bluuebunny/crossref_metadata_2025 huggingface dataset:
A Modified Simultaneous Perturbation Stochastic Approximation Algorithm for Active Noise Control
Authors: Gu Zhiwu , Shi Li , Zou Haishan , Chen Kai
Published: December 2023

Secondary path modeling is an important step in active noise control. Keeping the active noise control system stable, when the secondary path changes over time, is a widely studied problem. Using the simultaneous perturbation stochastic approximation algorithm, can update the control
filter without secondary path modeling, avoiding the problem of increased noise caused by secondary path modeling. In this paper a variant of the simultaneous perturbation stochastic approximation algorithm is proposed, which incorporates historical coefficients of the control filter, to correct
the direction of the gradient calculation. Based on an experimental setup with a realistic transfer path, this paper demonstrates that the proposed algorithm has superior performance in terms of convergence speed and noise reduction amount, than the general simultaneous perturbation stochastic
approximation algorithm.
Determination of the noise reduction potential at bus stops through the use of hybrid and electric buses
Authors: Henning Arne , Kowalski Thomas , de Haan Peter
Published: December 2023

To investigate the noise reduction potential of electric buses at bus stops, extensive microphone measurements were conducted during the stopping process of IC powered, hybrid, and all-electric buses. A number of 18 microphones were placed along the roadway at heights of 1.2 m, 3 m,
and 4.5 m. The distance between the mics in the direction of travel was 6 m in each case. In the course of the measurement, 3 bus types were measured. More than 200 measurements were performed in total. The stopping maneuvers consisted of decelerating from 30 km/h and 50 km/h, staying at a
fixed position, opening and closing doors, and accelerating to 30 km/h and 50 km/h, respectively. The maneuvers were performed in both directions of travel.
Determining disturbance sounds in aircraft sound events using a CNN-based method
Authors: Nakayama Tsumugi , Naito Taisuke , Kouda Shunsuke , Yokota Takatoshi
Published: December 2023

In this paper, we propose a method to determine whether an aircraft sound event contains disturbance sounds through a combination of sound source recognition models developed using a convolutional neural network. First, considering road traffic noise as a disturbance sound, distinct
recognition models for aircraft and road traffic noise were developed. Second, simulated signals in which aircraft noise and road traffic noise were superimposed with different signal-to-noise ratios were input into the two recognition models. We investigated the variations in the output of
each recognition model with respect to the signal-to-noise ratio. Subsequently, we obtained the output of each model for the case in which disturbance sounds affected an aircraft sound event. Third, we measured the aircraft noise around an airport, and the aircraft sound events on which road
traffic noise was superimposed were input into the recognition models to examine the proposed method. It was confirmed that the proposed method helps detect the disturbance noise when intermittent noise from passing vehicles is included in an aircraft sound event.
Reverberant Sound Field Analysis of a Rectangular Room by Modal Synthesis Method
Authors: Takano Yasushi , Hanayama Ryouhei , Makino Yusuke
Published: December 2023

It is well known that the reverberation time within an enclosed space is dominated by its boundary surface absorption. The absorption can then be interpreted as averaged damping ratio of acoustical modes or a loss factor. The damping ratio can be determined during steady state excitation
or during the transient decay or reverberation process. In this paper, acoustical reverberant field is considered as a synthesis of independent acoustical modes with their corresponding damping ratios. Each damping ratio is calculated from the absorption coefficient of the enclosed space considering
the wavenumber vector. It is suggested that the consideration for the wave travelling direction in determining the modal decay rate give better results for a simple rectangular room.
Acoustics performance of compact micro-perforated panel absorber with grazing flow
Authors: Li Ying , Choy Yatsze
Published: December 2023

This paper presents numerical and experimental investigations into the acoustic behaviour of a micro-perforated panel (MPP) backed by a shallow cavity under a fully developed grazing flow. A three-dimensional time-domain computational fluid dynamics approach is applied alongside hybrid
evaluation methods to accurately capture the acoustic behaviour variations of an MPP orifice. Meanwhile, a hybrid Rayleigh's end correction model for T-shaped resonators is utilized to calculate the acoustic reactance of a very shallow cavity and an acoustics impedance model of an orifice
backing with shallow cavity at grazing flow is established. The proposed acoustic impedance model of orifice has been validated by experimental study. The practical significance of this study is that it elucidates the influence of cavities upon the acoustic behaviour of MPPs in the presence
of grazing flows; furthermore, it proposes an impedance model that is more suitable for predicting the acoustic performance of booming compact meta-structures.
Wideband fast multipole boundary element method for flow-induced noise analysis based on Lighthill's equation
Authors: Masumoto Takayuki , Mori Masaaki , Yasuda Yosuke , Inoue Naohisa , Sakuma Tetsuya
Published: December 2023

