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This paper reviews the propagation of sound in the atmosphere to study the impact of aircraft noise, especially looking at the impact from large scale low altitude Unmanned Aircraft (UA) operations for Urban Air Mobility (UAM) in near future. Considering all potential attenuation sources and accounting for uncertainty in aircraft noise emission measurements, major noise sources in an electric Vertical Take-Off and Landing (eVTOL) aircraft are identified and experimentally characterised. Analysing the noise signature for both manned and unmanned aircraft will aid in identifying the models and tools essential for accurately predicting the aeroacoustic performance in varying atmospheric conditions. These surrogate acoustic models can be shown to be sufficient to predict the sound propagation in atmosphere without relying on elaborate computational models or the need to look up aircraft noise databases. The results derived from the analysis can potentially drive the design, test, and operation of noise certification standards for UAM and even improvement of current standards pertaining to noise for conventional aircraft operations. [ABSTRACT FROM AUTHOR]

The article discusses Maxwell's equations, which help the electromagnetic waves' propagation is described. The problem is considered within the multicomponent ion-magnetosphere model framework. Its influence on the electronic system characteristics and quality indicators s is noted. The auroral irregularities that influence radio wave scattering are considered. The Maxwell function is used as the zero approximation distribution function. Under the wave electromagnetic field influence in the ion-magnetosphere ionized gas, placed in an external uniform microwave field—an electric field, perturbation a partial electric current arises. To calculate it, the Boltzmann kinetic equation is used, which determines the charged particles' velocity distribution function perturbation spatial and temporal evolution. It is also shown that the ion-magnetosphere model can be extended to the case when a high electron density ionized gas layer appears near the aircraft. [ABSTRACT FROM AUTHOR]

Noise generated by aircraft engines has been a rising cause for concern. The use of acoustic liners for noise attenuation have been extensively studied in the past. In this study, the application of an acoustic metamaterial in a grazing flow impedance tube is explored using a simulation tool to demonstrate its efficacy in the reduction of broadband noise. Numerical simulation of the Navier-Stokes equation is performed using a commercially available multi-physics software, COMSOL. Simulation results indicate that the acoustic metamaterial liners provide a reduction of 5-15 dB in low-frequency broadband noise and thus could serve as candidate materials towards an effective aircraft noise mitigation strategy. A phenomenological theory based on the breakdown of larger eddies into smaller eddies and their eventual decay is also proposed for the observation of such reduction of noise levels. [ABSTRACT FROM AUTHOR]

Brigham Young University has been investigating best practices for recommendation to NASA in upcoming X-59 sonic thump measurements. This preparatory work has focused both on obtaining highfidelity data and standardizing signal analysis techniques for sonic thumps. Included in the research are topics such as whether to use a ground-based or elevated microphone, how to use low-noise microphones and still recover high-fidelity data at low frequencies, and estimating the uncertainty in a given measurement due to local atmospheric turbulence effects. Also included is a study of windowing techniques, zero padding, and the removal of high-frequency ambient noise contamination. [ABSTRACT FROM AUTHOR]

