrepancy between actual and perceived noise levels by nurses. Perceived noise levels had more impact on nurses than actual noise. By incorporating both objective measurements and subjective perceptions into efforts aimed at reducing noise, health care providers can create quieter intensive care units.

An Experimental and Analytical Approach to Evaluate Transponder-Based Aircraft Noise Monitoring Technology

Aviation is a vital modern transportation sector connecting millions of passengers globally. Sustainable aviation development holds substantial community benefits, necessitating effective management of its environmental impacts. This paper addresses the need for an accurate and cost-effective aircraft noise monitoring model tailored to non-towered general aviation airports with limited resources for official air traffic data collection. The existing literature highlights a heavy reliance on air traffic data from control facilities in prevailing aircraft noise modeling solutions, revealing a disparity between real-world constraints and optimal practices. Our study presents a validation of a three-stage framework centered on a low-cost transponder unit, employing an innovative experimental and analytical approach to assess the model’s accuracy. An economical Automatic Dependent Surveillance-broadcast (ADS-B) receiver is deployed at Purdue University Airport (ICAO Code: KLAF) to estimate aircraft noise levels using the developed approach. Simultaneously, a physical sound meter is positioned at KLAF to capture actual acoustic noise levels, facilitating a direct comparison with the modeled data. Results demonstrate that the developed noise model accurately identifies aircraft noise events with an average error of 4.50 dBA. This suggests the viability of our low-cost noise monitoring approach as an affordable solution for non-towered general aviation airports. In addition, this paper discusses the limitations and recommendations for future research.

Validating aircraft noise models: Aviation environmental design tool at Heathrow

Aircraft noise models are fundamental tools for noise abatement, control, enforcement, evaluation, and policy-making. Validation of aircraft noise models is necessary to ensure their reliability and credibility, particularly given their significant impact on society, the economy, and public health. However, validating such models is often a complex undertaking, and an acceptable validation methodology still needs to be developed. In this study, the Federal Aviation Administration's (FAA) Aviation Environmental Design Tool (AEDT) aircraft noise model is validated by correlating the calculated and measured noise levels for a specific aircraft flying in a particular flight path at Heathrow Airport. The validation results suggest that the AEDT noise model estimates the actual noise level quite accurately for landings, with a variation less than 2 dB(A), but might be inaccurate for takeoffs for certain aircraft types, with variations reaching 10 dB(A), resulting in a considerable difference between the measured and calculated noise levels.

A Robust Noise Estimation Algorithm Based on Redundant Prediction and Local Statistics.

Blind noise level estimation is a key issue in image processing applications that helps improve the visualization and perceptual quality of images. In this paper, we propose an improved block-based noise level estimation algorithm. The proposed algorithm first extracts homogenous patches from a single noisy image using local features, obtaining the covariance matrix eigenvalues of the patches, and constructs dynamic thresholds for outlier discrimination. By analyzing the correlations between scene complexity, noise strength, and other parameters, a nonlinear discriminant coefficient regression model is fitted to accurately predict the number of redundant dimensions and calculate the actual noise level according to the statistical properties of the elements in the redundancy dimension. The experimental results show that the accuracy and robustness of the proposed algorithm are better than those of the existing noise estimation algorithms in various scenes under different noise levels. It performs well overall in terms of performance and execution speed.

ANN-based averaging scheme for damage detection of high-rise buildings under noisy conditions

