Showing papers on "Aircraft noise published in 2011"

Design of the Next Generation Aircraft Noise Prediction Program: ANOPP2

Abstract: The requirements, constraints, and design of NASA's next generation Aircraft NOise Prediction Program (ANOPP2) are introduced. Similar to its predecessor (ANOPP), ANOPP2 provides the U.S. Government with an independent aircraft system noise prediction capability that can be used as a stand-alone program or within larger trade studies that include performance, emissions, and fuel burn. The ANOPP2 framework is designed to facilitate the combination of acoustic approaches of varying fidelity for the analysis of noise from conventional and unconventional aircraft. ANOPP2 integrates noise prediction and propagation methods, including those found in ANOPP, into a unified system that is compatible for use within general aircraft analysis software. The design of the system is described in terms of its functionality and capability to perform predictions accounting for distributed sources, installation effects, and propagation through a non-uniform atmosphere including refraction and the influence of terrain. The philosophy of mixed fidelity noise prediction through the use of nested Ffowcs Williams and Hawkings surfaces is presented and specific issues associated with its implementation are identified. Demonstrations for a conventional twin-aisle and an unconventional hybrid wing body aircraft configuration are presented to show the feasibility and capabilities of the system. Isolated model-scale jet noise predictions are also presented using high-fidelity and reduced order models, further demonstrating ANOPP2's ability to provide predictions for model-scale test configurations.

Aircraft Noise: Assessment, Prediction and Control

Abstract: A review of the aircraft noise problem Environmental impacts of airports Description of aircraft noise Basic equations Criteria and methods of aircraft noise assessment Control of noise impact Regulations and standards for aircraft noise The main sources of aircraft noise Jet noise Fan and turbine noise Combustion chamber noise Airframe noise Propeller and helicopter noise Aircraft noise propagation Factors influencing outdoor sound Predicting the ground effect Comparisons of measured and predicted ground effects Shadow zones Classification of meteorological effects Typical sound speed profiles Sound propagation in a turbulent atmosphere Sound propagation over noise barriers Sound propagation through trees Methods for aircraft noise prediction Introduction An acoustic model of an aircraft Evaluation of an acoustic model of an aircraft Prediction of noise under the flight path: trajectory models Effects of ground, atmosphere and shielding by wing and fuselage Prediction of aircraft noise during ground operations Prediction of noise in the vicinity of an airport The influence of operational factors on aircraft noise levels Aircraft on the ground Under the flight path Takeoff and climbing Descent and landing Methods of aircraft noise reduction Reduction of noise at source Noise reduction under the flight path Noise reduction in the vicinity of an airport The efficiency of acoustic screens for reducing noise from airport ground operations Reduction of noise impact by optimum scheduling of aircraft operations Monitoring of aircraft noise Reasons for noise monitoring Instrumentation for aircraft noise monitoring Uncertainties in measurements and predictions Identifying sources of noise events Interdependencies and tradeoffs between noise and other environmental factors associated with civil aviation

Trends in aircraft noise annoyance: The role of study and sample characteristics

Abstract: Recently, it has been suggested that the annoyance of residents at a given aircraft noise exposure level increases over the years. The objective of the present study was to verify the hypothesized trend and to identify its possible causes. To this end, the large database used to establish earlier exposure-response relationships on aircraft noise was updated with original data from several recent surveys, yielding a database with data from 34 separate airports. Multilevel grouped regression was used to determine the annoyance response per airport, after which meta-regression was used to investigate whether study characteristics could explain the heterogeneity in annoyance response between airports. A significant increase over the years was observed in annoyance at a given level of aircraft noise exposure. Furthermore, the type of annoyance scale, the type of contact, and the response percentage were found to be sources of heterogeneity. Of these, only the scale factor could statistically account for the trend, although other findings rule it out as a satisfactory explanation. No evidence was found for increased self-reported noise sensitivity. The results are of importance to the applicability of current exposure-annoyance relationships for aircraft noise and provide a basis for decisions on whether these need to be updated. © 2011 Acoustical Society of America.

A multi-objective optimization strategy for designing aircraft noise abatement procedures. Case study at Girona airport

Abstract: The optimization of aircraft noise abatement procedures involves several conflicting factors, including location specific noise sensitivity and aircraft operating costs. This paper presents a multi-objective optimization strategy that employs goal, lexicographic-egalitarian and hierarchical optimization techniques. The presented methodology aims at better assessing the design of site-specific noise abatement procedures that take into account the actual populated areas, their type and distribution, the hour of the day where the trajectory is supposed to be flown and the aircraft type. An illustrative example is given with the design of the East departures at Girona airport, Catalonia. Results point out how the noise annoyance impact of current operational procedures can be significantly reduced by the optimized trajectories and show, as well, an important dependency on the type of aircraft and the hour of the day.