With the advent of the Environmental Noise Directive (END) population-level modeling of exposure to aircraft noise has increased within Europe. Present noise exposure legislation focuses on airports whereas the greatest potential to implement noise reduction technologies lies with the airlines and aircraft manufacturers. This work focuses on modeling the noise emission of the fleet of Europe's largest airline by passenger numbers, Ryanair. The potential for noise reduction through fleet level decisions will be evaluated and the impact of changing fleet makeup assessed. The airline's current fleet consists of 409 Boeing 737-800 aircraft and 29 Airbus A320-232 aircraft, while 210 new Boeing 737-8200 aircraft are on order. The new aircraft has a 60% smaller footprint in the 85 dB(A) noise contour during take-off than the existing 737-800. The 85 dB(A) contour of 737-800 extends to around 4.5 km along the runway, while the contour of 737-8200 is reduced to ca. 2.5 km. This is achieved by implementing a new winglet design and more efficient power units, which operate with lower fuel consumption (and thus lower aircraft weight), fewer carbon emissions, and lower noise emissions. The impact of this change on the fleet level noise emission is evaluated through a case study of departure operations at Dublin Airport. Noise contours generated with SoundPLAN show the noise effects of the different aircraft types of the current and future Ryanair fleet under realistic operating conditions. It was shown that in a scenario where Ryanair switched its aircraft at Dublin Airport to the 737-8200, the area in which noise from departure exceeds the 55 dB(A) day time threshold could be reduced by over 25%. This would lead to a beneficial change for 10,000 residents in the current > 55 dB(A) area around Dublin Airport. The generated noise contours provide an evidence base for decision making within the airline for investments aiming to reduce noise levels around airports and meet sustainability targets. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicles (UAVs) are currently being used for reconnaissance missions, tactical surveillance, and infrastructure inspection. When legislation allows it, these devices will provide additional services close to inhabited areas, which could lead to noise complaints. On most UAVs, the propellers are the dominant source of noise. As a result, researchers have studied the impact of propeller shape and blade count on noise. Much of this work, however, has focused on isolated propellers. While different UAV concepts are equipped with ducts for aerodynamic and protection reasons, few studies focus on the acoustic benefit of ducts, as is achieved, for example, on turbofan aircraft. The objectives of this paper are: first, to simulate the noise radiation of a UAV propeller in static conditions based on its location in a hard wall duct; second, to analyze the contribution of the different acoustic source components (i.e., thrust, torque, and thickness); and third, to validate the approach with experiments conducted in the NASA Small Hover Anechoic Chamber over a range of propeller rotation rates. For the propeller and duct geometries considered in this experiment, it is shown that the best attenuation is achieved when the propeller is centered axially in the duct because of interference between upstream and downstream radiated waves. [ABSTRACT FROM AUTHOR]

Aircraft noise affects large areas around airports. Noise calculation programs therefore need to account for air operations with high accuracy. In this contribution, we simulated several thousand single flights with three aircraft noise calculation models, namely sonAIR, FLULA2 and AEDT, and compared the results among each other and with corresponding noise measurements to evaluate their accuracy. While FLULA2 and sonAIR calculations are adjusted to local conditions, AEDT was run with default settings (NPD data and standard procedural profiles) to assess its performance when using unadjusted input data. We found that results of all three programs on average agree well with measurements and with each other. sonAIR is more accurate when using flight configuration data, but also in greater distances to the airports. Exemplarily adaptations of AEDT input data to local conditions showed that such adaptations clearly improve its calculation results. The contribution thus shows that, despite their inherently different modelling approaches, (a) all three programs are on average equally capable of reproducing the sound exposure in the vicinity of airports, (b) adaptions of input data to local conditions substantially improve results and (c) sonAIR is able to reproduce single flights with higher accuracy when provided with flight configuration data. [ABSTRACT FROM AUTHOR]

Most methods for quantifying annoyance from aircraft noise only consider residents that are highly annoyed. The much larger population that are annoyed to a lesser degree are usually neglected in such calculations. A method has been proposed that combines the noise level and the number of exposed people in order to give a single-number quantification of the total annoyance experienced by an airport community. The method is particularly useful for assessing the effect of changes in airport operations. [ABSTRACT FROM AUTHOR]

At Harstad/Narvik Airport Evenes, a NATO QRA detachment using F-35 fighter planes has changed the noise characteristics at the airport dramatically. The challenges of determining the correct health hazard values to avoid hearing damage to passengers and employees at an operational airport is difficult. Initial noise mapping shows large areas around the terminal building and the car park shows very high noise levels during F-35 take-offs using afterburner. The noise level increases rapidly during a take-off, but it is not comparable to an impact noise event. The focus of the work is twofold; Finding the right noise limits to avoid hearing damage risk at the same time as establishing noise abatement measures that are necessary to avoid hearing impairment to employees and passengers on their way to and from aircraft. A noise limit of LASmax = 115 dB is established but insufficient due to the spectral and temporal quality of the noise from the F-35. [ABSTRACT FROM AUTHOR]

