bluuebunny/crossref_metadata_2025 huggingface dataset:
PLR and take-off speed implications on noise contours and local gaseous emissions for SST business jet concept aircraft
Authors: BERTSCH Lothar , PLOHR Martin , NöDING Michel
Published: October 2024

DLR has established a simulation process to evaluate the landing and take-off of novel civil supersonic transport (SST) aircraft. This process was applied to two business jet concept aircraft in order to assess the certification noise levels according to novel regulations under discussion
at ICAO CAEP. It has to be noted, that neither of the concept aircraft is optimized for low noise nor for low boom. At DLR, modifications to departure flight procedures are under investigation, i.e., an automated thrust reduction referred to as Programmed Lapse Rate and an increased take-off
speed. These measures as proposed by NASA promise to reduce the certification noise levels for the two departure locations. For the two considered concept aircraft, promising procedures with reduced noise at the certification locations have been identified previously. This paper now addresses
the impact of these promising departure procedures on noise contour areas and local gaseous emissions. Impact on EPNL and SEL contours and differences in CO2 and NOX are assessed along the simulated flights. It is demonstrated, that the proposed procedures do not only reduce noise at the certification
locations but also noise contour areas and gaseous pollutants.
Comparison of the noise perception of conventional aircraft and Unmanned Aircraft Systems
Authors: GREEN Nathan , RAMOS-ROMERO Carlos , TORIJA Antonio J.
Published: October 2024

The use of Unmanned Aircraft Systems (UAS) for commercial applications is seeing steady growth in numerous sectors as the technology improves and more applications are realised. Whilst research into human response to UAS noise is a relatively new field, there is a far greater understanding
of the perception and impacts of conventional aircraft noise. Therefore, a listening experiment was designed to investigate the relationship between perception of conventional aircraft and UAS flyover noise. The experiment used mono ground plate recordings of flyovers from several different
aircraft and UAS, these recordings were re-spatialised to simulate flyovers over a multi-channel loudspeaker system. Participants were then asked to rate the annoyance of the sounds through a series of A/B comparisons. Results of the experiment demonstrate a clear positive correlation between
Loudness and annoyance. However, Sound Quality Metric analysis also suggests that Sharpness of the UAS sound and Tonality and/or Roughness of aircraft sounds can also be a significant factor for annoyance. The finding of this experiment may contribute to the understanding and development of
exposure-response relationships for UAS noise, building upon the extensive existing evidence on human response to conventional aircraft noise.
Relationship between psychologican and physiological responses to broadband water sounds
Authors: ASAKURA Takumi
Published: October 2024

This study aimed to investigate the effects of reproducing an ultrasonic sound above 20 kHz on the subjective impressions of water sounds using psychological and physiological information obtained by the semantic differential method and electroencephalography (EEG), respectively. The
results indicated that the ultrasonic component affected the subjective impression of the water sounds. In addition, regarding the relationship between psychological and physiological aspects, a moderate correlation was confirmed between the EEG change rate and subjective impressions. However,
no differences in characteristics were found between with and without the ultrasound component, suggesting that ultrasound does not directly affect the relationship between subjective impressions and EEG energy at the current stage. Furthermore, the correlations calculated for the left and
right channels in the occipital region differed significantly, which suggests functional asymmetry for sound perception between the right and left hemispheres.
Development of a gunshot location detection system based on acoustic data
Authors: TAşDELEN Yusuf , BAğCı Baran Berk , GöK Umut Murat , ŞEN Osman Taha
Published: October 2024

Determination of sound source location is a crucial problem, especially for the assault threat detection in crowded areas or military applications. The chief objective of this study is to design a microphone array to detect the location of explosion type sound sources, such as gunshot,
which have significant amplitudes when compared to the background noise levels. Furthermore, the time arrival difference algorithm is utilized for the determination of time arrival differences and sound source location. Evidently, for stationary microphones that are positioned close to each
other, determination of time arrival differences with high accuracy is a significant problem. Thus, a significant effort is given to enhance the accuracy of time arrival difference predictions via proper sampling. The design process of the microphone array is conducted computationally, where
the sound data received by the microphones are generated. The time arrival differences are then calculated numerically, which are used for the prediction of sound source location. The number of microphones, relative positions of the microphones are determined accordingly via digital experiments.
Finally, the designed microphone array is built and experiments are conducted. In conclusion, it is observed that the numerical model successfully predicts the sound source location of the computational model.
A procedure for estimating mitigation effect of air injection on ship underwater radiated noise
Authors: LLOYD Thomas , LAFEBER Frans Hendrik , BOSSCHERS Johan
Published: October 2024

