bluuebunny/crossref_metadata_2025 huggingface dataset:
The relationship between acoustic characteristics and landscape elements with different hydrodynamic environment in Jiuzhaigou World Heritage Site, China
Authors: Xu Xiaoqing , Pu Baojing , Du Jie
Published: December 2023

A large number of studies are exploring the applicability of acoustic indices, and studies have been conducted to reveal the relationship between environmental factors (vegetation, microclimate, geology, etc.) and acoustic indices in different temperature zones and under different ecosystem
conditions. On the one hand, studies in water ecosystems with different hydrodynamic characteristics are relatively lacking, and on the other hand, the accuracy of acoustic index calculation under the influence of continuous hydrodynamic features still needs to be continuously explored. This
study explores whether acoustic indices can provide relatively accurate revealing results of landscape characteristics under different hydroacoustic intensities. In this paper, we collected 19 typical hydrodynamic soundscape resources including waterfalls, streams and haizi in Jiuzhaigou World
Natural Heritage Site, a typical water ecosystem environment, as the object of the soundscape study. The landscape features were identified using semantic segmentation image techniques, and some specific feature factors were scored by eight people to complement. The relationships between 7
commonly used acoustic indices (i.e., Bioacoustic Index-BIO, Acoustic Entropy Index-AEI, Acoustic Diversity Index-ADI, Acoustic Evenness Index-AEI, Acoustic Complexity Index-ACI, Normalized Difference Soundscape Index-NDSI, Acoustic Richness Index-AR) and landscape elements were explored.
The results show that (i) different hydrodynamic characteristics cause great differences among the acoustic indices, and (ii) the extent to which acoustic indices characterize landscape elements varies under different hydrodynamic characteristics. The study reveals the characteristics of the
hydrodynamically dominated acoustic environment in Jiuzhaigou, and collects response data for subsequent monitoring of environmental changes using acoustic indices, as well as laying the foundation for conservation management.
Frequency domain online secondary path modelling for active noise control without auxiliary noise
Authors: Lian Siyuan , Li Tianyou , Wang Shuping , Lu Jing , Gu Jincheng , Hu Yuxiang , Zhu Changbao
Published: December 2023

The identification of the secondary path transfer function is of vital importance for active noise control (ANC) system. Online secondary path modeling method is preferable to offline modeling due to its tracking capability in time-varying acoustic environments. However, the auxiliary
noise of online modeling mixed with the residual error signal diminishes the noise control performance. In this paper, we propose a frequency domain online secondary path modelling algorithm based on our previous work which achieves simultaneous acoustic paths modeling and noise control without
auxiliary noise. The uniqueness of the solution is theoretically analyzed, and the computational burden is shown significantly lower than the previously proposed method. Simulations are conducted to verify that the proposed algorithm also has a better convergence behavior.
Symplectic time-domain finite element method (STD-FEM) for room acoustic modeling
Authors: Huszty Csaba , Izsák Ferenc
Published: December 2023

A new, extended symplectic time-domain finite element method (STD-FEM) is proposed for room acoustic modeling. As a mathematical model for sound propagation and reflection, the classical time-domain wave equations are used, which can be extended with air absorption. Frequency-dependent
locally reactive boundary conditions are also introduced to the model. Spatially, a third-order tensor product type spectral element discretization is applied, which allows us to use explicit time steps. For this purpose, a partitioned Runge-Kutta method is employed, which is an extension
of a third-order symplectic time-discretization. The method is validated on a number of examples and the performance and stability benefits are presented. We present the implementation of the method in the soundy.ai application.
Optimized tools and process for a better prediction of future aircraft noise perception
Authors: BOULLET Isabelle , MINARD Antoine , PELLEGRIN Nathalie , BOUSSARD Patrick
Published: December 2023

Reducing the annoyance related to the noise generated by aircraft flyovers near airports is a major concern of the aeronautical industry. Noise source reduction is one of the pillars of the balanced approach of the International Civil Aviation Organization of, but further research is
still needed to understand and reduce unpleasantness and annoyance due to aircraft noise. From a psychoacoustics point of view, it is particularly important to understand and assess the effects related to perceived phenomena such as tonality, roughness, and beats created by produced tones
whose frequencies can be more or less close to each other. Indeed, these phenomena increase unpleasantness at similar noise levels. This article describes optimized tools and overall process used for studies applied to current and future aircraft noise perception such as: noise source modeling,
simulation of the propagation to the ground, 3D sound rendering on a multi-speaker system, perceptual evaluation, statistical analysis, and regression analyses between measured unpleasantness and Effective Perceived Noise Level (EPNL) and other indicators.
A subwavelength insulation panel for acoustic and aeroacoustic sources
Authors: Lecoq Damien , Gauthier Natacha Aberkane , Lagarrigue Clément , Romero-García Vicente , Pézerat Charles , Molerón Miguel
Published: December 2023

