bluuebunny/crossref_metadata_2025 huggingface dataset:
A 3D complex urban sound propagation benchmark case
Authors: Renterghem Timothy Van
Published: December 2023

Predicting sound propagation in the dense urban fabric is challenging as it involves multiple and higher-order reflections, both specular and diffuse in nature, diffraction around complex objects like building edges and roofs, and atmospheric effects especially relevant at non-directly
exposed locations. Over the last decades, there has been a continuing interest in enclosed courtyards, a micro-environment with the potential to offer human restoration in a busy city. Also roofs are increasingly being designed as outdoor spaces. The sound exposure in such zones could be especially
challenging to predict. To gain more understanding in the related physics and accuracy of prediction schemes, a 3D urban benchmark case is presented, consisting of 4 building blocks with a fully symmetric geometry. Receivers and acoustic sources are positioned in the streets, on the roofs,
and in the courtyards. Simulations with the reference finite-difference time-domain technique show pronounced differences in the time responses, and allow assessing the impact of including (geometrical) façade details. Additional simulations show the impact of openings from within the
streets towards the courtyards. The simulation results allow checking the accuracy of sound propagation models and their simplifications.
Input force contribution separation method for utilizing blocked force and operational TPA
Authors: Morita Yuto , Yoshida Junji
Published: December 2023

In recent years, various transfer path analysis (TPA) methods have been proposed to separate contribution from multiple input points to the response point. In general, TPA methods require transfer function from input to the response points by hammering tests. However, obtaining accurate
contribution becomes difficult in case the transfer function varies according to the operating condition or the complexity of the transfer path. In this study, we then considered input force contribution separation method for the difficult condition by combining operational TPA and blocked
force used in component TPA. In the method, blocked force in the operational condition is obtained by component TPA at first, and operational TPA is applied between the obtained blocked force and the response point acceleration signals to obtain the transfer function without hammering tests.
The contribution is calculated by multiplying the blocked force and the transfer function at the condition. As the verification, the proposed method was applied to a simple vehicle model equipped with a motor. And the response point vibration could be decreased well by measuring the high contributing
part according to the contribution separation result. Through the verification test, the effectiveness of the proposed procedure was confirmed.
Cumulative noise metric design considerations for the NASA Quesst community test campaign with the X-59 aircraft
Authors: Vaughn Aaron B. , Doebler William J. , Christian Andrew W.
Published: December 2023

The National Aeronautics and Space Administration (NASA) plans to collect X-59 aircraft dose-response data to inform international regulators in their efforts to establish acceptable noise standards to replace the current ban on overland supersonic commercial flight. For this upcoming
community test campaign, the sound level from a supersonic overflight of the X-59 constitutes a single-event dose, and an end-of-day survey after multiple flight events constitutes a cumulative response. This study considers how X-59 community tests could be designed to explore the relationship
between multiple single events and cumulative annoyance response. Presently, a day-night level summation of single-event doses formulates the cumulative dose; however, a generalization method may improve the understanding of the linkage between multiple single events and cumulative response.
This work utilizes an analysis method that employs a parameter to vary the cumulative dose metric such that it can represent the loudest single event, remain as the day-night level summation, or be more responsive to the number of events. The analysis is demonstrated on simulated dose-response
datasets derived from previous NASA field studies and from expectations of X-59 community tests. Results demonstrate that certain dose designs are more efficient for exploring the linkage between multiple single events and cumulative response.
Heavy-weight floor impact sound in the state of coupled vibration of floor slab and girder of a pure framed structure
Authors: Uemura Tomoaki , Hashimoto Norihisa , Harada Masatoshi
Published: December 2023

Examples of poor heavy-weight floor impact sound insulation performance of pure framed structures with reinforced concrete were observed relative to the floor slab thickness. To investigate the cause of the poor performance, the floor vibration characteristics of actual pure framed
structures were measured during heavy-weight impact. As a result, the floor vibration characteristics of the displacement of girders and the coupled vibration of the girders and floor slabs not seen in conventional floor structures surrounded by girders with reinforced concrete walls were
observed. The propagation of the vibration of the floor slab was observed in more than the range surrounded by girders and in the next slab beyond the girders owing to the vibration of the girder itself. It was confirmed that these physical phenomena can be evaluated using a numerical calculation
method. The effect of the changes in girder depth on the coupled vibration of the girder and floor slab was also investigated analytically. As a result, the coupled vibration of the girder and floor slab specific to pure framed structures that contribute to heavy-weight floor impact sound
insulation performance was clarified physically.
Evaluation of noise reduction performance of new steel noise barrier for Shinkansen
Authors: Sato Daigo , Sueki Takeshi , Abe Yukio , Yamamoto Kenjiro , Nakamura Yuta
Published: December 2023