Structural health monitoring (SHM) is crucial for assessing the condition of deteriorated high-rise buildings subjected to sudden and hazardous loads. This study proposes a novel averaging scheme to enhance the performance of an existing hybrid damage detection technique based on Artificial Neural Networks (ANNs). The proposed technique is validated numerically on a 30-storey building. The objective is to address the discrepancy between noise levels used during training and those present in generated modal data, thus mitigating the impact of measurement noise on damage predictions. By employing a series of ANNs trained with varying noise levels, a diverse range of predictions is obtained. These predictions are averaged to yield decisive conclusions, even when indecisive predictions outnumber decisive ones. This averaging scheme effectively reduces the influence of random noise, particularly when there is a notable disparity between the actual noise levels in measured data and statistical networks. Moreover, this study investigates the impact of the number of measurements on noise reduction, recommending approximately 100 measurements, in line with other experimental studies. Through the integration of the averaging scheme and increased measurement numbers, the ANN-based damage detection technique achieves remarkable accuracy in damage detection. Storey-level detection can be achieved when the noise levels in mode shapes reach up to 3.5 %. Additionally, the approach exhibits promising results in detecting damaged walls, with a noise threshold of up to 3 %. For damaged columns, a more modest threshold of 0.75 % suffices for light and complex damage scenarios.

Assessment of noise levels by using noise prediction modeling

The third-most dangerous type of pollution, after air and water pollution, according to the World Health Organization, is noise pollution. Brief and prolonged exposure to noise pollution can have negative consequences on people, including psychological disorders, including anxiety and depression, hypertension, hormonal imbalances, and a rise in blood pressure that can result in cardiovascular disease. The WHO estimates that up to 40% of individuals in Europe are currently exposed to loud noises. This study makes an effort to predict noise levels in and around the School of Architecture and Planning (SAP) campus using data on traffic volume and flow, vehicle speed, and geometric mean of the road. Additionally, it does a comparison between the expected and actual noise levels and offers workable noise reduction techniques. A mathematical model that takes into consideration has been used to forecast the equivalent noise level. By comparing the expected and actual noise levels, it was found that all values are beyond the permitted limits. Five different locations within SAP were used to assess the amount of noise present. The Lobby recorded the highest and lowest noise levels, respectively, at 75.63 and 74.15 dB (A). There were 73.05, 71.01, 71.81, and 70.5 dB (A) accordingly as the strongest noises in the classroom and auditorium. The maximum noise levels in the library was 63.76 and 64.54 dB (A), respectively. A maximum noise level of 75.29 and 68.14 dB (A) was recorded for the studio.

Comparison of cabin noise of turboprop and turbofan aircrafts

Turboprop aircrafts are typically used for transporting cargos and for low-capacity short-haul air transport between regional cities. The new designs of turboprop aircrafts tend to focus on noise and comfort level of the aircrafts. Although turboprop aircrafts are known to have relatively higher cabin noise, there are limited reported studies in the open literature examining the actual cabin noise level in commercial flights. In this study, the cabin noise of the ATR 72-500 turboprop aircraft was examined and compared with that of the Bombardier CRJ 900 turbofan aircraft during actual commercial flights. Both are passenger planes which are designed to carry fewer than 100 passengers and are deemed to be a more compatible comparison. Both are single isle aircraft with two seats on each side of the isle. The Bombardier CRJ 900 is found to have a lower cabin noise in terms of both dBA and dBC for both taxing and cruising. As the average equivalent continuous sound pressure level (Leq) for cabin noise is found to be well below 85 dBA, there is no risk of exceeding the daily exposure to noise of 85 dBA for eight hours under the National Institute for Occupational Safety & Health (NIOSH) regulation. However, as many reported studies have shown that prolonged exposure to low frequency noise may lead to disorders, discomfort, sensitivity to and irritability from noise, annoyance, hearing loss, and cardiovascular diseases, there may be a need to carry out a more detailed study of the effect of low frequency noise on passengers.

