Showing papers on "Aircraft noise published in 2007"
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TL;DR: After controlling for confounders, subjects who have been chronically exposed to high aircraft noise level are more likely to report stress and hypertension compared with those not exposed to aircraft noise.
83 citations
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TL;DR: It is concluded that a population exposed to a nocturnal equivalent continuous air traffic noise level of Leq(3) = 50 dB(A) for three quarters of a given time has a higher average blood pressure compared to a population exposure to the same equal energy noise level for only one quarter of the time.
Abstract: The aim of this study
was to evaluate subjective noise
perception and objective parameters
of circulation in the vicinity of
the Frankfurt airport. Two areas
were selected in which aircraft
noise was the predominant source
of noise (and was) created by
planes induced by take off but not
during landing. Data of residents
living in the two areas were observed
over a period of twelve
weeks, one area being exposed to
air traffic noise for three quarters
of the given time, the other for one
quarter of the time. Fifty
three volunteers (age 50–52 ± 15 y)
monitored their blood pressure
and heart rate over a period of
three months by using an automatic
device with digitized readings.
They also protocolled their
own subjective perception of noise
and sleep quality. Thirty one probands
were living West of the airport
(West group) and were exposed
to a nocturnal equivalent
continuous air traffic noise level of
Leq(3) = 50 dB(A) outside, during
flight direction 25 to the West.
Twenty two probands were living
East of the airport (East group)
and were exposed to Leq(3) = 50 dB
(A) during flight direction 07 to
the East. During the opposite flight
directions air craft noise corresponded
to Leq(3) = 40 dB(A) in
both areas. Frankfurt airport operates
direction 25 for about 75%
of the time on average and direction
07 for 25% of the time. The average blood pressure was
significantly higher in the West
group with higher noise exposure.
Morning systolic blood pressure
was 10 mmHg and diastolic pressure
8 mmHg higher in the West
group. Throughout the observation
period, the East group showed
a parallel between daily changes in
noise and subjective noise perception.
In the West group such a
parallel did not appear. This reaction
was considered to be the
consequence of the high noise exposure
of the West group. It is concluded that a population
exposed to a nocturnal
equivalent continuous air traffic
noise level of Leq(3) = 50 dB(A) for
three quarters of a given time has a
higher average blood pressure
compared to a population exposed
to the same equal energy noise
level for only one quarter of the
time. Within the East group a
parallel between noise exposure
and noise perception was observed,
while in the West group
this parallel did not appear. The
difference is considered to be the
consequence of higher noise stress
levels in the West group. The data
are in accordance with recent epidemiological
studies and indicate
that a nocturnal aircraft noise of
Leq(3) = 50 dB(A) can have negative
effects on subjective noise
perception and on objective parameters
of circulation.
79 citations
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21 May 2007TL;DR: In this paper, the authors report on an investigation of full-scale landing gear noise measured as part of the 2005 Quiet Technology Demonstrator 2 (QTD2) flight test program.
Abstract: With continued growth in air travel, sensitivity to community noise intensifies and materializes in the form of increased monitoring, regulations, and restrictions. Accordingly, realization of quieter aircraft is imperative, albeit only achievable with reduction of both engine and airframe components of total aircraft noise. Model-scale airframe noise testing has aided in this pursuit; however, the results are somewhat limited due to lack of fidelity of model hardware, particularly in simulating full-scale landing gear. Moreover, simulation of true in-flight conditions is non-trivial if not infeasible. This paper reports on an investigation of full-scale landing gear noise measured as part of the 2005 Quiet Technology Demonstrator 2 (QTD2) flight test program. Conventional Boeing 777-300ER main landing gear were tested, along with two noise reduction concepts, namely a toboggan fairing and gear alignment with the local flow, both of which were down-selected from various other noise reduction devices evaluated in model-scale testing at Virginia Tech. The full-scale toboggan fairings were designed by Goodrich Aerostructures as add-on devices allowing for complete retraction of the main gear. The baseline-conventional gear, faired gear, and aligned gear were all evaluated with the high-lift system in the retracted position and deployed at various flap settings, all at engine idle power setting. Measurements were taken with flyover community noise microphones and a large aperture acoustic phased array, yielding far-field spectra, and localized sources (beamform maps). The results were utilized to evaluate qualitatively and quantitatively the merit of each noise reduction concept. Complete similarity between model-scale and full-scale noise reduction levels was not found and requires further investigation. Far-field spectra exhibited no noise reduction for both concepts across all angles and frequencies. Phased array beamform maps show inconclusive evidence of noise reduction at selective frequencies (1500 to 3000 Hz) but are otherwise in general agreement with the far-field spectra results (within measurement uncertainty).