Since Shinkansen viaducts are aged, a large-scale renovation project has been planned. In this project, aged noise barriers are scheduled to be removed and replaced. In this background, it is required to develop a new noise barrier with high constructability and high effectiveness in
noise reduction. Therefore, the authors have developed a steel noise barrier without the decrease of noise barrier performance, of which weight is about 1/3 of existing concrete noise barriers. It is expected that the load on floor slabs by the developed noise barrier is more reduced, and
no crane truck is basically needed for installation work. One of the features of the developed noise barrier is that all the surfaces on track side are consisted of sound absorbing materials with steel plates with small holes on it. The sound absorbing material used in the developed noise
barriers has suitable sound absorbability for the frequency characteristics of the noise generated during train running. In order to evaluate the noise reduction performance, the developed noise barrier was tested on the Shinkansen track and noise measurement was conducted at the place with
certain distance from the Shinkansen viaduct. As a result, the noise generated from the lower part of cars was significantly reduced on the overall level.
Analysis of the noise mechanism and interactions of torsional decoupling devices in the belt driven 48V mild hybrid powertrain
Authors: Park Keychun , Kwon Daehyeon , Bae Sunghoon , Hwang Jungyeoul , Kim Hyungjin , Kim Sukzoon
Published: December 2023

This paper analyzed the mechanism of rattle noise from a decoupling damper pulley in a 48V belt driven mild hybrid powertrain with a three-cylinder turbo engine. To decouple the 48V belt drive from the high engine torque fluctuation of the engine, a decoupling device at the front end
of engine is employed, which interacts with the rear end decoupling device and results in the rattling issue. In this study as opposed to the conventional engine torsional vibration studies which neglect the low inertia belt drive, the effective inertia of 48V belt drive is considered in 1D,
3D torsional vibration analyses of the entire powertrain as it easily reaches up to 20% of the whole torsional inertia. In this way, the impact inside the crank torque fluctuation decoupler was identified as the source of the rattle noise, which verified in the experiments. The interaction
of the front end belt drive and the various types of rear end flywheel is also analyzed through parametric studies.
Acoustic environment and its restorative potential in small urban green spaces
Authors: Shu Shan , Tang Jiaxin , Geng Xuechuan
Published: December 2023

Small urban green spaces (SUGS) in dense city areas have been widely demonstrated to have restorative benefits to surrounding residents. However, residents' usage and experience of SUGS were indicated to be adversely influenced by adjacent traffic noise, whilst natural sounds inside
could provide restorative soundscape resources. Thus, this study investigated the acoustic quality and its restorative potential in 12 SUGS in Qingdao via field measurements and questionnaire surveys. The results show that: (1) The noise level of SUGS largely ranged in 50-60 dBA, with dominant
road traffic noise. Three perceptual soundscape dimensions were identified: appreciation, diversity and dynamics. (2) Scenic SUGS featured more natural sounds, lower noise levels, and more appreciation; residential SUGS featured more human sounds and worse soundscape evaluation; and business
SUGS featured higher noise levels. (3) The acoustic environments in scenic SUGS showed much more restorative potential than residential and business ones, and the restorative potential of SUGS was highly influenced by sound levels (LAeq, L10, and L90), sound sources (traffic noise and natural
sounds), and soundscape qualities (appreciation and diversity). The findings were expected to provide references for the sustainable planning and design of small urban green spaces in dense cities.
Study on the Influence of Transfer Floor on Dynamic Response of Building Structure under Subway-Induced Vibrations
Authors: Zhang Jing , Wu Yubin , Liu Bideng , Song Ruixiang , Wu Qiong
Published: December 2023

In order to meet the functional requirements, it is often necessary to set the transfer floor in the high-rise building structure. From the perspective of the influence of transfer floor on the subway-induced vibration response characteristics of building structure, the finite element
method is used to calculate the floor vibration response of the building with transfer floor under the excitation of subway train based on the actual project. Through the above analysis, the influence of the position of transfer floor on the subway-induced vibration response of the building
is analyzed. The results show that the vibration level of the transfer floor roof decrease obviously when the position of the transfer floor moves up gradually, and the vibration levels of most other floors are increased to varying degrees. The third floor, that is the roof of the original
transfer floor, has the most significant change in vibration.
Acoustic measurement for resin-based acoustic liner on turbofan engine testbed
Authors: Kagaya Ryo , Oishi Tsutomu , Yamanaka Shohei , Hojo Masahiro , Makida Mitsumasa , Okai Keiichi
Published: December 2023

