bluuebunny/crossref_metadata_2025 huggingface dataset:
A study of the ultrasonic and audible frequency response of commercial loudspeakers for use as parametric acoustic arrays
Authors: FANTINELLI DE CARVALHO Augusto César , ARNELA Marc , BURBANO-ESCOLà Ricardo , VAQUERIZO-SERRANO Jesús
Published: October 2024

Parametric acoustic loudspeakers (PAL), also known as parametric acoustic arrays (PAA), are speakers that use ultrasonic waves to generate directive audible sound. They emit an ultrasonic carrier modulated in amplitude by the desired audible signal, and due to non-linear propagation
in air, this signal is reproduced in the audible range. Typical applications include audio reproduction for entertainment, but also active noise control and acoustic measurement of material properties. PAA typically consist of an array of piezoelectric transducers set on a surface. However,
there are other speakers in the market that, due to their characteristics, could also achieve the PAL effect. This work examines the performance of commercial speakers when reproducing. First, the ultrasonic frequency response of each speaker is examined in free-field conditions using exponential
sine sweeps (ESS). This enables searching for potential carrier frequencies to modulate the ESS in the ultrasonic range. The ESS are next modulated in the desired ultrasonic region and emitted through each speaker, obtaining their audible and ultrasonic impulse responses. The results show
that some commercial speakers can also operate as PALs, which is interesting from an industrial point of view as it lowers costs and simplifies the assembly process.
Effective models of metasurface/metainterface made of three-dimensional Helmholtz resonators
Authors: TACHET Sarah , PHAM Kim , MAUREL Agnès
Published: October 2024

We study a reflective metasurface made of 3D subwavelength Helmholtz resonators. We provide an effective model in the time domain obtained by using a three-scale asymptotic approach. The metasurface is reduced to an homogenized boundary condition involving a resonant, frequency dependant
impedance. Our effective model takes into account boundary layer effects near the neck opening, and we provide a precise method to calculate the " added length ". The study is extended to meta-interface in transmission, where the set of effective boundary conditions are replaced
by effective jump conditions, and the results are discussed in frequency domain with comparison with direct numerical simulations.
Far-field sound field estimation using robotized measurements and the boundary elements method
Authors: PASCAL Caroline , MARCHAND Pierre , CHAPOUTOT Alexandre , DOARé Olivier
Published: October 2024

Sound Field Estimation (SFE) is a numerical technique widely used to identify and reconstruct the acoustic fields radiated by unknown structures. In particular, SFE proves to be useful when data is only available close to the source, but information in the whole space is required. However,
the practical implementation of this method is still hindered by two major drawbacks: the lack of efficient implementation of existing numerical methodologies, and the time-consuming and tedious roll-out of acoustic measurements. This paper aims to provide a solution to both issues. First,
the measurements step is fully automated by using a robotic arm, able to accurately gather geometric and acoustic data without any human assistance. In this matter, a particular attention has been paid to the impact of the robot on the acoustic pressure measurements. The sound field prediction
is then tackled using the Boundary Element Method (BEM), and implemented using the FreeFEM++ BEM library. Numerically simulated measurements have allowed us to assess the method accuracy, and the overall solution has been successfully tested using actual robotized measurements of an unknown
loudspeaker.
Acoustic black hole combined with microperforated plate for a rectangular waveguide
Authors: CERVENKA Milan , BEDNARIK Michal
Published: October 2024

The concept of an acoustic black hole (ABH) for anechoic termination of waveguides has been well-established and extensively studied. The fundamental principle underlying an ABH is the deceleration of acoustic waves, leading to the accumulation and subsequent absorption of acoustic
energy within the thermoviscous boundary layer formed along the ribs forming its internal structure. The primary advantage of ABHs, in contrast to classical solutions, lies in their avoidance of porous or fibrous materials, rendering them suitable for deployment in challenging environments.
While the majority of published works have focused on ABHs with circular cross-sections, recent advancements have demonstrated the effectiveness of the ABH effect also in waveguides with rectangular cross-sections. However, it has been revealed that these ABHs require very fine internal structure
for optimal performance, posing challenges in manufacturing. This study addresses this issue by utilizing a microperforated plate to provide the necessary resistance. To model these ABHs, a simple mathematical model is proposed, enabling the optimization of their parameters. Subsequently,
their performance is investigated through numerical experiments. The validity of the results is confirmed by comparing them with a detailed mathematical model, ensuring the accuracy and reliability of the proposed approach.
Sound quality improvement on industrial products
Authors: WAKUI Kohei , MATSUDA Michiaki , WATANABE Yusuke , TOI Takeshi
Published: October 2024