Increasing evidence exists that underwater radiated noise (URN) from ships has a negative impact on marine ecosystems. This has led to numerous initiatives aimed at monitoring and mitigating ambient sound levels generated by shipping. Within the European Union, noise abatement is being
addressed by a wide range of stakeholders, with activities focused on developing procedures and thresholds for evaluating noise impact as well as knowledge on the effectiveness of a range of mitigation measures. In the SATURN project, MARIN is studying air injection systems for mitigation
of both propeller cavitation and machinery noise; the so-called "Prairie" and "Masker" systems. Model-scale tests have been performed in order to quantify performance in terms of sound level reductions for a range of test conditions. In this paper we elaborate a procedure
for applying the processed measurement data to ship-scale URN predictions for assessing mitigation potential during the early design stage. Data reduction of the model test results is explained, leading to a model for estimating the mitigation effect and power requirement of the two systems.
We subsequently apply the model to a number of test cases, covering both measured and calculated source levels. Limitations of the approach will also be discussed.
Deep learning-enhanced blind separation of incoherent and spatially disjoint sound sources
Authors: WU Xian , ROGER Boustany , BOULEY Simon , MINCK Olivier , DENAYER Hervé , ANTONI Jérôme , GRYLLIAS Konstantinos
Published: October 2024

Separating incoherent sound sources within complex acoustical fields presents a significant challenge in acoustic imaging. Existing methods, such as Principal Component Analysis (PCA) applied to the Cross-Spectral Matrix (CSM), yield 'virtual' sources based on statistical orthogonality.
However, this approach often fails to accurately identify distinct physical sources, primarily due to its reliance on statistical orthogonality solely. A state-of-the-art method involves computing a rotation matrix to enforce criteria such as least spatial entropy, or spatial orthogonality
among sources, a process that, while effective, significantly increases computational complexity and time. This work introduces a hybrid approach combining PCA and deep learning for predicting spatially disjoint source maps from virtual sources. By simulating sound sources in random quantities
and locations, we train a neural network tailored to this task. We address the order mismatch between PCA-derived virtual sources and pre-simulated labels by framing source separation as a set prediction problem, utilizing the Hungarian loss for efficient mismatch resolution. This method simplifies
the separation process, offering faster post-training computations and eliminating the need for complex optimizations. Validation in simulated environments and real-world datasets has shown the model's effectiveness in source separation for acoustic imaging, indicating the potential of integrating
deep learning with existing methods.
Applications of vibrational phenomena to evaluate the effect of hydrogen solution on the elasticity and fatigue properties of industrial metal plates
Authors: UCHIDA Helmut Takahiro , ITO Taisei , HASEGAWA Yoshinosuke , TUNG Yi Yuan , TSUCHIYA Hirotarou
Published: October 2024

Understanding resonance phenomena in materials is crucial in many fields, from controlling noise in small mobile devices to designing seismic-safe large structures or in energy harvesting. Resonance depends on material elasticity and its shape, influenced by temperature. While controlling
elastic properties can control vibrations, seeking practical alternatives is essential. This research focuses on introducing hydrogen into industrial metal materials as a method to control resonance conditions, which is particularly relevant in the context of the upcoming hydrogen society.
Controlled amounts of hydrogen were introduced to industrial metal plates (Ti, W) using electrochemical methods to investigate changes in their resonance characteristics. The results indicate that the introduction of hydrogen into Ti resulted in a maximum 20% reduction in Young's modulus,
while W exhibited a 10% decrease. Additionally, the recovery of their modulus by hydrogen desorption was confirmed. This confirms that the control of hydrogen allows the manipulation of the modulus of elasticity at constant temperature, controlling the resonance without changing the dimensions.
Furthermore, similar evaluations were performed on high hardness steel. The results showed fatigue failure due to vibration, increased Young's modulus with the introduction of hydrogen, and an observed trend toward decreased life to failure.
Nonlinear ultrasonic test applied to discern factors controlling cracking of cement mortar affected by reinforcement corrosion
Authors: RAMIS-SORIANO Jaime , CARBAJO SAN MARTíN Jesús , POVEDA MARTINEZ Pedro , MIRó OCA Marina
Published: October 2024

Intermodulation ultrasonic testing technique was used to detect corrosion- induced cracking in prismatic mortar samples. Three sets of five specimens were prepared and subjected to accelerated corrosion conditions. The different times of exposure allowed to attain unlike damage conditions
in every sample of each set. The onset of damage was monitored through the evolution of the accumulated Intensity Modulation Ratio (R) and crack width measurements. The accumulated values of the Intensity Modulation Ratio were used to study the effect of different testing factors (cover depth,
corrosion rate or amplitude of the input pump signal) and increased monotonically clearly discriminating the different damage levels. These observations point to the possibility of stablishing damage thresholds to detect cracking using nonlinear ultrasonic (NLU) techniques.
Identification of strategic location for environmental noise control through the application of land use regression (lur) in a neural network platform
Authors: KUMAR Saurabh , GARG Naveen , ALAM Md Saniul , RAB Shanay
Published: October 2024