Initial Assessment of Open Rotor Propulsion Applied to an Advanced Single-Aisle Aircraft

Abstract: Application of high speed, advanced turboprops, or propfans, to subsonic transport aircraft received significant attention and research in the 1970s and 1980s when fuel efficiency was the driving focus of aeronautical research. Recent volatility in fuel prices and concern for aviation s environmental impact have renewed interest in unducted, open rotor propulsion, and revived research by NASA and a number of engine manufacturers. Unfortunately, in the two decades that have passed since open rotor concepts were thoroughly investigated, NASA has lost experience and expertise in this technology area. This paper describes initial efforts to re-establish NASA s capability to assess aircraft designs with open rotor propulsion. Specifically, methodologies for aircraft-level sizing, performance analysis, and system-level noise analysis are described. Propulsion modeling techniques have been described in a previous paper. Initial results from application of these methods to an advanced single-aisle aircraft using open rotor engines based on historical blade designs are presented. These results indicate open rotor engines have the potential to provide large reductions in fuel consumption and emissions. Initial noise analysis indicates that current noise regulations can be met with old blade designs and modern, noiseoptimized blade designs are expected to result in even lower noise levels. Although an initial capability has been established and initial results obtained, additional development work is necessary to make NASA s open rotor system analysis capability on par with existing turbofan analysis capabilities.

Equitable Aircraft Noise-Abatement Departure Procedures

Abstract: This paper deals with the optimization of aircraft noise-abatement departure procedures. A multicriteria optimization strategy is presented, where the fairness of the optimal trajectories is assessed vis-a-vis the different noise-sensitive locations around the airport of study. This equitable optimization is formulated as the minimization of the maximum noise-annoyance deviation regarding all considered locations. This strategy is complemented with an iterative lexicographic optimization algorithm which, in turn, guarantees the Pareto efficiency condition of the final solution. Aircraft operating costs are also considered by neglecting the marginal benefits of noise reduction below a certain threshold value. An application example is shown (as an illustrative case) based on a departure of runway 02 at Girona airport in Catalonia, Spain. The results show the feasibility of this technique, which is intended to be used by procedure designers or airport authorities.

The Parametric Aircraft Noise Analysis Module - status overview and recent applications

Abstract: The German Aerospace Center (DLR) is investigating aircraft noise prediction and noise reduction capabilities. The Parametric Aircraft Noise Analysis Module (PANAM) is a fast prediction tool by the DLR Institute of Aerodynamics and Flow Technology to address overall aircraft noise. It was initially developed to (1) enable comparative design studies with respect to overall aircraft ground noise and to (2) indentify promising low-noise technologies at early aircraft design stages. A brief survey of available and established fast noise prediction codes is provided in order to rank and classify PANAM among existing tools. PANAM predicts aircraft noise generated during arbitrary 3D approach and take-off flight procedures. Noise generation of an operating aircraft is determined by its design, the relative observer position, configuration settings, and operating condition along the flight path. Feasible noise analysis requires a detailed simulation of all these dominating effects. Major aircraft noise components are simulated with individual models and interactions are neglected. Each component is simulated with a separate semi-empirical and parametric noise source model. These models capture major physical effects and correlations yet allow for fast and accurate noise prediction. Sound propagation and convection effects are applied to the emitting noise source in order to transfer static emission into aircraft ground noise impact with respect to the actual flight operating conditions. Recent developments and process interfaces are presented and prediction results are compared with experimental data recorded during DLR flyover noise campaigns with an Airbus A319 (2006), a VFW-614 (2009), and a Boeing B737-700 (2010). Overall, dominating airframe and engine noise sources are adequately modeled and overall aircraft ground noise levels can sufficiently be predicted. The paper concludes with a brief overview on current code applications towards selected noise reduction technologies.