Even with efforts to reduce the noise level (dB) of industrial products, some people remain dissatisfied with the sound of products due to annoyances remained. Annoyance is closely related to the sound quality (SQ), especially in quiet environments such as hospitals and laboratories,
it is essential to improve the sound quality (comfort of listening) of products. We defined a method for evaluating the sound quality of industrial products that we handle using both existing and developed sound quality indices that focus on the high-pitched sound, the prominent peak noise,
the rough sound and the beat/moan noise, and improved our actual products based on the method. In this paper, we introduce the evaluation method and the sound quality improvement in actual products, including one of research activities that contributes to the business unit and has the potential
to create future customer value.
Aircraft noise and ischemic heart disease: an update of the evidence
Authors: SEIDLER Andreas , ROMERO STARKE Karla , SCHRECKENBERG Dirk , KUHLMANN Julia , GUSKI Rainer , SCHUBERT Melanie
Published: October 2024

Aircraft noise exposure is harmful to health. The World Health Organisation (WHO) summarized the evidence on health effects of environmental noise up to 2015. We updated the evidence by conducting a systematic review with meta-analysis including scientific literature from 01/01/2015
to 03/02/2023. The study protocol was registered a priori at PROSPERO. Three publications on incident ischaemic heart diseases (IHD) and six publications on IHD mortality met our eligibility criteria. Four studies on IHD mortality were included in the meta-analysis, revealing an increase in
IHD mortality by about 9% per 10 dB Lden aircraft noise (starting point 30 dB; risk ratio RR=1.085, 95% confidence interval CI 0.997-1.181, p=0.06). For IHD incidence fewer than three comparable new studies were available. In addition, we pooled our studies with the WHO results. The risk of
aircraft-noise related IHD mortality was statistically significantly increased by 7% per 10 dB Lden (RR=1.069, 95% CI 1.004-1.139, p=0.04). For IHD incidence, the pooled risk estimate was 2% per 10 dB (RR=1.020, 95% CI 0.986-1.054, p=0.25). Limit values for aircraft noise should take into
account risk increases for IHD even at relatively low aircraft noise levels. We thank the Frankfurt Aircraft Noise Commission (FLK) for funding!
Vibro-acoustics based sound pressure minimization in a cam-follower system using micro-geometric modifications on minimizing the noise
Authors: SHRIPAD Kumar Milind Rewanand , JONNALAGADDA Sai Charan , SUNDAR Sriram
Published: October 2024

The systems with inherent combined rolling-sliding contacts, such as cam-followers, gearboxes, and clutches, generate undesirable noise. It affects operator well-being, environmental acoustics, and component wear during operation. The sound produced due to interaction between the cam
and the follower can be reduced by micro-geometric changes, i.e., profile modification of the cam surface while maintaining the macroscopic geometry of the system. This study aims to identify an optimal profile modification to the cam, using a vibro-acoustic relationship between the contact
forces, sound pressure to minimize the sound pressure. The methodology utilizes a mathematical model of a cam-follower system to estimate the contact forces for different parametric values, and an equivalent finite element model to obtain vibro-acoustic transfer functions for various profile
modifications. Sound pressure is predicted for each profile based on the obtained transfer functions, and contact forces. The optimal profile is then selected based on a comparative evaluation of the predicted sound pressure levels. The outcome of this study would lead to the development of
quieter systems with combined rolling-sliding contact.
Vibrothermography for NDT : dynamic control of thermal sources by acoustic fields
Authors: BOUE Hugo , MEZIANE Anissa , GIREMUS Audrey , ABISSET-CHAVANNE Emmanuelle , GROZ Marie-Marthe , ARNAUD Adrien
Published: October 2024

Among the plethora of Non-Destructive Evaluation (NDE) techniques, the coupling of acoustic/vibration and thermography has emerged as a powerful method, more particularly denoted as sonothermography, utilizing the principle of energy conversion from acoustic waves to thermal heat sources
to reveal structural abnormalities or create tunable volumic sources in materials. The calculation of the displacement field induced by acousto-vibrational excitations, using the analytical expression of energy conversion, has led to the generation and modeling of localized thermal sources
in space over time within a material. By manipulating the input parameters of acoustic signals (frequency, phase, amplitude), we have demonstrated that it is possible to strategically position these sources in space and optimize the dissipation of thermal energy. The variation of parameters
(creating a phase shift, a beat, a reversal law, etc.) makes it possible to control and move these internal heat sources to scan the material (in numerical approach and in the near future experimentally). The analysis of the resulting fields (acoustic-vibration and thermal), using inverse
methods, opens up new possibilities for measuring the physical properties (mechanical, thermal) or characterizing defects in a material.
Design of lightweight aircraft trim panel with a high sound transmission loss
Authors: RAHARIMANANA Tiffany , SIMON Frank , SEBBANE Delphine , ELIA Pautard
Published: October 2024

