bluuebunny/crossref_metadata_2025 huggingface dataset:
Localization of higher order exceptional points from finite element model and their applications to duct acoustics.
Authors: Nennig Benoit , Perrey-Debain Emmanuel , Ghienne Martin
Published: February 2023

This work reviews the state of the art for high order perturbation method for parametric eigenvalue problems and propose some extensions for the multiparameters case. This approach allows to locate high order exceptional points (EP) arising in eigenvalue problems. EP correspond to a
particular tuning of some complex-valued parameters which render the problem degenerate. These non-Hermitian degeneracies have raised considerable attention in the scientific community as these can have a great impact in a variety of physical problems (PT-symmetry, thermo-acoustic or fluid-structure
instability, etc.) and their numerical solution. For applications dealing with dissipative acoustic waveguides, strong modal attenuation can be achieved close to EP and a maximum of attenuation occurs at EP of high order corresponding to the coalescence of more than two modes. The method is
based on the automatic computation of the successive derivatives of some selected eigenpairs with respect to the parameters so that, after recombination, regular functions can be constructed. This algebraic manipulations permit to build a reduced order model allowing i) to quickly solve the
eigenvalue problem for other parameters values, ii) to follow modal branches, iii) to locate higher order EPs. The method is applied to the particular case of a circular duct with a locally reacting liner at its wall which admittance varies with azimuthal position.
On the decay of entropic-compositional sources of indirect noise in combustors
Authors: Fattahi Abolfazl , Rahmani Ebrahim , Karimi Nader , Hosseinalipour S. Mostafa
Published: February 2023

For nearly half a century, indirect combustion noise in gas turbine combustors was entirely attributed to entropy waves, as the convecting hot spots. However, recent studies identified another source of indirect noise called compositional waves, which consists of convecting chemical
blobs. Understanding the evolution of this new source during its journey throughout the combustor requires attention due to the unknown physics of the turbulent, heat transferring flow in which it moves. In the current study, a hot chemical blob including a mixture of combustion products is
introduced at the channel inlet. During its convection along the channel, degeneration of various thermal and chemical components of the entropic-compositional wave is investigated in the frequency domain using large-eddy simulations. It is shown that the wave annihilation due to wall cooling,
as found in real combustors, can exceed those imposed by the flow hydrodynamics. Through a coherence analysis, it is found that mixture fraction is mainly responsible for deteriorating the chemical sources and that the contribution of potential function is comparatively smaller. Overall, it
is concluded that compared to entropy waves, compositional waves are up to 20% more prone to decay.
Methods of Mode Generation Inside Hollow Core Photonic Crystal Fibers
Authors: Kincaid Peter Seigo , Porcelli Alessandro , Arimondo Ennio , Neves Antonio Alvaro Ranha , Camposeo Andrea , Pisignano Dario , Ciampini Donatella
Published: February 2023

Microspheres trapped inside Hollow Core Photonic Crystal Fibers (HCPCF) could provide a way to monitor the temperature in hydrogen combustors, thereby helping to provide a warning system for flashback and thermoacoustic oscillations that can lead to expensive combustor damage. The temperature
of a particle trapped in a HCPCF may be extracted by the analysis of the particles' motion, which can be in turn controlled by opportune manipulation of the spatial intensity profile of the light in HCPCF. To this aim, an intermodal beating intensity pattern may be created inside the HCPCF
using a mixture of LP01 and LP11 modes. In this work, methods of generating the optical modes, which involve the use of spatial light shaping techniques, are presented and analysed. This is an important step to producing a controllable intermodal beating pattern.
Evaluating the restorative potential of church buildings
Authors: Laplace Josée , Guastavino Catherine
Published: February 2023

We report the preliminary results of a study on the experience of soundscape and architectural ambiances of church buildings, with an emphasis on their restorative qualities. Through questionnaires, soundwalks and interviews with 16 diverse participants, we aim to characterize the sensory
qualities of 2 contrasting church buildings in Montreal. Our data collection instruments operationalize concepts at the intersection of different research fields: soundscapes, attention restoration, quiet areas, architectural ambiances and heritage (including religious) places. As such, it
encompasses a broad range of descriptors and outcomes. At a methodological level, we discuss the relative contributions of the different methods used and how they complement one another to provide a better understanding of experiences of church interiors. At a theoretical level, we report
the main findings in term of experiences of space, sound, ambiance and associated benefits. In particular, we discuss the restorative potential of church building(s) and questions raised in relation to the particular context of this field work.
An audio-based vehicle classifier using convolutional neural network
Authors: Bakirci Ekim , Aygun Haydar
Published: February 2023