Transportation noise annoyance has been investigated in a widely standardized way over the last decades, which allows studying the evolution of exposure-annoyance relationships over time. A temporal comparison reveals an increase of high annoyance in recent studies for railway and aircraft noise, compared to rather stable relationships for road traffic noise. Yet the reasons for these disparate developments remain only little explored. In this paper, potential explanations for the observed divergences are discussed, namely changing values and expectations in society, changing semantics of words used in survey instruments, changes in the attitude towards the different types of traffic, and changes in exposure strength and exposure characteristics. On that basis, considerations are made about the suitability of noise annoyance as a noise effect informing noise limits. [ABSTRACT FROM AUTHOR]

People demand better acoustic comfort for higher travelling quality and security in aircraft. It is necessary to evaluate and predict the subjective annoyance caused by the noise in aircraft cabins. This study investigates the noise-induced annoyance in a large passenger aircraft. We recorded the noise at 21 positions in the aircraft cabin without passengers and selected 21 stimuli during the cruising. Each stimulus has a duration of 5 seconds and a sound pressure level in the range of 72-81dB(A). The psychoacoustic parameters such as loudness, sharpness, roughness, and fluctuation strength were also calculated. Twenty-four subjects evaluated the subjective annoyance of the stimuli by the absolute magnitude estimation method. Results showed the noise annoyance at the middle section of the cabin is significantly higher than that in the front or rear section. The principal component analysis and correlation analysis found that annoyance is mainly affected by loudness, sharpness, and roughness and is dominated by loudness. We proposed a multiple linear regression model between the subjective magnitudes of annoyance and the psychoacoustic parameters to evaluate and predict the noise annoyance in the aircraft cabin well. [ABSTRACT FROM AUTHOR]

The present study investigates crackle noise of the impinging jet over the flat and corrugated plate. The experiments are conducted using a 10 mm diameter (d) orifice for jet production. The standoff distance is varied from 1.5d to 6d, incrementing 0.5d. The nozzle pressure ratio (NPR) is varied from 4 to 5.6 with a step size of 0.2. Results are discussed by plotting the probability density function of normalized pressure data and its derivative and the measured skewness values. For the flat plate, the positive skewed pressure data associated with strong compression and expansion is observed for all NPRs, and the skewness value fluctuates with the change in NPR. The crackle noise is absent in the corrugated plate for most NPRs and standoff distances, although it is observed within a short duration at some NPRs. In contrast, the crackle noise is persistent for the flat plate throughout the time range and is observed even the skewness of the normalized acoustic pressure exceeds the skewness of the derivative of acoustic pressure data. [ABSTRACT FROM AUTHOR]

Aircraft engines, especially when mounted directly to the fuselage, inject a considerable amount of tonal vibrations into the airframe causing audible and comfort reducing cabin noise. Reducing this noise requires the development of specialised noise reduction systems. This is a time consuming and expensive endeavour. To speed up and ease this process a sufficiently detailed numerical model of the aircraft structure and the force injected by the engines is required. The DLR ISTAR, a Dassault Falcon 2000LX, was used for an extensive vibration measurement campaign. The goal of this campaign was twofold: Getting spatially dense information about the aircrafts vibro-acoustic behaviour to later update a finite element model for calculations in the mid-frequency range and to analyse the vibration injected by running engines into the fuselage structure. The measurements include the vibration response to both shaker excitation and engine vibration of the DLR ISTAR at about 1300 positions acquired by a rowing grid of sensors. The results are presented in the form of operational deflection shapes and first calculations of energy transfer paths using structural intensity analysis. [ABSTRACT FROM AUTHOR]

There are three airports in the Osaka area and each of them has been analyzing and evaluating aircraft noise and publishing its results. However, since these three airports are adjacent to each other, the airspace is complicated, and the monitoring range is wide, which caused so much manual work for data review before obtaining an accurate noise impact assessment. This paper introduces a new aircraft noise monitoring system that has been constructed to reduce the human workload and accurately and integrally monitor aircraft noise at the three airports with flight-track measurement. The new system reduces the time for noise analysis and evaluation using artificial intelligence, and it has become possible to publish accurate noise conditions more quickly and at a lower cost. In addition, since it is difficult for an airport operator to obtain air traffic control data, we constructed a system that can monitor the position coordinates of aircraft as recent as 15 seconds ago. By operating this system integrally with the noise system, we can now visually confirm the noise level at the measurement point and the position of aircraft on a map, and publish the real-time noise data online for residents living near the airports. [ABSTRACT FROM AUTHOR]