The trim panels of aircraft cabin are frequently made up of multilayer materials including a honeycomb, typically in the form of sandwich panels, which have the advantage of being lightweight and space-saving, but lack good acoustic insulation. It has been shown that, for 10% more mass,
weights arranged in a fractal pattern in the honeycomb affect the vibratory pattern of a sandwich panel by creating multiple reflections of the bending waves on the inclusions. They thus generate a phenomenon of focusing vibratory waves providing localized modes while attenuating the structure's
acoustic radiation. The objectives of this paper are to describe: first, the vibro-acoustic model of an overloaded homogenized bending panel (to mimic a trim panel with a fractal pattern); second, the physical phenomena associated to this concept; third, the impact on the modal behavior and
the vibratory and acoustic responses.
A rapid aerodynamic noise prediction model for multi-rotor unmanned aircraft systems with inclusion of wake effect
Authors: WANG Zimo , CHEN Qidong , ZHONG Siyang
Published: October 2024

In this work, the effect of wake on the rotor aerodynamics and aeroacosutics is studied based on an efficient rapid prediction model, which incorporates the induced effects of tip vortex on the blades into the blade element momentum theory. The tip vortex model is estimated using the
free vortex wake method. The aerodynamic flow variables, as well as the unsteady loadings due to the radial flow and induction of tip vortices, are employed to model to equivalent sources and, therefore, noise emission, using Goldstein's acoustic analogy. The comparison between the hybrid
algorithm and blade element momentum theory shows that the wake effect is not significant in the case of axial flow only. During forward flight conditions, the wake vortex correction greatly affects high frequency harmonics. In addition, a preliminary case study of a quad-rotor vehicle is
also discussed, demonstrating the proposed low-fidelity computational framework is helpful for low-noise design and operation of the multi-rotor UAS vehicles.
Determination of the dynamic stiffness matrix of a rail damper and application to vibration decay rate
Authors: SHENG Xiaozhen , YUE Songtao , ZHANG Linli , ZHONG Shuoqiao , ZHOU Xin
Published: October 2024

In this paper, the 6×6 dynamic stiffness matrix of a rail damper seen by a short section of rail is defined based on the force simplification theory, and a method to determine the matrix is presented. According to the method, frequency response functions (FRFs) between specific
points on the rail as a rigid body are measured with hammer testing. These FRFs are then used to express the acceleration of the mass center of the rail as well as the rail's angular acceleration. As the third step, the equations of motion of the rail are established based on the laws of momentum
and moment of momentum, from which the dynamic stiffness matrix can be worked out. The method is then applied to determine the dynamic stiffnesses of a typical damper, and the determined dynamic striffnesses are combined with an infinite periodic track model to stduy the effect of the damper
on the verical and lateral vibration decay rates of the rail.
Classification scale for road surface noise based on the CPX method in the Czech Republic
Authors: MARKOVA Petra , MACHANEC Jan , HABLOVICOVA Blanka , KRIVANEK Vitezslav
Published: October 2024

The intention of the research project of the Technology Agency of the Czech Republic is to propose a classification scale for the evaluation of the noise level of pavement layers based on long-term repeated measurements using the Close Proximity Method (CPX). With regard to the other
variable parameters (skid resistance, surface unevenness, bearing capacity and defects) that are monitored in the Czech Republic, a five-point scale was also proposed. The scale was tested on the busiest motorway section in the Czech Republic between Prague and Brno, which has been modernized
in recent years. The first sections were put into operation in 2014 and the last in 2021. The evaluation of the results of the CPX measurements carried out in regular one-year cycles from 2013 to the present allowed to test the proposed classification scale. This paper will present the results
obtained from the modernization of the highway and the proposed classification scale.
A time-domain approach to predict sound radiation from track vibrations
Authors: THEYSSEN Jannik , NIELSEN Jens , PIERINGER Astrid
Published: October 2024

With the intended shift of transport from road to railway, noise exposure due to railway noise will increase. Auralisation of the noise is a key tool for assessing noise perception beyond equivalent sound pressure levels. Researching the connection between, for example, track design
parameters and perceived sound quality holds potential for perception-centered track design. A computationally efficient model is required to render the sound field generated by the track vibration. In this paper, using simulated time-domain surface velocities of a rail and sleepers as input,
such a model is presented. The sound pressure signal in a position on the side of the track is efficiently predicted by convolving these velocities with precalculated acoustic transfer functions. For a typical ballasted track, the necessary spatial discretisation of the evaluated velocities
is determined in a convergence study. Further, the required length of the finite section of the track to be included in the prediction is specified. Finally, pass-by signals generated by track vibration are demonstrated.
Qualifying and quantifying the different ways in which people are annoyed by aircraft noise
Authors: TARDIEU Julien , LEGRIFFON Ingrid , MAGNEN Cynthia , RICHARD Isabelle , BOULLET Isabelle , LAVANDIER Catherine
Published: October 2024

