bluuebunny/crossref_metadata_2025 huggingface dataset:
Active noise control for open windows
Authors: Sohrabi Shahin , Svensson Peter , Pàmies Gómez Teresa , Garbi Jordi Romeu
Published: September 2021

Over the last decades, the applications of the active noise control system are broadened. In this study, the active noise control is modeled to reduce the noise pass through an open window. The objective is to define a suitable location for the control sources and error microphones
to achieve more noise level reduction at the other side of the window. The performances of the active noise control system are calculated for two different arrangements: (1) the control sources on the edge of the opening and (2) the control sources distributed on the surface of the window.
Furthermore, two cost functions are considered to model the noise control system including the minimization of the total squared pressure at cancellation points and the minimization of sound intensity at the surface of the aperture.
Diffraction in phase gradient acoustic metagratings: multiple reflection and integer parity design
Authors: Uzair Mohammad , Li Xiao , Fu Yangyang , Shen Chen
Published: September 2021

Diffraction occurs when acoustic waves are incident on periodic structures such as graded metasurfaces. While numerous interesting diffraction phenomena have been observed and demonstrated, the underlying mechanism of diffraction in these structures is often overlooked. Here we provide
a generic explanation of diffraction in phase gradient acoustic metagratings and relate high-order diffractions to multiple reflections in the unit cells. As such, we reveal that the number of unit cells within the metagrating plays a dominant role in determining the diffraction patterns.
It is also found that the integer parity of the metagrating leads to anomalous reflection and refraction with high efficiency. The theory is verified by numerical simulations and experiments on planar metagratings and provides a powerful mechanism to manipulate acoustic waves. We further extend
the theory to cylindrical waveguides for the control of sound vortices via topological charge in azimuthal metagratings. The relevance of the theory in achieving asymmetric wave control and high absorption is also discussed and verified both numerically and experimentally.
Noise control engineering on neonatal incubators
Authors: Adams Christian , Stutz Regine , Kaiser Elisabeth , Bous Michelle , Goedicke-Firtz Sybelle , Hornberger Franziska , Zemlin Michael
Published: September 2021

Neonatal incubators provide suitable environmental conditions for premature newborns and allow for medical treatment such as medication and monitoring of vital functions such as blood pressure. The incubator includes several system components such as a control system, an oxygen supply,
a scale or flaps and drawers for patient care and storage of medical material, respectively. These system components generate noise such as monitoring alarms, noise of the oxygen supply, or noise due to opening and closing of flaps during medical treatments. The noise leads to a significantly
increased sound exposure inside the incubator. Increased sound exposure is known to cause distress and to increase the risk of acute or chronic diseases in the preterm neonate. This paper presents acoustic measurements on an incubator in a neonatal intensive care unit. Several vibration and
acoustic measurements are performed inside the incubator as well as in the surrounding environment in order to characterize typical acoustic scenes from everyday life on the neonatal intensive care unit. Based on the measurement results, the scenes are categorized in terms of sound exposure.
This forms the basis for a future design for acoustics of the incubator.
Resonant metamaterial designs for a broadband mitigation of flow-induced vibrations
Authors: Alves Pires Felipe , Sangiuliano Luca , de Melo Filho Noé Geraldo Rocha , Hervé Denayer , Deckers Elke , Desmet Wim , Claeys Claus
Published: September 2021

Resonant metamaterials have recently emerged as lightweight and performant noise and vibration solutions for the hard-to-address low-frequency ranges. These engineered materials are made by an assembly of resonant elements onto a host structure. Their interaction leads to tuneable frequency
ranges, known as stop bands, in which they can outperform classical noise control measures. However, these stop bands have a limited frequency range effect. To broaden the noise and vibration performance also outside the stop band, this paper presents a design approach for a finite resonant
metamaterial plate. Two regularly spaced grids of resonant elements are both added to a plate. In the first grid, the resonant elements are tuned to the same nominal frequency and stop band behaviour is achieved. In the second grid, the tuned frequency of each resonant element is found through
an optimisation procedure, with the goal of minimising the dynamic response of the plate outside the stop band. To speed up the optimisation, model order reduction and a dynamic sub-structuring method are employed. The performance of this finite resonant metamaterial plate design is validated
by evaluating its vibration response due to a broadband grazing flow excitation and comparing it to a plate with equivalent mass additions.
Improving single flyover noise prediction for subsonic aircraft
Authors: Zaporozhets Oleksandr , Jagniatinskis Alexandras
Published: September 2021