Audio-based event and scene classification are getting more attention in recent years. Many examples of environmental noise detection, vehicle classification, and soundscape analysis are developed using state of art deep learning techniques. The major noise source in urban and rural
areas is traffic noise. Environmental noise parameters for urban and rural small roads have not been investigated due to some practical reasons. The purpose of this study is to develop an audio-based traffic classifier for rural and urban small roads which have limited or no traffic flow data
to supply values for noise mapping and other noise metrics. To develop an audio-based vehicle classifier a convolutional neural network-based algorithm was proposed using Mel spectrogram of audio signals as an input feature. Different variations of the network were generated by changing the
parameters of the convolutional layers and the length of the network. Filter size, number of filters were tested with a dataset prepared with various real-life traffic records and audio extracts from traffic videos. The precision of the networks was evaluated with the common performance metrics.
Further assessments were conducted with longer audio files and predictions of the system compared with actual traffic flow. The results showed that convolutional neural networks can be used to classify road traffic noise sources and perform outstandingly for single or double-lane roads.
The effect of the vibrissa shaped cylinder on the aeolian tone mitigation
Authors: Chen Guanjiang , Liu Xiao , Zang Bin , Azarpeyvand Mahdi
Published: February 2023

This paper studies vibrissa shaped cylinder as a passive control method for reducing the aerodynamic noise of the flow past a cylinder. One elliptical cylinder is also investigated for comparison. The far-field noise results show that compared with the cylinder case, the tonal peak
almost disappears in the vibrissa shaped cylinder case and the sound pressure level (SPL) could be reduced by up to 30dB within the velocity range from 8m/s to 35m/s. The elliptical cylinder only shows a slight SPL reduction by about 4 dB with a shift in the tonal peak frequency from St=0.2
to St=0.39. Furthermore, some noticeable variations occur in the noise directivity pattern for the vibrissa shaped cylinder case. The shift in the tonal peak frequency, the reduction in noise and modifications in the noise directivity is related to the changing and breakdown of the vortex
shedding caused by the interference with the elliptical and vibrissa shaped cylinder surfaces. The LES is conducted to the elliptical and vibrissa cylinder case for the fluid field information to further understand the mechanism of the noise reduction due to the vibrissa shaped cylinder and
elliptical cylinder.
The meaning of sound environment for children with special needs: Action research on room acoustics in the child development support center
Authors: Noguchi Saki , Arai Minami , Ueno Kanako , Funaba Hisao , Matsumoto Tomoko , Watanabe Ryoko
Published: February 2023

This study aimed to investigate the meaning of the sound environment for children with special needs. We conducted action research on room acoustics in a child development support center. First, we investigated actual conditions through acoustic measurement, behavioral observation,
and interviews with teachers. Results revealed loud voices, for example, crying and screaming voices, as daily sounds. The teachers had awareness of the problems with sound environment. In addition, it was observed that the teacher was personally engaged with the child to support their language
development and communication skills. They tried to speak politely, indicating a need for a sound environment that facilitates calm communication with children. Second, we conducted an experiment to improve the sound absorption performance in the classroom. The effects of the alleviation of
noisiness and enhancement of calmness were confirmed in the sound environment. From the interviews, we discovered that experiencing an environment with different reverberations was an opportunity for teachers to become aware of their own voices.
Towards high frequency boundary element methods for multiple scattering
Authors: Chandler-wilde Simon , Langdon Stephen , Phillips Oliver
Published: February 2023

Standard Boundary Element Methods (BEM) for time-harmonic acoustics, using piecewise polynomial finite-element type approximation spaces, have a computational cost that grows rapidly with frequency, to ensure at least a fixed number of degrees of freedom per wavelength. Hybrid Numerical-Asymptotic
(HNA) BEMs, based on enriched approximation spaces consisting of the products of piecewise polynomials with carefully chosen oscillatory functions, have a computational cost that is almost frequency-independent for some problem classes (e.g. Chandler-Wilde, Graham, Langdon, Spence, Acta Numerica
2012), but the technology is largely undeveloped for problems where multiple scattering is important. In this paper we present computational experiments, supported by mathematical analysis, which suggest that multiple scattering configurations may be within reach. Specifically, we solve, by
a HNA BEM, scattering by a pair of screens in an arbitrary configuration, which we anticipate may serve as a building block towards algorithms for general multiple scattering problems with computational cost independent of frequency. The specific configuration considered, as we discuss, is
relevant to the efficient simulation of multiple outdoor noise barriers.
Experiences with source characterization methods within and beyond the scope of EN 15657
Authors: Schöpfer Fabian , Kruse Tobias , Weinzierl Johanna , Mayr Andreas , Schanda Ulrich
Published: February 2023