Aircraft noise remains a major problem for many people living near airports, despite the efforts of the various air traffic operators and aircraft manufacturers to reduce the nuisance. Noise abatement usually relies on quantitative approaches based on noise measurements at source or
in residential areas. However, field studies have shown that the level of annoyance experienced within a given noise exposure zone varies widely, demonstrating that noise levels alone do not explain the experience of local residents. The present work brought together a wide range of disciplines
(aeronautics, acoustics, linguistics, psychoacoustics, social and environmental psychology) to define a common framework for reconciling field and laboratory studies on aircraft noise annoyance. A survey of 1250 people living near airports enabled us to precisely qualify the annoyance experienced,
and to identify 6 highly differentiated annoyance profiles based on non-acoustic factors. Focus groups and laboratory experiments with people living near airports revealed an impact of annoyance profiles on both qualitative and quantitative evaluation of noise annoyance, which confirms the
diversity of their experiences in the same listening situation.
The development of a new technical regulation on acoustics in buildings in Croatia
Authors: HORVAT Marko , VERšIć Zoran , JAMBROšIć Kristian
Published: October 2024

Even though Croatia gained its independence 32 years ago, up till now its legislation has not regulated the requirements that concern the acoustics in buildings. Instead, the regulations inherited from the former state of Yugoslavia were left in effect and have remained in use even
after they were officially withdrawn, as no new regulations were adopted to replace them. To address this issue, a committee has been formed of experts affiliated with relevant governmental and professional organizations, and representing their respective fields of expertise, with the task
of developing the new Technical Regulation on Acoustics in Buildings in Croatia. This document is to set detailed technical requirements on sound insulation as the means of protection from outdoor and indoor noise, the maximum permissible levels of indoor noise caused by service equipment,
and the room acoustics design criteria for achieving optimal acoustics and/or as a noise reduction measure, to be partly or fully applied to a wide range of public and privately-owned buildings, with exceptions such as dedicated performance venues like concert halls or theatres. This paper
presents the motivation for creating this document, its scope, and key aspects, as well as a brief overview of similar endeavors in the past.
Accelerated iterative DG finite element solvers for large-scale time-harmonic acoustic problems
Authors: MODAVE Axel
Published: October 2024

Finite element methods are widely used to solve time-harmonic wave propagation problems, but solving large cases can be extremely difficult even with the computational power of parallel computers. In this work, the linear system resulting from the finite element discretization is solved
with iterative solution methods, which are efficient in parallel but can require a large number of iterations. In standard discontinuous Galerkin (DG) methods, the numerical solution is discontinuous at the interfaces between the elements. In hybridizable DG methods, additional unknowns are
introduced at the interfaces between the finite elements, and the physical unknowns are eliminated from the global system, resulting in a hybridized system. We have recently proposed a new strategy, called CHDG, where the additional unknowns correspond to transmission variables, whereas in
the standard approach they are numerical fluxes. This strategy improves the properties of the hybridized system for faster iterative solution procedures. In this talk, we present and study a 3D CHDG implementation with nodal finite element basis functions. The resulting scheme has properties
amenable to efficient parallel computing. Numerical results are presented to validate the method, and preliminary 3D computational results are proposed.
Broadband acoustic metamaterial absorber
Authors: ZHOU Zhiling , HUANG Sibo , CHENG Qian , WANG Xu , ZHU Jie , LI Yong
Published: October 2024

Constrained by the causality nature, it is a challenge to achieve low-frequency broadband efficient absorption via passive materials. By coupling local resonances as many as possible, broadband metamaterial absorbers can be realized. In this scenario, the coupling effect is crucial
for improving the absorption efficiency. Here, we demonstrate a kind of acoustic metamaterial absorber capable of high-efficiency broadband absorption by optimizing the non-local coupling effect. Cascade neck-embedded Helmholtz resonator is designed as the subunit of the metamaterial absorber.
By coupling 36 subunits, a metamaterial absorber is constructed with the aid of optimization algorithm. The simulation results suggest that strong non-locality is induced in the near field, which effectively suppresses the impedance oscillations and absorption dips at the antiresonance frequencies.
Eventually, the presented metamaterial absorber realizes impedance matching to the air from 320 Hz to 6400 Hz, leading to efficient broadband absorption performance. The results and methodologies in this work reveal the significance of non-local coupling effect in coupled-resonant metamaterials.
Structural dynamics of individual plant fibres: a contribution to the understanding of damping properties of bio-based composites
Authors: PELISSON Fanny , BUTAUD Pauline , OUISSE Morvan , PLACET Vincent
Published: October 2024