Around airports having multiple runways, aircraft noise affected areas vary depending on the runway operation because the flight path changes by the operation. Therefore, it is important to figure out exactly which runway was used for analyzing the noise impact on the surrounding area. For this purpose, runway information included in flight data provided by the airport operator can be used in most commercial airports. However, for some airports, the data is unavailable or not always accurate. We developed "Takeoff/ landing runway determination system; DL-TLS" for determining runway operations and have been utilizing it to aircraft noise analysis. However, that system requires to place measurement stations at the end of each runway to ensure the high level of accuracy. To solve this issue, we focused on difference in acquisition time of the same transponder signal at two measurement stations. This new approach achieved satisfactory level of runway determination accuracy, by matching the time difference changes with template for each runway. We proved that this method can be used in combination with the current DL-TLS with even higher accuracy. In addition, we showed the possibility of reducing number of measurement stations and eliminating the measurement location constraint. [ABSTRACT FROM AUTHOR]

In aircraft noise calculation by international guidelines such as ICAO Doc.9911, NPD (Noise Power Distance) data that relates aircraft thrust and noise are used. In these guidelines net-thrust use as power in NPD data. However, net-thrust of an aircraft engine cannot be measured directly. Therefore, net-thrust has to be estimated using the conversion equation with engine parameters such as N1% RPM and EPR, as well as speed. Meanwhile, for recent aircraft types, the coefficients for the N1% and speed terms of the conversion equation are not available. For this reason, Japanese aircraft noise models use N1% and EPR directly in place of net-thrust to create NPD. These parameters change the most at the start of the takeoff roll, and it is necessary to confirm the validity of the noise calculation in this area. In this study, noise measurements at the side of the runway and aircraft onboard data were analyzed to investigate an alternative method of estimating noise changes to net-thrust. The result shows that it is reasonable to correct the noise according to the speed change in addition to the noise calculation in the section of lower speed state of takeoff roll. [ABSTRACT FROM AUTHOR]

More than 60 years have passed since the introduction of jet aircraft to civil aviation, and technological innovations have made aircraft much quieter. Nevertheless, people still complain that they experience severe suffering from aircraft noise. The changes in lifestyles, values concerning the sound environment, and aircraft operating conditions including the air traffic control system, over time, may have influenced the differences in annoyance responses. This paper overviews and considers the changes over time in the aircraft sound exposure level around the airport and the community annoyance caused by aircraft noise. Then it discusses the issue of recent noise complaints associated with the introduction of new air traffic management systems and flight routes as well as views the impact of coronavirus pandemic over the last two years or longer. Finally, it gives a minor consideration to how we should deal with these changes in the annoyance response. [ABSTRACT FROM AUTHOR]

The hydraulic pumps are considered to have a major contribution to the structure borne noise generated inside aircrafts. Methods such as Component-Based Transfer Path Analysis (CB-TPA) are promising tools for aircraft manufacturers to build internal processes for the specification, design and validation of the impact of vibrating systems on new aircrafts. However, the experimental applicability of these methods remains limited due to some experimental difficulties. CB-TPA' formulation is based on dynamical quantities, which require the determination of terms related to rotational degrees of freedom. Indirect methods such as Virtual Point (VP) are commonly employed for this purpose, but it results in more cumbersome experimental set-ups and increased measurement uncertainties. The implementation of these methods can also be difficult in the case of a flat and thin receiving structure as commonly encountered in aircraft applications, since in-plane translational excitations have to be applied and the access to the vibrating system/structure interface points is limited. In this work, a decoupling procedure is used to overcome these issues. A numerical model is used to investigate the influence of model uncertainties on the CB-TPA' predictions, when the dynamical quantities are provided by VP method including the decoupling procedure. [ABSTRACT FROM AUTHOR]