Prediction of machinery noise in buildings requires knowledge about the airborne sound radiation and the structure-borne sound excitation from the source of interest. Laboratory methods to determine the airborne sound power of sources are well established since many years. However,
standard methods for the characterization of structure-borne sound from building service equipment were first described in EN 15657-1:2009 which was then superseded by EN 15657:2017. In recent years the test methods described in this standard were applied in several research and development
projects in the laboratory for sound measurement (LaSM) at Rosenheim Technical University of Applied Sciences. For this purpose the experimental equipment and the facilities of the laboratory were expanded which involves a variable reception plate test rig that was built in 2017. This paper
describes the experience with test methods within and beyond the scope of the EN 15657:2017 using the available laboratory resources.
Systematic Review of meta-analyses for noise
Authors: Chen Yingxin , Blackmore Claire , Eminson Katie , Gong Xiangpu , Hansell Anna
Published: February 2023

In the context of constructing a burden of disease toolkit for noise exposures in England, we sought to identify meta-analyses to provide exposure-response coefficients that would update those available from the WHO Noise Guidelines for the European Region published in 2018. We conducted
a systematic review of systematic reviews relating to noise exposure and selected health outcomes published in 2017-20. We used the AMSTAR checklist to score all selected systematic review papers at the same time as data extraction. A new review needed to have at least a moderate score on
AMSTAR to be recommended as an alternative/update to the WHO analyses. Twenty-three papers were included in the review, of which 11 studies provides quantitative effects estimates. Eight considered environmental noise associations with metabolic outcomes, seven with mental health outcomes,
six with cardiovascular outcomes, and five studies systematically reviewed on wellbeing, sleep, and annoyance. We recommend one new meta-analysis on diabetes and one on hypertension, plus a further new meta-analysis on IHD to be considered for use in place of the WHO systematic review. Our
review also suggested there are now enough papers available to conduct a future new meta-analysis for noise and dementia.
Noise effects on health in studies in Low-Middle-income-countries (LMICs): a narrative review update of epidemiological evidence
Authors: Chen Yingxin , Hansell Anna , Cai Samuel
Published: February 2023

Noise has been linked to adverse non-auditory health problems, including annoyance, sleep disturbance, cardiovascular disease, and impaired cognitive function. However, most studies on these topics have been conducted in developed countries. This review focussed on studies in Low-and
Middle-income-countries (LMICs), which are generally considered to suffer from worse noise pollution. We conducted a literature search of Medline and Web of Science from 2009-2021, supplemented with specialist journal hand searches and identified relevant 56 studies in LMICs. Thirty-four (60.7%)
of the 56 studies assessed exposure based on sound level meter monitoring, eleven with noise mapping, six with subjective ratings, three with portable sensor measurements, and two used meteorological data provided by atmospheric administration. Twenty-four (42.9%) of the 56 studies looked
at noise annoyance and perception and found, as with non-LMIC studies, higher noise levels are associated with higher annoyance. Thirteen studies examined cardiovascular outcomes (mainly blood pressure or hypertension) of which 11 found adverse associations with noise exposure. Eleven studies
considered mental health status, but the findings were inconclusive. A meta-analysis was not possible due to the variability of the study designs. This review will help inform further studies and health-based recommendations in LMICs.
Structureborne noise transmission from a sports court
Authors: Dong Wayland , Rawlings Samantha , LoVerde John
Published: February 2023

The authors recently investigated a multifamily high-rise building that included a sports court. Noise from bouncing basketballs and similar sources generated undesirable noise transmission in adjacent units. While that was not surprising, the pattern of transmission throughout the
building was not as expected. Vibration measurements taken in the building are compared to predicted impact flanking transmission to evaluate the vibration paths through the building. While sports courts are not that common, the results are also applicable to impacts from fitness center sources,
and even to prediction of impact noise in lateral and diagonal directions.
The city of Ravello and its hundreds clerical buildings. Acoustic discoveries of the St Mary Gradillo's church
Authors: Lombardi Ilaria , Parente Rosaria , Sukaj Silvana
Published: February 2023

Hundreds of churches and monasteries have been erected in a small town nearby Naples during the Medieval Age. A recent proposal by the local authority regards the utilization of some clerical buildings to be part of the places selected to host musical venues during the festival that
is annually recurring in Ravello. The St Mary Gradillo's church has been built during the 11th century, to be composed by three naves marked by columns, following the architectural features of a basilica. The different height and typology of roof, to be a double slope in the central nave and
vaulted in the lateral ones, is characterised by a dome located at the junction of the wings crossed at the level of the altar. This paper deals with the assessment of the existing acoustic conditions of the church. The evaluation is based on the analysis of the main acoustic parameters in
accordance with ISO 3382-1. Measures adopted to adjust the acoustics to host musical venues have been treated in terms of additional absorbing panels other than mountable solutions for a temporary wooden stage
Numerical study of sonic boom propagation through atmospheric turbulence using open data of weather research and forecasting
Authors: Koganezawa Shinya , Naka Yusuke , Ishikawa Hiroaki , Shimada Ryo
Published: February 2023