Valuing Aircraft Noise: Stated Choice Experiments Reflecting Inter-Temporal Noise Changes from Airport Relocation

Abstract: The relocation of Athens Airport provided a rare experimental context in which residents experienced significant changes in noise levels due to the introduction or removal of aircraft noise. This paper reports the results from surveys around both airport locations, using stated choice experiments to estimate values for aircraft noise. The respondents were offered actual inter-temporal noise change scenarios rather than hypothetical variations, which is uncommon in the literature, incorporating the presence or absence of an airport and other relevant transport attributes that also changed with the airport relocation. Whilst there is some variation in the valuation of the airport closure and opening, when these values are adjusted to reflect the actual change in decibels, there is remarkably little difference between the old and new airports. However, a significant variation in aircraft noise values is identified between different areas, with respect to education and to a lesser extent income. Our preferred estimate of the monthly household willingness to pay for terminating aircraft noise exposure is 13.12€ and for avoiding the onset of aircraft noise is 9.53€.

Combined Noise Exposure at Home

Abstract: In everyday life people are simultaneously exposed to several sound sources, which emerge from background soundscapes of considerable variability due to building layouts, residential pattern, topography, meteorology, and lifestyle. In contrast, noise regulation, planning, and control treat the sound environment by separating it into pieces and describe it by a one-number indicator. This practice ignores the possibility of any effect modification (by inhibition, partial or full additivity, or synergism). This effect modification can take place not only between sound sources (multisource issue) but also with simultaneously occurring environmental factors (vibration and air pollution) from the same source or through other contextual factors (multistressor issue). What people know about auditory perception of combined sound exposure mainly rests on experimental work using short-term loudness judgments in repeated designs in controlled settings. Recent psychoacoustic experiments did not find full support for the most prevalent models in practice (e.g., simple energy summation), when the context of the assessment is more carefully distinguished (sound heard within combined sound or alone). The findings are difficult to compare with field studies where long-term judgments of annoyance take place in the immediate context of the subject's living environment. The combined noise paradox is such a finding. It describes the phenomenon that total annoyance is often judged equal or even lower than the dominant source alone. Some call it compromise judgments suggesting them to result from ambiguous questions or misinterpretations of the frame of reference when total annoyance should be assessed. In experiments, compromise judgments were observed mainly with unequally loud and time-separated sounds. But also increases in total annoyance have been observed in the field studies. Although masking partly explains lower annoyance, higher annoyance due to equally loud sources is less well understood. Further effect modifications have been observed with simultaneously occurring vibrations, low-frequency annoyance, and tonal and impulsive components of heterogeneous sound sources such as those from industry. The larger annoyance effects observed can vary in terms of decibel equivalents between −3 and +15 dBA. The highest values are associated with impulsive noise and low background noise context. Eventually, air pollution and other contextual factors can further contribute to total annoyance. Incomplete accountance of effect modifications in environmental risk assessments will lead to errors in planning and less than optimal noise control.

Can exposure to noise affect the 24 h blood pressure profile? Results from the HYENA study

Abstract: Objective To study the association between exposure to transportation noise and blood pressure (BP) reduction during nighttime sleep. Methods 24-h ambulatory BP measurements at 15-min intervals were carried out on 149 persons living near four major European airports. Noise indicators included total and source-specific equivalent indoor noise, total number of noise events, annoyance scores for aircraft and road traffic nighttime noise. Long-term noise exposure was also determined. Multivariate linear regression analysis was applied. Results The pooled estimates show that the only noise indicator associated consistently with a decrease in BP dipping is road traffic noise. The effect shows that a 5 dB increase in measured road traffic noise during the study night is associated with 0.8% (−1.55, −0.05) less dipping in diastolic BP. Noise from aircraft was not associated with a decrease in dipping, except for a non-significant decrease noted in Athens, where the aircraft noise was higher. Noise from indoor sources did not affect BP dipping. Conclusions Road traffic noise exposure may be associated with a decrease in dipping. Noise from aircraft was not found to affect dipping in a consistent way across centres and indoor noise was not associated with dipping.

Emerging Community Noise Reduction Approaches

Abstract: An overview of the current NASA research portfolio in the area of aircraft noise reduction is presented. The emphasis of the research described herein is on meeting the aggressive near- and mid-term national goals for reducing aircraft noise emissions, which NASA internal studies have shown to be feasible using noise reduction technologies currently being developed in-house or in partnership with NASA s industry and academic partners. While NASA has an active research effort in airframe noise reduction, this overview focuses on propulsion noise reduction only.

Human Response to Aircraft Noise

Abstract: How can it be that one person is extremely annoyed by the sounds of aircrafts, while his neighbour claims not to be bothered at all? The present thesis attempts to explain this observation by applying a range of quantitative methods to field data gathered among residents living near large airports. Whereas previous explanatory models of aircraft noise annoyance generally lacked theoretical foundations, the developed models are explicitly informed by theories of noise annoyance and, in effect, shed new light on the human experience of aircraft noise.