Some aspects of the impact of noise on the health of the population of the city of Vladivostok

In this work, sociological, laboratory, medical and statistical research methods. The population of the city of Vladivostok was chosen as the object of the study from 2019 to 2022. For the study, the points of measurement of noise generated by a commercial port, motor transport, railway near residential buildings and social facilities located in close proximity to the noise source were determined in the conditions of the existing residential development. During the study period, 202 measurements of the actual noise level were carried out.Based on the calculations of the levels of risk to public health, the existing noise levels in the territory of the city of Vladivostok, the probability of an adverse effect from the nervous system and hearing aid is estimated as a moderate risk to health, from the cardiovascular system is close to extreme. Based on the results obtained, measures are needed to organize constant monitoring of the noise load on the residential territory of the city of Vladivostok. It is recommended to develop measures to reduce the noise load taking into account the medium and short term (1–3 years). When assessing the impact of traffic noise on the health of the population of the city of Vladivostok, within the framework of social and hygienic monitoring, it is necessary to take into account the combined effects of chemical and physical factors. Based on the results obtained, measures are needed to organize constant monitoring of the noise load on the residential territory of the city of Vladivostok.

No Effect of Forest Representations on State Anxiety, Actual and Perceived Noise

Abstract Previous research indicates that nature and nature representations might have positive effects and noise negative effects on various facets of life, such as performance, perceived life quality, and physical and mental health. In this intervention, we observed whether posters showing a representation of nature (forests) can be used to reduce actual noise, perceived noise, and state anxiety in university library users. Measurements were taken twice daily for a 5-day period pre-intervention (before posters were installed) and again during the intervention, when posters were installed. No significant differences were found for perceived or actual noise levels or for self-report state anxiety levels between pre-intervention and intervention phase. Correlations between actual and perceived noise, and actual noise and state anxiety, were small in their magnitude and non-significant, with the exception of state anxiety and perceived noise during the intervention phase, suggesting a weak positive relationship. Finally, in hierarchical linear regression models, actual and perceived (overall and talking) noise and intervention phase were non-significant predictors of state anxiety. Small effect sizes of nature representations on state anxiety, as well as actual and perceived noise, suggest posters of forests to not be an effective intervention for anxiety and actual and perceived noise reduction in a university library.

Frequency compensation for in-ear noise dosimetry

Personal noise dosimeters (PNDs) are used in the prevention of noise induced hearing loss (NIHL) by monitoring noise exposure. Exposure of a worker is typically estimated by measuring the noise level at the shoulder location and subtracting the estimated protection provided by any worn hearing protection devices. Current noise dosimeters in the marketplace are deficient because the noise level at the shoulder does not necessarily represent the noise exposure in the ear canal due to shadowing, canal resonances and other acoustical phenomena. Moreover, workers often deliberately insert earplugs to shallow canal depths to better hear their environments, and earmuff attenuation is inconsistent due to variations in head geometry. Thus, the estimated hearing protection is often in error. In-ear personal noise dosimeters (iPNDs) can solve these problems because they incorporate a microphone within a hearing protection earplug that measures the actual noise level in an ear canal. However, the acoustics of the in-ear measurement are quite different compared to the shoulder measurement, and in-ear measurements must be frequency compensated to achieve valid results. This paper discusses in-ear noise dosimetry, why frequency compensation is needed and how to compensate the microphone signal. [This work was funded by a CDC SBIR grant.]

Guidebook: how to reduce noise annoyance from road traffic

The objective of the FAMOS project was to develop a European guidebook with practical applications for the National Road Administrations on how to handle noise annoyance by non-acoustic moderators in planning of roads. When all technically feasible and economically possible measures to reduce the noise have been used, there can still be need for further reduction of the annoyance. Analyses reveal that only 1/3 of the variance in the annoyance response is caused by the noise level. 2/3 are determined by so-called non-acoustic factors. The annoyance response therefore can be altered without changes to the actual noise level. The project searched moderators that have a large impact on the annoyance without changing the noise level. The search was an international literature survey on annoyance studies. Moderators found were: •Expectations to and visual appearance of noise barriers •Presence of vegetation/greenery •Access to a quite façade •Neighbourhood soundscape •Attitudes towards authorities and road owners •Perceived traffic safety Experimental tests using sound walks, questionnaires and listening tests have been performed to quantify some moderators. Various methods have been used to find, extract and analyse data and turn the results into models for moderators formulated for practical use.