Current ICAO Doc 9911 provides the algorithm to calculate aircraft noise levels for any kind of airport flight scenario. The essential difference exists between the measured and calculated sound levels, especially for single flight noise events. Doc 9911 recommends using this method
for equivalent sound levels L and noise indices L first of all. A number of national noise regulations still require for single noise event assessment. An article analyzes a number of reasons to explain the inaccuracy of noise event calculations. For example, the differences between calculated
balanced flight parameters (thrust and velocity first of all) and supervised in real flights may influence the accuracy first of all. Statistical data was gathered to make more general view on these differences and some proposal to use them in calculations has being proved. Also, the assumptions
of the ICAO Doc 9911 method may contribute to the inaccuracy of calculations. Among them are the homogeneous atmosphere for sound propagation, generalized for overall fleet noise directivity pattern, etc. Ground effect model defines the values for aircraft absent in operation currently. The
first assumption provides a conflict with flight path calculations for varied atmosphere parameters with height over the surface.
Investigating the influence of microphone mismatch for acoustic traffic monitoring
Authors: Gourishetti Saichand , Abeßer Jakob , Grollmisch Sascha , Kátai András , Liebetrau Judith
Published: September 2021

The development of robust acoustic traffic monitoring (ATM) algorithms based on machine learning faces several challenges. The biggest challenge is to collect and annotate large high-quality datasets for algorithm training and evaluation. Such a dataset must reflect a broad variety
of vehicle sounds since their emitted acoustic noise patterns depend on a variety of factors such as engine noises at different speeds and road conditions. Additionally, the characteristics of the employed microphones have a strong influence on the data. If microphones with different directionality
and frequency responses are used during the model development and the final deployment phase, a data mismatch is caused, which can have a deteriorating effect on the performance of machine learning algorithms. In this paper, the influence of mismatched recording locations and microphone characteristics
on the proposed ATM system is investigated. To evaluate these effects, we implement state-of-the-art convolutional neural networks to detect passing vehicles, classify their type, and estimate their speed and direction of movement. The evaluated models perform well on low- and high-quality
recordings at different locations when using the same recording device for training and testing. However, the results indicate that microphone mismatch causes several issues, which need to be carefully addressed.
A case study on the noise effects of elevating existing train tracks
Authors: Suits Joelle
Published: September 2021

When modeling rail noise on an elevated track, there are several adjustments that need to be considered relative to modeling at-grade operations. These adjustments include the effects of re-radiated noise from the track and support structure, reduced ground attenuation due to an elevated
noise source and a reduction in the potential for shielding from adjacent rows of buildings. These adjustments are built into the model as a part of the design of a project. This case study examines a unique situation where a project involved elevating existing at-grade tracks to eliminate
a bottleneck related to an at-grade crossing of two perpendicular train tracks. The project elevated one main track over the other and shifted the track closer to noise sensitive receivers. The US Federal Transit Administration and Federal Railroad Administration guidance, which were used
to assess noise impacts, produced unexpected results during the initial assessment due mainly to the assumptions regarding the changes in shielding and ground attenuation with the elevated structure. This presentation will discuss the initial assumptions used in the project, the limitations
of the model relative to changes in shielding and ground attenuation, and the solutions that were implemented to obtain reasonable results for the impact assessment.
Development of a dynamic model of the axisymmetric railway wheel for sound radiation prediction
Authors: Andrés Víctor , Martínez-Casas Jose , Carballeira Javier , Denia Francisco
Published: September 2021

In this work, a vibroacoustic model is developed to predict the dynamic response and sound radiation of an axisymmetric railway wheel under a non-axisymmetric excitation. To do this, first, the energy equation of the wheel is analytically integrated along the circumferential direction
after an expansion of its response as Fourier series. Then, the vibrational dynamics of the three-dimensional wheel is solved through a set of two-dimensional problems which come from that integration. Subsequently, the three-dimensional sound radiation of the railway wheel is calculated from
the solution of the aforementioned two-dimensional problems by means of analytical relations based on the harmonic distribution of the dynamics in the circumferential coordinate. Additionally, the wheel rotation is introduced in the model using an eulerian approach, in order to consider the
associated gyroscopic and inertial effects. The proposed model presents a greater computational efficiency compared to full three-dimensional methodologies, without compromising the precision of the results. This allows the implementation of the sound radiation calculation in optimization
algorithms with the aim of achieving quieter designs of railway wheels.
Acoustic analysis of impact sound on vibrating circular membranes
Authors: Kaselouris Evaggelos , Alexandraki Chrysoula , Orphanos Yannis , Bakarezos Makis , Tatarakis Michael , Papadogiannis Nektarios A. , Dimitriou Vasilis
Published: September 2021