A new kind of panel with strong transmission loss, breaking the mass law by 15 dB and composed by a soft solid plate with embedded solid cylindrical inclusions is studied numerically and experimentally. The presence of the inclusions introduces resonant and antiresonant phenomena in
the subwavelength regime (the thickness is 30 times smaller than the equivalent wavelength in air), leading to an elastic band-gap and a destructive modal interference able to interact with each other. We also report on an experimental campaign demonstrating that the panel is very effective
at insulating aeroacoustic sources (tested up to Mach 0.6), showing even better performance than with an acoustic source excitation. A new analysis tool, the vibroacoustic band diagram, is introduced to better apprehend theoretically all these results.
Open-source software to calculate industrial, railway, and road traffic noise
Authors: Loon Rob van , Kok Arnaud
Published: December 2023

Dutch noise legislation provides instructions and formulas to calculate noise exposure levels on a similar level to Cnossos or ISO 9613-2. The instructions are implemented in commercially available software packages. Each implementation includes a pathfinder and a sound propagation/attenuation
module. Whilst the attenuation is described in detail in the legislation, the pathfinder is not and its design is left to the software company. Currently there are only proprietary, closed-source implementations available. That is going to change. Based on a previously closed-source solution,
we are working towards an open-source, national implementation to calculate noise levels based on 3D model input. We implemented the updated Dutch calculation method and improved the pathfinder. For example, this now includes sloped barriers. Only the calculation core is part of this project:
the development of a graphical user interface is not planned, but can be provided by others. Also, other implementations of the Dutch noise calculation directive can still co-exist next to our open-source solution, since the legislation only specifies the instructions and has no requisite
for a specific implementation. In this paper we will discuss the open-source implementation, the impact on noise modelling in the Netherlands and its potential applications outside of the Netherlands.
Assessment of a wind-tunnel test-bed for drone aeroacoustics in simulated flight conditions
Authors: Rosa Ilaria , Puroja Brian , Pereira Lourenco Tercio Lima , Zamponi Riccardo , Ragni Daniele , Fiscaletti Daniele
Published: December 2023

This study presents the motivation and preliminary assessment of a test bed for the aeroacoustic characterization of Scaled-Flight models and Unmanned Aerial Vehicles (UAVs). The acceptance of urban air mobility and drone operations in urban environments depends on the noise emitted
by these vehicles. For that, it is fundamental to create means to assess these emissions reliably in a controlled environment. The highly transient nature of the operations of these vehicles in the urban environment, caused by gusts, incoming turbulence, and maneuvers, requires measurements
of the vehicle's acoustic emissions during realistic flight conditions. In this study, the importance of assessing the acoustic emissions under transient conditions is discussed. Measurements of a multirotor vehicle under a transient operation are used to highlight the discrepancies between
the quasi-steady assumption and the real operation on the noise emissions. The study is concluded with a discussion on the possible realization of a wind-tunnel test-bed facility at TU Delft that allows the assessment of vehicles in conditions of maneuvering and response to gusts.
Numerical study on the sound insulation potential of the ventilating double-leaf facades
Authors: Bajraktari Egzon
Published: December 2023

Double-leaf facades can be designed to allow natural ventilation while providing adequate sound insulation. The key concept is based on the displacement of the opening in the second layer relative to the opening in the first layer, resulting in a significant improvement in sound insulation
compared to a direct opening. This sound insulation can be further improved if the sound absorption in the cavity of the double facade is increased. An extensive laboratory study was conducted to investigate the impact of different variables of such a system (e.g., the size of the openings,
the location of the openings, the relative displacement of the openings in the two layers, the sound absorption in the cavity, the location of the sound absorption panels, etc.) using an experimental modular double wall. Empirical prediction models have been developed to predict the sound
transmission through such double leaf facades with open elements. Their prediction is validated by measured data. In this paper, we analyze different scenarios of double leaf facades in building-scale dimensions and we use empirical models to calculate their sound insulation. This offers an
insight into the sound insulation properties of a potential real-building double facade.
Overview of concept designs and results of the New Acoustic Insulation Meta-Material for Aerospace (NAIMMTA) project
Authors: Ghinet Sebastian , Bouche Patrick , Padois Thomas , Doutres Olivier , Kone Tenon Charly , Panneton Raymond , Atalla Noureddine
Published: December 2023

Reducing aircraft cabin noise to improve the comfort of passengers is an important and challenging issue in aeronautics. Relatively uncomfortable high noise levels of around 80 to 90 dBA with strong low frequency range components (below 500 Hz) and a tonal character, predominantly related
to the engine fan during take-off and approach, are deemed critical. The conventional acoustic materials seem to have reached their physical limits in terms of sound proofing, and therefore non-conventional solutions, such as metamaterials, are sought for their promising performance such as,
a significant noise attenuation rate (dB/m), and the capability to be tuned at tonal or narrow band frequencies. An international collaborative project was created to develop novel technologies aiming at improving the existing noise control systems by obtaining an additional 5 dB noise reduction
in the low frequency range (100 to 400 Hz) without deteriorating the thermal insulation. Moreover, the proposed solutions were expected to be tunable with respect to tonal noise (bandwidth of 5 Hz) or narrowband noise (bandwidth of 40 Hz). A major design and integration constraint imposed
that the metamaterial had to be embedded in the current existing insulation blanket and add a maximum of 20% additional mass in comparison to the conventional insulation. This paper presents an overview of the various solutions developed from numerical simulations and novel manufacturing procedures
development and optimization to performance characterization and validations.
Experimental investigation of aerodynamic sound radiated from flow around an airfoil placed in the turbulent flow generated by active turbulence generator
Authors: Kobayashi Noriaki , Suzuki Yasumasa , Kato Chisachi
Published: December 2023