The significant causes of rising noise pollution within urban areas lie in extensive transportation networks, industrial operations, and commercial activities. Addressing this complexity, our study employs Land Use Regression (LUR) modelling to assess the intricate relationship between
land-use features and environmental noise in urban landscape. The objective of this study is to provide a framework for predicting environmental noise levels in Delhi, India. For which, Lday, Lnight, LAeq, 24h, and Ldn noise descriptors were modelled at daily resolution data from 31 fixed-site
monitors. The prediction at first stage for LUR was found to be R2 = 0.53 which was validated using the n-1 method. The model was later optimized using a NN. Output from the NN is included in the GIS environment to identify the hotspot of the noise. Previously identified engineering interventions
applicable to urban contexts that were listed from the literature review were allocated as per hotspots because of the modelled output. The study also explored the avenue of using Delhi-specific transport variables developed from Google travel time data for prediction improvement of the noise
level. The research contributes to advancement of noise pollution assessment and management methodologies, particularly in situations with no available validated traffic noise models.
Acoustic characterization of porous windscreens for sound pressure and particle velocity sensors
Authors: FERNANDEZ COMESANA DANIEL , NAYAK Ashwin Sadanand , PRIETO ANEIROS Andrés
Published: October 2024

Acoustic measurements of ground vehicles, wind turbines or aircrafts are often performed outdoors in presence of wind. Air movement around an acoustic sensor may significantly disturb the measured signals due to flow-induced vibrations and turbulence. This is specially relevant for
pressure-gradient and particle-velocity based acoustic transducers which are more sensitive to these perturbations. To attenuate this effect and improve measurement quality, the sensors are typically covered with windscreens made of porous materials. However, designing an appropriate windscreen
poses a challenging task, demanding a deep understanding of sound transmission characteristics. This study works towards quantifying acoustic properties of rigid-frame porous materials through in-situ measurements and fitting a parametric fluid-equivalent model to find optimal model parameters.
The parameters are subsequently investigated by comparing windscreen insertion loss through finite-element numerical simulations and measurements on a sound intensity PU probe.
Vibroacoustic simulation for truck tire tread noise prediction
Authors: DARIO Garofano , DOTOLO Dario , ERRICO Fabrizio
Published: October 2024

In the last years, the introduction to the market of electric vehicles and a new labeling system introduced by the European Commission raised a strong interest in the noise produced by the tire-road interaction. The reduction of noise emissions became a strong challenge for the tire
manufacturers that are constantly in need of developing new simulation tools capable of predicting the noise emitted by a tire. In this paper, the application of a simulation methodology capable of predicting the noise performance of a tire is shown and validated by means of experimental data.
The experimental activities consisted of the acquisitions of noise produced by three truck tires made up of a particular tread pattern in which a single geometric feature is analyzed in each configuration, in a near field indoor condition. The simulation process aims to faithfully reproduce
the procedure of the experimental test and involves the use of non-linear explicit finite element analysis followed by a vibroacoustic simulation to account for the radiated noise by structural vibrations and fluid-pumping.
A transfer matrix model to predict acoustic attenuation of earplug filters made up of elastic film and air cavity
Authors: LIU Shuhan , PILE Raphaël , PEROT-LE GAL Joséphine , PETIT Robin , THOMAS Olivier
Published: October 2024

The sound attenuation of earplugs, commonly used for noise protection, can be improved by adding acoustic filters. However, the effect of acoustic filters featuring an elastic film and cylindrical air cavities on sound attenuation needs to be better understood. This study seeks to predict
acoustic attenuation of an elastic film filter via the development of an analytical model. Its advantage, as compared to numerical simulations, is to offer quicker solutions and a more profound comprehension of each physical parameter's impact. The total acoustic transfer matrix of the filter
has been established by coupling the air cavity with the film under assumption of plane wave. The transfer matrix of the vibrating elastic film is based on the Kirchhoff-Love theory and could take into account all its dynamic behaviors, including possible in-plane tension. The model is then
validated by comparison with numerical simulations using the finite element method. It is found that the plane wave assumption is valid in almost practical geometries of the air cavity such that the sound attenuation obtained from the analytical model align consistently with those from simulations.
Potential limitations are addressed and evaluated.
Impact of air gap thickness on acoustic metamaterials with internal simple expansion chamber structure
Authors: SAHU Nihar Ranjan , MANDAL Bibhuti Bhusan
Published: October 2024

The air gap thickness plays a significant role in enhancing sound absorption. This study explores the role of air gap thickness in enhancing sound absorption in 3D-printed acoustic metamaterials (AMMs) featuring a Simple Expansion Chamber (SEC) structure. Nine samples (B1 to B9) were
designed and then 3D-printed with varying SEC lengths (2-18 mm) maintaining an area expansion ratio of 16. An air gap (5-30 mm) was introduced between each sample and the rigid backing. The Sound Absorption Coefficient (SAC) was measured using the Impedance Tube Apparatus. Results showed a
notable increase in peak SAC from 0.57 to 0.96 with a 5 mm air gap for a sample with a 2 mm long SEC. However, this effect did not replicate across other samples, suggesting the peak SAC was unaltered by further variation of the air gap. Additionally, the peak absorption frequency exhibited
an exponential reduction with increasing air gap thickness. This research illuminates the nuanced relationship between air gap thickness and the acoustic performance of 3D-printed materials, offering insights for optimizing sound absorption in diverse applications. Keywords: Air gap thickness,
Simple Expansion Chamber, Area expansion ratio, Sound Absorption Coefficient, Sound Transmission Loss
Measurement of anisotropic airflow resistance characteristics of mineral wool samples
Authors: BOLBERG Mads , MASCHE Marvin , BELLASTEROS Monica
Published: October 2024