Towards Prediction of Dual-Stream Jet Noise: Database Generation

Abstract: The accurate prediction of jet noise from dual-stream nozzle exhaust geometries typical of high bypass ratio turbofan engines has practical relevance for aircraft design studies and in aircraft noise certification. Existing empirical methods do not provide good predictions against measured data; in addition, they are restricted to lower area ratio (secondary to primary) nozzle geometries and lower bypass ratios (BPR). The area ratio and BPR of newer engines have increased substantially, well beyond the range of validity of existing prediction methods. Therefore, there is a dire need to develop an accurate empirical prediction method that is valid over a wider range of jet operating conditions and nozzle geometries that are representative of current engines. A wind tunnel test has been completed and a comprehensive database from realistic geometries and operating conditions has been generated. The data have been analyzed and investigated with an eye towards modeling that would lead to an empirical prediction method. The area ratio and BPR cover wide ranges that encompass all current engines and potential ultra-high BPR engines of the future. The spectral characteristics have been examined and the effects of the following parametric variations are reported in this paper: (1) impact of area ratio with fixed, but over a range of, power settings; (2) at a given As/Ap, fixed primary jet and systematically varying secondary conditions; (3) at a given As/Ap, fixed secondary jet and systematically varying primary conditions; and (4) the effects of forward flight for the above situations. It is established that the characteristics of dual-stream jets with velocity ratio less than 0.5 are similar to those for a single jet, with the velocity ratio being the main controlling parameter and the area ratio playing a lesser role. At higher velocity ratios, contributions from the secondary shear layer is dominant at higher frequencies and the contributions from the mixed jet component controls the peak spectral levels in the peak radiation sector at large aft angles. At low inlet angles, the spectral shape remains invariant for all jet and geometric conditions.

Empirical prediction of flap tip noise.

Abstract: In this paper, DLR’s empirical prediction model for flap tip noise is presented and discussed in details. The prediction scheme is based on a comprehensive acoustic and aerodynamic database acquired in the Acoustic Wind Tunnel Braunschweig. It was verified, through successful scaling of the measured noise spectra, that the cross-flow velocity at the flap tip is an important parameter characterizing the flow mechanism(s) responsible for the noise production. This finding led to the definition of a universal flap tip noise spectral shape in terms of a linear least-squares fit of the corresponding measurement data. Using a similar approach, a model for the flap tip noise directivity was formulated. The prediction model was compared against full-scale fly-over measurement data (B747-400 and A319) and an acceptable agreement of the overall predictions was found. A slight underprediction of the noise levels at high frequencies suggests that additional airframe noise sources might be needed in the complete aircraft noise prediction scheme to get a better agreement between measured and predicted noise levels. It is also found that, for large flap deflection angles, flap tip noise dominates the high frequency part of the predicted complete aircraft high-lift noise spectra. Knowledge of the flap tip noise peak frequency and high-frequency decay are therefore sufficient to account for this noise source in the total aircraft noise prediction. Finally, the limitations of the prediction scheme are discussed and research needs are identified.

A measurement model for general noise reaction in response to aircraft noise

Abstract: In this paper a measurement model for general noise reaction (GNR) in response to aircraft noise is developed to assess the performance of aircraft noise annoyance and a direct measure of general reaction as indicators of this concept. For this purpose GNR is conceptualized as a superordinate latent construct underlying particular manifestations. This conceptualization is empirically tested through estimation of a second-order factor model. Data from a community survey at Frankfurt Airport are used for this purpose (N = 2206). The data fit the hypothesized factor structure well and support the conceptualization of GNR as a superordinate construct. It is concluded that noise annoyance and a direct measure of general reaction to noise capture a large part of the negative feelings and emotions in response to aircraft noise but are unable to capture all relevant variance. The paper concludes with recommendations for the valid measurement of community reaction and several directions for further research.

Aircraft Noise Simulation for a Virtual Reality Environment

Abstract: Aircraft noise annoyance predictions based on traditional tools lack fidelity when modelling a single aircraft flyover. For evaluating annoyance of new procedures, different aircraft types or changing atmospheric conditions, a new modelling approach is necessary. A research effort has been initiated to develop a toolchain that links each of the relevant components. This allows the use of synthesized sound in a virtual reality simulator and enhances follow-up annoyance investigations. The toolchain components and current capabilities are presented in this paper. Audible results are illustrated by spectrograms to show the difference between different atmospheric conditions. Through the development of the toolchain, it becomes possible to demonstrate audible results of changing aircraft procedures, type and atmosphere in a virtual reality environment. This opens new ways to investigate how people value aircraft noise in different atmospheres in combination with smart planning of aircraft procedures.