Acoustic liner is one of the most effective devices for suppressing fan noise emitted by aircraft engines. IHI and Japan Aerospace Exploration Agency (JAXA) have developed a resin-based acoustic liner for fan noise attenuation that is lighter than conventional acoustic liners in production.
In this study, an acoustic measurement of the full-scale resin-based acoustic liner was conducted on the turbofan engine testbed installed at the JAXA test facility to evaluate its noise reduction capability in actual operating environment. The in-duct and in-cell acoustic measurements were
performed during the test campaign. A baseline hardwall liner and the production acoustic liner were also tested for comparison. The tonal and broadband fan noise reduction of the resin-based acoustic liner relative to the hardwall liner was evaluated as well as that of the production acoustic
liner. According to the test results obtained in the enclosed testbed, it was found that the resin-based acoustic liner has good noise reduction performance as expected for typical acoustic liners. The maximum noise reduction is equivalent to the production acoustic liner for both tonal and
broadband components over the wide range of engine power settings.
Actual measurement on vibration propagation of embankment and cut road
Authors: Sano Yasuyuki
Published: December 2023

Institute of Noise Control Engineering of Japan (INCE/J) proposed a prediction model of road traffic vibration "INCE/J RTV Model 2003". The scope of this prediction model is only for flat roads. Prediction of Road Traffic Vibration subcommittee is trying to expand the scope
of application. This paper discussed expand the scope for embankment and cut road with actual measurement. Regarding whether the prediction formula for flat roads can be applied to embankment and cutting roads, It is compared with the actual measurement result of a runnning truck on the cutting
road. It also describes inpact tests of ground vibration propagation on cut roads.
The effect of aluminum body on acoustic characteristics of vehicle
Authors: Jung Jungwha , Lee Seung , Mo Hyungkyu , Jun Pilgeun
Published: December 2023

Automobile manufacturers have extensively researched on applying various lightweight materials to automobiles to match with the strict emission standards. In recent automotive industry, in terms of material, a main stream to reduce vehicle weight could be divided into aluminum and engineering
plastic, respectively. When it comes to cost, reusability, aluminum materials have greater advantages than engineering plastics. In this study, the effect of the sound characteristics of the vehicle according to the body material was confirmed. Accelerator Position Sensor 100%, Constant speed
(80kph), PBNR (Power Based Noise Reduction), Input Point Stiffness and Acoustic Sensitivity were tested under the condition that the same sound absorbing parts were applied to two vehicles made of steel and aluminum, each FRONT FLOOR, REAR FLOOR, LUGGAGE FLOOR, and ROOF panels of the vehicle
body. As a result of test data comparison between steel and aluminum bodies, the study shows pros and cons of respective materials.
Flanging, squeal and corrugation-induced noise: Insights from recent measurement campaigns at interconnected tight curves
Authors: Pandey Priyadarshi , Kochanowski Radoslaw , Milton Evan
Published: December 2023

High noise events at tight curves often comprise of squeal, flanging and corrugation-induced noise. All noise types have the potential to cause annoyance at sensitive receivers in close proximity to the rail line. The presence of squeal, flanging and other high noise events at three
interconnected sharp passenger curves on the metropolitan network in Sydney, New South Wales is investigated in the context of measured parameters. Rail and noise parameters were measured at ten locations in 2021, with a repeat of the measurements undertaken at three locations in 2022. Differences
in high noise events were analysed and quantified to understand the underlying causes of curving noise in this area. The role of the wheel-rail interface contact conditions, train type, rail roughness, friction and speed is investigated to provide insights into the mechanisms leading to curving
noise events at this site.
Development of Acoustic Metamaterial Sheets with Two-Dimensional Array of Hollow Local Resonators
Authors: Komamura Takahiro , Inoue Kazuma , Matsuoka Takeshi , Saito Yuya , Uchida Naoyuki , Nakayama Masanari , Akasaka Shuichi , Koga Shogo , Komamura Takahiro , Akasaka Shuichi
Published: December 2023

Novel practical acoustic metamaterial sheets with hollow local resonators that can be processed with simple integral molding have been developed. This acoustic metamaterial is a variant of the acoustic metamaterial sheet reported by our group in 2021, which consists of two-dimensionally
connected non-hollow-shaped stubs embedded with metal weights. Each hollow-shaped stub can work as a local resonator using the vibration mode of a circular membrane. This acoustic metamaterial can handle lower frequencies even with smaller and lighter stubs compared to those with the non-hollow-shaped
stubs we previously reported. It has a particular advantage when used for objects with limited space and weight. It is also possible to control the resonant frequency by altering the material properties or adjusting the shape and size of the stub. It has been experimentally shown that significant
sound insulation performance exceeding the mass law can be obtained around the resonant frequencies of the hollow stubs. We show the results of finite element method simulations, modal vibration testing, and transmission loss measurements.
Development and Validation of the Aircraft Noise related Fairness Inventory (fAIR-In)
Authors: Hauptvogel Dominik , Rothmund Tobias , Schreckenberg Dirk , Schmitz Marie-Therese , Bartels Susanne
Published: December 2023