In the field of acoustics, the airflow resistance of a porous materials like stone wool is one of the governing parameters. As a starting point, measuring the airflow resistance in the normal direction can be used for good estimations of sound-absorbing abilities when using empirical
models. However, more complex models, like equivalent fluid models and Biot models, need more input parameters. The next natural step is to move into 2D and 3D interactions. An obstacle to overcome is obtaining accurate input parameters to qualify the models. The production process of stone
wool introduces an inherent geometric anisotropy in the material. The aim of the study is hence to develop test and sample preparation methods that enable the measurement of the airflow resistance of stone wool sample in 3 directions by means of testing a cubic specimen. The airflow resistance
was measured using a modified unidirectional static airflow apparatus. The paper presents test results obtained with the apparatus for a range of stone wool samples of varying densities. The results show noticeable differences in airflow resistance of more than 1.5 times between testing directions.
This paper also, includes comparisons to results obtained using an alternating airflow method as per ISO 9053-2:2020.
Multiphysical design for optimised ventilation and noise attenuation in ducts: an approach using metamaterials
Authors: FUSARO Gioia , BILLI Rachele , D'ORAZIO Dario
Published: October 2024

Noise generation and propagation through mechanical ventilation and air conditioning (MVAC) ducts have been increasingly investigated since commercial solutions allow sensible noise attenuation while reducing the duct section. So, a commercial silencer forces the MVAC power to rise
to overcome the flow resistance, increasing the noise source. For this reason, this study focuses on soundproofing ventilation ducts through acoustic metamaterials with no inner duct section decreasing. A crucial part of this study falls into the multiphysical interaction between acoustics
and fluid dynamics, which is a phenomenon that may result in a challenging analytical model. In conditions of flowing motion, the wave vector has been modelled according to the Lighthill model: the component of the velocity rotor potential becomes significant, influencing the soundproofing
performance due to the metamaterial placed at the edge of the inner surface of the duct. FEM analysis helped design a series of samples which then have been tested experimentally in static conditions. Once the numerical method is calibrated, further multiphysical numerical analysis are used
to implement the sound insulation properties of the metamaterial-based filter through dynamic flow conditions. Guidelines for multiphysical setup for wave-based simulation are drawn, and preliminary experimental results are presented.
Insertion loss of pipe clamps: Quantity for prediction or manufacturer's advertising?
Authors: DäUBLE Lukas , SCHECK Jochen , ZEITLER Berndt
Published: October 2024

The noise emitted by water conveying pipes as part of sanitary installations is, in most cases, dominated by structure-borne sound transmission. The water flowing through the pipe causes a vibration of the pipe system that is transmitted to the installation wall through pipe clamps.
A common mitigation measure is an elastic inlay inside the pipe clamps. Some manufacturers of these clamps advertise the insertion losses determined by non-standardized tests. Recent studies show a high dependency of the insertion loss on the mounting conditions, e.g. how tight are pipes fastened
in the clamp. This contribution aims to answer the question of whether and how the mounting condition affects the insertion loss of the pipe clamps and thus how representative the specified values can be for the building situation. The investigations are carried out in-situ on the reception
plate and in a building like test stand with an excitation by flowing water as well as with impact hammer excitation. This study is part of a research project with the overall aim to provide source data for the prediction of the sound transmission in buildings using EN 12354-5.
Inference of the acoustic properties of transversely isotropic porous materials
Authors: BERZBORN Marco , VORLäNDER Michael
Published: October 2024

Transversely isotropic porous materials are well represented by equivalent fluid models based on semi-phenomenological models such as the Johnson-Champoux-Allard-Lafarge (JCAL) model and a set of material parameters. Direct measurements of these parameters, however, are often difficult
or time consuming. As an alternative, inverse estimation methods provide a simple and fast framework to identify the JCAL model parameters, since they can be performed on single impedance tube measurements. In this work, we present a stochastic inverse identification method of the JCAL parameters
for transversely isotropic materials. We consider the flow resistance and characteristic viscous length and the static tortuosity to be anisotropic and the frame to be fully rigid, resulting in nine unique parameters to be identified. The method is based on reflection factor measurements of
a material in different orientations corresponding the transverse and isotropic principal axes. Hence, a priori knowledge of the orientation of the principal axes of the material is required. Results of the parameter inference are presented based on experimental data for a glass wool sample.
A parametric study of dynamic stress in acoustic black holes
Authors: KEYS Archie , CHEER Jordan
Published: October 2024