Flight Effects on Supersonic Jet Noise from Chevron Nozzles

Abstract: Currently tactical aircraft supersonic jet noise studies are conducted at near static conditions motivated by the need to develop nozzle concepts for mitigating aircraft carrier launch crew noise levels. Effects of forward flight on supersonic jet noise source mechanisms need to be included as the next step to demonstrating concept benefits for community noise reduction during training scenarios where aircraft operate from land based airfields. Hence, the current study was directed at the flight effects on far field noise from round and chevron nozzles in model scale experiments conducted in the United Technologies Research Center (UTRC) open jet acoustic wind tunnel. The objective was to document the statistical characteristics of the noise at tunnel Mach numbers up to Mt =0.4 since there is limited generic data for military engine supersonic exhaust conditions under such forward flight scenarios. The study focuses on the noise characteristics in the aft quadrant which dominates the tactical aircraft noise signature. A generic chevron nozzle, developed for noise reduction, was included in the evaluation as part of tracking the noise reduction consistency with increasing forward flight. The chevron geometry consisted of the baseline shock-free round nozzle with 12 chevrons attached at the nozzle exit. Exit diameter corresponded to 2” for both nozzles. Static temperature ratios ranged from isothermal to Tr =2. The impact of chevrons on impulsive signature skewness reduction was tracked in the acoustic far field at near static conditions. Both the round and chevron nozzle were also operated at off-design conditions with over and underexpanded nozzle pressure ratios (NPR) for the skewness study.

Large Eddy simulations of high Reynolds number jets with microjet injection

Abstract: Continued growth of the aviation industry and increasingly strict noise requirements set by international bodies and airport authorities alike means that novel methods of reducing aircraft noise must be found. Engine noise represents a majority contribution to total aircraft noise during take-off and turbulent mixing of the exhaust gases is the dominant noise source of the engine at take-off. While bypass ratio has been the historical, and rather convenient means, of reducing jet noise, an upper limit to bypass ratio is now being approached and additional means of reducing jet noise must be found. One method that has shown potential for reducing aeroacoustic jet noise is the application of small, high pressure jets to the circumference of the jet nozzle. These jets, termed microjets, have the advantage over static devices that the microjets can be activated only when the noise benefit is required and deactivated when emitted noise is not an issue, such as in cruise, thereby reducing the thrust penalty associated with the devices over the majority of the flight. Large eddy simulations have been performed to investigate the impact that the addition of microjets has on the aerodynamic flowfield and radiated far-field noise of a high Reynolds number, Mach 0.9, propulsive, laboratory scale jet. Far-field noise was predicted through a new implementation of the permeable Ffowcs Williams Hawkings surface method in the solver. In addition to single-point flowfield statistics and far-field noise, spatio-temporal second- and fourth-order correlations are investigated. Two pairs of simulations were conducted, a coarse mesh containing 100 million elements and a fine mesh with 200 million elements. The coarse mesh included an azimuthal clustering of the cells in the near-microjet region. The non-uniformity of the azimuthal cell size was shown to adversely affect the development of the initial shear layer, yielding a delay in transition to a fully turbulent state and larger coherent structures in regions with larger cells. Radial velocity and turbulent kinetic energy profiles show good agreement with experimental results. A previously unidentified periodic interaction between the main jet and microjets was found. The dynamic interaction gives rise to velocity and pressure fluctuations in the near microjet region that match a tonal frequency found in the microjet far-field spectra that is absent from the clean jet case. Second- and fourth-order correlation distributions show large periodic regions of high correlation amplitude in the near microjet region. The evidence demonstrates that the main-microjet interaction is a clear high-frequency noise source. Despite the high-frequency noise associated with the main-microjet interaction, the addition of microjets yields a 1-2 dB reduction in overall sound pressure level. Additionally, over a significant portion of the length of the potential core the microjets reduce the amplitude of the majority of the six main correlation amplitudes that can be used in far-field noise prediction. Finally, the generation of the counter-rotating vortex pair downstream of the microjets was investigated. It is commonly presumed that this vortex pair is similar in origin to the counter-rotating vortex pair present in a jet in a crossflow. Vortex identification methods, velocity vectors and streamlines in the near microjet region demonstrate that the horseshoe-like vortex is the source of the counter rotating vortex pair that is present downstream of the microjets. The horseshoe-like vortex in the microjet case has the same sense as the vortices in the microjet shear layer and appears to be generated by the development of a recirculation region of microjet fluid during the main-microjet interaction.