A finite element method (FEM) - boundary element method (BEM) model is developed to compute the sound generated by of a force acting on a circular membrane (drumhead). A vibro-acoustic analysis that combines modal FEM analysis, a FEM steady state dynamic analysis (SSD), considering
harmonic loading and boundary element acoustics, is performed. The drumhead vibrates due to the force impact and the sound is emitted in the air. The vibration of structural response is initially computed, and the obtained results are set to be the boundary conditions of the acoustic analysis
in the vibro-acoustic simulation. The radiated sound can be computed at any point of the solution domain. Various materials used by drumhead manufacturers are tested and a parametric analysis focusing on the mesh density of the models is presented. The impact sound and the acoustical characteristics
of the simulated test cases are evaluated. The Rayleigh method is also applied to the acoustic simulations and is further compared to the BEM simulation results. The outcomes of this study may be further used as reverse engineering inputs, to machine learning models for the estimation of the
physical and mechanical parameters of drumheads from audio signals.
Ground Attenuation Factor Based on Measurements
Authors: Lin Dan , Eng Andrew
Published: September 2021

Assumptions made on the ground types between sound sources and receivers can significantly impact the accuracy of environmental outdoor noise prediction. A guideline is provided in ISO 9613-2 and the value of ground factor ranges from 0 to 1, depending on the coverage of porous ground.
For example, a ground absorption factor of 1 is suggested for grass ground covers. However, it is unclear if the suggested values are validated. The purpose of this study is to determine the sound absorption of different types of ground by measurements. Field noise measurements were made using
an omnidirectional loudspeaker and two microphones on three different types of ground in a quiet neighborhood. One microphone was located 3ft from the loudspeaker to record near field sound levels in 1/3 and 1 octave bands every second. The other microphone was located a few hundred feet away
to record far field sound in the same fashion as the near field microphone. The types of ground tested were concrete, grass, and grass with trees. Based on the measurement data, it was found that grass and trees absorb high frequency sound well and a ground factor of 1 may be used for 500Hz
and up when using ISO 9613-2 methodology. However, at lower frequencies (125 Hz octave band and below), grassy ground reflects sound the same as concrete surfaces. Trees absorb more low frequency sound than grass, but less than ISO 9613-2 suggested.
Two-step computational aeroacoustics approach for underhood cooling fan application
Authors: Chaudhari Parag , Magalhaes Jose , Salunkhe Aparna
Published: September 2021

Aeroacoustic noise is one of the important characteristics of the fan design. Computational Aeroacoustics (CAA) can provide better design options without relying on physical prototypes and reduce the development time and cost. There are two ways of performing CAA analysis; one-step
and two-step approach. In one-step CAA, air flow and acoustic analysis are carried out in a single software. In two-step approach, air flow and acoustic analysis are carried out in separate software. Two-step CAA approach can expedite the calculation process and can be implemented in larger
and complex domain problems. For the work presented in this paper, a mockup of an underhood cooling fan was designed. The sound pressure levels were measured for different installation configurations. The sound pressure level for one of the configurations was calculated with two-step approach
and compared with test data. The compressible fluid flow field was first computed in a commercially available computational fluid dynamics software. This flow field was imported in a separate software where fan noise sources were computed and further used to predict the sound pressure levels
at various microphone locations. The results show an excellent correlation between test and simulation for both tonal and broadband components of the fan noise.
Experimental study on cushioning behaviors of foam with different skin-liked covers
Authors: Xiao Heye , Yuan Focai , Zhang Xudong , Xu Chizhen , Zhou Jie
Published: September 2021

Periodic structures were used in foams to improve their cushioning ability in previous studieswhich are usually constructed by additive manufacturing methods with high cost. To improve cushioning property of the foam materials at a low cost, foams with skin covers are proposed in this
paper to provide a new idea for a structural design that is inspired by the composition of animal skins. The foam without covers and covered with three different skin types, including square shape, circle shape, and Pearlfish skin, are investigated in this study. The stiffness and acceleration
responses of these structures are measured by static loading and dropping test respectively, which are used to evaluate their static and dynamic cushion properties. Based on the tested results, it demonstrated that the cover skins could improve the stiffness of the foam materials and decrease
acceleration response of mass fixing on them in dropping test at 0.4 m and 0.5 m. The enhancement for cushion ability of the proposed structure in this paper is proved experimentally.
Design of axial flow fans for reduced noise and improved efficiency
Authors: Quaranta Erika , Smith Malcolm
Published: September 2021

Axial flow fans are used in a wide variety of applications, from cooling systems for electronics to ventilation in buildings. Whatever the application, there will be competing design constraints which make it difficult to achieve the required pressure-flow performance characteristic,
within a specified space envelope, whilst meeting a target aerodynamic efficiency and noise level. This paper describes a design methodology for optimizing aerodynamic performance and noise. It is based on use of a semi-analytic 2-D design tool for preliminary predictions and design, combined
with a 3-D numerical CFD analysis to visualize the flow. Both models can be extended to the design of multi-stage systems. The 2-D model predicts the flow velocity at the trailing edge of the blades for each point on the fan performance curve, which is then used to estimate self-noise characteristics
of the rotor using a classical model of airfoil trailing edge noise. The CFD analysis provides detailed validation of assumed airfoil characteristics, including the effect of 3D design features such as blade sweep, and confirms the flow and aerodynamic efficiency predictions; it can also used
to estimate parameters such as turbulence intensity that is a key driver for the noise level.
Improvement of sound atmosphere in the compartment of construc-tion machine
Authors: Hashimoto Takeo , Hatano Shigeko
Published: September 2021