Sonic boom noise is a major issue to be addressed for the realization of supersonic transport, and has therefore attracted considerable attention among stakeholders as well as researchers. In particular, the deformation of waveforms and changes in noise levels due to atmospheric turbulence
have been studied from the viewpoint of assessing annoyance and certification standards. Atmospheric turbulence conditions vary depending on the environmental factors (e.g. region, season, time), and it is essentially a chaotic phenomenon; therefore, statistical evaluation is necessary to
understand its effect. Although many studies on the effects of atmospheric turbulence on sonic booms have been conducted, few studies have investigated realistic trends of atmospheric turbulence. In this study, numerical analysis of sonic boom propagation considering atmospheric turbulence
is performed for C609, an early type of NASA's X-59 Low-Boom Flight Demonstrator. The model equation for propagation is heterogeneous one-way approximation for the resolution of diffraction (HOWARD) and the Wilson and Ostashev model is chosen to define the atmospheric turbulence spectra. The
parameters characterizing the atmospheric turbulence are set based on publicly available datasets of weather research and forecasting simulation. The sonic boom waveforms obtained by the numerical simulations and their noise level variations are statistically processed and evaluated.
The impact of the COVID-19 pandemic on community noise
Authors: Park Sang Hee , Shin Hye-Kyung , Kim Kyoung-Woo
Published: February 2023

The COVID-19 pandemic has caused considerable changes in our lives. It has influenced our society, education, economy, and environment as well as our lifestyle. We have got used to wearing facemasks daily. Working or studying from home is not an unusual thing anymore. On the other hand,
some that we used to regard as normal, such as travelling abroad, have become less normal in this era. These changes subsequently influenced the acoustic environment in our community. Countries have closed their borders, set travel restrictions, and ordered their residents to stay home. Due
to the reduced number of travelling, recent studies have noticed changes in traffic noise exposure. In addition, people gather less (e.g. at pubs or social events) during the pandemic - it also has an impact on the acoustic environment in our community. This paper provides a review of the
literature on the effects of the COVID-19 pandemic on community noise. Based on the review, this paper concludes with suggestions for future research directions to create a better acoustic environment in the post-COVID era.
Quantifying and Reducing Embodied Carbon in the Acoustic Design of Mass Timber Buildings
Authors: Bligh James
Published: February 2023

An adoption of mass timber construction is the construction industry's best shot at reducing its significantly large contribution to global CO2 emissions. Acoustic design in mass timber buildings typically relies on mass and facing materials in order to meet design criteria,
and can account for a high proportion of the embodied carbon (CO2e) per m² on a build. In order to fit with the ethos of mass timber construction; low embodied carbon, reusable, cradle to cradle materials must be adopted. This paper presents the findings of a study into the
relationship of acoustic performance and CO2e, and proposes alternate approaches that reduce the CO2e/m² of the acoustic design by up to 66% with little to no detriment to acoustic performance. Through single variable analysis in third party laboratory testing, and
in situ testing, it has been found to be possible to utilise low CO2e acoustic systems that reduce the CO2e/m² in not only the acoustic design, but structural, M&E and architectural disciplines, too.
Low Frequency Noise - An inventory of literature and of the situation in the Netherlands
Authors: White Kim , Versteeg Anja , Kok Arnaud , van Poll Ric , Dusseldorp Annelike
Published: February 2023

Low Frequency Noise (LFN) is an environmental stressor causing annoyance and, potentially, sleep disturbance. It is a topic of increasing social concern. In the Netherlands, an increasing number of complaints about LFN in the home environment is filed each year. A consortium of four
ministeries has asked the RIVM to prepare an overview on LFN, including literature, an update on the Dutch situation and advise on how to move forward in the field of LFN. To gain insight in the way that LFN complaints are handled in the Netherlands, a questionnaire was filled in by officials
of municipalities and other public authorities, and by audiologists This paper will contain an overview of LFN literature, findings of our questionnaire study and recommendations for future research on LFN.
Experimental study on vibration response of wooden house façade to low-frequency outdoor sound
Authors: Liu Jinyu , Inoue Naohisa , Sakuma Tetsuya
Published: February 2023

