Calculated Noise Levels Research Articles

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.

Comparison of results from road noise measurements and road noise calculation methods CNOSSOS-EU, Nord2000Road and Nord96

To gain more experience with CNOSSOS-EU a series of road noise measurements was conducted to compare actual measurements with calculated results. These measurements were taken along an urban four-lane motorway in Oslo with speed limit 70 km/h, during the summer of 2023, in accordance with Norwegian standard NS 8174-02 as far as practicable. The resulting road noise levels LAeq, 24t were compared to the calculated levels obtained using three different methods for road traffic: Nord96, Nord2000 and CNOSSOS-EU. The measurement locations were chosen to span from open areas to more complex situations. The key finding is that the calculated noise levels consistently exceed the measured levels across all three calculation methods. Interestingly, the discrepancies between measured and calculated levels are highest in open areas and tend to diminish in more complex scenarios. Specifically, Nord2000 yields higher levels than Nord96 and CNOSSOS-EU, although the differences between Nord2000 and the other two methods become negligible in complex situations. Additionally, the transition in software from Cadna/A to SoundPLAN influences the results. These findings indicate a need for further investigation into source data for vehicles, and potentially road surfaces.

Assessing the ecological impact of industrial noise pollution on wildlife behavior in Okomu Forest Reserve, Nigeria

The study identified sources and established the levels of industrial noise in Okomu National Park with the aim of determining the impact of industrial noise pollution on wildlife in Okomu National Park. It also modelled propagation of ambient noise levels associated with the established levels as well as determined impacts of ambient noise obtained from industrial activities on wildlife of the National Park. Locations of identified sources of noise including industrial activities sources relative to the National Park were established and digital maps of the identified locations was generated. Ambient noise levels were obtained for wildlife populations around selected locations. Noise assignment was done at each of the hotspots for industrial activity that had been detected using EXTEC sensors. The average noise levels from the industrial sources were then processed into a model using NoiseMap. The calculated noise levels from identified sources were represented with contour map. The results identified sources of noise pollution in Okomu Forest Reserve as: Okomu Palm Oil processing mill and Michelin rubber Processing factory. The result showed that activities within these industries produced at least 40 dB during the period of study. The effects of noise from the industrial activities forced the migration of the animals out of the National Park to favourable habitats with less noise sources. The retreat of the animals caused energy depletion and reduced the chances of their survival. The study concluded that industrial activities such as Palm oil processing, rubber processing, logging and vehicles are a major source of noise pollution that threatens the sustainability of wildlife in the Okomu National Park.

Discrete Distribution Model of Ship Noise Source in Shipping Channel

Ship noise plays an important role in low-frequency ocean ambient noise. With the increasingly busy sea traffic, the randomness of the spatiotemporal distribution characteristics of ship noise is also increasing. However, most ships sail in a relatively fixed range in different sea areas. Most of the previous studies assumed that the ship noise sources in shipping channel satisfy a uniformly distribution, actually all kinds of large ships are not uniformly distributed in the shipping channel, and there are also many small boats distributed on the channel that contribute significantly to low-frequency ocean ambient noise. The channel within a certain sea area will be divided into different regions, and ship information (AIS) in different regions will be analyzed statistically in this paper. It is assumed that the ship noise sources in different channel regions are discrete point noise sources that obey a certain spatiotemporal statistical distribution, combined with the noise source level models of different types of ships to form a discrete source model of ship noise in shipping channel. Using the ray propagation theory considering the horizontal refraction of sound energy, the vertical distribution of the ship noise level in this sea area is calculated, and compared with the vertical noise level distribution of ship noise source uniform distribution model, the variation range of noise level vertical distribution of two models is close calculated noise level (such as maximum and minimum values) is consistent with the measured data. The discrete source model of ship noise established in this paper may provide a technical support for predicting low-frequency ambient noise characteristics near the channel.

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.