Noise inside the compartment of construction machine makes the operator feel annoyed and exhausted due to the unwanted component of noise. This paper deals with the treatment of sound inside the compartment of construction machine to make the sound atmosphere desirable for the operator.
The main cause of annoyance due to the exposure of noise is the peaky engine order components. This paper provides the method to reduce annoyance for the operator inside by the reduction of peaky components.
Customized sound mitigation with micro-perforated panels
Authors: Kaltenbacher Manfred , Floss Sebastian
Published: September 2021

Micro-perforated panels in combination with an air-tight back volume constitute the micro-perforated absorber (MPA), an alternative means in the category of sound absorbing (meta)materials. In contrast to the conventional porous and fibrous materials, the MPA does not mitigate sound
in broad frequency range, but rather has to be customized to a specific noise frequency range. In this contribution, we demonstrate the simulation framework based a genetically fitted equivalent fluid model. Application examples show the advantages and disadvantages of using MPAs in room acoustic
scenarios as well as with a background mean flow in ducts. The investigations found that the MPA's effectiveness strongly depends on the sound field characteristic. The MPP's surface roughness and back volume composition in-part significantly influence the efficiency of an adjacent turbo-machine.
Modeling and analysis for dynamic behavior of elevator traction system under the braking of safety gear
Authors: Ma Xiaolong , Zhang Peng , Li Ni , Shi XI , Zou Huaiwu
Published: September 2021

In the emergency case when the elevator car is over speeding in the downward direction, the traction car will be stopped rapidly by the braking of safety gear. However, the counterweight and the traction sheave are still moving, which maybe induces the collision between the counterweight
and the traction sheave, the slip and off-track between the traction sheave and the rope. Therefore, a two sides mass-spring-damping rope model was proposed in this paper to investigate the dynamic behavior of elevator traction system under the braking of safety gear. In this model, the interaction
between the car and the counterweight on both sides of the traction sheave was introduced. Meanwhile, the slip behavior and various constraints between the rope and traction sheave were respected in this model. Especially, the rope slack and the rope length change were considered to approach
the mechanical properties of real rope. Furthermore, a numerical scheme based on Newmark- method was applied to solve the proposed dynamic model. Then the impacts of the braking force on the dynamic behavior of elevator traction system under different working conditions were deeply studied.
Results showed the braking force of the safety gear, the speed and the acceleration of the traction sheave had great influences on the bounce of the counterweight. In fact, the braking performance, the vibrations of the car, rope and counterweight could be well analyzed based on this model,
which is key for the realization of the steady and safe braking of traction elevator.
On the resonance sound generated in a vehicle cabin moving at low speed due to breaking force
Authors: Li Zhe , Kiyotaki Ryo , Terashima Osamu , Poddar Vinay , Murakami Takashi
Published: September 2021

To improve the comfortability in a vehicle cabin, unwanted noise which is recognized as an allophone generated from automobile wheels was experimentally studied to investigate its generation mechanism and to develop its reduction countermeasures. In this experiment, simultaneous measurements
of sound pressure and vibrational acceleration of the wheel surface were performed. Then, frequency analysis, vibrational modal analysis and operational transfer path analysis were performed by using measured data. The results show that this kind of noise started in a low frequency first and
then became higher. Furthermore, the high-frequency noise was mainly generated by vibrational acceleration at its center and near the rim when the wheel spoke gets close to the brake caliper. The high-frequency noise is around 250Hz, 750Hz, 1000Hz and 1250Hz, and the wheel spoke easily gets
vibration and resonance mainly from around 750Hz and 1000Hz. Vibration at 750Hz occurs on the side of the wheel spoke in the rotation direction, while vibration at 1000Hz occurs at the midpoint of the wheel spoke. The closer to the brake caliper, louder noise was generated at the wheel spoke.
Development of a hybrid SmEdA/SEA model for predicting the power exchanged between low and high modal density subsystems
Authors: Zhu Guang , Maxit Laurent , Totaro Nicolas , Le Bot Alain
Published: September 2021