In order to reduce the computational load for the analysis of three-dimensional flow-induced noise based on the Lighthill equation using the boundary element method (BEM), an efficient method is developed on the basis of the fast multipole BEM (FMBEM). The common hierarchical cell structure
for grouping boundary element nodes, sound-receiving points and flow-induced noise sources is used; this enables coefficients of the FMBEM to be reused during the calculation of sound pressure at boundary element nodes and receiving points, thereby further accelerating the analysis. In addition,
to deal with the increasing hierarchical level for encompassing flow-induced noise sources, which are often widely distributed around the object to be analyzed, a wideband version of the FMBEM is applied. Following the computational procedure, two application examples are presented for discussion.
First, noise from a cylinder located in a flow is analyzed to discuss the accuracy of the method. Then, a problem with large number of degrees-of-freedom and flow-induced noise sources is analyzed to demonstrate its applicability to large-scale problems.
A hybrid analysis of Mach cutoff noise using nonlinear acoustics and finite-difference time-domain method
Authors: Tsuchiya Takao , Kanamori Masashi
Published: December 2023

This paper proposes a two-dimensional, hybrid analysis method of so-called Mach cutoff noise, which treats boom signature and its disturbance due to collision of the signature with atmospheric turbulence separately. A combination of the augmented Burgers equation analysis and the nonlinear
Tricomi equation analysis is applied to the former, while the conventional compact-explicit finite-difference time-domain method is applied to the propagation analysis to the latter. Some numerical experiments were conducted with the method, resulting in the larger Perceived Level at the ground
than those by the conventional linear analysis. It was also shown that the Mach cutoff noise on the ground is mostly affected by the incoming boom.
Contextual event-based sound quality metrics
Authors: Sottek Roland , Lobato Thiago , Bray Wade R. , Fiebig André
Published: December 2023

Sound quality metrics are often used to analyze complex sound scenarios, such as soundscape applications. Sound quality can also affect the health and well-being of people in a given environment. Therefore, it is of the utmost importance that the definition of good sound quality in
a particular context is as precise as possible. In this aspect, psychoacoustic indicators such as maximum, average, or percentile values of psychoacoustic parameters are usually used in a linear combination to create a metric based on listening experiment results. However, this linear approach
may disregard many complex nonlinear parameter dependencies that could be helpful for a better description of human perception. Instead of using summary statistics, the importance to perception of individual events in terms of their duration, magnitude, and frequency should be considered.
For example, individual tonal events of a certain duration may have a strong influence on the perceived quality, even with low average tonality and percentile values. And the low-frequency tonal content of music may be perceived as an important aspect of a high-quality sound event, whereas
the same amount of low-frequency tonality would be not accepted for a technical sound. Interview evidence from people immersed in various soundscapes appears to indicate significant "contextual weightings" involving both time and frequency, which might be applied to or evolved from
current psychoacoustic metrics according to contextual classes. In this paper we provide an overview and some practical guidance for developing contextual event-based sound quality metrics.
Consideration on accuracy on road traffic noise prediction model "ASJ RTN-Model 2018" in power level and equivalent noise level
Authors: Maeda Naoto , Okura Takashi , Kaneshige Hitoshi
Published: December 2023

This paper introduces the study on verification of prediction accuracy about road traffic noise prediction model "ASJ RTN-Model 2018" used as standard for prediction of road traffic noise in Japan. The effects of vehicle type classification, traffic volume and regional characteristics
on prediction accuracy were examined for the power level LWA representing the sound source characteristics of the traveling vehicle and the equivalent noise level LAeq of the evaluation value used for noise control standards. As a result, it was confirmed that the prediction accuracy of this
model was generally good regardless of the traffic volume, regional characteristics and the vehicle type classification.
Low Mach number aeroacoustic computations of airfoils in application with Pierce's wave equation
Authors: Spieser Étienne , Zhang Xin
Published: December 2023

The airflows generated by drones are fairly different from those arising for conventional aeronautical architectures. They are low Mach number, relatively low Reynolds number and transient regimes play a dominant role. The goals of this work are twofold. This study firstly seeks to
present an aeroacoustic model built on Pierce's wave equation, which is adapted to the specificity of this physic, and which is consistent and robust. The second part of this contribution then focuses on the use and the validation of a high-order highly scalable solver relying on an open source
C++ library to solve the large scales of the flow turbulence by means of an explicit filtering. The flow corresponding to a benchmarked Re = 5 · 104 airfoil in full stall is computed and results are briefly discussed.
Modeling of multi-material beams in analytical SEA
Authors: Sekiguchi Shu , Yamagiwa Ichiro , Yamaguchi Zenzo , Yamazaki Toru
Published: December 2023

This study presents a method for predicting vibrations in multi-material, multi-layer beams using Analytical Statistical Energy Analysis (ASEA) by considering them as homogeneous beams with equivalent bending characteristics. This approach enables the simultaneous achievement of weight
reduction and noise and vibration performance, which is essential in the current trend of using lightweight materials such as high strength steel, aluminum, and fiber-reinforced plastics in vehicle body structures. The proposed method is validated through Finite Element Method (FEM) calculation
and the vibration energy transfer characteristics of multi-layer beams are examined. Additionally, an example of replacing a steel single-unit beam with a multi-layer beam is presented to demonstrate the potential of the proposed method in achieving lightweight and low vibration.
Review and discussion of recent publications on underwater noise from shipping
Authors: Kamiirisa Hikaru , Windén Björn
Published: December 2023