48 citations
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TL;DR: A literature review of recent field studies of aircraft noise-induced sleep disturbance finds that reliable generalization of findings to population-level effects is complicated by individual differences among subjects, methodological and analytic differences among studies, and predictive relationships that account for only a small fraction of the variance in the relationship between noise exposure and sleep disturbance as mentioned in this paper.
Abstract: Aircraft noise-induced sleep disturbance (AN-ISD) is potentially among the more serious effects of aircraft noise on people. This literature review of recent field studies of AN-ISD finds that reliable generalization of findings to population-level effects is complicated by individual differences among subjects, methodological and analytic differences among studies, and predictive relationships that account for only a small fraction of the variance in the relationship between noise exposure and sleep disturbance. It is nonetheless apparent in the studied circumstances of residential exposure that sleep disturbance effects of nighttime aircraft noise intrusions are not dramatic on a per-event basis, and that linkages between outdoor aircraft noise exposure and sleep disturbance are tenuous. It is also apparent that AN-ISD occurs more often during later than earlier parts of the night; that indoor sound levels are more closely associated with sleep disturbance than outdoor measures; and that spontaneous awakenings, or awakenings attributable to nonaircraft indoor noises, occur more often than awakenings attributed to aircraft noise. Predictions of sleep disturbance due to aircraft noise should not be based on over-simplifications of the findings of the reviewed studies, and these reports should be treated with caution in developing regulatory policy for aircraft noise.
45 citations
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TL;DR: In this paper, a study of community annoyance caused by civil aircraft noise exposure was carried out in 18 areas around Gimpo and Gimhae international airports in order to accumulate social survey data and assess the relationship between aircraft noise levels and annoyance responses in Korea.
44 citations
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08 Jan 2007TL;DR: In this article, the thrust and climb gradient for low jet noise during the entire take-off was optimized to achieve the Silent Aircraft Initiative (SAI) target of 60 dB at the sideline location but is approximately 5dB above the target at the flyover location.
Abstract: Meeting the Silent Aircraft Initiative (SAI) design goal during take -off drives the aircraft and engine design towards a multi -engine configuration with low specific thrust and high cruise altitude. These design choices enable the engine fan to operat e at part -speed during take -off, significantly increasing the benefit of a variable area nozzle in relation to fan and jet source noise reduction. By optimizing t he thrust and climb gradient for low jet noise during the entire take -off it is possible to re duce jet noise to the SAI target of 60 dBA . Using this approach overall aircraft noise meets the SAI target at the sideline location but is approximately 5dB A above the target at the flyover location. By considering turbomachinery and airframe noise source s when optimizing thrust and climb gradient it is possible to match the peak noise produced at all times during take -off giving an overall noise level of 62 dBA .
43 citations
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TL;DR: In this article, aircraft noise annoyance is interpreted from the perspective of risk society theory as described by Ulrich Beck, and the logic of wealth distribution is replaced by the logical logic of risk distribution.
Abstract: Air mobility spans most of the globe, but its side effects are concentrated in relatively small localities. In this paper aircraft noise annoyance is interpreted from the perspective of risk society theory as described by Ulrich Beck. With the increase in air mobility, side effects like noise nuisance gradually dominate the air mobility discussions. The logic of wealth distribution is thereby replaced by the logic of risk distribution. General annoyance statistics support this interpretation. But these statistics actually construct noise annoyance in the first place. Airport planners and professionals intentionally introduced the issue of noise annoyance to a wider audience. This exemplifies the ambivalence of risk theory as proposed by Beck. He employs a constructivist perspective, however he has a tendency to naturalize hazards. The dynamics that Beck describes as reflexive thrive on the inherent capacity of pollutants to confront the society that brought them forth. This article uses a constru...
40 citations
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TL;DR: A flap scheduling algorithm with complementary interface has been developed that takes noise nuisance and in-trail spacing into account and confirmed the conflict-free performance benefits and the feasibility of self-spacing during continuous decelerating/descent approaches under actual flight conditions.