There is limited evidence on deprivation distribution of noise exposure. Noise data (Lden, Laeq24, Lnight, Levening, and Lday) were available for London Heathrow airport for 2014-18. These were linked with different measures of deprivation: the Carstairs deprivation index (UK Census-derived), fuel poverty rate and the avoidable death rate. We used a random effects model, accounting for year and % ethnic minority to quantify the association. Our findings consistently indicate that areas with the least deprivation are the quietest. We found that quintiles 2 - 5 of all deprivation variables exhibit a positive association, indicating that the least deprived areas are consistently the quietest. There is some evidence of a dose-response relationship with aircraft noise in terms of avoidable death rate. Carstairs index quintiles are significantly associated with all four metrics. Fuel poverty has a significant but relatively weak relationship with aircraft noise, compared to Carstairs and avoidable death rate. There is less conclusive evidence of gradients for Carstairs index and fuel poverty rate. Results will be discussed with community groups near Heathrow prior to Internoise 2022. As air transport increases post-pandemic, information on noise exposures as well as views from community groups can inform future airport policies. [ABSTRACT FROM AUTHOR]

The introduction of drones in urban areas for surveillance, parcel delivery services, air taxis, or other services have raised the issue of public acceptability. How can this concept known as Urban Air Mobility (UAM) be successfully introduced in an area without upsetting communities? And how can currently unknown benefits of these services be compared to anticipated drawbacks? Noise impact is already considered to be one of the main concerns for successful introduction of UAM, but focusing on noise levels exclusively may not be enough. Based on recent research on noise annoyance and how it affects individuals and communities, a holistic approach, including noise impact, as well as non-acoustical factors, is promoted to address the annoyance towards these disruptive air vehicles. Other subjective measures should be considered including demographic factors, as well as perceptional factors, such as the visual environment where these vehicles operate, and emotional factors such as attitude towards drones and air taxis. Using this approach, studies on noise impact of UAM will be able to evaluate the use cases in their intended setting and with the appropriate target communities to assess the true impact and define the real challenges to overcome for noise research in the coming decade. [ABSTRACT FROM AUTHOR]

Global restrictions on domestic and international travel introduced in March 2020 as a result of the Covid-19 pandemic resulted in a significant reduction in air traffic movements around the world. This paper presents the findings of research carried out at London Heathrow Airport exploring the day-by-day changes in aircraft noise exposure and event levels over the period March 2020 to June 2020. The research was carried out using validated modelling of aircraft procedures and noise profiles alongside radar data obtained from the airport. This allowed trends in metrics such as LAeq, N65, and overflight to be considered in the form of contours, and at community locations. This was facilitated using geospatial databases and interactive dynamic reporting toolkits. The research has allowed estimates to be made of the point where aircraft noise at Heathrow Airport reached a minimum. It also provides some helpful insight as to the potential of generating daily noise exposure data and the advantages, and disadvantages of modelling using radar data. [ABSTRACT FROM AUTHOR]

Civil aviation is being constrained by the poor understanding of environmental and operational interdependencies. Noise, and carbon emissions belongs to different physical spheres not directly comparable and managed under separate regulations. Noise reduction has been the priority for the aviation industry for many years, but this recently shifted to decarbonisation to achieve Net Zero emissions. Although carbon emissions are one of the main contributors to environmental impacts at global level, we still must consider local impacts, like noise, affecting environment and communities. We developed a process to describe the interrelations between carbon and noise emissions for Airspace Management. Through this process, overall environmental benefits and disadvantages of airspace change concepts, operational procedure changes are assessed, considering both the monetisation of harmful effects and the costs of the carbon emissions impacts on the environment. While some designs provide benefits for noise or carbon emissions, others might provide minimum benefits despite the high costs associated either for noise or carbon, or their effectiveness might depend on the location where they occur. In the context of sustainable aviation, the process we developed provides a tool for airspace developers to identify the trade-off between noise and carbon emission to design an effective sustainable airspace. [ABSTRACT FROM AUTHOR]