Generally wooden house has low sound insulation performance for low-frequency outdoor noise due to the lightweight façade wall system. Moreover, the sound insulation performance is caused by the vibration responses of window and wall systems, that are strongly coupled with normal
modes in a room. In order to clarify the complicated phenomena, field measurements of vibration characteristics are conducted for a test house with Japanese traditional wooden structure, under the cases with single/double window systems. As outdoor sound source, low-frequency band noise from
25 Hz to 160 Hz is emitted from a subwoofer, and vibration acceleration is measured on each element, such as window glazing, interior walls, floor and ceiling. From the analysis of measured vibration transfer functions and indoor sound pressure distribution, the vibration characteristics of
the whole coupled system are discussed, especially on the effect of different window systems.
Influential Factors on Recognition of Sound Emitting Direction Using in Evacuation Guidance System
Authors: Miyoshi Tetsuya
Published: February 2023

It is difficult to find an appropriate evacuation route in complicated buildings and underground malls. Therefore, evacuation guidance systems using sound and light has been proposed. The method of the emitting sound was proposed as one of them. In this evacuation guiding method, several
influential factors such as speaker setting configurations and sound emitting methods affect the recognition of the emitting direction of sound. In this paper, we discuss the sound emitting configuration to improve the performance of the sound direction recognition through the experiments
changing the emitting configurations of audio speaker distance and emitting time interval.
Autonomous noise monitoring system based on digital MEMS microphones: development of a smartphone application for remote communication
Authors: Mello Felipe Ramos de , Fonseca William D'Andrea
Published: February 2023

Noise monitoring is a useful diagnostic tool for making better decisions in noise control projects and understanding the sonic behavior of a place. Traditionally, sound pressure levels are measured using a sound level meter (SLM), usually for a limited time frame. However, recently
much interest has arisen in developing wireless sensor networks that work continuously, especially using cost-effective embedded systems. In this sense, digital micro-electrical-mechanical (MEMS) microphones are a great promise in creating such devices due to their low-cost, high-quality,
and integrated analog to digital converter. This paper presents a noise monitoring system based upon digital MEMS microphones and an Arduino compatible microcontroller (Teensy). The system connects to a server through an ethernet cable (providing also a power supply), and sound pressure level
data is saved both on the server and an SD card (for redundancy). Furthermore, a backup power supply guarantee that the system continues working even in power shortage situations. The device was deployed in an office and successfully measured throughout a week. Ultimately, the system could
be applied to indoor noise monitoring (such as in condominiums and buildings) and used to assess the effectiveness of noise control projects, for example.
Analysis and Control of Acoustic Modes in Cylindrical Cavities with application to Direct Field Acoustic Noise (DFAN) Testing.
Authors: Hargreaves Jonathan
Published: February 2023

It is well known that acoustic cavities have frequencies at which certain free-response 'modes' of propagation respond especially strongly. In the absence of significant damping, these cause peaks of high SPL in the frequency response as well as spatial non-uniformity and temporal ringing.
The spatial non-uniformity is especially problematic since it means the room cannot be 'EQ'd' to compensate, since the SPL is different in different positions. This phenomenon has been studied extensively in the room acoustics literature and various strategies for mitigation proposed. Many
of these make use of the theoretical mode shapes for a cuboid with a rigid boundary condition, since this is a common shape of room and a reasonable approximation for a solidly constructed wall. But modes exist for other shape spaces too. Of particular interest is the cylindrical cavity that
is formed when large enclosing arrays of loudspeakers are used to perform high-intensity acoustic tests on space hardware. These possess problematic modes that can cause over-testing in some positions and under-testing in others. In this work, it is investigated how a simple FEM simulation
can compute Q-factors for these modes and identify which will be problematic. How this might inform control system design is discussed.
Listening Difficulty of Public Announcement at Subway Platform with Long Reverberation Time
Authors: Song Eun Sung , Kim Su Hong , Kim Jeong Hun , Lee Song Mi , Kim Do Kyung , Eom Chun Won , Ryu Jong Kwan
Published: February 2023

The subway platform is a unique spaces where the reverberation time (RT) is extended depending on the distance from the sound source. Moreover, various noise sources is being occurred at the subway platform such as the train approaching noise, crowd noise, and so on. The purpose of
this study is to determine which factor affects the listening difficulty of announcement through listening test based on the acoustical data from on-site measurements. The results of listening test show that the difference according to the types of noise sources, S/N ratio, and RT was found
to be significant. In particular, the difference between RT of 2.2 s and 3.6 s showed the largest difference of up to 65.1 % in listening difficulty rating. In addition, the influence of noise type on listening difficulty rating was found in the condition of RT 2.2 s, but not in RT 3.6 s.
Announcement combined with the crowd noise was to be the most difficult to listen to among noise types in the better acoustical condition.
Sound masking of residential noise by a birdsong depending on spectral and temporal characteristics
Authors: Lee Songmi , Eom Chunwon , Kim Jeonghun , Kim Suhong , Song Eunsung , Kim Dokyeong , Ryu Jongkwan
Published: February 2023