Abstract: A current trend in aircraft noise abatement around airports is exploiting the benefits of revised arrival and approach procedures with computational aids, such as onboard and ground-based trajectory prediction algorithms and displays. The challenge for these upcoming advanced noise abatement procedures is to mitigate the noise impact without sacrificing runway capacity. A proposed solution, implemented in the three-degree decelerating approach, is to delegate the task of spacing the aircraft to the cockpit during the approach. To assist the pilots, a flap scheduling algorithm with complementary interface has been developed that takes noise nuisance and in-trail spacing into account The design and functionality of this support system is presented and evaluated with three experiments. Monte Carlo simulations indicated adequate and consistent performance and robustness of the self-spacing algorithm for various wind and traffic scenarios. A pilot-in-the-loop simulator experiment verified that, with the aid of the algorithm, pilots were able to execute the noise abatement procedure consistently while maintaining safe spacing. The support system reduced pilot workload up to an effort level comparable to current standard approaches. The concept was demonstrated in flight, which confirmed the conflict-free performance benefits and the feasibility of self-spacing during continuous decelerating/descent approaches under actual flight conditions.
37 citations
01 Jul 2007
TL;DR: In this article, the major sources of noise in a modern aircraft are discussed, and current techniques for predicting aircraft noise are reviewed, including the effects of source definition and acoustic treatment.
Abstract: Air travel in the UK has increased five-fold over the last 30 years. Half the population now flies at least once a year and freight traffic at UK airports has doubled since 1990. Similar statistics hold for other developed countries. It is likely that this growth will be eclipsed in the years to come by the expansion in civil aviation within emerging giants such as India and China. Civil aviation links distant communities for social and business purposes and gives affordable access to foreign travel for leisure purposes. It is unlikely however that the global community can continue to enjoy the benefits of air travel through increased capacity regardless of environmental cost. To tackle this problem, a balanced approach is essential which recognises the importance of air travel, but which also deals with environmental issues such as noise and emissions. Predicting the effects of noise and emissions is a first essential step towards such a solution. This article focuses on the prediction of aircraft noise and on developing noise reduction technologies. The aircraft noise issue is that of reducing the environmental impact of exterior noise at take-off and approach. This constitutes a major nuisance to residents near airports. It has resulted in stringent local airport regulations, such as the ‘quota count’ system at Heathrow, which are now more restrictive in defining acceptable limits for aircraft noise than are the international noise regulations promulgated by ICAO which first brought aircraft noise within a regulatory framework in the sixties and seventies. In this article, the major sources of noise in a modern aircraft are discussed, and current techniques for predicting aircraft noise are reviewed. These include the effects of source definition and acoustic treatment. Recent advances in noise reduction technology will be presented and their performance assessed in the light of noise targets set by the Advisory Council for Aeronautics Research in Europe (ACARE) in their ‘vision 2010’ and ‘vision 2020’ plans. Finally some specific noise reduction technologies will be described which have been developed and assessed in recent EC projects.
26 citations
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TL;DR: Changes in present USA noise-measurement procedures and noise-control guidelines are proposed that provide more accurate predictions of annoyance, related adverse effects, and criteria for setting "tolerable" limits of noise exposure in residential areas.
Abstract: A demonstration field-research study reveals that aircraft noise measured at two one-story houses is ∼9dB less attenuated from measured outdoor levels than is street traffic noise, and, found in other studies, ∼14dB less than railway noise. Comparable differences are found between these noises from the application of basic acoustical formulas for quantifying attenuations that occur on site of one- and two-story houses. Reasonably consistent with those findings are results from attitude surveys showing that daily exposure levels of aircraft must be ∼8dB less than levels of street traffic noise, and ∼13dB less than levels of railway noise to be perceived as an equal cause of annoyance and related adverse effects. However, USA government guidelines recommend that equal exposure levels of noise measured outdoors from vehicles of transportation should be considered as being equally annoying. Changes in present USA noise-measurement procedures and noise-control guidelines are proposed that provide more accurate...
22 citations
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TL;DR: In this article, the authors used phase-array microphones to estimate installation noise of aerodynamic origin and found that the effect of forward flight is extremely important in the interaction between the flow around the wing flap and the jet.