Sound generated aerodynamically from a flow around an airfoil subjected to inflow turbulence is investigated experimentally to identify the dominant source of the sound. The test airfoil has NACA0012 wing section. The wind speed is set to 30 m/s, which results in an airfoil Reynolds
number of 300000. Its lift and drag coefficient are 0.78 and 0.06 when the angle of attack is 9 degrees. Wind tunnel experiments are conducted with Active Turbulence Generator (ATG) set at the nozzle exit. The ATG is controlled by the swing angles and rotation speeds of the stepping motors
to control the turbulence intensity and the eddy scale of the inflow turbulence, independently. The former is varied from 10 % to 20 % while the latter is varied from 300 mm to 1600 mm. As a result, we have found that the pressure fluctuation near the leading edge of the airfoil is remarkably
high, and therefore, it is most likely the cause of the considerable increase in the sound generated from the airfoil. Therefore, the higher the turbulence intensity, the higher the sound, and the higher the correlation between the power of the flow velocity fluctuation and the sound pressure
level at each frequency.
Verification of The Possibility of Air-void Recovery in RSBS Double-Layer Low-Noise Porous Asphalt Pavement
Authors: Kim Byungchae , Sung Suwhan , Kim Hyunjin
Published: December 2023

Radial type styrene-butadiene-styrene double-layer low-noise porous asphalt (RSBS DLPA) pavement is a type of porous asphalt pavement which had high air-void ratio, and well-known to absorb tyre/pavement noise and the rain through the pavement's layer. According to the Korea Meteorological
Administration, from July to August in 2022, the daily rain precipitation was more than 100 mm per day and categorized as heavy rain. Due to the high air void ratio in RSBS DLPA pavement, the rainwater will be transferred through the pavement layer. The heavy rain splashing onto the surface
pavement is similar to the method using the low water pressure and low-vacuum that our company developed which helps to recover the low-noise porous asphalt pavement. In this study, the CPX method was used to measure the noise level before and after heavy rain to differentiate the noise level.
The results showed that the heavy rain had an effect on reducing the noise level. Before heavy rain, the noise level was up to 89.9 dB, while the noise level was decreased to 87.7 dB after heavy rain. It is shown that our cleaning method able to recover the air-void content as same as heavy
rain.
Uncertainties and inaccuracies of micro-perforated and micro-slit panel absorbers in multiple layers
Authors: Chen Ziqi , Xiang Ning
Published: December 2023

Multilayer micro-perforated/slit panels (MPP/MSP) are used to achieve broadband absorption in Architectural Acoustics. Both micro-perforated and micro-slit panels can achieve a high absorption coefficient, but the frequency bandwidth is usually narrow for single-layer panels. For this
reason, the multilayer design is proposed to achieve a broadband high absorption coefficient. This work applies Bayesian inference to the design of multilayered micro-perforated/-slit panels for a given design scheme. A higher level of inference, Bayesian model selection, estimates the parsimonious
number of layers needed to achieve the design scheme. The lower level of inference estimates MPP/MSP parameters once the structure of the multilayer design is chosen. Once the exact parameters and the model are given, the theoretical absorption coefficient is compared with the measurement
results. The causal inference is further applied to analyze the possible reasons for the deviations between the model and the experimental data. Applying the Bayesian framework and causal inference minimizes the uncertainties and inaccuracies during the manufacture and leads to a satisfactory
design.
Applications of ventilation-enabling sound insulation devices based on mock-up test findings
Authors: Yuen K.C. Gary , Yeung B.K. David , Chiu K.F. Calvin , Cheng C.M. Tony
Published: December 2023

Road traffic, railway and industrial noise sources are main challenges in maintaining satisfying acoustical environment for living habitat in Hong Kong. Ventilation-enabling sound insulation devices has been introduced to Hong Kong residential development in the aim of striking a good
balance between indoor ventilation and sound insulation. In the form of windows and balconies, the sound insulation devices were applied to mitigate the potential road traffic, railway, and fixed noise impacts. The sound insulation performances of the devices were verified in a 1:1 mock-up
test and indicated by in-out difference, which contributed from the outdoor and indoor noise levels. The in-out difference of the sound insulation devices varies with the adopted spectrum, depending on flat layout configurations. The enhancing performance of applied acoustic material to the
sound insulation devices, and that of applied acoustic fin adjacent to the devices are also studied.
Can the perceived affective quality scales evaluate the restorativeness of soundscapes?
Authors: Nagahata Koji , Saito Minori , Funayama Taiki , Ishii Takumi
Published: December 2023