This study aimed to investigate the sound masking according to spectral and temporal characteristics of residential noise and natural sound through auditory experiment. Since there are various types of residential noise sources (maskee) and natural sounds (masker), stimuli to be used
for experiment were selected by dividing the sound source groups through the k-means cluster method. The stimuli consisted of a total of 7 maskee including a brown noise, and 7 masker (birdsongs and water sounds). In the auditory experiment, the preference of masker and the annoyance and unpleasantness
of single maskee and masker and mixed sources (maskee+masker) were investigated. Result showed that Phoenicurus auroreus and stream-Fast were the highest preference among masker, and masker preference were significantly correlated with masker annoyance. In addition, it was found that impact
sound (children jumping and running and piledriver) show relatively higher annoyance than other sound sources. Relative annoyance of mixed sources (maskee+masker) to single maskee was analyzed and masking effect was discussed based on spectral and temporal and the Zwicker's parameters of each
sound source.
Sonic boom, more than two centuries of investigation !
Authors: Coulouvrat François
Published: February 2023

Seventy-five years ago, Chuck Yeager on Bell-X1 broke the sound barrier. Five years later, Whitham published his seminal paper linking the shape of a supersonic body to its boom. In 1962, the French-British agreement was signed, launching the Concorde program. First flight occurred
seven years later, a climax period for sonic boom research, before its current renewal following the first SSBD demonstration of in-flight boom reduction in 2003. Before this "golden-age", sonic boom, though not known under this name, was not ignored. Booms from meteoroids may have
been one of the clues proving their extraterrestrial origin (Biot, 1803) following the hypothesis of Chladni (1794). Infrasound of great Siberian meteorite was recorded in 1908. Shock from the tip of a cracking-whip, the oldest human-made supersonic object, was visualised by Carrière's
schlieren shadow photographies in 1927. This method was already used by Mach in 1887, exhibiting the conical shockfront produced by a bullet, now bearing his name but earlier conceptualised by Doppler. During World War One, trying to localise acoustically artillery guns, Esclangon established
the modern ray-tracing equations launched from the Mach cone of a supersonic gun shell. The paper will briefly discuss these early works and some others.
A comparative study of semi-empirical noise emission models based on the PANAM and sonAIR aircraft noise simulation tools
Authors: Felix Greco Gil , Wienke Felix , Bertsch Lothar , Zellmann Christoph , Schäffer Beat , Ring Tobias P. , Langer Sabine C.
Published: February 2023

In the context of aircraft noise simulations, an accurate representation of the aircraft noise sources is crucial so that reliable predictions can be obtained. In this contribution, we present a comparative study between the predictions provided by the emission models based on the DLR
in-house code PANAM and the sonAIR simulation software. Both are based on semi-empirical descriptions of the engine and airframe noise contributions, meaning that the emission levels are modeled separately for each noise source according to the operational conditions of the aircraft. This
allows the comparison of the emission models not only in terms of the aircraft's overall noise levels, but also regarding its different noise sources. The comparative study considers models representing the noise emissions of an A319 aircraft, which are provided by both simulation tools but
further simulated within the sonAIR software environment in order to yield noise immission levels on a large calculation area. In general, a good agreement is observed for the departure procedure due to the similar performance of the engine noise models. In contrast, larger differences are
observed during the approach procedure and at larger distances from the runway, which might be explained by differences in the airframe noise models.
Wave-based numerical investigation on diffraction correction for a low-height barrier in energy-based sound propagation model for road traffic noise
Authors: Yasuda Yosuke , Kamiya Yu , Morinaga Makoto
Published: February 2023

In energy-based noise propagation prediction methods, such as CNOSSOS-EU in Europe and ASJ RTN-Model in Japan, sound propagation is calculated by using the equation of sound attenuation by the geometrical divergence of the sound power from a sound source and adding various attenuation
corrections such as diffraction effect and ground effect. In the ASJ RTN-Model, the insertion loss due to a semi-infinite barrier to a free field is generally used for the diffraction correction for a single barrier, the top of which is regarded as a knife wedge, whereas the diffraction correction
for a low-height barrier is different from that for a general single barrier. It is given as the insertion loss due to a low-height barrier to a semi-infinite barrier, the top height of which is at the ground surface level, in a free field: the diffraction correction is zero when the low-height
barrier is 0 m high. However, its range of application is not clear. In this paper, the diffraction correction for a low-height barrier is discussed by comparing the results of three-dimensional wave-based numerical analysis and propagation calculations using the ASJ RTN-Model.
New guidance manual for the monitoring and evaluation of aircraft noise in Vietnam with an experimental application to the aircraft noise monitoring at Noi Bai International Airport
Authors: Nguyen Thu Lan , Vu Thi Thanh , Shinohara Naoaki , Makino Koichi , Sakoda Keishi , Yamada Ichiro
Published: February 2023