Abstract: T IS known experimentally, since the late 1970s, that a jet installed under a wing of an aircraft radiates more noise than the same jet in a standalone condition. The excess noise is the propulsion-airframe integration noise or commonly referred to as installation noise. When a jet is placed near a wing, there is an increase in noise in the flyover directions because of the reflection of sound by the wing. Here, installation noise includes not merely the noise increase due to the reflection of sound by the wing. The major part of this noise is generated aerodynamicly by the nonlinear interaction between the flow around the wing flap and the jet. In this work,ourprimaryinterestistomodelandtopredictinstallationnoise of aerodynamic origin. Installation noise increases not only the total aircraftnoiseinthe flyoverplanebutalsointhesidelinedirections.It is especially important during landings and takeoffs when the flaps are down. Duringthe1980s,anumberofexperimentswerecarriedouttrying to quantify the characteristics and intensity of installation noise [1– 4]. Most of these experiments involved the measurements of the jet alone noise and the noise when the jet was placed near a model of an aircraft wing inside an anechoic chamber. The experimental measurements by Wang [2] were the most systematic. In his experiment,ascaledmodelofthewingofaDC-10aircraftwasused. Large noise increase was observed in the flyover plane in the lowfrequencypartofthespectrum.Theincreaseinhigh-frequencynoise was less. In directions at small exhaust angles, the installation noise intensity was quite low. In the sideline, the radiated noise characteristics, on the other hand, were quite different. Overall, the measured data indicated that installation noise had a unique spectral shape and a directional pattern of its own. Recently, there is a renewed interest in propulsion-airframe integration noise. Mead and Strange [5] investigated the under-thewing installation effects on jet noise with special emphasis on the sidelinedirections.Theirinterestinthesidelinewasmotivatedbythe experience that it was generally more difficult to meet legislative limit on sideline noise level requirements. They reported the measurement of high installation noise level in the low-frequency range. One drawback of the Mead and Strange experiment [5], as well as most of the previous works, is that the experiments were carried out in static conditions. Upon realizing that the effect of forward flight is extremely important in the interaction between the flow around the wing flapandthejet,aseriesofnewexperimentsoninstallationnoise was conducted by engineers of The Boeing Company (Shivashankara and Blackner [6], Blackner and Bhat [7], and Bhat and Blackner [8]). They employed an open wind tunnel at M � 0:28 tosimulatetheforwardmotionoftheaircraft.Byusingellipticmirror microphones and the newly developed phase-array microphones, they were able to obtain noise source location maps as well as farfield noise data.
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08 Jan 2007
TL;DR: The Preliminary Aircraft Design and Optimization tool (PrADO) is presented as a means of performing multidisciplinary, integrated preliminary design of unconventional aircraft configurations, with a focus on green aircraft concepts.
Abstract: The Preliminary Aircraft Design and Optimization tool (PrADO) is presented as a means of performing multidisciplinary, integrated preliminary design of unconventional aircraft configurations, with a focus on green aircraft concepts. High fidelity numerical methods for some of the involved disciplines are discussed as key elements of this process. A noise propagation module is described as a first step towards introducing aircraft noise analysis into the preliminary design process. Application of the tool to a specific Low Noise Aircraft (LNA) concept is shown. Although the structural weight of the LNA is significantly higher than that of a conventional reference aircraft designed for the same transport mission, the results of the design analysis indicate that the LNA can still achieve advantages in terms of direct operating costs if certain economic and operational conditions are met.
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TL;DR: In this article, the authors studied the case of Hurghada airport, Egypt, with a focus on evaluating, both theoretically and practically, the airport noise and its impact on the city.
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01 May 2007TL;DR: It is shown experimentally, that microphones close to the helicopter can be used to estimate the specific noise sources that radiate to the far field, if the microphones are positioned correctly relative to the noise source.