The field of bio-based composites faces challenges in understanding the physical mechanisms providing excellent compromise between stiffness and damping. Potential sources of damping, including the matrix, the fibre, and the interfaces (fibres/fibres and fibres/matrix) are identified
in the literature. To better understand damping at the composite scale, it is necessary to understand the dissipation causes at each scale of the material. However, the mechanical characteristics of individual plant fibres, such as modulus and damping, can be uncertain due to the complexity
of measuring their properties at such small scale (10 µm diameter, a few mm long). To address this knowledge gap, this work proposes a method based on dynamic response of individual plant fibres. By exciting the fibre with a piezoelectric actuator and using high-speed camera image processing
to evaluate displacements along the fibre, it becomes possible to determine intrinsic dynamic properties such as the loss factor and storage modulus. Controlled environment tests are conducted to investigate the influence of external parameters such as temperature and pressure on the measurement
results. By utilizing this method, the aim is to obtain a better understanding of the damping properties of plant fibres and ultimately improve design choices for bio-based composite materials.
Aerodynamic and aeroacoustic characterization of an axial fan using Adaptive Mesh Refinement (AMR) based CFD and CAA
Authors: GAYET Christophe , AUZA GUTIERREZ Rodrigo
Published: October 2024

This work focuses on numerical analysis of a low-pressure axial fan using Computational Fluid Dynamics (CFD) and Computational Aeroacoustics (CAA) methods. These simulations are performed with the commercial software Hexagon's Cradle scFLOW. The investigation focuses on flow prediction
using incompressible Large Eddy Simulation (LES), and acoustic propagation based on the Ffowcs Williams-Hawkings (FW-H) equation. We present a method to evaluate the mesh resolution for LES and a mesh refinement approach to resolve strong flow interactions, particularly near the tip-gap region.
Both the aerodynamic and aeroacoustics performance of the fan are compared to experimental measurements for model validation. The pressure rise, velocity profiles and surface pressure fluctuations are captured well. Similarly, the sound propagation results are in good agreement with the experimental
measurements. At low-mid frequencies, the blade passing frequencies and subharmonic peaks are captured, and at high frequencies, the broadband energy content is underpredicted, but still reasonably correlated. Additionally, a discussion regarding the mesh quality for LES is presented.
Effect of entropy waves generated by different flame models on the thermoacoustic instability
Authors: TANG Jiayuan , DU Jingtao , LIU Yang , LI Aoqi
Published: October 2024

Thermoacoustic instability can be an important problem for aero-engine and gas turbine combustion chambers, especially for lean premixed combustors designed for low NOx emissions. This instability is caused by the interaction of acoustic waves with unstable heat release. Entropy waves
generated in the combustion chamber also produce acoustic waves during acceleration, known as indirect combustion noise or entropy noise, which are reflected upstream to affect the thermoacoustic instability. In this paper, the effect of entropy waves generated by different flame models on
the thermoacoustic instability is investigated, and the main controlling factors and coupling mechanisms of entropy thermoacoustic modes are studied, in which both flames and entropy waves break the original acoustic field and introduce new modes. It is found that entropy waves change the
modal frequency of ITA, the choked outlet and the flame plane may form similar boundary conditions with the same time delay for ITA modes. In addition, the filter flame decreases the frequency of entropy thermoacoustic modes and ITA modes.
Measurements of noise emissions for classification of highway expansion joints
Authors: RUDOLF Rok , ZALAR Andraž , ŠVRAKA Ratko , MALOVRH REBEC Katja
Published: October 2024

In this paper, we classify expansion joints on Slovenian highways by their potential as noise sources. To measure this potential, we utilized a close proximity measurement chain with additional vibration measurements on the car's undercarriage. By combining these measurements, we were
able to amass a large amount of noise relatable data specific to expansion joints. By correlating this data to expansion joint types present on a number of bridges and viaducts, we were able to statistically analyse and rank various joint types regarding their noise emission. Our previous
research activities focused on noise complaints associated with specific cases that showed that the problem can be very annoying, even though it was quite localized. Our study opens up a new way to assess expansion joints during regular close proximity measurements on the road network, and
simultaneously presents a quantifiable measurement data basis to exhibit the expansion joint noise emission problems near highways.
Improved direct-parallel active noise control systems for applications with narrowband noises
Authors: CHANG Cheng Yuan , HO MING-HAN , KUO Sen M.
Published: October 2024

Rotary machinery generates noises at the fundamental frequency and its harmonics. The direct-parallel form active noise control (ANC) system, which is capable of reducing multiple narrowband noises, uses many harmonically related sinusoids as the reference input. The idea of direct-parallel
form ANC is to split these sinusoids into several mutually exclusive sets, so each set has frequencies spaced out as far as possible. This paper proposes an improved direct-parallel form method to separate the reference sinusoidal signals and to enhance the noise reduction performance. Several
experiments regarding to the ANC with a muffler model is made to verify the performance of the proposed method.
A survey of integrating wireless technology into active noise control
Authors: SHEN Xiaoyi , SHI Dongyuan , LUO Zhengding , JI Junwei , GAN Woon-Seng
Published: October 2024