The IMO is currently deliberating on revisions to the Guidelines for the reduction of underwater noise from commercial shipping. To shed light on the knowledge base that these deliberations are based on, and the views of important stakeholders, state-of-the-art papers on the issue of
underwater shipping noise and mitigation of impacts on marine life through design, engineering and operational measures were reviewed in this project. These are the same publications that have been selected by the IMO to guide their deliberations in the latest round. This paper summarizes
the current progress at the IMO, including the revised guidelines and proposed revisions by Japan, and puts it into context with the reviewed publications. Thirty-six papers on mitigation methods, modeling, measurement techniques and ecosystem impacts were reviewed. It is concluded that the
most appropriate guidelines for many stakeholders would consist of: 1) clear procedures and instructions for setting and adhering to target noise level, 2) identifying measurement procedures, 3) numerical modeling, and 4) monitoring plan to achieve the goal. Based on the results of the paper
review, we discuss future research approaches to establish useful guidelines.
Machine fault diagnosis based on data reassembly for a deep neural network trained by imbalanced acoustic recordings
Authors: Chen You-Siang , Lin Yi-Hsuan , Bai Mingsian R.
Published: December 2023

For high-tech equipment, online monitoring and diagnostics play a critical role in ensuring production under normal conditions. While the machines are generally in normal condition, fault conditions are often difficult, if not impossible, to simulate. In this paper, we propose a data
augmentation approach to address the challenge of machine fault diagnosis for the above-mentioned scenarios where the normal and abnormal acoustic data sets are imbalanced. To overcome this limitation, we propose a data reassembly approach to generate new signal samples by randomly combining
data segments from different machine states. The resulting sample is annotated as a vector according to the proportion of the corresponding machine state. The training with data reassembly is performed for a deep neural network (DNN)-based classifier using the log Mel spectrum as the acoustic
features. To validate the proposed approach, we conducted experiments using a rotor kit. Acoustic data associated with the normal and seven abnormal conditions were recorded using a four-microphone uniform circular array (UCA). The results showed that the classifier with data reassembly had
superior diagnostic performance compared to the classifier without data reassembly. The proposed method is also compared to several data generation baselines in terms of accuracy and F1 score.
Subjective evaluation on vibratory feeling to noises containing a low-frequency tonal component
Authors: Yonemura Miki , Sakamoto Shinichi
Published: December 2023

Machinery noises sometimes contain low-frequency tonal components and cause an increase in noise annoyance due to the tones. It is also known that the oppressive or vibratory feeling is a unique sensation to low-frequency sounds below 100 Hz, which may also account for the increase
in noise annoyance. In this study, auditory experiments were conducted to investigate the relationship between the intensity and frequency of the tonal components and the vibratory feeling. The test stimuli were broadband noises that simulated environmental noises with one additional tonal
component. The frequency and the tonal audibility were varied in the range of 31.5 to 400 Hz, and 0, 3, 6, 9, and 12 dB, respectively. As a result, the energy of the component below 100 Hz was found to be strongly correlated with the vibratory feeling. Furthermore, the relationship between
sound pressure level and the vibratory feeling was examined using LSL weighting characteristics, which have been proposed for the evaluation of vibration and oppression sensation caused by low-frequency sound.
Effects of hearing aids and cochlear implants on the education of deaf and hard-of-hearing children and sound environment improvement
Authors: Sato Masayuki , Chonan Hirohito , Watanabe Anna
Published: December 2023

In recent years, the functional improvement of hearing aids and cochlear implants and the spread of new-born hearing screening have a major influence on the start of early educational intervention and the early application of hearing aids and cochlear implants. It has been clarified
that the performances of children who are utilizing hearing aids and/or cochlear implants are comparable to those of hearing children in language development such as phonological awareness and vocabulary, and in cognitive development such as working memory. At the same time, such children
will understand their own hearing/listening characteristic and as a result they will be able to propose the appropriate sound environment for themselves.
Estimation of the sound power of multiple sources using SPL measurements and room acoustic simulations
Authors: Richard Antoine , Monteserin Carlos , Christensen Claus Lynge , Gaudeoso Caroline
Published: December 2023