Abstract: A special acoustic flight test program was performed on the Bell 206B helicopter outfitted with an in-flight microphone boom/array attached to the helicopter while simultaneous acoustic measurements were made using a linear ground array of microphones arranged to be perpendicular to the flight path. Air and ground noise measurements were made in steady-state longitudinal and steady turning flight, and during selected dynamic maneuvers. Special instrumentation, including direct measurement of the helicopter s longitudinal tip-path-plane (TPP) angle, Differential Global Positioning System (DGPS) and Inertial Navigation Unit (INU) measurements, and a pursuit guidance display were used to measure important noise controlling parameters and to make the task of flying precise operating conditions and flight track easier for the pilot. Special care was also made to test only in very low winds. The resulting acoustic data is of relatively high quality and shows the value of carefully monitoring and controlling the helicopter s performance state. This paper has shown experimentally, that microphones close to the helicopter can be used to estimate the specific noise sources that radiate to the far field, if the microphones are positioned correctly relative to the noise source. Directivity patterns for steady, turning flight were also developed, for the first time, and connected to the turning performance of the helicopter. Some of the acoustic benefits of combining normally separated flight segments (i.e. an accelerated segment and a descending segment) were also demonstrated.
01 Jan 2007
TL;DR: A large field study with 2312 residents from 66 areas around Frankfurt Airport was performed in 2005 in order to investigate the effects of aircraft noise on annoyance and health-related quality of life as discussed by the authors.
Abstract: A large field study with 2312 residents from 66 areas around Frankfurt Airport was performed in 2005 in order to investigate the effects of aircraft noise on annoyance and health-related quality of life. The survey was carried out in a period between the announcement and the planned implementation of an airport extension (construction of a new runway). The results show among others a shift in noise annoyance in comparison to dose-response curves generated from meta-analyses including older studies. In addition to noise exposure non-acoustical factors like attitudes towards the noise source, expectations concerning future residential situation after airport extension and (dis-)trust in authorities had a substantial influence on noise annoyance.
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21 May 2007TL;DR: This is the first time an extensive set of landing gear noise directivity data are available to compare and assess predictive capabilities, and both methods predict comparable amplitudes and trends for the flyover locations, but deviate at sideline locations.
Abstract: The NASA Aircraft NOise Prediction Program (ANOPP) includes two methods for computing the noise from landing gear: the "Fink" method and the "Guo" method. Both methods have been predominately validated and used to predict full-scale landing gear noise. The two methods are compared, and their ability to predict the noise for model-scale landing gear is investigated. Predictions are made using both the Fink and Guo methods and compared to measured acoustic data obtained for a high-fidelity, 6.3%-scale, Boeing 777 main landing gear. A process is developed by which full-scale predictions can be scaled to compare with model-scale data. The measurements were obtained in the NASA Langley Quiet Flow Facility for a range of Mach numbers at a large number of observer polar (flyover) and azimuthal (sideline) observer angles. Spectra and contours of the measured sound pressure levels as a function of polar and azimuthal angle characterize the directivity of landing gear noise. Comparisons of predicted noise spectra and contours from each ANOPP method are made. Both methods predict comparable amplitudes and trends for the flyover locations, but deviate at the sideline locations. Neither method fully captures the measured noise directivity. The availability of these measured data provides the opportunity to further understand and advance noise prediction capabilities, particularly for noise directivity.
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TL;DR: In this paper, the authors present a method to reduce the risks of over-interpreting the accuracy and precision of community noise impact assessments by using estimated prediction intervals, which is similar to our approach.
Abstract: Evaluations of the adverse consequences of community exposure to transportation noise often place more credence in measurements, predictions of noise effects, and interpretive criteria than is warranted by their underlying precision. If reports and assessments of such noise measurements and their effects were accompanied by estimated prediction intervals, the risks of over-interpreting the accuracy and precision of community noise impact assessments would be reduced.
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13 Nov 2007TL;DR: This paper presents an original work for aircraft noise monitoring systems and it analyzes the airplanes noise signals and a method to identify them using processed spectral patterns and a neuronal network feed-forward, programmed by means of virtual instruments.
Abstract: This paper presents an original work for aircraft noise monitoring systems and it analyzes the airplanes noise signals and a method to identify them. The method uses processed spectral patterns and a neuronal network feed-forward, programmed by means of virtual instruments. The obtained results, very useful in portable systems, make possible to introduce redundancy to permanent monitoring systems. The noise level in a city has fluctuations between 50 dB (A) and 100 dB (A). It depends on the population density and its activity, commerce and services in the public thoroughfare, terrestrial and aerial urban traffic, of the typical activities of labor facilities and used machinery, which give varied conditions that must be faced of diverse ways within the corresponding normalization. The sounds or noises that exceed the permissible limits, whichever the activities or causes that originate them, are considered events susceptible to degrade the environment and the health.