Annoyance caused by aircraft noise is largely influenced by non-acoustic factors, such as the attitude towards the noise source, perceived control over the noise and the predictability of noise occurrence. Underlying many of these non-acoustic factors is perceived fairness, e.g., regarding
information provision by the noise source or opportunities for noise-affected residents to participate in noise-related decision-making. A validated instrument to assess a variety of fairness aspects in surveys has been lacking. Therefore, the Aircraft Noise related Fairness Inventory (fAIR-In)
has been developed, a multifaceted psychometric instrument. With 32 items, the fAIR-In assesses aspects of distributive, procedural, informational and interpersonal fairness of airport management. The development of the fAIR-In as well its validation by means of data from 1,367 residents living
around three German airports are presented. Results reveal a high degree of predictive validity with regards to annoyance, airport and air travel acceptance, as well as protest behavior. Our findings indicate that the fAIR-In is a useful tool for capturing existing community perceptions of
the airport, as well as facilitating the design, monitoring and evaluation process of interventions aimed at improving the relationship between the airport and its residents.
Sensor Misalignment Correction for Virtual Point Transformation
Authors: Zhang Jie , Geluk Theo
Published: December 2023

Frequency-based Substructure (FBS) is a widely used method in industries, allowing to obtain the dynamic characteristics of coupled systems from its uncoupled substructures. The dynamic characteristics of the uncoupled components represented by Frequency Response Functions (FRFs) can
be obtained by measurements or simulation models. The FRFs at the interfaces of the components can be difficult to measure directly as it can be impossible to physically place sensors at a connection interface. Obtaining the FRFs of a virtual point from several measured locations becomes an
important process to overcome this problem, known as Virtual Point Transformation (VPT). However, the unavoidable sensor orientation errors could cause inaccuracy in this process. First, these errors lead to non-reciprocal inaccurate interface FRFs. Second, matrix inversion of the interface
matrix in the FBS coupling process amplifies these errors. To solve this problem, a correction method is proposed to apply on measured data with orientation errors on both input and output. The objective is to identify and correct these errors and thus improve the reciprocity of the interface
FRFs. As a validation, tests have been performed on a typical passenger vehicle tire. By applying the proposed method to the measured data, the reciprocity of the interface matrix is significantly improved.
Estimation of annual sound pressure levels based on mobile measurements
Authors: Balastegui Andreu , Quintero Guillermo , Romeu Jordi , Maradey Jessica Gissella
Published: December 2023

In order to compute the population exposure to environmental noise and to design and apply convenient action plans to reduce it, European Directive 2002/49/EC defines an environmental noise map as a picture of noise levels for different sources and time intervals. According to the Directive,
since 2019 it is mandatory to compute noise maps by simulation, using the model CNOSSOS-EU. However, with the fast development of large sensor networks, in a near future, it can become cheaper and more convenient to compute noise maps by taking direct measurements. European Directive 2002/49/EC
requires that noise maps plot the annual values of sound pressure level. Previous studies have shown that it is possible to estimate the annual sound pressure levels with good accuracy using a sample of only 7-10 days. The present contribution explores the possibility of estimating the annual
sound pressure levels with random samples of a few seconds or minutes taken on separate random days. This kind of temporal sampling is possible by using mobile sensors moving throughout a city.
Can an artificially generated sound design improve the subjective evaluation of a vacuum cleaner noise? Results of a listening test with two vacuum cleaners.
Authors: Mueller Benjamin Johannes , Braunmiller Linn , Lehmann Josephine , Singer Michael , Socher Michaela , Herget Noemi
Published: December 2023

In this study, the sound of two vacuum cleaners was enhanced with a psychoacoustic based, artificially generated sound design. One sound design with a lower level (SD_quiet) and one with a higher level (SD_loud) were tested in addition to the condition without sound design (RB). A listening
test with 32 subjects was used to evaluate if the added sound design improves subjective evaluation of loudness, annoyance, and noise quality. The results showed a significant difference between the subjective ratings of SD_loud and the subjective rating of RB for both vacuum cleaners. The
operating noise with added sound design SD_loud was rated as more powerful, of higher quality, more efficient, and less howling. For one vacuum cleaner, although SD_loud was rated as significantly louder and had a higher sound pressure level than RB, it was not rated as more annoying. This
shows the high potential of the use of artificially added sound design in household appliances. Furthermore, the investigation showed that a sufficient volume for an added sound design has to be chosen because there were less differences between SD_quiet and RB regarding the subjective evaluation.
Evaluation of noise emissions of a ducted fan on a test rig
Authors: Koppelberg Jan , Stuhldreier Lukas , Liegert Robin , Lehrmann Niklas , Jeschke Peter
Published: December 2023