Statistical modal Energy distribution Analysis (SmEdA) was developed from classical Statistical Energy Analysis (SEA). It allows computing power flow between coupled subsystems from the deterministic modes of uncoupled subsystems without assuming the SEA modal energy equipartition.
SmEdA is well adapted in mid-frequency when the subsystems have not a very high modal density. However, for some systems e.g. the plate-cavity system, one subsystem can exhibit a low modal density while the other one a high one. The goal of the paper is then to propose an extension of SmEdA
formulation that allows describing one subsystem by its deterministic modes, and the other one as a diffuse field statistically supposing modal energy equipartition. The uncertain subsystem is then characterized by sets of natural frequencies and mode shapes constructed based on Gaussian Orthogonal
Ensemble matrix and the cross-spectrum density of a diffuse field, respectively. This formulation permits not only the computation of mean noise response but also the variance generated by the uncertainties and furthermore without bringing in much computation. It is demonstrated that the obtained
analytical results from the proposed hybrid SmEdA/SEA are consistent with numerical results computed by FEM with an appropriate degree of uncertainty.
Effect of stud material and structural properties on the transmission loss of partitions
Authors: Dong Wayland , LoVerde John , Shafer Benjamin , Hu Lin
Published: September 2021

A common light frame wall design is gypsum wall board (GWB) cladding on each side of a row of studs. Steel studs are available in a variety of metal thicknesses and designs, and wood studs can be solid lumber or engineered wood composite studs with a variety of structural properties.
Most published laboratory testing on these walls uses only a small subset of the available stud types, and the acoustical effect of changes to the stud parameters is not well understood. The authors and colleagues have performed several laboratory testing programs to systematically investigate
the acoustical effects of stud properties, some of which were presented at Internoise 2020. This paper analyzes the effects of stud material and structural properties on third-octave transmission loss values and single-number ratings.
Commercial Aviation, A New Era: summary of the 2017 TQA workshop
Authors: fleming gregg
Published: September 2021

More environmentally friendly aircraft designs, particularly with regard to noise, was a Technology for a Quieter America (TQA) workshop hosted by the National Academy of Engineering (NAE) held in May 2017. This workshop titled "Commercial Aviation: A New Era", centered on
the importance of commercial aviation to the U.S. economy, and what it will take for the U.S. to maintain global leadership in the aviation sector, including a forward-looking topic on more environmentally friendly aircraft designs. A principal focus of the workshop was the necessary step-changes
in aircraft engineering technology that must be addressed with the development and testing of flight demonstrators together with significantly increased funding of public-private partnerships. Government agencies which participated included NASA, the Federal Aviation Administration, and the
Department of Housing and Urban Development (HUD). There was also substantial participation from the aviation industry, airports, airlines, non-government organizations and academia.
MEMS digital microphone and Arduino compatible microcontroller: an embedded system for noise monitoring
Authors: Ramos de Mello Felipe , D'Andrea Fonseca William , Henrique Mareze Paulo
Published: September 2021

Noise assessment and monitoring are essential parts of an acoustician's work since it helps to understand the environment and propose better solutions for noise control and urban noise management. Traditionally, equipment to carry out this task is standardized, and, eventually, expensive
for the early career professional. This work develops a high-quality (and cost-effective) prototype for an embedded noise monitoring device based upon a digital I2S MEMS microphone and an Arduino compatible microcontroller, named Teensy. Its small size and low power consumption are also advantages
designed for the project. The system captures and processes sound in real-time, computes A and C frequency-weighted equivalent sound levels, along with time-weighted instant levels with a logging interval of 125 ms. Part of the software handles the audio environment, while the biquadratic
IIR filters present in the Cortex Microcontroller library are responsible for the frequency- and time-weightings - using floating-point for enhanced precision. The prototype results were compared against a Class 2 Sound Level Meter, rendering very similar results for the tested situations,
proving a powerful and reliable tool. Improvements and further testing are also being conducted to refine its functioning and characterization. Ultimately, the prototype achieved promising performance, confirming as a solution for noise monitoring.
Multi-tonal low frequency noise control using Helmholtz resonators with complex cavity designs for aircraft cabin noise improvement
Authors: Kone Tenon Charly , Ghinet Sebastian , Panneton Raymond , Dupont Thomas , Grewal Anant
Published: September 2021

The noise control at multiple tonal frequencies simultaneously, in the low frequency range, is a challenge for aerospace, ground transportation and building industries. In the past few decades, various low frequency noise control solutions based on acoustic metamaterial designs have
been presented in the literature. These solutions showed promising performance and are considered a better alternative to conventional sound insulation materials. In the present investigation, it was noticed that subdividing the cavity of a Helmholtz resonator allowed the control of multi-tonal
noise at several resonance frequencies simultaneously and a shift of the resonance peaks towards the low frequencies. This paper proposes concepts of Helmholtz resonators with subdivided cavities to improve the sound transmission loss (STL) performance and simultaneously control the noise
at several tonal frequencies. HRs with cylindrical shaped cavities were embedded in a layer of porous material. The STL of the metamaterial noise insulation configuration was predicted using serial and parallel assemblies of transfer matrices (TMM) incorporating a thermo-viscous-acoustic approach
to accurately account for the viscous and thermal losses of acoustic wave propagation within the metamaterial. The STL calculated using the proposed TMM approach were observed to be in excellent agreement with the finite element method (FEM) numerical results.
Acoustic Prediction Modeling and Sound Mapping of public transport users' exposure at a bus stop.
Authors: Lima Estercio Dayane Cristina , Soares Paulo Fernando
Published: September 2021