Recent situations of flight operation and noise exposure observed by the pilot noise monitors at Noi Bai International Airport in Vietnam

This paper introduces the result of data analysis on recent situations of aircraft operation and noise exposure at Noi Bai International Airport (NIA), using observations by the pilot noise monitoring equipment installed in 2019 under a cooperation project on airport environment preservation and aircraft noise monitoring in Vietnam. The results of the noise monitoring over the period from 2019 to 2023 reflect the significant changes in aircraft operation at NIA due to the pandemic of COVID-19. Noise exposure decreased after the epidemic outbreak, with a significant drop at the time when the government ordered travel restrictions, and gradually recovered under a new normal context. The result of data analysis suggests the degree of change in the sound environment in the vicinity of NIA under the different scenarios of aircraft operation. It also provides us with the information necessary to create noise prediction maps. The level of noise exposure observed at each monitoring station was largely in line with the calculated noise levels. Besides, analysis of aircraft operation and noise exposure situations by period revealed that the level of noise exposure varies with the time of day. Additionally, the analysis raises concerns about the impact of nighttime noise, which may disrupt the sleep of residents living near the NIA.

Open-source software to calculate industrial, railway, and road traffic noise

Dutch noise legislation provides instructions and formulas to calculate noise exposure levels on a similar level to Cnossos or ISO 9613-2. The instructions are implemented in commercially available software packages. Each implementation includes a pathfinder and a sound propagation/attenuation module. Whilst the attenuation is described in detail in the legislation, the pathfinder is not and its design is left to the software company. Currently there are only proprietary, closed-source implementations available. That is going to change. Based on a previously closed-source solution, we are working towards an open-source, national implementation to calculate noise levels based on 3D model input. We implemented the updated Dutch calculation method and improved the pathfinder. For example, this now includes sloped barriers. Only the calculation core is part of this project: the development of a graphical user interface is not planned, but can be provided by others. Also, other implementations of the Dutch noise calculation directive can still co-exist next to our open-source solution, since the legislation only specifies the instructions and has no requisite for a specific implementation. In this paper we will discuss the open-source implementation, the impact on noise modelling in the Netherlands and its potential applications outside of the Netherlands.

Three-dimensional visualisation of traffic noise based on the Henk de-Klujijver model

Abstract Visualisation of road traffic noise is vital for traffic noise planning policies. Several factors affect the noise from road traffic with physical and environmental conditions. Collecting noise levels around the world is not a possible task. Therefore, calculating noise levels by a valid noise model, and spatial interpolations, is prime to traffic noise visualisation. In this study, the Henk de Klujijver noise model is used. Designing noise observation points (Nops) embedding with a three-dimensional (3D) building model and identifying the best suitable spatial interpolation are important to visualise the traffic noise accurately. However, interpolating noise in 3D space (vertical direction) is a more complex process than interpolating in two-dimensional (2D) space. Flat triangles should be eliminated in the vertical direction. Therefore, the structure of Nop has a major influence on spatial interpolation. Triangular Irregular Network (TIN) interpolation is more accurate for visualising traffic noise as 3D noise contours than Inverse Distance Weighted and kriging. Although kriging is vital to visualise noise as raster formats in 2D space. The 3D kriging in Empirical Bayesian shows a 3D voxel visualisation with higher accuracy than 3D TIN noise contours.

A composite approach to modelling aircraft noise contours for improved annoyance prediction

Aircraft noise contours are an essential tool for land-use planning around aerodromes. They are intended as predictors of the effects of aircraft noise on communities, mainly in terms of aircraft noise annoyance. In practicality, these contours often fail to encompass a large percentage of the severely annoyed population at the prescribed noise thresholds for the onset of significant annoyance. This paper proposes a novel approach to modelling noise exposure contours that can improve their predictive power. Using Toronto Pearson Airport as a case study, data from a 2020 noise annoyance questionnaire and calculated noise levels from 25 noise monitoring terminals were used to examine the relationships between severe annoyance and noise exposure for six different airport operational scenarios, representative of both average and alternate traffic configurations. The findings indicate that a composite scenario that models noise exposure for both average and alternate traffic configurations is more predictive of severe annoyance than an average type scenario alone.