This paper presents an experimental research study on the sound excitation of a ducted fan designed for low-noise emissions. In particular, the influence of test rig vibrations as a significant systematic error when evaluating the noise emissions of ducted fans is discussed. A propulsor
test rig was used to measure the sound emitted by a ducted fan. Significantly increased sound levels are ascertained at specific frequencies. The corresponding sources are often unexpectedly identified at the casing and structure of the rig using a sound source localization. By comparing sound
pressures against vibrations, these sources are found to be excited by simultaneous test rig vibrations. When the rig vibrates, the sound pressure levels increase by up to 15 dB compared to vibration-free operation. The sound excitation caused by the rig vibrations predominates over the aerodynamically
induced sound since the ducted fan itself emits little noise. In summary, these rig-dependent vibrations can lead to a considerable systematic measurement error for low-noise ducted fans. This error significantly complicates an accurate sound evaluation of such a ducted fan on an acoustic
rig. Therefore, these results emphasize the importance of a vibration-free operating range and the necessity to quantify the sound excitation by rig-specific vibrations.
Acoustic Analysis and Experimental Validation of Acoustic Metamaterial
Authors: NAGAMI Tadashi , MIYAKAWA Takayuki , ENOMOTO Toshio
Published: December 2023

In this study, a unique sound insulation performance of a lightweight acoustic metamaterial consisting of a stiff honeycomb plate coated with a thin rubber membrane was experimentally demonstrated. An acoustic transmission measurement of the acoustic metamaterial showed that the sound
insulation performance of the acoustic metamaterial exceeded the mass law predicted performance in three frequency ranges. An analysis of the acoustic-structure interaction revealed that these unique sound insulation phenomena were due to the cancellation between two high-order eigenmodes
of the periodic structure or a high-order eigenmode of the periodic structure and an eigenmode of the membrane in each honeycomb cell. Subsequently, a prototype of this acoustic metamaterial was applied to a vehicle and its effectiveness on vehicle interior noise was investigated. The results
show that such materials can further improve the level of quietness with weight reduction in vehicles and other transportation applications.
A 3D modeling method of layered acoustic material structures with finite dimensions
Authors: Firtha Gergely , Huszty Csaba
Published: December 2023

Modeling of layered acoustic structures to predict the sound absorption characteristics of complex materials is a widely used method in room acoustic practice. Commonly used modeling techniques-such as the transfer matrix method-typically assume locally reacting surfaces of infinite
lateral dimensions and provide one-dimensional calculations only, offering limited accuracy, especially for resonant absorbers with finite dimensions. We present the direct, analytical modeling of sound propagation in extendedly reacting layered materials of finite dimensions allowing the
estimation of the surface impedance or admittance distribution of layered structures, from which sound absorption properties can be calculated. The theoretical results are validated by measurements, performed on a small-sized resonant panel absorber. We present the implementation of the method
in the soundy.ai application.
Error analysis of the compact microphone array for sound source localization
Authors: Jung In-Jee , Cho Wan-Ho , Ih Jeong-Guon
Published: December 2023

Smart sensing is used to provide specific information by using physical quantities measured by multiple sensors or multi-modal sensor modules. Nowadays, the smart sensor is configured as a compact system using very small transducers implemented by MEMS technology. Accordingly, the multi-modal
sensing device is getting miniaturized. A microphone array can be classified as a smart sensing device that estimates the sound field information. However, it is difficult to implement a compact system because the measurable frequency range is limited by the spacing between adjacent microphones.
Also, the calibration is difficult due to the irregularly shaped sensor element; therefore, the traceability is not yet established. In this study, sound source localization algorithms are applied for implementing the compact microphone array. The inherent error due to the sensor position
tolerance, magnitude difference, and phase mismatch is analyzed. Because the coherent noise increases uncertainty in the actual test environment, the estimation error depending on the critical distance is analyzed. Finally, a compact webcam-based multi-modal sensor is implemented and the localization
test result is reviewed.
Cultural soundscape as intangible or tangible cultural heritage
Authors: Noviandri Patricia Pahlevi , Djimantoro Michael I. , Septianto Eggi , Martokusumo Widjaja
Published: December 2023

Soundscape is a collection of sounds that individuals feel and understand in the context of a built environment. The soundscape is often associated with audial comfort in urban spaces. Nevertheless, soundscape investigation in historical areas requires different parameters. Sound is
comprehended not only from the sound object and the sound wave per se but also from its meaning and identity representation of the cultural heritage area. Therefore, this paper examines soundscape studies in historic areas to explain cultural soundscapes as tangible or intangible cultural
heritage. The author interprets the findings from the cultural soundscape research group to become a theoretical and conceptual explanation of the existing phenomenon. Based on observations in urban kampungs in Yogyakarta-Indonesia, namely Musikanan, Sayidan, and Pujokusuman, a cultural soundscape
exists as a collection of sounds with a significant identity, meaning and spatial forming values which show the cultural image of a location. This preliminary study also demonstrates the significance of the soundscape in evaluating the intangible elements of urban place experience. The conception
of a cultural soundscape is advantageous in providing research directions for intangible cultural heritage in Indonesia. Keywords: cultural soundscape, historic areas, intangible/tangible cultural heritage, urban kampung, Yogyakarta
Numerical prediction of the sound transmission loss of double panel configurations with acoustic structured and poroelastic materials
Authors: Kone Tenon Charly , Ghinet Sebastian , Panneton Raymond , Grewal Anant
Published: December 2023