Noise from airport ground activities can be a significant contribution to the ambient sound climate in communities close to airports. The shortfall in robust acoustic source data for aircraft ground activities, including taxiing and engine ground running, is a limitation to the accuracy of noise modelling supporting impact assessments associated with changes in airport operations. The aim of this study was to develop a robust survey methodology for the purpose of obtaining acoustic source data of aircraft ground activities. The study addressed two major challenges: the theoretical principle and experimental design for characterizing complex moving sources (i.e. the sound power, spectra and directivity); and the practical problems involved in on-site measurement. The theoretical principle is to consider an aircraft, moving in-line past a microphone, as reciprocally equivalent to a stationary aircraft alongside a line-array of microphones. Increasing the number of microphones in the array is equivalent to increasing the number of angles in the polar distribution plots. Measurements of the noise emissions from a selected aircraft gave a repeatability within 7.0 dB, and reproducibility within 15.7 dB. [ABSTRACT FROM AUTHOR]

The simultaneous control of multiple tonal frequencies and broadband noise, at low frequencies a challenge for the aerospace, ground transportation and building industries. The technologies proposed in the literature, using layered porous materials with embedded Helmholtz resonators HR) with a structured neck, exhibited considerable potential when tuned at tonal, multi-tonal, or narrow frequency bands. However, the resonance frequencies due to the structured necks of the metamaterial are narrow. Our recent investigations have shown that parallel arrangements of several structured metamaterials separated by membranes can broaden the resonance frequencies and increase the number of resonance frequencies to be controlled. This paper presents a parallel assembly of four sub-metamaterials structured and separated by membranes. Each of these sub-metamaterials is also a serial assembly of a periodic unit cell with a half-neck + cavity + half-neck configuration. The metamaterial is embedded in a layer of fiberglass. Comsol's coupled sound pressure and shell approaches in the frequency domain were used to predict the sound absorption coefficient of the metamaterial. The results obtained show a widening of the absorption frequency peaks and the appearance of additional frequencies due to the membranes. [ABSTRACT FROM AUTHOR]

Currently, noise control aims to optimise the psychoacoustic characteristics of aircraft interior noise to improve comfort and security during a flight. This study investigates the influence of transmission loss of aircraft panels on the sound quality of the cabin. We established an aircraft cabin acoustic model based on the statistical energy analysis method. The psychoacoustic metrics (i.e., loudness, sharpness, roughness, articulation index, and psychoacoustic annoyance) were simulated with the varying thickness of the aluminum alloy layer. Results showed that loudness and roughness significantly reduced, whereas sharpness increased with increasing thickness. The psychoacoustic annoyance also declined as the thickness increased. However, the articulation index appeared a sudden drop when the thickness increased. [ABSTRACT FROM AUTHOR]

UK Air Navigation Guidance (ANG) regards 51dB LAeq16hr for day time noise and 45dBLnight 8hr for night time noise as the levels at which aircraft noise annoyance occurs. World Health Organisation (WHO) guidelines (2018) concluded that health effects can occur at lower levels of 45dB Lden and 40dBLnight. Current policy recognises that noise annoyance can occur below 51dB LAeq16hr yet it is not known how many people around UK airports may be adversely affected at these lower levels. This paper will seek to estimate the population size impacted by aircraft noise below 51dB LAeq16hr around Heathrow airport. It will also seek to provide an international comparison of the noise policies of different airports in Europe and globally, the size of the population impacted and the minimum threshold for the onset of health effects. The most radical changes in UK airspace history will take place in the next decade. If more people are adversely impacted by aircraft noise at lower levels then this has significant ramifications for the cost benefit analysis of airspace changes. It is crucial that communities can understand the full health impacts of the proposals. [ABSTRACT FROM AUTHOR]

In 2007, the airport authority for Dublin Airport (DAA) was granted planning permission to build a new runway. This permission included several planning conditions, including operating restrictions during the night-time due to noise considerations. The plans were then put on hold due to the economic downturn, but in 2016, with increasing passenger numbers, the plans were revived. In the intervening years, the planning and legislative environment related to aircraft noise changed in Ireland, particularly with the implementation of Regulation 598/2014 and the establishment of the Aircraft Noise Competent Authority (ANCA). Then, in December 2020 the DAA submitted a planning application seeking to amend those 2007 conditions associated with night-time operating restrictions. The application was referred to ANCA for an assessment of the associated noise impact, and in November 2021 they issued a draft regulatory decision report. The draft report proposed a number of mitigation measures for Dublin airport, including the introduction of a noise quota system. This paper reviews the proposed noise quota system. [ABSTRACT FROM AUTHOR]