The sound power of sources is a key input to room acoustic simulations. However, existing measurement methods are generally unpractical as they require specific equipment, for instance a reverberation room in ISO 3743. A method is proposed to find the sound power spectrum of sources
for room acoustic simulations, based on in situ sound pressure level (SPL) measurements at known locations. The measured data is fitted to an ODEON simulation of the measurement space via an optimization algorithm. The method requires an accurate numerical model of the environment. A notable
advantage is the possibility of estimating multiple sources at once with the same set of SPL measurements. The proposed method is investigated in a dry room in which up to three sources are active simultaneously. It is found that at least three receivers per source are required to obtain robust
estimations, and it is beneficial to place them in the vicinity of the sources. The accuracy of the estimation also depends on the relative level between the sources, as a too strong source will mask a weaker one. Finally, dry environments are more suited to measuring multiple sources, due
to larger spatial variations in SPL.
Optimization of microphone array arrangements for wavenumber-frequency spectral measurements
Authors: Ogawa Katsuya , Yoshinaga Tsukasa , Iida Akiyoshi
Published: December 2023

The wavenumber-frequency spectral (WFS) analysis is a well-established technique widely used for the separation of pressure fluctuations in turbulent flow fields into hydrodynamic pressure fluctuation (HPF) and acoustic pressure fluctuations (APF). The WFS analysis requires an array
system comprising multiple microphones. The aim of this research is explored how the number and placement of microphones affect the accuracy of the analysis and determine an optimized microphone array layout for analyzing vehicle noise. We conducted separation analyses of HPF and APF using
pressure fluctuations from a diffuse sound field generated by a turbulent boundary layer with varying numbers of microphones and placement patterns. The results showed that a well-balanced combination of spiral or heterogeneous random array arrangements with 96 channels or more is necessary
to effectively separate APF and HPF in the frequency band from 500 to 5 kHz, which is crucial for automobile noise analysis. Based on simulation results, we constructed a compact and cost-effective system addressed issues related to wiring and complex data acquisition by utilizing a digital
MEMS microphone and an FPGA board. Consequently, the developed system can be mounted on a vehicle and utilized for WFS analysis in the flow field surrounding the vehicle.
In-situ measurement method of speech privacy focusing on statistics of acoustic features of speech and background noise
Authors: Sato Hayato , Nishimoto Takuya , Konishi Yuga
Published: December 2023

The evaluation of speech privacy in architectural spaces is done with a kind of transfer function of the space, such as the slope of the distance decay of the sound pressure level (SPL) and the level difference between the two rooms. From these functions, it is possible to estimate
the speech-to-noise ratio at evaluation points, and then we can evaluate the degree of information leakage and work disturbance. However, the above indices are obtained from acoustic measurements or numerical simulations by experts, and can not be measured in the target space under operation.
In this study, methods for estimating the speech-to-noise ratio from only the intruding speech recorded at the measurement point were investigated. We focused on steep changes in the SPL and the strength of the harmonic structure as acoustic features of speech that are considered to remain
even at low speech-to-noise ratios. These features were quantified for each short time window, and the percentage that exceeded a threshold predetermined from statistics of a steady-state noise was obtained as an index for the estimation. The proposed index corresponded with the speech-to-noise
ratio in both simulations and measurements.
Optimal design of low-frequency sound absorber based on Snake Optimizer
Authors: Sun Wei , Ren Shuwei , Liu Yiyang , Lei Ye , Wang Haitao , Zeng Xiangyang
Published: December 2023

In this work, a low-frequency sound absorber composed of a micro-perforated panel (MPP) and a coiled-up space configured by grooved corrugations is proposed. Due to the intricate interactions caused by the hole diameter and hole separation distance, it is difficult to achieve optimal
acoustic performance. Here, a high-efficient meta-heuristic optimization algorithm named Snake Optimizer (SO) is applied to flexibly obtain the prime configuration of acoustic absorbing and structure parameters. The expected sound spectrum characteristics are performed by substituting the
optimum into the 3D finite element model (FEM). Good agreement verifies the effectiveness of the proposed method. Our work paves the way for broadening the application of algorithms in the optimal design of acoustic metamaterials.
Psychological and physiological evaluations of time-varying noises produced by air conditioners
Authors: Soeta Yoshiharu , Onogawa Ei
Published: December 2023

Air conditioners are widely used in buildings to maintain thermal comfort for long time. Air conditioners produce sounds during operation, and air conditioners are regarded as one of the main noise sources in buildings. Most sounds produced by the air conditioner do not fluctuate over
time and sound quality of the steady sounds produced by the air conditioner have been evaluated. However, air conditioners sometimes produce time-varying noises. Customers criticizes such noises are annoying when they sleep and they spend time quietly in the living room. The aim of this study
was to determine the factors that significantly influence the psycho-physiological response to the time-varying noises produced by air conditioners. We assessed the A-weighted equivalent continuous sound pressure level (LAeq) and factors extracted from the autocorrelation function (ACF). Subjective
loudness, sharpness, annoyance, and electroencephalography (EEG) were evaluated. Relationships between psychological and physiological responses and physical parameters, LAeq, the ACF factors, and their standard deviation, were determined. The LAeq and peak of the first maximum peak of the
ACF were identified as significant factors for the time-varying noises.
Novel methodology for isolating rotational phenomena in tire testing
Authors: Minervini Domenico , Mastrodicasa Davide , Geluk Theo , Lorenzo Emilio Di
Published: December 2023