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21 May 2007
TL;DR: In this article, a Toboggan-shaped main landing gear noise reduction fairing was designed for full-scale flight evaluation on a B777-300ER aircraft in the QTD 2 program.
Abstract: The advances in aircraft engine noise reduction and the increasing demand for quieter aircraft has led noise research to focus more attention on airframe noise. Landing gears and high lift systems have been known to significantly contribute to the total aircraft noise at approach idle conditions, especially in cases where high by-pass ratio engines are used, when noise from the engines is low enough that it could be considered comparable or lower than the noise from the airframe. Landing gears in service on today’s aircraft were not designed with noise impact in mind and contain a myriad of possible noise generating features. Today’s landing gear designer is challenged to consider noise among many other factors when designing efficient aircraft landing gear systems. It is a challenge further complicated if noise reduction solutions are required for retro-fit applications. Much of the experimental noise research conducted on landing system noise has centered around the understanding of noise generating mechanisms and evaluation of noise reduction concepts in model-scale environments such as wind tunnel tests. These experiments have provided valuable insight into landing gear noise sources. However, little effort has been made to integrate noise reduction research with full-scale landing gear design and evaluate noise reduction potential in a full-scale flight environment. The work conducted under the Quiet Technology Demonstrator 2 (QTD2) program marks a first step in the successful integration of noise research with landing gear design with the focus being to design, implement and evaluate noise reduction solutions in a full-scale flight environment. This paper discusses the design and analysis of a ‘toboggan’ shaped main landing gear noise reduction fairing for full-scale flight evaluation on a B777-300ER aircraft in the QTD 2 program. The fairing was selected for flight evaluation after a series of model-scale wind tunnel acoustic experiments were conducted in conjunction with full-scale feasibility studies. The fairing design addressed issues such as gear kinematics and stowing, brake cooling, ground operations and noise reduction potential. The design was supported by static stress analysis and flutter analysis to ensure that the fairing was flight worthy.
01 Apr 2007
TL;DR: The FAA Integrated Noise Model (INM) 7.0 as mentioned in this paper was developed with support from the ATAC Corporation and the Department of Transportation Volpe National Transportation Systems Center (NTSC).
Abstract: The Federal Aviation Administration, Office of Environment and Energy, Noise Division (FAA, AEE-100) has developed Version 7.0 of the Integrated Noise Model (INM) with support from the ATAC Corporation and the Department of Transportation Volpe National Transportation Systems Center. The FAA Integrated Noise Model is widely used by the civilian aviation community for evaluating aircraft noise impacts in the vicinity of airports. The model is typically used in the U.S. for FAR Part 150 noise compatibility planning, FAR Part 161 approval of airport noise restrictions, and for environmental assessments and environmental impact statements under the current version of FAA Order 1050.1E. New features in INM 7.0 include: lateral attenuation calculations based on SAE-AIR-5662; flight path segmentation, flight procedure step types, bank angle calculations, and thrust reverser implementation based on ECAC Doc 29; helicopter modeling methods based on Version 2.2 of FAA’s Heliport Noise Model (HNM); an HNM study import function; a scenario annualization function allowing operations to be adjusted after performing a run; a multi-threaded run mode; fixed-spacing contour grid functionality; increased differentiation between different type of aircraft (civil, military, and helicopter); the ability to input location values in lat/long or X/Y; and many extended database fields. INM Version 7.0 software runs on PCs using a minimum hardware configuration of a Pentium III processor, Microsoft Windows 2000 or XP operating systems, 1.0-Gb RAM, mouse input device, hard disk drive, and CD-ROM drive.
01 Jan 2007
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21 May 2007TL;DR: A suitable method for optimizing the annular and cylindrical liners that make up the exhaust system is outlined and the effect that modal scattering between axial liner junctions can have on the acoustic performance of the system is explored.