The objective of this research is to develop a mathematical model to predict the road traffic noise level at the bus stop, to assess the level of noise that users of these urban facilities are exposed daily. To help assess the exposure and the environmental impact, sound mapping will
be performed using the IMMI software. In the model, the calculation of direct paths and specular reflections and diffuse was adopted. The study was applied in three sections in the city of Maringá, Brazil. At each point, the user was simulated standing and sitting. The sound source
was positioned on the axis of each strip, every five meters. In total, 5124 readings of source positions were evaluated in 84 measured points. For the validation, the Anderson-Kurze, Kang, Yang and Zhang, Bistafa and Naish model were applied, and then the t-Student test were applied. The results
showed a correspondence between the developed model, the data of the measurements and the reference models in the range of 25 Hz to 10000 Hz, there was a greater variance between the models applied in the high frequencies. It is concluded that the model was able to estimate the sound level
of the stretches evaluated.
The interplay of tourism and noise: A literature review
Authors: Wadle Lisa-Marie , Martin Noemi
Published: September 2021

Tourism is an important economic factor for countries, cities and individual beings. However, tourism also has an impact on the environment, e.g. in terms of noise. This does not only constitute a burden for locals but also effects tourists whose goal, among others, commonly is to rest
during their holidays. A literature review was conducted covering the last ten years (2011-2021) and will be updated until the conference. The terms or and noise as well as synonyms and related terms were used in the search string. The search results in over 400 documents which were reduced
based on their fit to the area of research interest and a practical screening. The overview gained by reviewing the literature indicates the most common noise sources with relation to tourism. Furthermore, several studies were found which analyse the consequences for locals and how they react
to and deal with the noise. Some of the studies focused on measures taken on noise reduction like reducing the noise source itself, developing new methods to measure or visualize noise as well as structural measures. Based on this review, future research areas were identified.
Measurement and Assessment on Environmental Noise Impact of Electric Vehicles in Accelerating Condition
Authors: Yamauchi Katsuya , Yoshino Jo
Published: September 2021

Noise emission from the vehicles propelled by electric system (such as pure electric and hybrid electric vehicles, EVs) is usually lower than the conventional internal combustion engine vehicles. Some previous studies have been shown the difference in A-weighted sound power level of
EVs from the conventional ones. The difference is not dramatically large, i.e. less than 4 dB when the cars running at constant speed of 20 km/h. In this paper, we present the additional measurement results of sound power level of EVs in accelerating condition. Because when the cars in accelerating
condition, the difference of propulsion systems becomes more significant on noise emission. The results are shown as regression model of sound power level depending on the vehicle speed. Moreover, the environmental noise impact of growing population of EVs is assessed through a prediction
of at a case of intersection.
Methodology of estimating the number of inhabitants to assess the population exposure to environmental noise in Japan
Authors: Suda Shota , Sugahara Akiko , Hiraguri Yasuhiro , Harada Kazunori , Oshima Takuya , Saito Yoshinori , Atobe Satoshi
Published: September 2021

Population exposure has been used in the risk assessment process for environmental noise. The number of inhabitants is essential data for the evaluation of population exposure. However, such data is not opened to the public to prevent privacy violation. There are several existing methods
for the estimation of the number of habitants, but only with limited accuracy. The purpose of this study is to propose a more accurate method for estimating the number of inhabitants using web scraping techniques and numerical maps issued by the Geospatial Information Authority of Japan. The
number of inhabitants is estimated from the number of households and the census. The number of households is calculated based on the total number of housing that is extracted from using web scraping techniques. The proposed method is found to present a better accuracy of the number of inhabitants
for the detached houses while the estimation for apartment houses should be still improved.
Development of virtual fan flow and acoustic performance testers based on RANS solvers and acoustic analogy
Authors: Ryu Seo Yoon , Cheong Cheolung , Kim Jong Wook , Park Byung il
Published: September 2021

As the potential of computational resources dramatically increases, the so-called computer-aided engineering readily replaces experiment-based engineering in related industrial fields. In this study, the virtual fan flow and acoustic performance testers are developed using the RANS
solvers and the acoustic analogy. Two types of forward-curved centrifugal fans are selected for numerical and experimental investigations into its flow and acoustic performances. First, to experimentally evaluate the performances of the centrifugal fan units, their P-Q curves and sound power
levels are measured using a fan flow performance tester and a semi-anechoic chamber, respectively. Second, the virtual fan flow and acoustic performance testers are constructed using the RANS solvers and the acoustic analogy based on the FW-H equation and CFD method. The validity of the current
virtual methods is confirmed by comparing the prediction results with the measured ones. During the validation, the effects of the wall functions, y+ distribution, and turbulence models on predicted flow performance accuracy are closely examined. The effects of the integral surfaces used for
the computation of the FW-H equations are also assessed on the predicted spectral levels of sound pressure.
Design, development and testing of digital MEMS pressure sensor array for full-scale vibroacoustic measurements
Authors: Joshi Pankaj , Khelfa Frank , Lehmkuhl Hendrik , Cordes Patrick , Naujoks Patrick , Scharowsky Thorsten , Kochan Kay
Published: September 2021