Many models have been proposed to clarify the interactive effects of acoustic and non-acoustic variables on human perception of noise. Due to the corona pandemic, all flights were closed at the end of March 2020, causing an unprecedented change in the acoustic environment around Tan Son Nhat Airport (TSN). Before the outbreak, TSN was the busiest airport in Vietnam and had severe noise problems. This study focused on determining how acoustic and non-acoustic factors affect community health before and after this change. Approximately 1200 responses were obtained from surveys conducted in 12 residential areas around TSN in 2019 and 2020. Structural equation models (SEM) for noise annoyance and insomnia were developed by linking the questionnaire items of the social surveys. The first effort aims to achieve a common model of noise annoyance and insomnia corresponding to community response to noise before and after the change. It has been found that the degrees of annoyance and insomnia were not reduced, as expected, but increased in 2020. The final constructed SEM indicates that acoustic and non-acoustic factors affected the community health in different structures before and after the noise reduction. [ABSTRACT FROM AUTHOR]

Along with air traffic expansion, an increasing number of complaints from residents regarding aircraft noise from the airport operation has raised an environmental awareness of aircraft noise pollution in Vietnam. It is an urgent task for local authorities to assess aircraft noise exposure reliably. Aircraft noise monitoring systems and suitable policies need to be developed for land use and flight operation control to reduce and prevent aircraft noise pollution. However, Vietnam has had no legal documents or instructions on measurement and evaluation methods or the equipment and monitoring systems for measuring and analyzing aircraft noise. Against that background, the Civil Aviation Authority of Vietnam (CAAV) has developed a new guidance manual to measure and evaluate aircraft noise within the cooperation project on Airport Environment Preservation and Aircraft Noise Monitoring in Vietnam. This project was implemented by the CAAV, the Japan International Cooperation Agency (JICA), and RION Co., Ltd. As a model case, a system of the minimum-required equipment with four noise monitors for the continuous monitoring of aircraft noise was installed around Noi Bai International Airport. This study explains the formulation of the new guidance manual and discusses the analysis results of the monitoring data obtained from January 2019 to August 2021. [ABSTRACT FROM AUTHOR]

The metric sound emergence relates source-specific sound levels to background noise. The approach of subtracting a residual sound level (total sound level without the level of a specific source) from the total sound level follows the definition of sound emergence in ISO 1996-1. Using exposure and survey data of the German NORAH study, the impact of sound emergence on aircraft noise annoyance was analysed. As total background sound levels were not available, information about source-specific and combined sound levels was used instead. That is, the road traffic sound level for daytime (LAeq,day,road) of the home address of survey participants was subtracted from the combined sound level of aircraft and road traffic noise (LAeq,day,air+road) with the combined sound level being a proxy for the total sound level, and the road traffic sound level being a proxy for the residual sound level. The probability of people being highly annoyed by aircraft noise, p(HAV), was predicted by LAeq,day,air and the emergence substitute es(air/road). The results show that particularly in low aircraft noise-exposed areas, p(HAV) is higher for those participants exposed to higher values of es(air/road). [ABSTRACT FROM AUTHOR]

Aircraft noise pollution is getting increasingly severe due to striding development of worldwide air transport. In high-density cities, a large number of residential areas are exposed to airport routes where flight-over noise poses a serious threat to public health. However, most existing research is limited to the thresholds for annoyance lacking in-depth exploration into the psychophysiological impacts that induce health responses. This study aims to examine the health effects of aircraft noise on both subjective evaluation and objective physiological indicators in a laboratory setting. Aircraft noise samples were collected in the under-route open spaces. The effects of aircraft noise on annoyance and physiological feedback, including Skin Conductance Response (EDA) and Heart Rate Variability (HRV), were examined using listening experiment and ErgoLab electrophysiological response monitoring. The study also analysed the effects of soundscape modulating and examined the relationship between psychophysiological responses and subjective annoyance. The results are expected to provide indicators to assess and improve the health of under-route communities. [ABSTRACT FROM AUTHOR]