Affective quality, defined as the ability to cause a change in core affect, is the one aspect of soundscape evaluation by people. To appropriately use the eight perceived affective quality scales (PAQS) proposed in ISO/TS 12913-2 in the soundscape design process, we must know what aspects
the scales can evaluate accurately. This study examined whether the PAQS can evaluate the restorativeness of soundscapes using the PAQS and the perceived restorative scale (PRS). The results of our two soundwalks and an audio-visual experiment showed that the evaluation structure of the PRS
was four-dimensional. Therefore, the PAQS alone cannot express the restorativeness of soundscapes correctly.
Improvement of the low-frequency sound insulation performance of hollow double-leaf panels by inserting a bending panel
Authors: Koizumi Hodaka , Matsuoka Akihiko
Published: December 2023

Air-borne sound transmission loss of building materials generally follows the mass law. Transmission loss decreases at lower frequencies and is minimal at the fundamental natural frequency f0. On the other hand, transmission loss increases below f0, and is controlled by stiffness. Moreover,
the stiffer the materials, the higher the f0. In the other words, even without increasing the mass, increasing the stiffness can improve low-frequency transmission loss. We focus on the fact that flexible lightweight panels are easily stiffened by bending deformation. We conduct a basic study
on the effect of inserting a bending panel into hollow double-leaf panels. Experimental results on single panels showed a correspondence between the increase of f0 by bending deformation and the improvement of low-frequency sound insulation performance. In the case of the double-leaf panels
with the lightweight bending panel inserted inside, the stronger the bending, the more low-frequency sound insulation performance tended to be improved.
Validation of a model on the coupling between circular membrane and Helmholtz resonator
Authors: Park Munhum
Published: December 2023

Recently, a model was proposed to describe the resonance characteristics of a modified Helmholtz resonator with a circular membrane fitted to one of the cavity walls. The model is based on two equations of motion: 1) One equation for the transverse wave formed on the membrane and 2)
the second for the displacement of the air volume in the port of the Helmholtz resonator. When two equations were solved for the displacement of the membrane as a function of the radius, it was shown that, due to the coupling, the resonance frequencies would vary depending on the parameters
of the Helmholtz resonator, which may be observed only for the modes with circular nodal lines. In the current study, the proposed model was further validated in a series of measurements under various conditions, and the results were discussed and compared to the predictions of previous models.
Study of filtered-x least mean square algorithm and its different variants for active noise control of complex real-world noises
Authors: Sharma Arvind Kumar , Majee Avijit , Puri Amrita
Published: December 2023

In various simulation studies for active noise control, noises are taken as tonal, multi-tonal, random broadband, and simulated chaotic noise. In reality, noises from real machines combine all these types of noises and background noise. This paper presents a comparative analysis of
filtered-x least means square, filtered-e least mean square, filtered-x recursive least mean square, filtered-u least mean square, and leaky FxLMS for active noise control. Experimentally recorded noises of Band saw, CNC, Compressor, and welding processes are utilized for the analysis. The
analysis is carried out for (a) linear primary and linear secondary paths, and (b) nonlinear primary and linear secondary paths. Their performance is evaluated based on steady-state residual noise and convergence time for various noises.
Study on indoor vibration and secondary radiated noise of rail-piercing buildings
Authors: Wu Qiong , Wu Yubin , Liu Bideng , Zhang Ximing , Zhang Jing , Song Ruixiang
Published: December 2023

In order to study the influence of train operation on indoor vibration and noise under the condition of co-construction of railway-building, the spectral characteristics of indoor vibration and structure-borne noise and their variation with speed were analyzed by on-site measurement
method of a track building in Beijing, which provided reference and data support for the evaluation and control of indoor vibration and secondary radiated noise under the condition of co-construction of railway-building.
Relation between sound absorption and speech intelligibility in room, part 2: Case study based on geometric simulation
Authors: Chen Keji , Hirose Ryoko , Sakuma Tetsuya
Published: December 2023

Sound absorption works for reverberation suppression and noise reduction, both of which contribute to improving speech transmission performance. In the previous paper, its combined effect was theoretically investigated to clarify the relationship among of reverberation time, average
absorption coefficient and speech intelligibility indices. In this paper, a case study is first conducted to examine the applicability of the theoretical estimation of clarity C50 based on geometric simulation. In rectangular rooms with different volumes, aspect ratios and absorption distributions,
impulse responses are simulated for various source-to-receiver positions, and then the distributions of the simulated C50 are compared with the theoretical values. Furthermore, a subjective experiment on speech intelligibility is conducted by using a 6-channel sound field reproduction system,
where a speech signal is convolved with the simulated impulse responses under background noise conditions. The results show the correlation between the listening difficulty rating and the estimated useful-to-detrimental ratio U50.
Study on airfoil tip with inflow turbulence and aerodynamic sound generated from it
Authors: Uda Shunya , Suzuki Yasumasa , Bai Lin , Miki Yuya
Published: December 2023