Slat Noise Simulations: Status and Challenges

Abstract: Noise radiation from the leading edge slat of a high-lift system is known to be an important component of aircraft noise during approach. NASA's Langley Research Center is engaged in a coordinated series of investigations combining high-fidelity numerical simulations and detailed wind tunnel measurements of a generic, unswept, 3-element, high-lift configuration. The goal of this effort is to provide a validated predictive capability that would enable identification of the dominant noise source mechanisms and, ultimately, help develop physics inspired concepts for reducing the far-field acoustic intensity. This paper provides a brief overview of the current status of the computational effort and describes new findings pertaining to the effects of the angle of attack on the aeroacoustics of the slat cove region. Finally, the interplay of the simulation campaign with the concurrently evolving development of a benchmark dataset for an international workshop on airframe noise is outlined.

Aircraft noise: accounting for changes in air traffic with time of day.

Abstract: Aircraft noise contours are estimated using model calculations and, due to their impact on land use planning, they need to be highly accurate. During night time, not only the number and dominant types of aircraft may differ from daytime but also the flight paths flown may differ. To determine to which detail these variations in flight paths need to be considered, calculations were performed exemplarily for two airports using all available radar data over 1 year, taking into account their changes over the day. The results of this approach were compared with results of a simpler approach which does not consider such changes. While both calculations yielded similar results for the day and close to the airport, differences increased with distance as well as with the period of day (day < first hour of the night < second hour of the night, respectively, day < evening < night). Only the detailed calculation always accounted for the flight path changes in full detail. Possible legal consequences of such different modeling approaches are estimated, and the model results are compared to monitoring measurements. Finally, the situations for which the simpler approach is sufficiently accurate are ascertained.

Design considerations of building elements for traffic and aircraft noise abatement

Abstract: The paper presents various design aspects based on exhaustive review of previous studies done so far and presents a database and design aspects of sandwich material combinations for applications in building elements, including various wall and roof constructions to combat traffic and aircraft noise. The paper includes a series of laboratory experiments carried out in Reverberation chambers at NPL for characterizing the sound insulation properties of sandwich dry wall partition panels in conjunction with the laboratory results published on masonry and drywall sandwich constructions by various researchers. The work provides an extensive database and physical understanding of theoretical phenomena proposed in previous studies for design and development of better sound insulative sandwich drywall constructions for their applications in building facades, walls, ceilings and doors for abatement of traffic and aircraft noise in Delhi city and tries to assimilate all the design guidelines in a cause and effect analysis diagram. The present work also envisages the significance and need of stricter building regulations w.r.t sound insulation of building elements for new residential projects planned especially in vicinity to airport or road traffic in India.

Community Oriented Solutions to Minimise aircraft noise Annoyance

Abstract: COSMA will help to improve the understanding of the effects of aircraft noise near airports, to develop engineering guidelines, methods implementing suitable design, operating practices aimed to minimise the noise annoyance, supported by a set of validated tools. An extensive literature study about annoyance around airports since 1980 was performed. A list of moderator variables that are affecting the annoyance around airports was established on the basis of this study. The power plant and aircraft definition was given, which is important for the further work in the technical work packages. Telephone and field studies are preparing part for the central annoyance studies in the project. More than 1.200 telephone interviews were performed to map the status quo of the current aircraft noise annoyance situation around 3 European airports. The field study will provide more detailed information about the current noise annoyance. An interactive Sound Synthesis Machine (SSM) was developed to improve the sound quality of a single aircraft fly-over. Subjects will be able to create their own preferred sounds for different aircraft using this tool. It consists of an on-line Sound Machine (SM) for interactive sound quality analysis and the Airport Noise Climate Synthesizer (ANCS), producing event sequences in real airport scenarios. Significant work was also carried out to improve source component and noise propagation models that are implemented in the ANCS tool. Further work was performed for developing an intelligent Data Reduction and Transformation (iDRT) module. Based on this reduced data a so-called “virtual listener” regression model was developed, predicting the annoyance. For long-term descriptors, a preliminary version of a neural network was developed. Finally, five different airport scenarios for investigation were defined, also the criteria for their optimisation. An interactive tool, to generate a sequence easily and of arbitrary length from the available data base, was written and is already available.