To deepen our understanding of the spatial and temporal distribution of various sound sources of environmental noise, which is observed by unattended aircraft noise monitors, we have been developing a method of acoustic scene analysis based on information on the 3D sound arrival direction. In the congress of INTERNOISE 2021 last year, we reported the basic idea of this method and some examples of the analysis. The method of acoustic scene analysis, named static mode and dynamic mode, is based on the information of the direction of arrival and sound pressure level of the sound in three dimensions from time to time. In this report, we describe the current status of efforts to improve the functionality of these two modes. In order to describe the results of the trial of the video availability for the static mode. The purpose is to create a document that will facilitate a deeper understanding of the sound environment. In order to improve the versatility of the Dynamic Mode Acoustic Scene Analysis method, we decided to improve the method's versatility. Because the travel paths are limited to those that satisfy the specified preconditions, there were restrictions on the sound sources moving over the applicable airspace. Therefore, by adding a sensor that observes the direction of sound arrival, the preconditions can be excluded. In this paper, we report on the study and experimental status. [ABSTRACT FROM AUTHOR]

Although the need to consider acoustics in the built environment is well-accepted, an understanding of 'what' constitutes 'good acoustics' is not. The authors present posteriori--reviews of historical events and of empirical evidence--to develop an understanding of the current landscape of Standards, Guidelines, and Codes. More specifically, special attention is devoted to the development of speech privacy metrics, as well as that of auditory and non-auditory effects of noise and sound on health. With a refreshed understanding of theory, a priori--i.e., an acoustical framework for design and/or performance verification with a special interest in speech privacy--is renewed and its impacts on the ongoing development of Standards, Guidelines and Codes is discussed. [ABSTRACT FROM AUTHOR]

Aircraft noise prediction models traditionally omit buildings to optimize speed. Buildings and vertical surfaces scatter and reflect incident sound, affecting sound levels around buildings and within streets. Previous studies showed the impact of buildings on aircraft noise, based on a small number of measurements. Based on additional numerical models, it was found that the shape of buildings, i.e. a slanted or overhanging roof, lead to lower sound levels compared to streets comprised of vertical and flat surfaces. To examine these findings, a fullscale field lab was built near Amsterdam Schiphol Airport, comprised of shipping containers. The experiment consists of three courtyards, in which ten microphones measure sound levels from aircraft flyovers, near facades facing towards and away from the sound source (airplanes). Measurements are matched with meteorological and radar data, which gives information about the position of aircraft and the local weather conditions. The measurements show substantial differences depending on the position, ranging between 8/9dB(A) for a courtyard with straight facades, up to 14dB(A) for facades in a courtyard with a slanted facade and a building inset. Results can be used to rethink the way areas near airports are designed. [ABSTRACT FROM AUTHOR]

The need has been identified for an overall outcome of any co-ordinated airport research programme to work towards a better understanding of airports impact on QoL with a requirement to better understand the value (in terms of noise reduction and health outcomes) and effectiveness of the interventions airports make - this includes the provision of respite. Anderson Acoustics Ltd (funded by Heathrow Airport Ltd) has been consolidating current knowledge on respite, particularly in relation to airspace design. That work has essentially continued the journey towards understanding respite and its effective implementation, linking together past, current, and potentially future activities, providing timelines, signposting to other reports and work. This paper presents a highlevel overview of HAL's journey to date on building knowledge on respite. [ABSTRACT FROM AUTHOR]

For the design of supersonic civil aircraft with a low noise level, it is necessary to develop methods for modeling the sonic boom phenomenon. This paper presents a numerical method for solving an equation that takes into account for the effects of a molecular vibrational relaxation on the transformation of the overpressure profile during propagation. The evolution of the plane wave during its propagation over long distances is shown. [ABSTRACT FROM AUTHOR]