This manuscript addresses design, development, and application of micro-electro-mechanical systems (MEMS) based digital pressure sensor array for vibroacoustic measurements. These vibroacoustic measurements were conducted on a A320 type single aisle aircraft demonstrator subjected to
broadband as well as tonal excitations. Cabin noise levels were measured with both condenser microphones as well as digital MEMS pressure sensor array. The measured cabin noise shows strong qualitative as well as quantitative agreement between both type of measurement devises for full scale
cabin noise measurements inside an aircraft demonstrator. The observed strong agreement is valid for both single wall (fuselage with thermal insulation) and double wall (fuselage with thermal insulation and trim panel) cabin noise measurements. Such strong agreement within 1.0 dB tolerance
is significantly motivating for further development of reliable but low-cost MEMS based measurement devises and corresponding efficient data post-processing algorithms for full scale vibroacoustic measurements in general. Additionally, it is also demonstrated that the large number of MEMS
based digital pressure sensors can be used in areas where the physical space constraints are high. This demonstration shows strong potential to derive additional vibroacoustic indicator for the development and the testing of future noise control solutions in a non-traditional way.
Non-linear beamformer with long short-term memory network
Authors: Mizumachi Mitsunori , Oka Ryotarou
Published: September 2021

Acoustic beamforming with a microphone array enables spatial filtering in a wide frequency range. It is a challenging issue to sharpen the main-lobe in the lower frequency region with a small-scale microphone array, of which the number and spacing of microphones are small. A neural
network-based non-linear beamformer achieves a breakthrough in sharpening the main-lobe. The non-linear beamforming works well for the narrowband signals but is weak in wideband beamforming. The non-linear beamforming with the long short-term memory is proposed to deal with wideband speech
signals. The long short-term memory network is trained in the recurrent neural network architecture with the sequence of audio data such as speech signals. The performance of the proposed beamformer is confirmed using a small-scale 8-ch MEMS microphone array, where eight microphones are linearly
arranged with the neighboring spacing of 10 mm, under a real environment. The beam-pattern of the proposed non-linear beamformer succeeds in sharpening the main-lobe although the linear delay-and-sum beamformer could not achieve frequency selectivity. The feasibility of the proposed beamformer
is also confirmed in speech enhancement.
Calculation tool NoBel for sound propagation assessment of noise from gasturbines on the ground
Authors: Zaporozhets Oleksandr , Karpenko Sergii , Levchenko Larisa
Published: September 2021

Gas turbine engines of aviation type are the basic element of gas-pumping stations of the pipelines around in the world. They produce harmful noise and the protection zone around the gas-pumping station must provide the safe distance to residence in its vicinity. Due to Ukrainian legal
requirements for the stationary (not movable) noise sources the sound pressure levels in octave bands must be used as limits for protection of the population complementarily to equivalent and maximum sound levels at day and night periods. A new calculation tool was designed to assess the effects
during sound wave propagation from stationary noise sources like gas-turbine installations, as for homogeneous atmosphere, so as for real meteorological and topographical conditions. The tool provides the possibility to predict the conditions of maximum noise exposure at point of noise control.
For homogeneous atmosphere the divergence, air absorption, ground surface reflection and acoustic screens contribute to propagation effects mostly. Their formulation in accordance with current knowledge provides more accurate sound levels assessment with differences ± 2 dBA at the boundaries
of protection zone in comparison with existing national legal requirements of noise protection calculations. In real atmosphere temperature and wind (in direction and speed) vary with altitude over the ground surface always. These real conditions provide the dependence of sound speed with
altitude, and in consequence the refraction of sound waves. For specific conditions of positive sound refraction the tool predicts the sound levels at the receiver up to 10 dBA higher, at negative sound refraction - on 5-7 less than in homogeneous atmosphere for legal protection distances.
Tool NoBel is appropriate to be used for specific airport stationary noise scenarios, like for aircraft engine run-ups after their maintenance or repair.
The vibrational response of a fluid-loaded baffled plate near a free surface
Authors: Kha Jamie
Published: September 2021