Determining and quantifying effects of Favourable Propagation on CNOSSOS-EU Calculated Noise Levels

The United Kingdom Department for Food and Rural Affairs (Defra) commissioned a series of studies investigating the sensitivity of the CNOSSOS-EU noise assessment method. CNOSSOS-EU presents challenges in terms of input data accuracy and availability. For this reason, the studies were commissioned to support data decision making and quantify potential uncertainty in Defra's national noise model. A study was undertaken to identify approaches to quantifying the effect of favourable propagation (FP) when calculating noise levels using the CNOSSOS-EU noise assessment methodology. Literature reviews allowed the identification of two methodologies for quantifying the occurrence of FP, and their respective data requirements. Data requirements were reviewed against data available from meteorology stations across UK and a method selected. FP was calculated for met sites in England and presented in tables and in the form of meteorological roses. Analysis was then undertaken exploring the effect of including of FP on sound propagation using CNOSSOS-EU using a test model. Comparisons were then made against assuming 100% favourable and 100% homogeneous conditions to identify the importance of calculating the occurrence of FP in noise exposure data.

Impact of Ground Cover Dataset Selection on CNOSSOS-EU Calculated Levels

The United Kingdom Department for Food and Rural Affairs (Defra) commissioned a series of studies investigating the sensitivity of the CNOSSOS-EU noise assessment method. CNOSSOS-EU presents challenges in terms of input data accuracy and availability. For this reason, the studies were commissioned to support data decision making and quantify potential uncertainty in Defra's national noise model. A study was undertaken to identify how the selection of a ground cover dataset may influence calculated noise levels using the CNOSSOS-EU noise assessment method and computational load. Acoustic test models were developed incorporating prepared ground cover datasets based on CORINE Land Cover 2018, CEH Land Cover Map 2019 and OS Mastermap Topography. Noise calculations in accordance with CNOSSOS-EU were carried out for rural and urban/suburban propagation environments. A statistical analysis of the differences between each selected dataset was then undertaken. The paper discusses the findings of this analysis along with generic rules which were identified with respect to modelling ground effect using CNOSSOS-EU.

Effect of the charge-carrier–phonon interaction on the fundamental 1/f voltage noise

It is known that quantum indeterminacy sets a lower bound on the power spectrum of voltage fluctuations in any conducting medium. The low-frequency asymptotic of this bound is $\ensuremath{\sim}1/f$ in the case of freely propagating charge carriers. It is found that on account of the charge-carrier--phonon interaction, the asymptotic becomes $\ensuremath{\sim}1/{f}^{\ensuremath{\gamma}},\phantom{\rule{4pt}{0ex}}\ensuremath{\gamma}\ensuremath{\ne}1.$ Its general expression is derived in the case of charge carriers subject to the piezoelectric interaction with acoustic phonons. The sign of $(\ensuremath{\gamma}\ensuremath{-}1)$ depends on the state filling for charge carriers, so that $\ensuremath{\gamma}$ may exceed unity despite the absence of a low-frequency cutoff. It is shown that under stationary physical conditions the voltage variance grows with time as ${t}^{\ensuremath{\gamma}\ensuremath{-}1},$ in agreement with observations. It is proved that despite this growth the power spectrum is well defined and finite for $\ensuremath{\gamma}<2.\phantom{\rule{0.16em}{0ex}}\mathrm{A}$ practical attainability of the quantum bound is discussed. A comparison with the experimental data on $1/f$ noise in InGaAs quantum wells and high-temperature superconductors is made. It is demonstrated that the account of $\ensuremath{\gamma}\ensuremath{\ne}1$ brings the calculated noise levels uniformly within an order of magnitude of the measured. This holds true whether the voltage fluctuations are measured along or across the electric current, though the observed noise levels in the two cases are significantly different.