Moderation of people's subjective reactions to road noise

When the road administrations have used all technically feasible and economically possible measures to reduce the noise, there can still be a need for further reduction of the annoyance. Analyses reveal that only about 1/3 of the variance in the annoyance response is caused by the noise level itself, the other 2/3 are determined by so-called non-acoustic factors. The annoyance response therefore can be altered without changes to the actual noise level. The FAMOS project quantify how different factors modify people's subjective reactions to traffic noise. A literature survey has been carried out and experimental tests using sound walks, questionnaires and listening tests have been performed. The result was a European guidebook with practical applications for the National Road Administrations on how to handle noise annoyance by non-acoustic moderators in planning of roads etc.

The Possibility of Providing Acoustic Comfort in Hotel Rooms as an Element of Sustainable Development

The noise problem in hotel rooms is strictly connected to noise generated by heating, ventilating, and air conditioning (HVAC) devices. Hospitality industry companies in many countries have specific requirements and monitor the noise level with technical equipment inside the hotel room. To ensure an adequately low level of noise from the HVAC system, proper calculations and tests are performed before the final application of the system in the hotel room. One of the best methods for assessing the noise level from HVAC devices in hotel rooms is to create a testing room (mock-up) in a certain available space, e.g., in a warehouse, and to perform appropriate standard measurements for the noise level. This method is a popular choice in the hotel industry because the noise level can not only be verified, but also, the installation and operation of the HVAC system inside the room can be checked. The main factors in choosing the space in which the mock-up will be made are availability and appropriate volume. It is not always possible to provide a hall space with a very low background level of noise. This article shows that the selection of a mock-up space is also determined by the noise level in the selected space. The background noise level—thus, the noise level in the mock-up room—must be low enough to be able to reliably measure the noise level from the HVAC equipment to avoid the phenomenon of acoustic masking by other noise sources (background noise) not related to the measurement. Background noise at too high a level will lead to invalidation of the measurement results or overestimation of the actual noise level in the room from the tested HVAC devices. In this study, background noise level measurements made in the testing rooms are described. The results are discussed, and a conclusion is drawn.

Emission of Structural Noise of Tank Wagons Due to Induced Vibrations during Wagon Operation

Railway transport is considered relatively environmentally friendly in terms of energy consumption and air pollution, but it is relatively unfriendly in terms of noise pollution. Noise and vibrations propagating to railroad surrounding areas are disturbing populations. In order to minimize this noise, legislation and regulations such as TSI NOI have been adopted and research of noise and vibrations generated by railway transport has been carried out. Such research has been carried out also by our team focused on experimental investigation of noise generated by railway wagons, in this particular case on tank wagons. We simulated the structural eigenfrequencies of both bogies and tanks using FEM models to find vibrations and corresponding noise levels generated by these vibrations. Theoretical results have been compared with results of measurements of noise generated by impact hammer and visualization of noise fields using a digital acoustic camera Soundcam. Based on the simulation and measurements, principal frequency noise domains of fundamental noise sources were determined—rolling (40–63 Hz), tank (200–1000 Hz), bogie (400–1600 Hz), and wheel (800–10,000 Hz). Measurements on the railway line under real operational conditions at two train speeds have been carried out, too, to see the actual external noise levels.