Acoustic Black Holes (ABHs) make modifications to a structure that act to reduce the speed of a wave travelling through the ABH region. The reduced wavespeed has a corresponding reduced wavelength which increases the effectiveness of damping treatment applied to the ABH. A common way
in which the reduction of wavespeed can be achieved is by gradually reducing the thickness of a structure. This is commonly implemented as a beam termination, which results in a thin tip. In this case, the energy focusing effect of the ABH causes high amplitude vibrations to occur in the thin
section of the structure, raising concerns about high levels of dynamic stress that could result in fatigue failure. This paper presents an investigation into the effect of changing the ABH taper length, tip height and power law on the dynamic stress in an ABH terminated beam. This is achieved
via numerical model of the structure, which enables a full parametric analysis to be carried out. For each ABH parameterisation, the performance is also quantified in terms of reflection coefficient so that trade-offs between performance and stress can be observed.
How artificial intelligence applied to sound recognition can help gas leak detection in acoustically complex environments?
Authors: MASSON Florent , WATREMEZ Xavier , LEVENT Sylvain , PREUILH Julien , URFELS Laetitia
Published: October 2024

From production to storage and transport, detecting leaks of flammable gases is a major challenge, particularly in terms of occupational safety and health, and environmental considerations. The emergence of hydrogen as an energy source makes acoustic-based technologies a key element
in this value chain. For these reasons, Metravib Engineering, in collaboration with the R&D Safety Project of TotalEnergies One Tech, has been developing since 2019 the AGLED system, for the early detection, localization and classification of these leaks. The system performs acoustic detection
in the audible frequency range, using antennas consisting of 4 microphones and physics-based artificial intelligence. Over 5,600 signals were recorded on a site fairly representative of gas production and storage facilities in order to build a robust learning database. Several algorithms were
implemented to limit the number of false detections delivered by the system. A relearning strategy was developed to handle unexpected disturbances relative to specific noise environment. This paper describes the overall architecture of the system, from signal acquisition to gas leak detection
and 3D localization. It delves into the relearning algorithm and its performance during two full-scale industrial pilots of TotalEnergies - La Mède (France) and Tempa Rossa (Italy) - that included nitrogen controlled leaks tests campaigns.
Experimental observation of super-Klein tunneling in phononic crystals
Authors: MERKEL Aurélien , ZHU Yifan , ASSOUAR Badreddine
Published: October 2024

We numerically and experimentally report the acoustic analogue of the super-Klein tunneling in a heterojunction of phononic crystals formed with Willis scatterers that exhibit pseudospin-1 Dirac cones. Pseudospin-1 Dirac cones are characterized by a triple states degeneracy in the band
structure where two linear bands intersect with a flatband. The scattering properties of pseudospin-1 quasiparticles comprise an unity transmission through one potential barrier at its center frequency for all incident angles, which is called the super-Klein tunneling. In addition, the unity
transmission does not depend on the barrier width. The Super-Klein tunneling differs from the conventional Klein tunneling, which consists of perfect transmission only under normal incidence through a potential barrier of any width. The Klein tunneling is predicted in pseudospin-1/2 systems
like graphene, which are characterized by a two states degeneracy with two intersecting linear band. This direct observation in this acoustic analogue may have important implications in the exploration of the rich physics of pseudospin-1 quasiparticles.
Effect of cross-frequency correlation on the auralization of acoustic scintillation in outdoor sounds
Authors: MAILLARD Julien , BRESCIANI Andrea P. C.
Published: October 2024

Outdoor sound propagation is modified by random fluctuations in the acoustic refractive index due to atmospheric turbulence. This phenomenon, known as acoustic scintillation, results in fluctuations in the amplitude and phase as well as reduced spatial coherence of the sound waves.
Recently, a physics-based model was proposed to construct time domain realizations of the amplitude and phase fluctuations for application in the auralization of outdoor sound sources. The approach assumed the frequency-dependent fluctuations, considered in separate 1/n octave frequency bands,
are either fully correlated or fully decorrelated. This paper extends the method by including specific model-based cross-frequency correlation in the fluctuations. The approach is first presented, followed by examples of applications and a subjective evaluation of auralized samples with and
without cross-frequency correlation.
A low-complexity adaptive speech dereverberation approach based on multichannel linear prediction
Authors: ZHU Zhen , HE Hongsen , QIU Zhimin , YU Yi
Published: October 2024

The adaptive multichannel linear prediction (AMCLP) technique is one of the most effective methods for speech dereverberation in real-time application systems. However, the computational complexity of the associated AMCLP algorithms is very high. In this paper, we propose a low-complexity
speech dereverberation approach based on AMCLP. The coefficient matrix of the multichannel dereverberation filter is decomposed into a linear combination of a set of low-dimensional sub-filter matrices and a set of low-dimensional sub-filter vectors through Kronecker product. According to
these sub-filter models, we define two sets of signal models and cost functions, from which the adaptive speech dereverberation algorithm is established. This solution not only leads to effective dereverberation performance, but also reduces the computational cost, which is very conducive
to realistic speech systems.
Modeling aeroacoustic interaction of rotating propeller with porous treatments using LBM (Lattice Boltzmann method) simulations
Authors: MBAILASSEM Fulbert , CHEVILLOTTE Fabien , BECOT François-Xavier
Published: October 2024