The sound transmission loss of multilayer system assemblies made of Noise Control Treatments comprising metamaterials and poroelastic materials, sandwiched between two structural panels is of utmost importance in aerospace, automotive, building and several other engineering applications.
The integration of acoustic metamaterials in these systems introduces a number of challenges at the level of numerical simulation in order to predict their acoustic and structural behavior. This paper presents a methodology for the numerical simulation of the sound transmission loss of structural
configurations comprising acoustic metamaterials embedded in a glass wools layer, sandwiched between two elastic panels. The metamaterial is designed as a parallel assembly of four sub-metamaterials. Each of these sub-metamaterials is also a series assembly of a periodic unit cell having a
neck + cavity + neck type configuration. The four sub-metamaterials are designed so that their first resonance frequencies are grouped together in order to improve the sound transmission loss at the first two natural frequencies of the double panel. The COMSOL Multiphysics finite element method
solver is used. The normal incidence and diffuse field sound transmission loss numerical results are presented and discussed in comparison with results from literature for validation.
The impact of accelerometer location and frequency weightings on the prediction of pleasantness ratings for vertical whole-body vibrations on an aircraft seat bench
Authors: Töpken Stephan , Krause Louis , Par Steven van de
Published: December 2023

Noise and vibration are two physical factors that can reduce the perceived comfort of passengers during a flight. In this application context, vibrations are often measured using accelerometers placed at the seat rail or with a seat pad between the seat surface and the buttock of a
sitting person. To develop pleasant aircraft cabin environments, it necessary to know which measurement location best reflects subjective ratings and whether the application of a frequency weighting as proposed in the ISO 2631 standard is beneficial. In this study, 40 participants rated the
pleasantness of sinusoidal whole-body vibrations in the vertical direction while seated on a typical aircraft seat bench and listening to a synthetic broadband aircraft cabin noise over headphones. The vibration signals covered seven frequencies and four vibration levels and ratings were made
on a verbally anchored scale. The results showed that an increase in vibration level leads to more unpleasant ratings for each of the tested frequencies, independent of the accelerometer position. Although the ISO frequency weighting underpredicts the ratings for high frequencies in both cases,
applying it to the seat rail measurements seems to reflect the pleasantness ratings better than the seat pad measurements proposed in the ISO 2631 standard.
Vibration Analysis Based on Video Data for Buildings and Structures
Authors: Vonrhein Benjamin , Höhna Philip
Published: December 2023

ODS (Operation Deflection shapes) based on video data holds the possibility to analyze objects with several advantages. The hardware costs are low, as only a camera is required, the measurement is simple and can be performed with little expert knowledge and the post processing is fast
and straight forward. It is a contact free method, so the object's vibration is not influenced and by applying methods based on artificial intelligence it is in most cases not necessary to prepare surfaces. The limits of ODS based on video are mainly defined by the used camera and lens. This
work will explore the advantages and limitations of the method applied in measurements of buildings and big structures. Results of measurements of large-scale buildings and bridges will be shown and compared to traditional methods and simulations. Advantages and disadvantage as well as limitations
in hard- and software of the introduced method will be discussed.
A precision sound pressure level measurement system
Authors: Wu Lixue , Koukoulas Triantafillos
Published: December 2023

Noise pollution affects human and wildlife. It is in the public interest to reduce noise levels. Measures to be taken to reduce the noise are normally expensive and must be based on facts and reliable measurements of noise. Therefore, sound pressure level measurements are key evidence
to determine whether there is a breach of noise limits. The sound pressure measurement method should comply with the metrological principles concerning validation, measurement traceability and estimation of measurement uncertainty as stated in ISO/IEC Directives, Part 2, Principles and rules
for the structure and drafting of ISO and IEC document. For this reason, a precision sound pressure measurement system has been developed at the National Research Council Canada. The system utilizes the latest advances in digitization and is metrologically transparent, facilitating the evaluation
of measurement uncertainties. In this paper, the design and implementation of the system based on IEC 61672-1, Electroacoustics - Sound level meters - Part 1: Specifications is described. The technical challenges, such as truncation, are discussed. Closed-form solutions are obtained for typical
sinusoidal sound signals. Experiments were conducted for the validation of the system. The measurement results are presented showing that the discrepancy between theoretical calculations and measurements is only 1.6 ppm.
Modeling of a flexible perforated membrane backed by granular materials
Authors: Mo Zhuang , Song Guochenhao , Shi Tongyang , Bolton J. Stuart
Published: December 2023