Due to electrification, tire/road noise is one of the key contributors to the vehicle noise performance. With the advent of component-based NVH representation, capturing the realistic dynamic behavior of the substructures is of primary interest for the industry. Tire dynamics are highly-subjected
to changes due to operational conditions, such as preload, inflation, and rotating speed. Due to rotation, the standing wave pattern of a non-rotating tire mode shape can evolve into two opposite travelling waves with different natural frequencies, having the same mode shape. Separating the
contributions of mode splitting due to rotation from mode splitting due to geometrical asymmetry caused by preload deformation is essential for a correct model validation. This paper presents a novel methodology for characterizing the modal behavior of rotating tires without contact patch
deformation, observing rotational-only dependencies. By means of an original impact testing technique, a rubber sphere excites a free-spinning tire with constant energy at different velocities. By doing so, the changes due to pure rotational phenomena can be captured by contactless measurement
devices, such as laser doppler vibrometer or high-speed cameras.
Design of full vehicle PBNR based on side windows with embedded acoustic black holes
Authors: WU Xian , QIN Shengjie , ZHU Zhiwei , LIU Mingyang , SHAO Jianwang
Published: December 2023

Acoustic black holes (ABH) have been proven to be a lightweight structure with wide application prospects in wave tuning, energy recovery, and vibration and noise reduction. The side window glass is one of the important noise propagating paths into vehicle interior. In this paper, a
new side window glass based on ABHs is designed and the influence of the new side window glass on the full vehicle PBNR is analyzed. A full vehicle SEA model is established and verified using the PBNR test. The transmission paths contributing the most noise energy to the driver's head cavity
under excitations at different positions are analyzed. The results show that the side window glass is the main weak component needed to be optimized in the analysis frequency band. The influence of the new type of side window glass on the whole vehicle PBNR is studied based on the full vehicle
SEA model. It is observed that by comparing with the traditional glass, the new glass can significantly improve the PBNR at the coincidence frequency of glass under different paths and meanwhile reduce the weight of the glass. It can provide a new technology for improving vehicle interior
noise control.
Numerical study on flow-induced vibration and radiated noise of tube bundle in a shell-and-tube heat exchanger
Authors: Han Wang , Cao Yipeng , Liu Chen , Liu Gongmin
Published: December 2023

This paper presents a numerical study of the flow-induced vibration and radiated noise characteristics of the heat exchange tube under external transverse turbulence excitation. A three-dimensional numerical model of the densely packed staggered tube bundles was established, the large
eddy simulation (LES) was used to simulate the flow field around the tube bundle, and the analyses of the lift and drag forces on the surface of the tube bundle are performed in the time and frequency domains. Then, the turbulent exciting force on the surface of the tube was extracted and
used as fluid load, the dynamic mode decomposition (DMD) method was used to reduce the order of the high-dimensional turbulent exciting force, the vibration of the bundle induced by the turbulent distribution force was obtained. Finally, the displacement of the bundle was extracted as noise
source, and the boundary element method (BEM) was used to calculate the radiated noise characteristics of the bundle. The results show that the prediction of the flow induced vibration and radiated noise of the heat exchange tube using the simplified method is quite accurate, but greatly reduces
computational consumption.
An improved artificial compressibility method for aeroacoustics at low Mach numbers
Authors: Zhang Zhicheng , Li Yuhong , Spieser Étienne , Zhou Peng , Zhang Xin
Published: December 2023

This work presents an improved artificial compressibility method that enables correct sound propagation behaviour in low Mach number flows. As an extension of incompressible approaches, it offers the advantage of low computational costs since compressible flow equations are simplified
under the isentropic assumption, and the coupling of flow and sound is preserved. The non-uniform speed of sound is considered in this method, and eigenvalue analysis of the modified governing equations reveals that the propagation speed of pseudo waves restores to that of physical acoustic
waves. The effect of Mach number on the dissipation and dispersion error is then studied using a two-dimentional monopole example with uniform background flow. The results suggest that the proposed method can provide a satisfactory prediction of sound propagation when the Mach number is below
0.3. Lastly, a direct noise computation of the aerofoil trailing-edge noise problem is performed to assess its capability to deal with the interaction between flow and sound. It shows that the present method can well capture the multiple-tone phenomenon.
Investigation on Lateral Vibration Transmission Control of a Shaft-hull System with a Piezoelectric Actuator Support
Authors: Zhu Yueyue , Xie Xiling , Zhang Zhiyi
Published: December 2023