Active Noise Control (ANC) is a widely adopted technology for reducing environmental noise across various scenarios. This paper focuses on enhancing noise reduction performance, particularly through the refinement of signal quality fed into ANC systems. We discuss the main wireless
technique integrated into the ANC system equipped with some innovative algorithms in diverse environments. Instead of using microphone arrays, which increase the computation complexity of the ANC system, to isolate multiple noise sources to improve noise reduction performance, the application
of the wireless technique avoids extra computation demand. Wireless transmissions of reference, error, and control signals are also applied to improve the convergence performance of the ANC system. Furthermore, this paper lists some wireless ANC applications, such as earbuds, headphones, windows,
and headrests, underscoring their adaptability and efficiency in various settings.
Acoustic camera applied on sound transmission identification in closed spaces
Authors: DAL MORO Priscila M.M. , LIBOUBAN Lanig
Published: October 2024

In the ongoing context of office partitioning, users are increasingly paying attention to acoustic insulation between rooms. The issues commonly related are translated by confidentiality problems and annoying use of sound-enabled videoconferencing. In practice, when an insulation defect
is perceived, standardized acoustic insulation measurements are carried out to characterize the overall insulation performance. However, it is often challenging to precisely identify by ear the various paths of sound transmission: through the partition, by poorly caulked junctions, through
the ceiling, through the facade, etc. Acoustic antenna solutions employed to identify the location and frequency content of sources have existed for several decades. But, in addition of being expensive and bulky, until now their use was reserved for detection of sources on transportation vehicles
(trains, cars, planes, etc.) or industrial equipment (wind turbines, boiler rooms, etc.). In recent years, more accessible and practical antenna solutions known as "acoustic camera" have become available. In this sense, we have been handling an acoustic camera to assist on the detection
of the sound transmission paths between two rooms. This work address what has been experienced, outlining results obtained through the (evolving) methodology for sound transmission identification with acoustic camera in closed spaces.
Assessing the behavior of highly damped multilayered structures with controllable patches using condensation models
Authors: DA SILVA RAQUETI Rafael , ATALLA Noureddine , OUISSE Morvan , SADOULET-REBOUL Emeline
Published: October 2024

This study presents the finite element modeling of an adaptive sandwich structure that can be configured to exhibit various behaviors depending on the arrangement of the temperature fields in its core, which is made of a shape memory polymer with outstanding damping capacity. The sandwich
structure is divided into patches corresponding to homogeneous temperature fields. Each patch is modeled as an equivalent thin plate using a condensation model and the effective properties are determined by preserving the real part of bending, shear (transverse) and extension (quasi-longitudinal)
wavenumbers. The damping loss factor is estimated independently using the forced response from an analytical discrete model of the sandwich structure and the Power Input Method. Two different configurations of the sandwich structure are presented: in the first, the modal behavior of the sandwich
structure is slightly affected; In the second, vibrations are reduced throughout the frequency range. The use of a suitable condensation model can be particularly interesting for solving optimization problems and determining optimal configurations. The behavior of the sandwich structure can
be evaluated with reduced computational cost whenever an update of the temperature fields is required.
Structured acoustic materials for mitigating low-frequencybroadband aircraft noise: transfer matrix method
Authors: KONE Tenon Charly , GHINET Sebastian , RAYMOND Panneton , GREWAL Anant
Published: October 2024

This study investigates, by numerical modeling, the mitigation of low-frequency broadband aircraft noise using a structured assembly of acoustic materials using the Transfer Matrix Method. The prevalence of low-frequency aircraft noise poses challenges to environmental sustainability
and passenger comfort. The investigation focuses on an approach that employs strategically arranged structured acoustic materials to attenuate undesirable noise frequencies. The Transfer Matrix Method is used to model the acoustic behavior of the structured assembly, enabling a comprehensive
analysis of sound transmission and absorption properties. This method supports the design and optimization of the assembly. The performance of the structured assembly to selectively attenuate low-frequency broadband noise is assessed through numerical simulations. The paper discusses implications
for aircraft design, considering factors such as weight and cost. The benefits for environmental impact and passenger experience are also explored. Challenges and limitations in the implementation of structured acoustic materials are examined. The configuration studied presents an assembly
of structured metamaterials arranged in series and in parallel which are integrated into a layer of glass wool. Present research contributes to the development of sustainable solutions for low-frequency aircraft noise. The structured assembly analyzed shows promise for significant noise reduction
while considering practical constraints.
Time response of active sound control with a harmonic acoustic pneumatic source: simulations and experimental results
Authors: SCHIAVINI Alexandre , MICHEAU Philippe , GRANDJEAN Pierre , GABARD Gwénaël
Published: October 2024

Active noise control is studied as a solution to reduce the blade passing frequency tonal noise of turbofans during landing and takeoff. A promising alternative to loudspeakers used as secondary sources is the Harmonic Acoustic Pneumatic Source (HAPS), that has been designed to generate
a high harmonic noise level controllable in amplitude and phase using slow time varying signals. The objective is to design, characterize and optimize an active control system capable of following a time varying primary noise. A configuration with a loudspeaker acting as a primary source,
a HAPS mounted laterally on a rectangular duct and an error microphone is considered. A first single-input-single-output controller for the case of plane wave control has been tested and allowed a convergence time of about 2 seconds to reach 20 dB attenuation of the acoustic pressure at 440
Hz. The results are consistent with simulations of the system and the convergence time can be explained by the dynamics of the HAPS. This study is a first step towards the objective of performing multimodal active noise control in duct with multiple sources in presence of flow.
Research on underwater target recognition based on auditory EEG signal features and deep learning
Authors: NA Zihan , ZENG Xiangyang , GUO Changhao , JIANG Meiqiao
Published: October 2024