Porous treatments are more and more employed in presence of flow as passive noise control means to mitigate the generated noise. They are generally designed according to their acoustic dissipation properties under no-flow conditions. Nevertheless, in-flow porous treatments can alter
the aerodynamic properties, modify the main acoustic source itself or even generate secondary acoustic sources. While most of the modelling methods (analytical, FEM, ...) are able to model the acoustic dissipation, they do not allow to model the interaction with the main source or the possible
generation of spurious acoustic sources. The Lattice Boltzmann Method (LBM) is a computational fluid dynamics method able to run Direct Numerical Simulations (DNS) as well as Large Eddy Simulations (LES). The LES method resolves the macroscopic scale of turbulence and uses a sub-grid model
for the small scales of turbulence. The low numerical dissipation of the LBM enables to compute both fluid flow and acoustics quantities in a single run. In this work, the LBM implemented in ProLB software is used to model the airborne noise generated by an electric propeller installed on
an aircraft wing and the effects of sound absorbing treatments. Various treatments are investigated numerically and compared to experimental data when available.
The effects of noise on objective and subjective measures during speech recognition tasks as stress indicators: preliminary results
Authors: SAMELLI Alessandra , PERRINI Beatriz , SANTOS Juliana
Published: October 2024

Objective indicators of stress associated with annoyance scales are essential tools to advance knowledge in the area. Electrodermal activity (EDA) can be used to evaluate physiological responses, providing a picture of autonomic nervous system. Twenty-five adults were evaluated at three
situations of speech recognition tasks with monosyllables: in quiet, competitive noise at 65 dBA and 75 dBA. After each situation with noise, the annoyance scale was applied. After, low-pass filtering was used, and phasic phase was analyzed. Results showed that the percentage of speech recognition
hits decreased significantly with noise at 75 dBA (p<0.01), when compared to the situation without noise. Furthermore, it was found that annoyance increased significantly as noise at 75 dBA (p<0.01), when compared to 65 dBA. In relation to EDA, there was a significant increase in the
number of peaks when comparing speech recognition situations without noise and with noise at 75 dBA (p<0.01), but not for noise at 65 dBA. Regarding the amplitude of the first skin conductance response peak, there was no significant difference between the three situations. These findings
suggest that higher noise levels impact on speech recognition and annoyance, causing greater listening effort and increasing stress levels.
Influence of characteristic lengths on the aeroacoustic properties of in-duct tube bank configurations
Authors: VADDAMANI Charitha , BOIJ Susann , BODéN Hans , KARLSSON Mikael
Published: October 2024

The flow over circular cylinders or tubes arranged in different configurations is widely employed in various engineering applications, ranging from combustion systems to HVAC systems. The Reynolds number serves as the governing parameter defining the flow around the tubes, determining
the separation of the flow from the tube surface, and establishing a separation point. This separation point, in turn, dictates the formation of a jet with parameters such as jet height, jet velocity, and jet length. The jet formation, influenced by varying Reynolds numbers, introduces the
possibility of various characteristic lengths, including the diameter of the tubes, height of the duct, gap between adjacent tubes, jet height, and jet length. This study aims to explore the profound influence of these characteristic lengths on the aeroacoustic properties and the flow acoustic
coupling at cylinders in cross flow. The jet parameters are derived from the analysis of experimental and analytical modeling data. Through a systematic investigation, we examine the interdependencies between these characteristic lengths and the resulting aeroacoustic properties.
The frame around a test specimen and its influence on the measured sound absorption coefficient
Authors: HOLøYEN Gjermund V.
Published: October 2024

For most practical cases of reverberation room measurements of sound absorption coefficient according to ISO 354:2003, the standard requires the edges of the test specimen to be covered by a reflective frame. The purpose of this requirement is to keep the edges of the test specimen
from absorbing sound. While this statement is consistent with practical measurement results at medium to high frequencies, it has been shown that the low frequency performance of a high-absorbing test specimen worsens when a frame is not in place. To further investigate this phenomenon, a
series of reverberation room measurements have been carried out on several variations of a porous absorber test specimen. The goal of the measurements has been to determine whether the size and dimensions of the test specimen affect the test results, and if any such affections are dependent
on the presence of a frame. Additionally, the sound absorption area of the frame itself has been measured to elucidate whether the frame is likely to give a significant contribution to the total sound absorption area of a framed test specimen. The results will be presented and discussed in
this paper.
Experimental characterization of stall noise on a pitching airfoil in an anechoic wind tunnel
Authors: COTTé Benjamin , SICARD Lisa , RAUS David , MONCHAUX Romain , JONDEAU Emmanuel , SOUCHOTTE Pascal , ROGER Michel
Published: October 2024