An analytical model to predict the vibrational response of a simply supported rectangular plate embedded in an infinite baffle with an upper free surface under heavy fluid loading and excited by a point force is presented. The equations of motion of a thin plate are solved using­­­­­­
modal decomposition technique by employing admissible functions for an in-vacuo plate and by directly solving the Helmholtz equation for acoustic waves in a fluid. The vibrational response for a flat plate in an infinite baffle and unbounded domain (semi-infinite domain) using analytical formulation
available in literature is initially computed. These results are then compared against present results to observe the effect of a free surface. Predictions from analytical models are validated by comparison with results obtained by numerical models. The proposed analytical approach presents
a novel formulation to describe a fluid-loaded flat plate in a waveguide and an efficient method for predicting its vibrational response.
Research on commercial vehicle sound quality objective evaluation
Authors: Qian Kun , Hou Zhichao , Liu Ruixue , Sun Dengke , Luo Rongkang
Published: September 2021

With the increasing demand of users for the acoustical comfort of commercial vehicles, the sound quality has become one of the important indicators of comfort evaluation. The research focuses on the objective evaluation method of the subjective perception of the sound quality in commercial
vehicle. The interior noises of commercial vehicle with an inline six diesel engine are measured. The five psychoacoustic parameters (loudness, roughness, sharpness, fluctuation strength, tonality and articulation index) are applied to the evaluation and analysis of the interior noises of
the commercial vehicle. Using psychoacoustic parameters to evaluate the noises in commercial vehicle, it is of great significance for the analysis and control of the noises in commercial vehicle. The research results provide a theoretical basis for guiding the sound quality design and development
of commercial vehicles.
An experimental study on acoustical performance of cross rib diffuser
Authors: Yoshida Takumi , Ueda Yasutaka , Mori Norimasa , Matano Yumi
Published: September 2021

The preset paper proposes a novel acoustic diffuser which we call cross rib diffuser (CRD) and investigates its acoustical performance in rooms experimentally. CRD consists of overlapping two one-dimensional periodic rib diffuser (OPRD) with different structural configurations. CRD
can achieve high scattering coefficient with wider frequency band than OPRD. Moreover, unlike other diffusers with high scattering property such as metadiffuser and two-dimensional quadratic diffuser, CRD keeps simple and familiar design of OPRD suitable for use in various architectural spaces.
In the paper, we firstly evaluated random-incidence scattering coefficient of CRD using 1/5 scaled reverberation room. Then, random-incidence absorption coefficient was measured in 1/1 reverberation room. Finally, an implementation experiment was conducted to examine applicability of CRD in
improving acoustics in small meeting room with small absorption treatments. The results indicated that CRD reduced EDT and reverberation time, and increased D50 more than JND values. Additionally, CRD improved reverberation and speech intelligibility more significantly than OPRD with same
installation area.
Moving object detection and tracking based on Doppler ultrasound
Authors: Jo Hyeong Geun
Published: September 2021

Fetal health monitoring during pregnancy has become a necessary procedure. Fetal heart rate (FHR) monitoring can determine fetal development or presence of heart disease and evaluate fetal well-being. The FHR measurement uses typically an acoustic probe-based Doppler ultrasound. Doppler
ultrasound method transmits a continuous wave signal to the abdomen of a pregnant woman to receive a reflected signal from the fetal heart. Periodic displacement of the heart tissue produces the Doppler effect and the phase change of the reflected wave is proportional to the velocity of the
fetal heart. The reflected signal is modulated into a phase signal and the received signal is demodulated to detect the heart rate. The current clinician system consists of a single probe and requires the probe to be manipulated to the optimal position to measure FHR. The system is highly
dependent on trained diagnostic experts. The movement of the pregnant woman and the fetus leads to the misaligned acoustic beam which degrades the reliability of the measurement. This work presents a detection and tracking system using a Doppler signal to compensate for the target's movement.
The system is implemented by integrating multi-channel probes interfaced to a Doppler signal converter with a 2-degree of freedom (DOF) motor device. This work describes the characteristics of two key components: Doppler signals of multi-channel probes according to the direction of the acoustic
beam and the algorithm with a 2-DOF tracking system.
Sound arrival direction and acoustic scene analysis for the monitoring of airport noise
Authors: Sakoda Keishi , Yamada Ichro , Shinohara Kenji
Published: September 2021

The authors have developed a sound direction detection method based on the cross-correlation method and applied it to automatic monitoring of aircraft noise and identification of sound sources. As aircraft performance improves, noise decreases, and people are interested in and dissatisfied
with low-level noise aircraft, especially in urban areas where environmental noise and aircraft noise combine to complicate the acoustic environment. Therefore, it is necessary to monitor and to measure not only aircraft noise but also environmental noise. Since our surveillance is aircraft
noise, it is important to analyze noise exposure from acoustic information rather than trucks or images. In this report, we will look back on the development process of this sound direction detection technology, show examples of helicopters and application examples of acoustic scene analysis
to high-altitude aircraft, and consider the latest situation realized as acoustic environment monitoring. We believe that this analysis will make it easier to understand the noise exposure situation at the noise monitoring station. It also describes the future outlook for this method.