Target recognition is a key technical link in hydroacoustic detection, which has a broad application prospect in the fields of marine safety and resource exploration. In recent years, artificial involvement of underwater target recognition methods based on analysis of line spectra,
auditory spectra and other characteristics are broadly utilized in actual engineering applications, with their unique characteristics. Meanwhile, the learning tasks of human-computer interaction have been widely used, for machine learning and deep learning are also developing rapidly. Therefore,
in this paper, auditory EEG signals under the excitation of underwater targets' signals are used to carry out recognition research by combining human brain perception, artificial analysis, SVM and ResNet with atrous convolution. The results show that the recognition rate of four types of ship
radiated noise can reach 94.35% using the ResNet with atrous convolution, which can effectively classify and recognize underwater targets.
Comparing acoustic models with measured noise levels in a Polypropylene production industrial complex
Authors: SQUADRONE Giuseppe , BRUNAZZO Edoardo , BARIKCHANDRA Antaryami , BOSA Elena , GRECO Emanuela
Published: October 2024

This paper presents a detailed comparison between the final noise source data, as documented in the Project Report, produced noise map during design phase, and the field-measured noise values, along with the empirically generated noise map during the plant's operational phase. The study
investigates into the accuracy and reliability of the assessed noise map, evaluating its alignment with actual noise levels recorded on-site, identifies discrepancies between both the noise maps, pinpointing areas for improvement in predictive modelling. The goal is to see how well the predicted
noise levels match up with the real-world situation, helping improve noise control strategies, specifically focus on noisy equipment, checking if the expected or calculated noise levels are the same with field measured values. By shedding light on these disparities, this study contributes
to refining noise prediction models and improving the effectiveness of noise control measures in industrial settings.
Refinement method of equivalent source power level determination for traffic noise in urban noise mapping
Authors: XU Yiquan , GUO Jinyu , LUO Rui , YE Long , XIA Ming , DI Yajing , MIN Hequn
Published: October 2024

For traffic noise prediction, the predictive models of source power level determination commonly in use are the Technical Guidelines for Noise Impact Assessment in China or the Calculation of Road Traffic Noise model in the United Kingdom, which incorporate traffic flow and car speeds.
However, the accuracy of these models is often compromised due to urban traffic's complexity, vehicle diversity, and unforeseen events. This study investigates a refinement method based on noise on-site measurement and aforementioned approaches for equivalent source power level determination
for traffic noise in urban noise mapping. In the study, onsite measurements are conducted to collect noise and traffic data, and source power level calculated by refinement method is validated using measurement data. Different prediction methods are employed for measurement sites calculations.
By comparisons between predictions with noise on-site measurement data, the refinement method proposed in the study demonstrates a significant accuracy enhancement in traffic noise prediction over previous models for determining equivalent source power level. This enhancement highlights the
efficacy of adopting noise measurement-based methods for setting traffic noise source power levels, leading to more precise traffic noise predictions in complex urban settings, particularly in areas surrounding urban arterial roads.
Study on territory-wide application of low noise road surface in Hong Kong
Authors: CHAN KEI YUET , LO CHIN WING , LIN KIT MEI , LEE CHEE KWAN , TSANG SAI WING
Published: October 2024

Hong Kong is one of the metropolitan cities in the world, with highly concentrated road network system and densely populated developments. At times, it is inevitable to build residential buildings near noisy roads, and traffic noise is one of the environmental problems affecting the
locals. The Government strives to pre-empt traffic noise issue through planning new road projects or new residential developments. Concerning traffic noise from existing roads, the Government has implemented noise mitigation measures, for instance, to resurface existing roads with Low Noise
Road Surface (LNRS) materials, retrofitting of noise barrier or enclosure, to alleviate traffic noise impact. Moreover, the Government is continuously developing and trialing different LNRS materials such as Polymer Modified Stone Mastic Asphalt (PMSMA6) on roads in Hong Kong, which aims for
wider application of LNRS. To explore the feasibility and effectiveness of the wider application of LNRS on local roads, the Government has recently conducted a territory-wide study on the application of LNRS on local roads in Hong Kong. This paper attempts to share the common local road characteristics
of applying LNRS material and the latest technical findings, such as the effect on population exposure, of the territory-wide study in Hong Kong.
Research on the impact of traditional soundscapes on physiology and subjective restoration in historical and cultural districts
Authors: BA Meihui , LI Zhongzhe , ZHAI Furong , HUANG Shijia , KANG Jian
Published: October 2024