It has recently been shown that adding activated carbon particles to the interior of a Helmholtz resonator can improve the resonator's absorption at low frequencies. A similar improvement has been found when a layer of activated carbon partially fills the space behind a finite, tensioned
impermeable membrane. In that case, absorption peaks due to the modal response of the tensioned membrane were found to be significantly enhanced in the low frequency range. In the present work, the modeling aspects of the latter work are extended in a number of ways. First, the circular membrane
is considered to be both tensioned and flexurally stiff, and further, it is micro-perforated: i.e., it has a finite flow resistance. Secondly, the particle layer behind the membrane is modeled by using a finite difference procedure that accounts for interaction of the particle layer and walls
that contain it: i.e., the particle stack itself is allowed to exhibit modal behavior in the radial direction. Finally, the interaction of the membrane nearfield and the particle stack is fully accounted for. It is shown that previously observed behavior can be reproduced, and further that
the modal behavior of the particle stack may also enhance the system's absorption.
Investigation of characteristics and generating mechanism of wind noise on external microphone of mobile device
Authors: Choi Jihun , Lee Wonhee , Saravanan Vignesh , Kwon Seeyoun , Lee Soogab
Published: December 2023

The multipurpose external microphone of mobile devices is exposed to the outside windy environment, which inevitably generates wind noise. The wind noise acts as noise in signal processing, like Active Noise Control and capturing voice, and damages the user's experience. This paper
investigates the acoustic characteristics and generation mechanism of wind noise through experiments and numerical analysis for a commercial TWS earbuds model. The experimental results show that the wind noise has broadband characteristics with dominant low-frequency band noise (below 2500Hz),
unlike general cavity flow. On the same model, the Lattice-Boltzmann method numerical analysis has been performed through powerFLOW software. The numerical result shows good agreement of +-3dB with experimental results in the 1/3 octave band spectrum for the wind noise band. Numerical results
flow field investigation reveals that the disturbed flow field is induced by an interaction between the vortical structure of the inflow and separated flow field, which is governed by geometry configurations. The disturbances induce the complex pressure gradient on inflow into the microphone,
measured as wind noise on the microphone. These results show that the wind noise measured by the microphone of mobile devices is a flow phenomenon caused by external excitation.
Investigation of Effect of Mean Flow on Active Noise Control System in Duct
Authors: Saravanan Vignesh , Kim Dongwook , Kim Hyunkee , Lee Soogab
Published: December 2023

The increasing demand for a quieter living environment has driven the development of noise reduction and control technologies. Previous research has demonstrated the significant impact of mean flow on the performance of noise reduction devices. While efforts have been made to enhance
passive noise control systems in the presence of mean flow, research on the influence of mean flow on active noise control (ANC) systems is limited, particularly in terms of computational modeling. This study addresses this gap by investigating the effect of mean flow on ANC system performance
using a validated virtual controller within a computational framework, complemented by experimental investigations. The acoustic propagation inside the computational domain is computed using the Computational Aeroacoustics method, and the ANC system is modeled using FxLMS algorithm with the
virtual-controller method as proposed in our earlier work. Through experiments, it reveals that the presence of mean flow in duct reduces the performance of the ANC system. The numerical investigation exhibited a consistent trend in line with the experimental findings, showing a strong agreement
between the 3D numerical simulations and experimental data. These numerical results offer compelling evidence that the computational framework used in this study accurately models the impact of mean flow on ANC systems.
Dome-Shaped Ultrasonic Jammer for speech privacy protection
Authors: Hayasaka Noriyuki , Kondo Kazuhiro
Published: December 2023

Smart devices using voice recognition systems such as Google Assistant, Siri, and Alexa have rapidly become popular in recent years. Although these devices are convenient because they can be operated using voice, there is reported to be a risk of their unauthorized operation by sending
stealth voice commands from a remote location. In addition, there is the risk of private conversations being eavesdropped on, as conversations can now be recorded and possibly sent wirelessly using extremely small devices. Ultrasonic jammers are a countermeasure to these situations. Ultrasonic
jammers use ultrasonic waves to jam the recorder in such a way that the jamming is imperceptible to surrounding humans but adds significant noise to only recorded samples. We developed a prototype dome-shaped ultrasonic jammer, which can spread the jamming signal to a wide surrounding area,
and evaluated its initial performance. The performance evaluation results confirmed that the dome-shaped ultrasonic jammer can effectively jam a wider area than a conventional flat parametric speaker conventionally used for jamming.
Numerical Simulation Results of Double Nearfield Acoustic Holography method with extrapolation
Authors: Nagamatsu Masao
Published: December 2023

In my laboratory, the new sound localization method, Double Nearfield Acoustic Holography (DNAH) method is being developed. This method has high resolution in low frequency sound localization. It is presented at former inter-noise. On the other hand, the extrapolation of measurement
points is effective for Nearfield Acoustic Holography method in low frequency. Therefore, the extrapolation technique is also applied for DNAH method. In this presentation, the numerical simulation results of DNAH method with extrapolation of measurement points is reported. With extrapolation,
the DNAH shows higher resolution in low frequency sound localization than DNAH method without extrapolation, and higher resolution in low frequency sound localization than NAH method with extrapolation.
An Efficient Narrowband FxLMS Algorithm for A 3-Axis Active Mount
Authors: Heo Junyeong , Shin Seungmin , Cha Jaebin , Hwang Seorim , Park Youngcheol , Jung Kyu-chul , Son Sung-wan
Published: December 2023