Far-field sound measurements and LES analysis are carried out in order to clarify the relationship between the effect of turbulent inflow on the flow around the airfoil tip and the aerodynamic sound generated radiated from the flow. Wind tunnel test is carried out for flow of Reynolds
number of 1.0×10^5 and large eddy simulation is performed for flow of Reynolds number of 1.2×10^5. In this study, the case with a circular cylinder upstream of the airfoil to give von Karman vortex street as an inflow turbulence is investigated. Moreover, the airfoil tip flow affected
by turbulent inflow and aerodynamic sound generated from it are investigated.
Sound map of urban areas recorded by smart devices: case study at Okayama and Kurashiki
Authors: Hara Sunao , Abe Masanobu
Published: December 2023

This paper presents a sound map to visualize environmental sounds collected using a cloud sensing approach, i.e. participatory sensing and opportunistic sensing. Our sound map have two major extra functions than a simple noise map which visualized sound levels. The first one is introduction
of visualization of sound-type icons on the noise map to enrich information. The second one is animating a transition of sound levels on noise map to visible the change according to the time in a day as a simulation. To demonstrate our sound map and develop the functions, we carried out several
experiments. First, we developed a sound collection system to simultaneously collect physical sounds, their statistics, and their subjective impression. Then, we conducted sound collection experiments using the developed system in Okayama city and Kurashiki city. We analyze the data to focus
on the difference between the cities and the differences between the usual and the unusual days. Furthermore, the collected data included subjective impressions by participants. We try to predict bustle situations in sightseeing areas by two approaches; the first is using Gaussian Mixture
Models, and the second is using i-vector, which is well-known approach in the speaker identification tasks.
A high-order explicit time-domain FEM using 15-node tetrahedral elements for room acoustics modeling: Basic performance
Authors: Yoshida Takumi , Okuzono Takeshi , Sakagami Kimihiro
Published: December 2023

Time-domain room acoustic modeling using mass-lumped higher-order tetrahedral finite elements with an explicit time-marching scheme is highly attractive because of its excellent geometrical flexibility with unstructured meshing and applicability into massively parallel computing. However,
the standard mass-lumped tetrahedral elements yield an unstable scheme, and only implicit time-marching schemes are available. This study proposes a novel wave-based room acoustics solver based on a high-order explicit time-domain FEM. The present solver uses mass-lumped 15-node tetrahedral
elements for spatial discretization and a dissipation-free two-stage partitioned Runge-Kutta time integration for time discretization. The 15-node tetrahedral elements had been developed to apply mass-lumping methods to 10-node tetrahedral elements, which are the most common finite element
in engineering applications, but its applicability in room acoustics problems is unknown. Higher accuracy and efficiency of the proposed method over the standard method using 10-node tetrahedral elements is presented through an eigenvalue analysis of a long duct model and acoustic simulations
in a small room. Additionally, frequency-dependent sound absorbing boundary is implemented by revising an auxiliary differential equation method.
Uncertainty quantification and probabilistic reliability analysis for the self-excited vibration of a spline-shafting system
Authors: Ma Xinxing , Huang Shizhang , Song Yuxiang , Zhang Zhenguo
Published: December 2023

Floating involute splines are widely used in large-torque, high-speed aerospace power transmission systems. The spline rotor system may suffer from self-excited vibration due to poor lubrication. The unavoidable manufacturing tolerances, mounting errors, component deformation, and other
factors make the self-excited vibration occurrence conditions have significant uncertainties. This paper provides new insights into the uncertainty quantification and reliability analysis of self-excited vibration of a spline-shafting system based on an advanced Kriging surrogate model. First,
a rotor nonlinear dynamics model considering tooth surface friction is established. Then an effective Kriging surrogate model is developed to quantify the uncertainty propagation in nonlinear rotor dynamics considering the randomness of parameters such as friction coefficient, and load torque,
which enables the rapid estimation of statistical information of the self-excited vibration response by the time-domain numerical integration method. The probability of instability and reliability of the system under multi-parameter uncertainty for the occurrence of self-excited vibration
is also predicted. Finally, the validity of the proposed method is verified by Monte Carlo simulation. This contribution will further enrich the theory and applications of probabilistic statistical analysis and reliability assessment of complex rotating machinery.
Utilization of Embedded Surface Compliance for Suppression of Deep Cavity Flow Noise
Authors: NASEER Muhammad Rehan , ARIF Irsalan , LEUNG Randolph C. K.
Published: December 2023