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.
Basic study on the estimation method of burrows on the seafloor using ultrasound
Authors: Tachiki Hajime , Hirasawa Haruki , Asakura Takumi , Mizuno Katsunori , Seike Koji
Published: February 2023

There is concern about the noise effect of offshore energy facilities. For example, noise generated during construction and operation of them may affect some aquatic species. Aquatic environmental measurements have been conducted to assess this effect. However, the effect under the
seafloor remains unknown due to the lack of an efficient method for surveying a wide area. The marine environment is affected by the burrows formed by organisms living on the seafloor. Therefore, it is important to know the shape of the burrows of benthic organisms from the viewpoint of marine
environmental conservation. In this study, we investigated a method for estimating the length and diameter of the burrow by transmitting broadband ultrasonic waves into the burrow and measuring, analyzing the echoes. The model experiment and the acoustic simulation using the finite-difference
time-domain method were comparatively performed to verify the possibility of estimating the tube length and diameter. It was confirmed that the tube length was estimated with a relative error of about 3% for straight and U-shaped plastic tube models.
A benchmark study on room acoustic simulations with various material input complexities
Authors: Li Yue , Meyer Julie , Lokki Tapio , Cuenca Jacques , Atak Onur , Desmet Wim
Published: February 2023

This work investigates and evaluates the capabilities of an explicit finite-difference time-domain (FDTD), a fast multipole indirect boundary element method (FMBEM), and a ray-tracing (RT) solver in the context of room acoustic modeling and simulations. In room acoustic simulations,
the wave-based FDTD and FMEBM methods are known for generating accurate results at low frequencies, while the RT technique is in principle more valid at higher frequencies. The numerical aspects of setting up the solutions for each solver are discussed. Special attention is given to the influence
of material input data of various degrees of detail. Single/multiple frequency-independent/dependent materials are considered in the model setup. The modeling capabilities of the three solvers in handling material input with various complexities are analyzed. Numerical results are evaluated
in both frequency and time domains. Room acoustic parameters, including the reverberation time (T_20), early decay time (EDT), clarity (C_80), and definition (D_50), are compared. These results are also compared with available measurement data. Last but not least, the computational efficiencies
of the three solvers are briefly discussed.
Numerical prediction method for vibration characteristics of steel-framed ALC floor structure
Authors: Mizunuma Haruki , Asakura Takumi , Ishiwatari Yasuhiko , Shiraishi Takayuki , Satoh Fumiaki
Published: February 2023

The prediction of floor vibration is of great importance from the viewpoint of accurate prediction of sound environment. In this paper, applicability of the finite-element analysis to the vibration simulation of autoclaved lightweight aerated concrete (ALC) floor structure on a steel-framed
structure was verified. The results of a numerical case study has confirmed that the numerical coupling scheme of the ALC floor panels and the steel-framed structure had a significant influence on the simulated vibration characteristics of the ALC floor panels. Then, the validity of the proposed
method was finally confirmed by comparison with the measurement results.
FDTD-Based Simulation and Analysis of Noise Reduction Effects in Hospital Wards
Authors: Xu Yiquan , Xu Yiquan
Published: February 2023

The impact of domestic hospital acoustic environment on the health of patients and healthcare workers is attracting more and more attention. This paper investigated and analyzed the noise situation of typical double wards in hospital, and designed noise reduction schemes according to
its noise sources; based on finite difference time domain method (FDTD), sound fields in wards were simulated before and after noise reduction treatments, and noise reduction results were compared and analyzed. Results show that FDTD can be used to effectively model sound field of wards with
complex boundary conditions; meanwhile, the noise mitigation processes have significant effects on improvement of reverberation time and speech intelligibility in wards.
Study on the Optimal Strategy of Campus Concert Hall--Take the Concert Hall of Sun Yat-sen University as an Example
Authors: Yang Chenxi
Published: February 2023

With the increasing functional demand of universities, the construction of campus concert halls is become more common. In addition to being a venue for bands to perform, university concert halls are often used as conference halls, in particular. They not only require good music sound
effects, but also have certain requirements for speech intelligibility. Using the ODEON software to simulate the design plan of the concert hall of the Zhuhai campus of Sun Yat-Sen University, it is found that the acoustic parameters in the balcony area are unsatisfactory such as uneven sound
pressure level, low bass ratio and so on. In response to the shortcomings, the body shape was changed by adjusting the ceiling and adding floating cloud reflectors, so as to vary the distribution of sound field. This strategy can make the above-mentioned acoustic parameter values more evenly
distributed in the concert hall and keep the speech intelligibility in the auditorium at a medium level. The above design methods can effectively guide the sound quality design of university concert halls.
Sound absorption of porous composites with heated impervious inclusions
Authors: Núñez Gómez Gabriel Ignacio , Venegas Rodolfo , Boutin Claude
Published: February 2023