Dynamic stall noise is one of the potential source of amplitude modulations associated with wind turbine noise. This phenomenon is related to the periodic separation and reattachment of the boundary layer on the wind turbine blade suction side during its rotation. Within the framework
of the PIBE project (Predicting the Impact of Wind Turbine Noise), experiments were conducted in an anechoic wind tunnel in order to characterize stall noise on a pitching airfoil in both static and dynamic conditions. A first set of measurements was performed using an airfoil equiped with
pressure taps to measure both steady and unsteady wall pressure as well as far-field acoustic pressure. These measurements were used to identify the noise regimes associated with different angles of attack, and to relate them with the boundary layer evolution. In a second experiment, synchronized
flow and acoustic measurements have been obtained to identify the coherent aerodynamic structures responsible for the noise radiation. The velocity fluctuations evaluated from the time-resolved particle image velocimetry (TR-PIV) data are correlated with acoustic pressure to localize aeroacoustic
sources, and various tools such as vortex detection methods and spectral proper orthogonal decomposition are applied to identify the nature of these sources.
Identification of ultrasound characteristics in viscoelastic architectured materials by angular measurements in double through-transmission
Authors: POUDREL Anne-Sophie , BOCHUD Nicolas , ROSI Giuseppe , REBILLAT Marc , PEIXINHO Jorge , CHINESTA Francisco , MARGERIT Pierre
Published: October 2024

Recent advances in additive manufacturing of viscoelastic materials have paved the way towards the design of increasingly complex multi-material structures with heterogeneities from the micro- to the macroscale. However, the measurement of ultrasound characteristics in such viscoelastic
structures is a challenging problem, due to the strong attenuation related to both the constituent materials and the architecture. We propose here a methodological framework to identify the phase velocity and attenuation in viscoelastic multi-material quasi-heterogeneous samples. The proposed
approach relies on measurements achieved in double through-transmission at various incidence angles, referred as theta-scan. The forward modeling of the wave propagation in such media allows then to identify the ultrasound characteristics based on an inverse approach. Experiments were performed
on multi-material samples made of a random pattern of inclusions of a soft elastomer inside a rigid glassy polymer. The effects of the volume fraction of the constituent materials on the ultrasound characteristics was evaluated. This methodology open the path towards ultrasonic measurements
in highly attenuating architectures
Extending the frequency range of ISO 717-2 - a look at options and issues
Authors: HOLøYEN Gjermund V.
Published: October 2024

In 2019, the Norwegian Standard NS 8175, which defines requirements for sound insulation in Norwegian buildings, was revised to include low frequency spectrum adaption terms for new dwellings. This change affects the applicability of measurements of weighted improvement of impact sound
insulation, delta Lw, as the spectrum for calculating delta Lw, given in ISO 717-2, is limited downwards to 100 Hz. For a floating floor construction, this means that floors with a resonance frequency well below 100 Hz, and correspondingly a relatively high delta Lw, will be overrated in the
sense that the measured delta Lw will be unaffected by the poor low frequency performance of the floating floor. To properly address this increased focus on low frequencies, an extended range spectrum is needed. In the work leading to this paper, a selection of extended range values for the
reference heavyweight floor have been suggested, starting with a linear extrapolation of the values given in ISO 717-2. Data from laboratory measurements of delta Lw for floating floors have then been used to investigate the suitability of the suggested values. The results are summarised and
discussed in this paper.
Comparison of noise exposure cost and annoyance-related indicators in microscopic traffic simulations
Authors: NYGREN Johan , BACLET Sacha , RUMPLER Romain
Published: October 2024

Road traffic noise is one of the major sources of environmental noise and has been shown to increase risk of adverse health effects. For this reason, noise mapping is an efficient tool to assess and monitor city-wide noise levels in accordance with the Environmental Noise Directive
(END). To relate these noise levels to the associated health effects, the noise map may be further analysed using exposure-response models, or with cost models that calculate the noise-related externalities of the traffic. With the use of microscopic traffic simulations, this assessment may
be performed at a vehicle-specific level. A recently introduced methodology, the noise exposure cost, calculates the vehicle-specific contribution to the long-term social cost estimated at a macro-level based on the vehicle-specific noise contributions. However, the noise exposure cost methodology
may not reflect the relative noise impact of individual vehicles, but rather solely reflect the noise contribution regardless of its relative impact to the noise levels at the time. The aim of this study is to investigate the possibility to use the linear sensitivity indicator as a basis for
a non-linear weighting function in the noise exposure cost methodology, to allow the vehicle-specific noise exposure cost to better reflect the relative impact.
Predicting the impact of wind turbine noise: general overview and results of the PIBE project
Authors: ECOTIERE David , GAUVREAU Benoit , COTTé Benjamin , ROGER Michel , SCHMICH-YAMANE Isabelle , JUNKER Fabrice
Published: October 2024