131 Sleeping It Off - Are Hospital Wards Too Noisy to Allow Patient Recovery?

Abstract Aim Increased overnight noise levels are known to stimulate the release of multiple stress hormones and negatively impact upon objective and subjective sleep quality. Increasing levels of noise impairs physical and psychological recovery, and has been shown to slow wound healing, increase complication rates, and lengthen hospital admissions. Noise levels are therefore an important component of post-operative care and recovery. The purpose of this study is to document the actual noise levels experienced by patients overnight and analyse the sources of noise. Method Firstly, five-minute recordings were made during four separate hours throughout the night on two wards - one paediatric and one adult. Secondly, researchers described and categorised the sources of noise. Results The World Health Organisation (WHO) has recommended that average overnight noise levels in hospitals should not exceed 35 dB. The average recorded on the paediatric and elderly ward was 42.27 dB and 43.91 dB, with peak noise levels of 93.65 dB and 97.01 dB respectively. In every five-minute recording, there was at least one sound louder than 67 dB. Researchers identified multiple avoidable and non-avoidable causes. Conclusions The average noise level was significantly greater than the WHO recommendations. Every five-minute recording contained peak sounds of significance. Such noise levels have been linked to poor sleep, increased stress hormone release, delayed wound healing, and an increased post-operative recovery time. Many feasible solutions to address the avoidable causes of these sounds are identified. Addressing this issue is important for both medical and surgical units and is likely to improve patient outcomes.

Риски нарушения здоровья машинистов горных машин от шумо-вибрационного воздействия

Application of heavy-duty mining equipment can change the labor conditions for the employees, the intensity of the existing factors of the working environment and the labor process. Hygienic studies to assess the impact of vibration and acoustic factors on the modified EKG-8 and EKG-10 mechanical shovels and the BELAZ dump trucks showed that the actual noise and vibration levels in the operator cabins are significantly lower than those of the previously produced same types of machines. The probability of workers' complaints of the lower back pain, the risk of developing initial and moderate manifestations of the vibration disease, as well as the early signs of hearing loss and risks of its deterioration among the workers who service upgraded mining machines were calculated using the existing methods based on the obtained spectral characteristics of noise and vibration of the investigated mechanical shovels, dozers, dump trucks. The calculations show that the probability of developing the vibration disease of the 1st degree for operators of mechanical shovels within 10 years of employment decreased from 5.04% to 1.82% at vibration acceleration of 0.19 ms-2, and from 8.68% to 4.41% within 25 years of service. The risk of hearing loss among the personnel operating the upgraded machines is significantly lower and the early signs are observed after 25 or more years of work experience.

Noise prediction for infrastructure construction activities using simple prediction chart technique

Construction noise is one of the most severe pollutions in the environment and causes different physical and psychological damages to human beings. In recent years, the research archetype has transposed towards the prediction of construction noise for its adverse effects on the environment and construction workers. Hence, a reliable noise prediction method is mandatory to control, mitigate, and abate the potential hazardous noise. This study aims to validate the results between the predicted and actual noise levels of construction activities mainly on infrastructure works by using the simple prediction chart technique. This study was carried out by using the sound power levels emitted by an individual machine during different infrastructure construction activities to predict the noise levels at different locations. The results showed a high accuracy of predicted noise levels along with an absolute difference of less than 3.0 dBA and a relative error of less than 4.0 %. Besides, the predicted noise levels are reliable as the R-squared value was high. On that account, the simple prediction chart method technique has the potential to be utilized as a managerial tool that may help to reduce the negative impacts of environmental noise to the surroundings and occupational noise to the workers.

Perceived Listening Difficulty in the Classroom, Not Measured Noise Levels, Is Associated With Fatigue in Children With and Without Hearing Loss.

The purpose of this study was to examine if classroom noise levels and perceived listening difficulty were related to fatigue reported by children with and without hearing loss. Measures of classroom noise and reports of classroom listening difficulty were obtained from 79 children (ages 6-12 years) at two time points on two different school days. Forty-four children had mild to moderately severe hearing loss in at least one ear. Multiple regression analyses were conducted to evaluate if measured noise levels, perceived listening difficulty, hearing status, language abilities, or grade level would predict self-reported fatigue ratings measured using the Pediatric Quality of Life Inventory Multidimensional Fatigue Scale. Higher perceived listening difficulty was the only predictor variable that was associated with greater self-reported fatigue. Measured classroom noise levels showed no systematic relationship with fatigue ratings, suggesting that actual classroom noise levels do not contribute to increased reports of subjective fatigue. Instead, perceived challenges with listening appears to be an important factor for consideration in future work examining listening-related fatigue in children with and without hearing loss.