Cavity noise suppression is one of the extensively debated aeroacoustic research problem due to its application over the wide range of mechanical systems. This study presents a scheme of embedding surface compliance in form of elastic panels on cavity walls as a mean to achieve significant
tonal noise reduction. A deep cavity of aspect ratio D/L = 0.4 operating at Mach number 0.09 is considered. Using the Direct Aeroacoustic Simulation, the rigid cavity case is investigated to uncover the underlying physical processes driving the aeroacoustic coupling phenomenon between the
shear layer and the cavity mode. The analysis suggests that each cavity wall supports a certain coupling-associated activity and therefore provides a platform to modify the shear layer - cavity mode interaction in a tacit way through the well-designed positioning of elastic panels. The accordantly
mounted elastic panels are then excited with the flow perturbation energy to significantly reduce the pressure fluctuations magnitude of the cavity mode which strongly affects its synchronization with shear layer and hence presents the possibility of significant noise reduction.
Train Mitigation Measures in the Transmission Path: Seismic Metamaterial and Granular Barriers
Authors: Ouakka Slimane , Dec Patryk , Faure Baldrik , Verlinden Olivier , Kouroussis Georges
Published: December 2023

The development of new mitigation measures is an effective solution to the annoyance generated by the induced vibration coming from the railway traffic to the residents of urban areas. This paper aims to give a brief comparison of two novel concepts of mitigation measures applied within
the transmission path presented recently in the literature. In particular, the use of seismic metamaterial will be compared to the use of heterogeneous barriers, to evaluate to which extent these two mitigation measures can help to tackle the problem of ground-borne vibration and noise. These
two cases will be related by considering the same railway environment based on a two-step approach, already validated in the past; in this study, the soil simulated in the second step is reproduced using the finite element method and spectral element method for the seismic metamaterial and
heterogeneous barriers respectively. Finally, a parametric investigation is conducted to understand how the material and geometrical proprieties affect the attenuation levels of the two measures.
Study on suppression effect of air-conducted sound by bone-conducted sound
Authors: INOUE Shunsuke , TOYA Teruki , UEZU Yasufumi , UNOKI Masashi
Published: December 2023

This paper proposes a method for suppressing air-conducted (AC) sound by presenting bone-conducted (BC) sound. First, the amplitude and phase of BC tones at six frequencies (250, 500, 1000, 2000, 4000, and 8000 Hz) were examined by using a method of limits to suppress AC tones presented
via earphones. On the basis of the results of the first experiment, finite-impulse-response (FIR) filters, dependent upon participants, were then designed as "a compensation filter" to cancel out AC sound by presenting BC sound. Next, whether or not AC complex tones presented via
earphones could be suppressed by simultaneously presenting BC complex tones compensated for by FIR filtering was investigated. Finally, whether or not this method could be applied to suppress stationary noise was also investigated. From these investigations, the proposed method was found to
adequately suppress AC complex tones, and the average amounts of suppression for the AC and AC complex tones were approximately 5 and 1 dB, respectively. In addition, it was also shown that the proposed method can be used to suppress AC stationary noise but not greatly.
Improving the ISO 11819 standards for better characterization of noise reduction of porous pavements
Authors: Sandberg Ulf
Published: December 2023

The SPB method (ISO 11819-1) is designed to measure the acoustic properties in semi-free field of road pavements at a specific spot along a road, which in practice may characterize a 15-30 m length of the road lane. The CPX method (ISO 11819-2) is designed to correlate well to the SPB
method in characterizing road pavements, while extending the measured road section to an arbitrary distance. It is known that both methods may underestimate the noise reduction of porous pavements compared to dense pavements. A remedy for the SPB method may be to extend it to measure equivalent
sound exposure levels (SEL) instead. This will be discussed in the paper. Since the microphone locationsin the CPX method have been selected to give the best correlation between noise reductions measured by the CPX and the SPB methods, the inherent problem of the SPB method exists also in
the CPX method. As a remedy for the underestimation of noise reduction when using the CPX method, some users have applied other microphone positions around the reference tires than the two mandatory ones. This paper will analyze this problem and suggest how one can avoid it; essentially by
adding a microphone behind the tire.
Research on U.S. military base aircraft noise aircraft and aircraft flight routes in Okinawa Prefecture
Authors: Tokashiki Takeshi
Published: December 2023

Currently, about 70% of the area of US military bases nationwide is concentrated in Okinawa Prefecture, occupying an area of about 186.09 km2, which is about 10.4% of the prefectural land area of Okinawa Prefecture. Many of the US military bases are located in or near the center of
urban areas and have a great influence on urban planning. Among them, the aircraft noise problem is serious, and it has a great influence on the living environment of the surrounding residents, such as the sound of takeoff and landing and the sound of engine adjustment. In response to this,
the government is taking measures such as soundproofing work, but the current situation is that it has not been resolved. The purpose of this study is to (1) grasp and consider the actual situation of noise problems related to US military training through visual surveys, (2) derive the trajectory
of US military aircraft from the measurement results of precision sound level meters and visual surveys, and use the results to determine whether the measurement environment is appropriate. (3) Based on the obtained noise data and track charts, consider the noise damage situation at each point.
Comparison of power probability density functions for vertical sound propagation
Authors: Kamrath Matthew J.
Published: December 2023