The PIBE project aims to improve wind turbine noise prediction methods and to explore new solutions for noise reduction. This five years project brought together French experts in aeroacoustics, sound propagation, experimental noise characterization and wind engineering, and was structured
around three work packages. The first one aimed to study amplitude modulation phenomena and focused particularly the characterization of dynamic stall noise. Specific aerodynamic and acoustic measurements were carried out in a wind tunnel, showing the influence of several stall regimes on
noise production. The second work package focused on quantifying the uncertainties of noise prediction methods. It developed an open-access online application (WindTUNE) that quantifies uncertainties on noise prediction of a wind farm, and a parametric and uncertainties calculation tool for
the engineering application Code-TYMPAN. This axe also produced an open-access database of a 400 days campaign of meteorological and acoustical measurements around a wind farm. The last work package investigated new noise reduction devices using blades with modified leading and/or trailing
edges. The efficiency of the solutions were characterized in a wind tunnel, both acoustically and aerodynamically. The paper presents the main results obtained at the end of the project.
Eolization: A project on spatial auralisation of wind turbine noise
Authors: COLAS Jules , ALEXANDRE Loïc
Published: October 2024

The increase of onshore wind farm projects in Europe has heightened concerns regarding the noise emitted by wind turbines and the potential nuisance to nearby residents. To address this issue, advanced tools are required for accurately assessing and predicting the noise levels and perceived
annoyance from wind turbines. Physics-based auralization emerges as a promising approach for recreating with fidelity wind turbine noise in controlled environments. To enhance the immersive experience, this study proposes to extend the current methodologies with the spatial representation
of wind turbine noise using ambisonics. In this work, the sound emitted by each turbine is computed using an extended source model. The propagation is simulated with a parabolic equation method accounting for the flow surrounding the wind turbines. Finally, the signal is auralized and spatialized
using spherical harmonic decomposition. This methodology provides a complete framework for predicting and reproducing the three-dimensional time-varying sound field around the listener. Overall, these improvements offer valuable insights into the spatial characteristics of wind turbine noise.
Diatom frustule-inspired elastic metamaterials
Authors: GAZZOLA Chiara , FONSECA DAL POGGETTO Vinicius , ZHOU Xin , MINIACI Marco
Published: October 2024

Although a universally accepted definition of elastic metamaterials does not exist yet, the latter are often associated to man-made or artificially engineered media possessing properties typically not available in Nature. Pioneering studies have recently demonstrated that complex structural
organizations, often arranged in a periodic and/or gradient manner and spanning multiple length scales, typically found in many biological systems, exhibit extraordinary absorption/reflection functionalities enhanced by local resonances or Bragg scattering mechanisms. This has opened the road
to new designs of bio-inspired metamaterial. In this context, here we investigate the elastic dynamic response of diatom frustules, i.e., the exoskeleton structures of photosynthetic algae ubiquitously present throughout the planet in water environments. Firstly, we analyse and record their
structural arrangement in nano- and micro- scales by using the Scanning Electro Microscopy (SEM) and the optical profilometer. The results of the analysis are transferred to the metamaterial design. Secondly, through numerical models, we show the possibility of certain frustule-inspired geometries
to behave as frequency selective elastic filters thanks to the presence of elastic bandgaps. The work herein contributes to the perspective of elastic metamaterials inspired by Nature.
Optimizing acoustic black hole structures for vibration control in beams: a comprehensive analysis
Authors: CHERIF Raef , AGUIL Ahmed
Published: October 2024

Acoustic black holes (ABH) have caught the attention of researchers because of their potential to absorb sound and control vibrations. This study presents an analytical framework that determines reflection coefficients in ABH structures. It focuses on implementing an acoustic black
hole with a power-law tapered profile on beams. Moreover, this research investigates how various geometric shapes affect Damping Loss Factor (DLF) coefficients. This helps identify optimal approaches to optimize ABH structures based on specific requirements. The finite element method and a
topology optimization solver were used to optimize various parameters systematically. The aim is to reduce weight and response, thereby improving the efficiency of ABH designs, especially in low-frequency insulation applications. The results demonstrate that ABH exhibits excellent performance
in suppressing vibrations.
Model-supported analysis of comparative rolling noise measurements on two types of railway tracks
Authors: PIERINGER Astrid , THEYSSEN Jannik
Published: October 2024

Rolling noise measurements of in-service trains have been carried out at the demonstrator of a new type of slab track (the "3MB" originally devised in the FP7 Capacity4Rail project) and an adjacent ballasted track section on the iron-ore line in Northern Sweden in May 2023.
The analyses of the measurement data showed an increase in equivalent pass-by sound pressure levels (SPLs) at the slab track compared to the ballasted track, with, on average, about 2 dB observed at 7.5 m from the track. There was, however, a large spread in the results dependent on overall
SPL, train speed, train type, and train individual. In addition to the pass-by measurements, a detailed characterization of track dynamics and rail roughness has been carried out. These latter measurements partially explain the observed differences in SPL, but more insight can be gained with
a comprehensive model for rolling noise adapted to the conditions at the measurement site. In particular, the role of the rail roughness is investigated by simulations.