A piezoelectric actuator support (PAS) is proposed to suppress lateral vibration transmission from the shaft to the hull of underwater vehicles subjected to the excitation of propeller forces. The PAS consists of eight rhombic structures with embedded piezoelectric actuators and is
arranged between the stern bearing housing and the hull. The dynamic model of the shaft-PAS-hull system is developed to analyze the characteristics of power flow through the PAS. The suppression performance of acoustic radiation of the hull is analyzed to verify the effectiveness of the PAS.
Numerical results have shown that the PAS is able to suppress the transmission of lateral vibration induced by the propeller forces and accordingly reduce the hull vibration as well as sound radiation.
A diffusion filtered-x affine projection algorithm for distributed active noise control
Authors: Li Tianyou , Zhao Sipei , Chen Kai , Lu Jing
Published: December 2023

The well-known Filtered-x Affine Projection (FxAP) algorithm is usually deemed a better choice than the conventional Filtered-x Least-Mean-Square (FxLMS) algorithm when faster convergence speed is desired in active noise control applications. However, the improvement of its convergence
performance is obtained at the expense of increased computational complexity. It is usually unrealistic to regulate multichannel ANC systems using the centralized AP algorithm. Recently, distributed diffusion adaptation schemes over acoustic sensor and actuator networks have been introduced
to multichannel ANC systems, such as the Diffusion FxLMS algorithms. Distributed processing based on diffusion cooperation strategy allocates the computation load to the network nodes in a scalable manner. This paper proposes a distributed Diffusion Filtered-x AP (DFxAP) algorithm for multichannel
ANC systems. Simulation results and computational complexity analysis show that the DFxAP algorithm outperforms the Diffusion FxLMS algorithm in convergence performance and has lower computational complexity compared to the centralized AP algorithm.
A computational aeroacoustic study of a multi-rotor powered urban air mobility vehicle
Authors: LI Yuhong , MA Zhida , ZHOU Peng , ZHONG Siyang , HUANG Xun
Published: December 2023

The multi-rotor propulsion system has become one of the popular configurations for urban air mobility vehicles due to its capability of high-density vertical take-off and landing operations. The noise characteristics, as a critical criterion for urban air mobility, usually differ for
a multi-rotor configuration from a single-rotor configuration. In this work, we investigate the noise generated by a hexacopter configuration using delayed detached eddy simulations and the Ffowcs-Williams and Hawkings acoustic-analogy-based solver. The overall length and the rotor diameter
of the vehicle are 4 m and 2 m, respectively, and the target maximum take-off mass is 500 kg. The full configuration and three simplified setups that reduce several individual components are numerically studied to isolate the corresponding effect of each component and to identify their flow/acoustic
interactions. The results show that the rotor-rotor interaction leads to remarkable thrust fluctuations and further results in a considerable increase in tonal noise over a broad frequency range. The interaction between the rotors and the support arms also leads to significant thrust fluctuations
on the surfaces of both rotor blades and arms, which produces additional tonal noise at high-order harmonics of the blade passing frequency. In contrast, for the current configuration, the existence of the fuselage does not have a significant effect on noise generation. The research should
benefit low-noise vehicle design and operation.
Bearing Fault Diagnosis based on 2D-Acoustic Imaging and Convolutional Neural Networks
Authors: Mishra Sitesh Kumar , Shakya Piyush
Published: December 2023

Bearing faults are the common mode of failure in rotating machinery. Various techniques have been proposed for bearing fault diagnosis based on vibration signals. However, vibration-based fault diagnosis is restrained in some cases since they are limited by surface characteristics such
as temperature. Acoustic-based fault diagnosis has the edge of non-contact measurement over vibration-based fault diagnosis. Convolutional neural networks have been used widely in condition monitoring to learn features naturally from the raw data, which does not require exhaustive domain knowledge
and expertise. In the present study, 1D-acoustic signals are converted into 2D images and a Convolutional Neural Networks algorithm is applied to classify the bearing health conditions. The proposed method shows promising results on experimental data conducted on an in-house test rig.
Enhancing the noise reduction capability of the trailing edge serration at incidence using serration extension
Authors: Sundeep Shivam , Cantos Sinforiano , Zhou Peng , Zhong Siyang
Published: December 2023

This paper presents an experimental study to enhance the noise reduction capability of the trailing edge serration by shifting the serration root downstream of the trailing edge. The distance between the serration root and the trailing edge is referred to as extension length in this
study. Three different extension lengths of 5 mm, 10 mm, and 15 mm are employed. Experiments were performed on a 100 mm chord NACA 0012 wing model with sawtooth trailing edge serration. The acoustic beamforming was performed for various angles of attack and flow speeds between 20 m/s and 50
m/s corresponding to chord-based Reynolds number of 1.4 × 10^5 and 3.5 × 10^5 respectively. Results show that the extension can improve the noise reduction capability of the trailing edge serration, especially for the flapped serration it can reduce the broadband noise by up to
15 dB at 8.5 deg. angle of attack. To understand the observed noise reduction, we employ the particle image velocimetry measurements of the wall-normal plane along the serration root. With extension a gradual reduction in the turbulent kinetic energy is observed for the flapped serration.
Overall, the serration extension proves to be effective in reducing the trailing edge noise without aerodynamic penalty.
Acoustic Metamaterials for Electronics Cooling Fan Noise Reduction
Authors: Wasala Sahan , Zhao Wenguang , Ogun Oluwaseyi , Stevens Lon , Sosseh Raye , Kennedy John , Persoons Tim
Published: December 2023