Modeling the Influence of Roundabout Deflection on Its Efficiency as a Noise Abatement Measure

Challenges that emerge in roundabout design are mostly related to space constrictions and provision of appropriate deflection around the central island. This can result in speed profiles on roundabouts that might reduce their potential as a noise abatement measure. Because of this, the impact of a roundabout on noise levels and its applicability as a traffic calming device and a noise abatement measure should be investigated in the early design stage, by modeling noise levels. In this paper, the following hypothesis is tested: vehicle movement trajectories, defined during the fastest path performance check in roundabout early design phase, can be used as the road traffic noise sources when modeling noise at roundabouts using static noise model. This procedure (1) simplifies the preparation of the noise model, (2) results in a model that is closer to the real-world in terms of traffic flow conditions, (3) allows the noise calculations in the early stages of roundabout design, and (4) includes the influence of roundabout deflection on calculated noise levels. The abovementioned simplifications of the road traffic noise modeling process should encourage the optimization of roundabout geometry in terms of its noise reduction capabilities in the preliminary design phase of these intersections.

Noise of underwater explosions in the North Sea. A comparison of experimental data and model predictions.

An analysis is presented of sound measurements performed near two detonations of unexploded ordnance (UXO) in the North Sea, at distances ranging from 1.5 to 12 km. The charge masses of the detonations were 325 and 140 kg TNT equivalent. The objective of the measurements was to improve the accuracy of model predictions of the area where UXO detonations affect harbour porpoises in the North Sea. For the predictions, an explosion emission model is combined with a shallow-water propagation model. The prediction model was previously validated for distances up to 2 km. The measurements reported here allowed validation up to a distance of 12 km. The measured levels and spectra are well explained by the model calculations. The model results depend strongly on the sea sediment layering. The propagation of high-frequency components appears to be affected primarily by the silty top layer, while low-frequency components are affected also by deeper sandy layers. Measured and calculated noise levels are used to determine permanent-threshold-shift effect distances for harbour porpoises (Phocoena phocoena). Values ranging from 2 to 6 km are found for the two detonations.

THE INFLUENCE OF DYNAMIC PHENOMENA IN GEAR REDUCTIONS OF BRIDGE CRANES ON THE INTENSITY OF ACOUSTIC RADIATION

This article aims to research the generation of a vibration and noise by reduction gear to find opoportunities to reduce vibration, calculate noise levels, and develop engineering practices for the calculation of noise levels.

Implementation of noise data into building information model (BIM) to reduce noise in the environment and at workplace

Noise mapping is the best way to present information on the acoustic pollution. To design noise protection measures, authors use modern software package SoundPLAN, which is based on the up-to-date normative documentation and scientific researches. The program allows importing the results of calculations to Autodesk tools. Improving the efficiency of the noise protection design process is executed through the implementation of building information modeling (BIM). Data exchange between SoundPLAN, AutoCAD 3D or Revit and Navisworks is used in the development of building information model. In the article we present a new approach to noise reduction through implementation of noise data into the overall information model of the infrastructure or building project. BIM helps to track the collision of calculated noise levels with residential buildings, protected premises and workplaces. It lays a basis for the sound proof allocation of workplaces and development of protection measures. BIM also serves as a support tool for the design process of sound protection barriers, since it helps to avoid interconnection of noise barriers basement with engineering networks or paste a barrier in the proper place to provide its efficiency.

IMPLEMENTATION OF NOISE DATA INTO BUILDING INFORMATION MODEL FOR TRANSPORT AND UNDUSTRIAL NOISE REDUCTION

Noise mapping is the best way to present information on the acoustic pollution. To design noise protection measures, authors use modern software package SoundPLAN, which is based on the up-to-date normative documentation and scientific researches. The program allows importing the results of calculations to Autodesk tools. Improving the efficiency of the noise protection design process is executed through the implementation of building information modeling (BIM). Data exchange between SoundPLAN, AutoCAD 3D or Revit and Navisworks is used in the development of building information model. In the article we present a new approach to noise reduction through implementation of noise data into the overall information model of the infrastructure or building project. BIM helps to track the collision of calculated noise levels with residential buildings, protected premises and work places. It lays a basis for the sound proof allocation of work places and development of protection measures. BIM also serves as a support tool for the design process of sound protection barriers, since it helps to avoid interconnection of noise barriers basement with engineering networks or paste a barrier in the proper place to provide its efficiency.