The Active Mount (AM) controls the vibrations caused by the movement of a mechanical system resting on top of it. Vibration caused by mechanical systems often consists of several dominant frequency components. Therefore, we need an adaptive algorithm controlling tonal vibration components
effectively. The FxLMS algorithm widely used for active vibration control raises several issues as the tone number and control channel increase. This paper proposes an efficient narrowband FxLMS algorithm for controlling multiple tonal vibrations occurring in a 3-axis AM. To this end, the
secondary path's magnitude and phase responses are modeled tone-by-tone, independently using two-tap filters. Narrowband control filters are constructed for each tone using a narrowband signal model. In addition, a reference sensor is mounted on top of AM, from which tonal references are estimated
using adaptive notch filters (ANFs). The proposed algorithm was simulated using transfer functions obtained in a 3-axis AM. Results show that the proposed algorithm effectively controls multiple tonal components by minimizing total errors measured along the 3-axis.
Low frequency sensitivity enhancement of MEMS microphone using acoustic metamaterial
Authors: Huh Jiwon , Kim Jedo
Published: December 2023

In this study, we develop a multi-physics-based simulation model for 2D-based MEMS microphone to predict and characterize its performance. The 2D material is comprised of MoS2 which is a novel substance that is predicted to revolutionize many areas of energy-related fields. Here, we
apply the 2D material to the next-generation MEMS (Micro Electro Mechanical Systems) microphone. We present a model in which various parameters can be controlled and output performance is predicted. The effects of membrane size, shape, and number of layers, along with the electrode location,
vent-hole size, shape, and number, on the acoustic performance of the microphone are investigated. In addition, we explore the potential low-frequency performance enhancement of the miniature microphone using acoustic metamaterial.
Relation between sound absorption and speech intelligibility in room, part 1: Theoretical investigation
Authors: Hirose Ryoko , Sakuma Tetsuya
Published: December 2023

In Japan, requirements and design guidelines on sound absorption of a variety of ordinary spaces are currently under consideration. In general, sound absorption works for reverberation suppression and noise reduction, both of which contributes to improve speech intelligibility performance.
However, its combined effect is not fully clarified, especially on the relationship among of reverberation time, average absorption coefficient and speech intelligibility indices. In this paper, two theoretical case studies are performed based on the formulations of the clarity C50 and the
useful-to-detrimental ratio U50 in the conditions without and with background noise. For rectangular rooms with an aspect ratio of 1:2:4, those indices are calculated at three source-to-receiver distances, changing the room volume widely under different noise levels. The results demonstrated
that the absorption coefficient required for a target C50 increases with increasing the room volume, but it decreases beyond a certain volume. Moreover, it was shown that under high background noise, U50 is not effectively improved by increasing the absorption coefficient if the communication
distance is much longer than the critical distance.
Validation of estimated underwater radiated noise propagation from a ship using the parabolic equation method by underwater sound measurements in actual sea
Authors: Sakai Masahiro , Iwashima Yamato , Tsuchiya Toshio , Umeda Naoya
Published: December 2023

In 2022, the International Maritime Organization started a review of the nonmandatory guidelines for the reduction of underwater radiated noise (URN) from ships and a discussion about the next step. In the case of considering the extent of underwater radiated noise from a ship, the
propagation of the URN and the background noise in the sea area should be considered in addition to the source level of the URN. In this study, the time series of the received levels of underwater sound measured off Izu-Oshima Island, Japan, are shown in the 1/3 octave band level. The time
series of the received levels were compared with the propagation loss estimated by the parabolic equation method to validate the accuracy of the estimation of the propagation of underwater sound in the measurement area.
A finite element study of absorption coefficient measurement at low frequencies
Authors: Prinn Albert G.
Published: December 2023

The frequency-dependent absorption coefficients of an acoustically absorbent material sample can be measured using the reverberation chamber method, defined by the ISO standard 354:2003. The lower frequency bound for the measurement defined in the standard is 100 Hz, since measurement
data below this frequency may be unreliable. However, the ability to measure absorption coefficients at low frequencies is becoming increasingly more important, to facilitate the enhanced control of low frequency sound fields. This paper presents a finite element method study of the reverberation
chamber measurement method at frequencies below 100 Hz, and the predicted performance of the ISO standard method is reported. Additionally, a recently proposed method that makes use of finite element-based eigenvalue analyses to estimate the locally reacting complex-valued impedance of a sample
at modal frequencies is applied to the problem. It is shown that the proposed method can be used to estimate frequency-dependent absorption coefficients at modal frequencies below 100 Hz.