A healthy urban sound environment is the common pursuit of both residents and urban designers. The restorative effects of natural soundscape on physiology and psychology have been proved. However, the potential health benefits of the historical and cultural attributes of soundscapes
are yet to be explored. This study took the traditional sound sources and environments in the historical and cultural district as the research object, and presented the audio-visual scenarios in the laboratory. Finally, 7 physiological indicators and subjective evaluation of perceived recovery
soundscape scale (PRSS) of 37 subjects were assessed. The results indicate that historical soundscapes have an impact on subjective restorative factors such as Fascination and Being-Away. However, there is no significant influence on all physiological indicators. This suggest that the historical
and cultural attributes of soundscapes might have a positive effect on psychological restoration, but the impact on physiology is not significant.
Development of integrated noise analysis systems for ship propellers considering hull wake
Authors: HONG Suk-Yoon , JEE-HUN Song , MIN-HYEOK Kim
Published: October 2024

Recently, the requirements for underwater radiated noise (URN) reductions in ships have become significant issues, driven by concerns over the impact of naval vessel performance and noise on marine ecosystems. The majority of URN generated from ships is attributed to the propeller.
This study developed the integrated noise analysis systems that predict and analyze all the significant noises generated from the propellers, considering the hull wake. Since each type of noise has different sources and mechanisms, it is essential to analyze all types of noise to evaluate
the propeller noise performances comprehensively. The model was developed for cavitation noise by compression and expansion motion of bubbles to evaluate the radiated noise. For non-cavitation noise, a noise model on the frequency domain was derived to cover the noise generated by changes
in the wake. The unsteady pressure on the rotating blade was obtained using flow fields and wall pressure spectrum, extending to high frequencies. The developed system provides a valuable tool for propeller optimization designs by minimizing URN while considering the shape of the hull and
appendages.
Enhancing adaptivity of active sonar classifier considering loss landscape under dataset shift
Authors: KIM Geunhwan , YOUNGSANG Hwang , YOUNGMIN Choo
Published: October 2024

We study the loss landscape of deep neural networks and use it to solve dataset shift problems in active sonar classification. The dataset shift degrades the generalization performance of supervised learning-based classifiers. When test data samples are available, fine-tuning methods
can be used to mitigate the performance decrease. However, they can induce catastrophic forgetting and negative transfer because fine-tuned weights could be overfitted to the test data distribution. These problems are more severe in active sonar datasets with small amounts and less diversity.
To mitigate the two problems in conventional fine-tuning, we explore the loss landscape of supervised learning-based active sonar classifiers and apply it to derive adaptative weights from pre-trained weights. Our results showed promising performance.
Retro-diffraction - importance for the calculation of road traffic noise
Authors: BARTOLOMAEUS Wolfram
Published: October 2024

In geometric acoustics, "retro-diffraction" describes the loss of energy when reflected at the upper edges of noise screens. By bending the sound beam against the direction of propagation under consideration, reflected energy of the mirror sound source is reduced by up to
5 dB in addition to the absorption. This effect becomes particularly effective if the sound beam is blocked by a noise screen in the direction of propagation under consideration, meaning that diffraction also occurs in this direction. Sound attenuation by retro-diffraction can be found in
the French standard NF S 31-133, an alternative method to ISO 9613-2 for calculating sound propagation outdoors. It was incorporated into the French noise forecasting procedure NMPB in 2008. We also take it into account by using it in the procedure for calculating environmental noise (European:
CNOSSOS; German: BUB). This paper attempts to determine the impact of considering retro-diffraction in sound propagation. First, the equations from ISO 9613-2 and BUB regarding retro diffraction are compared in a simple geometric model. The level differences calculated in commercial sound
propagation software are compared with those from measurements on a 1:20 scale model. An estimate of the relevance of retro-diffraction in calculating sound propagation is given.
Manipulation of edge states in non-Hermitian acoustic Su Schrieffer Heeger chains
Authors: TONG GUO
Published: October 2024

A distinctive feature of topology is its unique ability to obtain and control robust interface states. Among other elements, it has been shown that non-Hermiticity alone can trigger topological phase transition in physical systems. In this work, we construct acoustic Su Schrieffer Heeger(SSH)
chains using different unit cells where only the non Hermitian components differ due to different distributions of onsite losses. Our study focus on exploring the emergence of edge states at the interfaces between two chains composed of different unit cells. Our findings delineate three distinct
types of edge modes. The topological, cavity and Parity-Time edge modes originate from the topological phase of the unit cells, the local parity symmetry at the interface and the existence of a Parity Time symmetric domain wall, respectively. We then compare the robustness of these different
edge modes against disorder, confirming the robustness of the topological edge modes. Parity Time edge states demonstrate superior robustness compared to classical cavity modes for low level of disorder. However, beyond a certain threshold, their eigenfrequencies importantly diverge.