Noise and Acoustic Fatigue Analysis in Valves (Case Study of Noise Analysis and Reduction for a 12″ × 10″ Pressure Safety Valve)

Safety and instrument engineers regularly analyze the noise in different types of valves to reduce its effect in sectors of the oil and gas industry such as offshore, refineries, and petrochemical plants. This paper reviews the mitigation strategies used to reduce acoustic fatigue and the risk of hearing damage from pressure safety valves and control valves used in piping systems. These two types of valves can generate high-frequency acoustical energy downstream of the valves. Different strategies are used to mitigate noise levels, such as installation of low-noise valves, process optimization to reduce the flow or delta pressure across valves, changing the valve design, acoustic piping installation, and increasing piping thickness. This paper discusses a case study of a noise calculation for a 12″ × 10″ pressure safety valve (PSV) at 1 m and 30 meters from the PSV discharge. The calculated noise level based on API 521, the standard for PSVs, has been compared with the maximum allowable noise limit from PSVs. The maximum allowable noise limit is calculated based on the NORSOK L-002 standard developed by Standards Norway. If the calculated noise level based on API 521 exceeds the allowable or acceptable noise limit based on NORSOK standards, the piping wall thickness should be increased to mitigate the risk of acoustic fatigue. The 12″ 6MO piping wall thickness outlet line of PSV is calculated based on the ASME B31.3 process piping code. The outlet pipe from PSV is in 6MO UNS 31254 material, which is expensive. Fortunately, there is no need to increase the piping wall thickness if the calculated noise based on the API 521 standard is within the accepted noise limit in the NORSOK standard.

Technical Approaches to Developing a Highway Noise Programmatic Agreement

There are many instances in which noise studies were completed for projects that were not likely to result in noise impacts. In this paper, the authors provide an analysis from their conducted study, validating a programmatic agreement (PA) intended to reduce the need for unnecessary noise analyses. The technical study considered a range of average daily traffic volumes between 500 and 28,000. The parameters of the PA rely solely on calculated noise levels at specified traffic volume, mix, speed, and roadway designs using the FHWA Traffic Noise Model (TNM®) version 2.5 to develop a series of TNM cases, testing impact thresholds at various speed and slope conditions. Using this data, the authors developed a regression model to enable the PA expansion and provide answers for a finer grid of traffic volume. Using the regression model results, the authors will develop a graphical user interface to assess project eligibility for the PA.

A Comparison of Finite Element Analysis (With Additional Aspects) For Predicting the Noise and Vibration for Railway Project in Malaysia

This paper is about predicting the noise and vibrations for railways project in Malaysia by using Finite Element Analysis method. In recent years, Malaysia is massively developing railways industry. This has created a great awareness in the public, regarding noise and vibration from railways trains during operations are generated from the rolling interaction of the wheels with the rails. Additional noise may be generated from brake squeals during braking at the stations and curved segments of the rail alignments. Over the years, it is relatively easy to measure the acoustic sound power of a train and to calculate noise levels. However, it would be advantageous to be able to reliably and efficiently predict the noise and vibration impact resulting from proposed railways projects. Comprehensive noise and vibration shall be predicted to determine noise and vibration levels along the entire track alignment to ensure that noise and vibration levels shall comply with Malaysia Department of Environment (DOE) approved limits. The result of analyses can be used to identify and to design noise and vibration mitigation measures for the entire railway project. Several methods have evolved to predict noise and vibration from various operational sources, but their suitability for prediction of noise and vibration from railways trains is not well known and has not yet been thoroughly tested. This study document finite element analysis undertaken for the noise and vibration aspects of the viaduct design of the railways track. Data and inputs for finite element model and analysis are including the aspect of “Geometry, atmospheric, ground effect, analysis type and boundary conditions”, as mentioned by Makarewicz (1998) and Lamancusa (2009). A comparison of finite element model and analysis will be conducted by adding the additional aspects of “Material properties and applied loads”, which to be determined as better accuracy of predicting noise and vibration from railways train.