Abstract: The increase in bypass ratios for modern day turbofan engines has led to fan rearward broadband noise emerging as one of the principal aircraft noise sources. The most widespread method for mitigating this noise source is the installation of acoustic liners in the ducting downstream of the fan. Mixed exhaust designs have the potential to be quieter than a three quarter cowl aeroengine due to the additional surface available for liner application. As a result, the Silent Aircraft concept design contains an embedded distributed propulsion system to exploit this opportunity. This paper outlines a suitable method for optimizing the annular and cylindrical liners that make up the exhaust system. To gain maximum benefit, liners should be designed to absorb the modal disturbances that are the most significant for an observer on the ground. The optimization uses an advanced noise footprint cost function to achieve this. Consequently, the liners and the length of the installation have been chosen to meet the aggressive noise target set for the aircraft. In addition, we explore the effect that modal scattering between axial liner junctions can have on the acoustic performance of the system. We find that energy interchange between radial modes will often have a detrimental effect on the overall attenuation, although this can be addressed by selecting the order of the liners in a more considered way. The assumption that scattering between liners can be neglected during optimization to allow design of the individual components therefore appears to be valid in this case. However, subsequent attention has to be directed to the order in which they are placed. Current and next generation mixed exhaust aeroengines will be restricted to smaller liner segment lengths than the Silent Aircraft. This analysis suggests that scattering and hence liner order is likely to more important for these designs.
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TL;DR: This paper proposes that practitioners be much more explicit in relating these supplemental noise metrics to the potential effects of noise and presents several examples that relate noise effects to lay terms.
Abstract: Airport noise analyses rely heavily on the use of complex exposure metrics that can be obscure to the layperson. Individuals often seek out information on aircraft noise levels, only to be frustrated by the complexity of the science. In recent years, there has been increasing use of supplemental or other nontraditional metrics to describe the impact of aviation noise on people. Implicit in this usage has been an assumption that supplemental metrics are better understood by the community. This paper proposes that practitioners be much more explicit in relating these supplemental noise metrics to the potential effects of noise and presents several examples that relate noise effects to lay terms. FAA's integrated noise model (INM) can predict noise impact on the basis of wellestablished relationships between noise effects and metrics available in the INM. Then, instead of presenting noise level information, it is possible to use these relationships to prepare graphical depictions that represent the extent of...
01 Jan 2007
TL;DR: In this article, the effects of road traffic noise and aircraft noise on annoyance were investigated and it was found that at high levels of aircraft noise exposure, the exposure effect curve even reverses, with other words: follows a negative trend.
Abstract: Although increasing consideration has been given to the effects of noise from the combination of rail and road traffic, data for the combined effects from road traffic and aircraft noise are rather scarce. In order to elucidate the combined effect of these two noise types on annoyance, previously published data from two aircraft noise annoyance surveys conducted in 2001 and 2003 among residents in the vicinity of Zurich Airport have recently been completed with road traffic noise exposure data. One of the research questions was, whether road traffic noise, due to its continuous nature, is better able to mask aircraft noise events and thus rather modifies aircraft noise annoyance than vice-versa. Analyses were conducted in accordance with the methodology outlined in the paper by Lercher et al. [1]. A similar effect as found with railway noise annoyance in the aforementioned paper has been found with aircraft noise: its annoyance reaction was modified through additional road traffic noise although the effect was not very strong. Interestingly, for road traffic noise annoyance, it was found that at high levels of aircraft noise exposure, the exposureeffect curve even reverses, with other words: follows a negative trend.
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TL;DR: The feasibility of developing a suitable artificial neural network to establish if a time signal, elaborated through a wavelet process, is or is not similar to others, having been recognized as originated from a defined type of aircraft is demonstrated.
Abstract: This paper deals with the experimental validation of an innovative system for the aircraft acoustic signature identification which has been developed by the vibration and acoustics laboratory of the Italian Aerospace Research Center. The system is composed of an algorithm for the acoustic signature identification and a dedicated neural network classifier, trained with a set of experimental aircraft noise data. The algorithm test and validation has been performed for different airplanes during takeoff and landing maneuvers. The experimental activity of ground noise measurements has been carried out at the Naples airport of Capodichino. More than 200 aircraft noise events of five aircraft types (Airbus A320, Boeing B737, McDonnel Douglas MD80, Fokker F100, Aerospatiale/Alenia ATR72), during both takeoff and landing maneuver, have been measured. This paper demonstrates the feasibility of developing a suitable artificial neural network to establish if a time signal, elaborated through a wavelet process, is or is not similar to others, having been recognized as originated from a defined type of aircraft. The artificial neural network was trained by the use of a subset of experimental data and then validated through a comparison with another subset of data from the same experimental campaign. The developed software demonstrated to give more than satisfactory results for each of the acquired spectra, with the maximum error always being under (10)%.