Acoustic noise is a significant obstacle that limits the performance of data centre Hard Disk Drive (HDD) storage systems. The primary noise source of these systems has been identified as cooling fans that are used for their thermal management. New acoustic metamaterial (AM) designs
can be used as a solution to this problem. AMs can be custom-designed to address specific tonal frequencies that HDD servo systems show high sensitivity to. This paper focuses on developing a 3D-printed annular AM treatment that can be easily attached to the inlet or outlet of an axial fan.
Initial design optimization was conducted using the Finite Element Method (FEM). Further FEM simulations were carried out using more realistic fan sources from high-fidelity Computational Fluid Dynamics (CFD) simulations. The AM geometry was tested experimentally with a fan that is commonly
used in a data centre storage system, where the fan speed was set to induce an acoustic tone that negatively affects the performance of HDDs. Then a full scale Finite Element Method simulation was ran using fan acoustic source data extracted from a high fidelity CFD simulation. Results indicate
significant noise reduction at the targeted frequency.
Vibro-acoustic analysis of sound-absorbing ducts using porous materials
Authors: Kurosawa Yoshio , Chengyao Ji , Yamashita Tsuyoshi , Ozaki Tetsuya , Nakaizumi Naoyuki , Fujita Yuki , Takahashi Manabu
Published: December 2023

The electrification of automobiles has progressed in response to environmental problems. Accordingly, the number of automobiles equipped with large and large-capacity batteries, such as electric vehicles and hybrid vehicles, is increasing. These batteries take in air from the passenger
compartment using ducts for cooling. However, since the cooling fan operates regardless of the running condition, sound may leak into the car interior through the ducts. To reduce such cabin noise, we examined the use of sound-absorbing ducts. We developed four types of test pieces using conventional
polypropylene resin, compression felt, and film on the inside and outside of the compression felt. We measured the insertion loss in two ways: one on the opposite side and the other on the outside from the entrance of the duct. Acoustic attenuation was measured. The results of creating and
calculating a similar FE model were then reported.
ARAUSv2: An Expanded Dataset and Multimodal Models of Affective Responses to Augmented Urban Soundscapes
Authors: Ooi Kenneth , Ong Zhen-Ting , Lam Bhan , Wong Trevor , Gan Woon-Seng , Watcharasupat Karn N.
Published: December 2023

The ARAUS (Affective Responses to Augmented Urban Soundscapes) dataset consists of a five-fold cross-validation set and independent test set of subjective perceptual responses to augmented soundscapes presented as audio-visual stimuli. However, key limitations in its original release
included a disproportionate number of participants being young university students and a relatively small test set. We aim to address this by publishing ARAUSv2, which adds responses from participants to the cross-validation set from an older, non-student population, as well as responses from
additional participants in a substantially larger test set consisting of new urban soundscapes recorded in a variety of settings in Singapore. The additional responses were collected in a similar fashion as the initial release, with participants rating augmented soundscapes (made by digitally
adding maskers to urban soundscape recordings) on how pleasant, annoying, eventful, uneventful, vibrant, monotonous, chaotic, calm, and appropriate they were. We also present a sample of multimodal prediction models for the ISO Pleasantness and Eventfulness of the augmented soundscapes in
ARAUSv2. The multimodal models use participant-linked information such as demographics and responses to psychological questionnaires, as well as visual information from the stimuli, which the baseline models presented in the initial ARAUS dataset did not utilize.
Simulating Combustion-Induced Noise from a Gas-Fired Water Heater
Authors: Jay Arvind , Kappagantu Ramana
Published: December 2023

Residential and commercial gas water heaters are designed for optimal performance for different operating conditions. These differences could arise from regional changes in fuel, local regulations for emissions, and the temperature preferences of the customer. From an engineering perspective
apart from performance, other issues such as fire safety, longevity (thermo-mechanical durability) and though rarely, noise and vibration (N & V) need to be addressed. Unlike other appliances, there are almost no moving mechanical parts in an atmospheric gas water heater. This makes the
N & V problem an interesting engineering challenge to diagnose and fix. In this paper, the authors consider different hypotheses for understanding the origins of combustion-induced noise. They propose a hybrid simulation methodology to predict noise and finally present the sound pressure
level comparison with the physical test.
Experimental study of applying plant-derived materials to sound-absorbing structures for cabin noise reduction of electric vehicles
Authors: NAKANO Sachito , TOMITA Sunao , SEGI Makoto , NISHIMURA Takuya
Published: December 2023