When sound travels through the atmosphere, fluctuations in the wind velocity and temperature generate fluctuations in the sound amplitude and phase, which makes source detection, localization, and identification more difficult. While there are several parametric probability density
functions for the signal power, the previous literature has not shown which model performs best in a wide variety of environments. This paper compares the noncentral Erlang, gamma, compound gamma, generalized gamma, and log exponentially modified Gaussian distributions' ability to approximate
the signal power distributions collected at the National Wind Technology Center (Colorado, United States) in 2018. This weeklong experimental campaign measured the vertical and slanted sound propagation of a non-moving, sinusoidal source (600-3500 Hz) on the ground using microphones mounted
to a meteorological tower up to 130 m high. The dataset included several different atmospheric conditions, which were recorded by the meteorological tower and resulted in a wide range of scattering regimes in the measured acoustic data. When evaluated using the Kullback-Leibler divergence,
the gamma distribution was the best two-parameter model, and the log exponentially modified Gaussian distribution was the best three-parameter model.
Structural vibration damping by the use of poro-elastic layers: a summary
Authors: Xue Yutong , Bolton J. Stuart
Published: December 2023

A properly designed limp porous materials such as fibrous layers can provide damping equivalent to conventional viscoelastic dampers while providing advantages such as light weight and effective sound absorption. This then allows porous layers to be used as multi-functional noise and
vibration control solutions in automotive and aerospace applications. Further, the addition of bulk elasticity to the solid phase of the porous medium is beneficial since it improves damping performance compared to equivalent limp treatments. In the work summarized here, porous media, such
as fibers and foams, were designed to serve as treatments for various vibrating structures to examine their damping effectiveness. Both analytical modeling and numerical simulation based on finite element methods were involved depending on the complexity of the structure. Specifically, a Fourier
transform-based computational method was introduced as the key step to allow accurate prediction of a panel's spatial response based on its wavenumber-frequency spectrum. Parametric studies have been conducted to identify the optimal bulk properties that would allow a porous layer to provide
the largest possible damping within a target frequency region. Finally, design concepts for achieving the maximum damping potential of porous layers are summarized.
Preliminary survey on the effects of indoor noise in the hospital located close to Tan Son Nhat Airport
Authors: Trieu Bach Lien , Nguyen Tran Thi Hong Nhung , Nguyen Thu Lan , Morinaga Makoto , Morihara Takashi , Hiraguri Yasuhiro , Yano Takashi , Sasazawa Yosiaki , Tran Quoc Viet , Bui Duc Thanh , Tran Ha Hieu , Nguyen Thi Ngoc Dung , Do Pham Nguyet Thanh
Published: December 2023

An awareness of the harmful effects of environmental noise on vulnerable populations is crucial for improving current guidelines for the design of welfare facilities and land use planning in developing countries. This paper aims to identify the impact of aircraft noise on patients'
health in areas with a high frequency of aircraft noise. To achieve this, a preliminary investigation was conducted in September 2022 at a hospital located approximately 1 km from the southeast runway end of Tan Son Nhat Airport (TSN) in Ho Chi Minh City. The noise levels inside and outside
the hospital rooms were measured throughout the day to assess the noise exposure levels. The health data of 28 nursing staff living in the hospital's inpatient ward and four patients were collected through face-to-face interviews and the heart rate variability (HRV) of two of them was measured
by using portable electrocardiograph monitors attached to their bodies. As an objective evaluation of the effects of noise, HRV data was analyzed to reveal the impact of noise exposure on health. The noise exposure and health data were then analyzed using multivariate analysis. The results
of the analysis provide a clear understanding of the impact of aircraft noise on patients' health in areas with a high frequency of aircraft noise.
Sound perception of tourists and locals in public squares: Istanbul Taksim case
Authors: Jumaa Anas , Ascigil-Dincer Mine
Published: December 2023

Urban soundscape perception is one of the main determinants of how people experience public open spaces. Istanbul city's most famous public space, Taksim, and its surroundings are at the top of the list for soundscape research when population density, utilization aims, cultural and
historical influences, diversity of architectural and urban characteristics, and diversity of acoustic settings are all considered. Urban soundscape questionnaires were executed, which took place at three different squares along Istiklal Avenue: Taksim Square, Galatasaray Square at the avenue's
center, and Tunel Square. Statistically, the sound perception of tourists and locals was found to be different. According to the findings, users' perceptions of soundscape vary depending on the purpose of their visit. The data revealed and evaluated in this study underlined the importance
of demographic factors on users' perception and experience of their surroundings.
The acoustic method for diagnosing machines operating under variable conditions
Authors: Pawlik Paweł
Published: December 2023