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21 May 2007TL;DR: In this article, the authors present the most recent advances in the development of a reliable and eective algorithm for the inclusion of community noise consideration within a multidisciplinary design optimization (MDO) framework.
Abstract: The paper presents the authors’ most recent advances in the development of a reliable and eective algorithm for the inclusion of community noise consideration within a Multidisciplinary Design Optimization (MDO) framework. The attention is here focused on the possibility to include sound quality issues as an alternative to the classical sound-level-based approach. The improvement of the sound quality could be seen as an additional “degree of freedom” available to the designer to reduce the impact of the air trac on residents’ life. One of the primary objectives of the European Research Project SEFA (Sound Engineering For Aircraft) is the definition of those characteristics that make the aircraft acoustic emissions less annoying. This is done by means of an extensive campaign of psychometric tests, supported by a careful sound engineering work. One of the outcomes of this activity is the synthesis of a target sound, having all the characteristics of “pleasantness” defined. The role of the authors within the project is the development of an algorithm capable to evaluate the feasibility of the target sound matching since the conceptual phase of the design of the aircraft. To accomplish this, a method for the quantitative evaluation of the dierence between the target sound and the acoustic emissions of the aircraft is needed. A careful definition of the “distance” between two sounds is introduced and validated, in order to identify a metric useful to properly build an objective function capable to drive the optimization process toward the target-sound-matching configurations. In this work, the evaluation of the sounds distance is extended to the analysis of non-stationary sounds and applied to match the emissions of recorded sounds in the final approach procedure. Specifically, the distance is evaluated as the L p -norm of the dierence between the current spectrum and target spectrum over the frequency-time domain. In order to evaluate the current spectrum, the computation of airframe noise, fan and compressor noise, buzz-saw and jet noise is performed. Atmospheric attenuation, ground reflection and doppler eect are also taken into account. In this work, an L 2 -distance between current and target spectra is taken as the objective function of an evolutionary algorithm. The static equilibrium of the aircraft is used as a constraint, whereas the variables space used includes both design and procedural parameters. Preliminary numerical results show that the method is capable to eectively drive the optimization process towards those configurations satisfying the sound-matching criterion.
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TL;DR: In this article, the authors investigated the impact of airport noise on the price of single-family homes in the Zurich Airport area, using spatial econometric techniques to measure the impact.
Abstract: The paper applies spatial econometric techniques to measure the impact of airport noise on the price of single-family homes in the Zurich Airport area. A hedonic model is specified with an error component accounting for spatial dependence. The paper takes a differentiated approach on the modelling of aircraft noise. We exploit a large database of geo-referenced noise measurements to investigate the reaction of prices to different noise metrics. The peculiar institutional setting of Zurich Airport, with changing patterns of runways configurations allows to distinguish the impact of noise at different times of the day. The use of neighborhood fixed-effects is compared to the results given by a costlier modelling strategy involving a rich set of GIS-based location descriptors. The paper documents a moderate impact of airport noise on housing prices. In the base model specification the Noise Discount Index is 0.93% with typical discounts in the range of -2% to -8%. Accounting for the spatiality of the data has little effect on the estimated coefficients and their standard errors.
01 Jun 2007
TL;DR: There will be a small benefit for airport residents compared to the current situation even if all traffic is rescheduled, but this benefit is likely to be outweighed by the increase in air traffic during shoulder hours.
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17 Sep 2007•
TL;DR: In this paper, various approaches to calculate aircraft noise are reviewed and the state-of-the-art is described; special attention is given to the description of airport operation, which has to be mapped into suitable input data for the calculations.
Abstract: The various approaches to calculate aircraft noise are reviewed and the state of the art is described. Special attention is given to the description of airport operation, which has to be mapped into suitable input data for the calculations. The key feature of any aircraft noise calculation program is the availability of reliable and accurate sound source data for the aircraft types. Therefore, the lack of detailed source data for a large number of aircraft types prevents many sophisticated models from being used outside research areas. Within the EU6 project Imagine the methods are developed to use for aircraft noise calculations the same acoustic approach as e.g. for traffic noise by separating source emission and propagation. The application of that concept to aircraft noise is described.