Electric vehicles generate different interior noise than internal combustion engine vehicles at low speeds. To investigate the cause of the interior noise of electric vehicles at low speeds (30 km/h) and to reduce the noise, a Helmholtz resonator made of molded pulp, a material derived
from plants, is fabricated, and its noise reduction effect is experimentally evaluated. First, a molded pulp Helmholtz resonator is fabricated and tested with an impedance tube. Then, this Helmholtz resonator is installed inside the tire and can reduce the cavity resonance noise. Then, driving
tests are conducted on an electric vehicle with tires equipped with this molded pulp, and it is possible to reduce the sound pressure at the ear position at the frequency of the tire cavity resonance. Finally, driving tests are conducted with standard tires, and this molded pulp in the cabin
reduces the noise at the tire cavity resonance frequency. From this, at low speeds (30 km/h), we can demonstrate that tire cavity resonance is the source of noise in an electric vehicle's cabin and that it is possible to reduce tire cavity resonance without directly installing Helmholtz resonator
in the tires.
Experimental investigation on the aeroacoustics of coaxial rotors
Authors: Ma Zhida , Liu Guangsheng , Wu Han , Zhou Peng , Zhang Xin , Zhong Siyang , Wang Puyuan , Zhou Guocheng , Chen Bao
Published: December 2023

Coaxial rotor configurations are adopted by drones and electric vertical take-off and landing vehicles due to the need of generating high propulsive power within a compact size. The aerodynamic interaction between two closely spaced rotors may induce different noise features than isolated
ones. This study presents an experimental investigation into the noise radiated from two small-scale coaxial contra-rotating rotors operated at different working configurations in an anechoic chamber. The noise was measured at 18 observer points using linear microphone arrays. The thrusts
and torques of both rotors were measured independently. When the two rotors were operated at the same speed, the blade-overlapping position was regulated using a synchrophasing control technique. The results reveal that the relative phase angle of the rotors has a significant impact on the
noise directivity patterns. The effects of axial separation distance on both spectral characteristics and noise directivities are also presented. This study provides insights into the low-noise design and operation for aerial vehicles using coaxial rotor configuration.
Micro-perforated mufflers based on the Acoustic Black Hole effect
Authors: Bravo Teresa , Maury Cedric
Published: December 2023

Attenuation of acoustic disturbance with compact and low-weight acoustical devices is a demanding requisite in industries such as vehicle exhaust mufflers, turbofan liners or ventilation systems. Acoustic Black Holes (ABH) is a concept that has been studied originally in the field of
vibration control for the design of a structure based on a power-law thickness profiles along its edges. The idea of wave trapping and dissipation has been extended to the field of duct acoustics using compact devices that avoid blocking the air flow. Based on this idea, in this work we propose
the study of a micro-perforated silencer that should prevent reflection and transmission of the sound waves over a wide range of audible frequencies. The use of micro-perforations over the facing cavities should help to extend performance towards the low frequency range. The acoustic behavior
of the ABH is assessed from theoretical and numerical modeling. The performance can be greatly improved when the physical constituting parameters are optimized simultaneously. Particle swarm optimization is a computational method inspired by the behavior of natural systems that is able to
provide a satisfactory solution with enhanced total dissipation.
Comparison of data-based and modeled-based analysis of aircraft departure noise using noise monitor network recordings
Authors: Huynh Jacqueline , Lepe Melissa , Lee Trinity , Hood Philip , Hansman R. John
Published: December 2023

A comparison of data-based regression analysis and modeled-based analysis of aircraft departure noise variations using airport noise monitor network recordings is presented. Accurate modeling of aircraft noise is useful for the assessment of departure procedures and provides insight
into the noise reduction potential of noise abatement flight procedures. In addition, many airports employ monitor networks that continuously record noise data produced by aircraft on departure, which can be used for assessing potential factors leading to variation in departure noise and for
comparison to results from modeling methods. In this paper, departure noise variations of Boeing 737-800 aircraft are correlated to departure climb procedure factors using both data-based approaches incorporating recorded noise collected at the Seattle International Airport monitor network,
and a method to model departure noise from on altitude, ground track, and ground speed from recorded operational surveillance data. Examples using both approaches indicate altitude and velocity result in the highest correlating factors for noise at the three noise monitor locations studied.
Limitations and areas of needed improvement for the different noise modeling methods are highlighted.
Machine Learning Applied to Acoustic Insulation Analysis in Residential Buildings - Part 2: Vertical partitions
Authors: Giner José Carlos , Fengler Bárbara , Rocha Raquel Rossatto , Sá Yann Ardanaz de , Soares Murilo
Published: December 2023

The use of Machine Learning (ML) tools has grown a lot in several areas, including in the civil construction space. Part one of this study tried to use ML to estimate results for sound insulation of floor systems and had concluded that ML is not applicable to those situations. Part
two tried some adjustments to the ML script and used an on-site vertical partition system test database as input with ML tools used to estimate new results based on the input data. The conclusion of this new study is that the tool is now more applicable to floor systems but it is not the best
form to predict the results, given the complexity of sound propagation between rooms, which is not considered in the statistical analysis of the machine.