The acoustic signal can be used for mechanical fault diagnosis in conditions where measurement with a vibration sensor cannot be realised. This problem often occurs on production lines, where it is necessary to stop the line to mount the sensor. However, the acoustic signal measured
in the diagnosis machine's vicinity may contain noise from other sources under industrial conditions. This causes the signal to require more advanced analysis methods than methods based on vibration measurement. The paper proposes a method for diagnosing rotating machinery insensitive to acoustic
interference from other machines based on the acoustic signal. The technique allows the diagnosis of machines operating under varying load, speed and temperature conditions. A laboratory experiment on a bench was carried out to analyse the functionality of the proposed method in gearbox diagnosis.
The new approach was compared with a method based on vibration measurement.
Effects of the preference for acoustic stimuli on sleep quality
Authors: Maki Shota , Otsuka Sho , Nakagawa Seiji
Published: December 2023

Since pharmacological treatment for sleep disorders has a risk of addiction, developments of non-pharmacological tools are needed. Colored-noise sounds characterized by the power spectrum, e.g., white, pink, brown, blue, and purple noises, are used in some non-pharmacological sleep
aids. Former reports showed that white and pink noises were effective for sleep, however the mechanisms how such noises promote sleep remain unknown. In this study, we proposed a hypothesis that effects of colored noises are depending on participants' auditory impressions and examined how
each participant's preference for the noises affected sleep-quality indices (the sleep latency and the duration of slow-wave sleep (SWS)). Sleep states of each participant were examined by EEG in three conditions: (i) listening the most preferred noise, (ii) listening the least preferred noise
for each subject and (iii) no sound stimulation. Sleep experiments were started at 3:00 PM in a soundproof room and the stimulus began to be presented at lights-out and continued for 60 min. In results obtained, there were no significant differences in the sleep-quality indices among the three
conditions. Since duration of the experiment may not be enough to observe the effect of the stimuli, further investigations are needed after reviewing the experimental conditions.
Mathematical model of reverberation decay in a rectangular room with uneven distribution of absorption
Authors: HANYU Toshiki
Published: December 2023

Based on traditional reverberation theories such as Sabine's or Eyring's theories, the reverberation energy decay becomes linear in logarithmic scale of energy. However, this is valid only in diffuse sound fields. Sound fields in actual rooms are non-diffuse sound field. It has been
well known that nonlinear reverberation decay occurs in a rectangular room with uneven distribution of absorption. Hence, reverberation times measured in such rooms are not correspondent with those calculated by the theories. Reverberation theories for such rectangular rooms have been proposed
by some researchers. However, these theories have not been sufficiently validated. In this study, a new mathematical model of reverberation decay in rectangular rooms with uneven distributions of absorption is proposed. Most of previous theories contained only exponential decays. The proposed
model in this study contains not only exponential decays, but also power law decays.
Relationship between non-destructive inspection and heavy-weight floor impact noises in a box-type test building
Authors: Kim Yong-Hee , Yeon Jun-Oh , Moon Soon-Seong , Kee Seong-Hoon , Im Jung-Bin
Published: December 2023

This study investigated the relationship between floor impact noise performance and non-destructive inspection methods for use in construction quality control prior to installing resilient floor-topping materials. The study measured floor impact noise characteristics using heavy-weight
impact sources in a box-type test building with a 180-mm thick bare slab. The study employed impact echo and ultrasonic tomography methods to estimate concrete thickness and other mechanical properties. The results showed that the highest impact noise levels were observed at the central area
in the frequency bands of 25 Hz to 50 Hz. However, the frequency bands of 63 Hz to 80 Hz showed different results as a peak characteristic at the middle area in the long direction. The study estimated the average slab thickness as 175 mm and 172 mm, respectively, using the impact echo and
ultrasonic tomography methods. The standard deviation of the thickness was up to 9.3 mm and 6.6 mm, respectively, depending on the impact position. Furthermore, the study analyzed the correlation between concrete thickness and impact noise performance by frequency bands and discussed the application
directions of the mechanical properties to manage noise performances during construction.
Predicting impulse prominence and tone audibility at remote assessment locations
Authors: Torjussen Matt , Hoyle Patrick , Webb Jo , Torija-Martinez Antonio J , Waddington David
Published: December 2023

This paper studies the prediction of impulse prominence and tone audibility at remote assessment locations, with a focus on industrial and commercial sound. The British Standard 4142 provides objective methods for determining graded corrections to the equivalent continuous sound pressure
level for impulsivity and tonality, but these methods require specific sound sources to be installed and operating. In planning applications, where the sources are proposed or the propagation path is intended to change significantly, the professional judgement of the acoustics practitioner
is relied upon to determine the likely prominence/audibility of these features at a remote assessment location. To address this issue, online listening tests utilising simplified auralisation ('auralisation-lite') were conducted among members of the Association of Noise Consultants in the
UK. The initial results suggest that objective evaluation can indeed offer an improvement over existing subjective evaluations. The work provides a new method for practitioners to predict tonal and impulsivity corrections for non-existent sources. This study also provides a comprehensive review
of relevant literature and standards, including ISO 9613-2:1996 and ISO/TR 17534-3:2015. The findings have practical implications for environmental agencies, industrial settings, and other fields where accurate prediction of sound level impacts are crucial.