This paper investigates the sound absorption properties of porous composites with solid impervious heated inclusions, i.e. heat sources, which allow the temperature tuning of the porous constituents and the control of the pressure diffusion phenomenon. By means of the two-scale asymptotic
method of homogenisation, the wave equation in the composites with heated impervious inclusions is derived, allowing the material to be modelled as an equivalent fluid with effective density and compressibility. Analytical and semi-analytical models for the acoustical properties of porous
composites with inclusions of different geometries are developed, which are also numerically validated using the finite element method. This work demonstrates that adjusting the temperature of the porous constituents can provide an alternative way of controlling the absorptive properties of
hard-backed porous composite layers, and highlights the dependence of pressure diffusion on temperature.
Active Vibration Control of a Rotating Mechanical System with a Rigid Coupling using Active Disturbance Rejection Control
Authors: Lin Tingyu , Halim Dunant , Ran Liaoyuan , Xu Zhuang , Thein Chung Ket
Published: February 2023

The work aims to develop an active control method for mitigating torsional vibration of a rotating mechanical system with a rigid coupling, driven by an electric motor, particularly for suppressing vibration associated with its mechanical resonances. It is commonly known that torsional
oscillations in a rotating system, which is normally used for various power transmission systems, can generate significant levels of vibration and noise. In this work, therefore, an active control system that was based on the Active Disturbance Rejection Control approach was utilized to develop
an active control system that was robust against uncertainties associated with the internal dynamics and external disturbances affecting the system. The dynamic interactions between the inertias of the electric motor and the load, which were connected through elastic shafts and a rigid coupling,
were investigated. The Extended State Observer was used to estimate the generalized disturbance consisting of not only the external disturbances but also the disturbances associated with internal dynamics of the rotating system. The effectiveness of the developed controller was demonstrated,
which showed that in the case of the varying load inertia, the control system could still perform well in mitigating the torsional vibration.
Context and Representation: Data Gathering Methodology for Soundscape Contextual Factors
Authors: Dwan Albert
Published: February 2023

The contextual dimension of subjective perception plays a crucial role in moderating listener evaluations of soundscapes. While Soundscape indicators are directly measured and have numerically determinable measurement uncertainty, the surveying of subjective perception via soundscape
descriptors presents methodological challenges pertaining to an indeterminate range of situational moderators which influence descriptor selection. Variations in subjective assessments by listeners have been shown to be correlated with factors such as perceived relevance of a sound source,
whether the acoustic environment meets their pre-existing expectations, and familiarity. This paper addresses these methodological challenges by detailing a new data gathering strategy and analysis process for assessing the "interrelationships between person and activity and place, in
space and time" (ISO 12913-1:2014). The methodology explored in this paper lends clarity to the dynamics of subjective evaluation within the surveyed population, by instrumentalizing a multi-level model of individual perception of physical environments, drawn from related studies in workplace
sociology, anthropology, and organizational studies. This model of perception enables numerical analysis of written responses from listeners about their environment, revealing contextual factors which can moderate subjective perception of the sounds within the environment. This additional
data can be applied to the development of conceptual frameworks during soundscape analysis.
Optimizing noise exposure in the Vehicle Routing Problem: A case study of last-mile freight deliveries in Stockholm
Authors: Venkataraman Siddharth , Baclet Sacha , Rumpler Romain
Published: February 2023

Improvements in noise mapping techniques and smart cities infrastructure have fostered the development of new ways to evaluate traffic noise exposure. An example of one such outcome is the noise exposure sensitivity map, which quantifies the noise exposure potential of a road network
as a function of the vehicle type, the prevailing background noise, and the population exposed. The potential for planning vehicle routing that is offered by the above-mentioned map calls for revisiting the Vehicle Routing Problem (VRP) with a focus on accounting for the noise exposure in
the optimization process. A case study is chosen for applying the VRP, and it is taken from last-mile off-peak deliveries performed in Stockholm, Sweden, in the context of the CIVITAS Eccentric project. The VRP is independently solved for the following objectives: distance travelled, driving
time, and driving noise exposure potential. Also considered is a heterogeneous objective that is consisting of a combination of these factors. The impact of the objective function on the resulting routes is presented. A sensitivity analysis is performed to determine the trade-offs between
the chosen factors.