bluuebunny/crossref_metadata_2025 huggingface dataset:
Eccentricity Effects on NVH Performance of Interior Permanent Magnets Machines for Hybrid and Electric Vehicles
Authors: Zhang Peng , He Song , Muir Michael C. , Gautam G. S. J.
Published: September 2021

For the hybrid electric vehicles (HEVs) and electric vehicles (EVs) applications, the electric machine drive unit system provides the main noise source, especially in the presence of faults. Eccentricity is one of the most common faults, which is mainly caused by the motors' package
design and assembling process. There are four main types of eccentricity for motors: static offset, dynamic offset, static tilt and dynamic tilt, which are presented and analyzed. Both two-dimensional (2D) and 3-dimentional (3D) finite element analysis (FEA) are utilized in the electromagnetic
field analysis for an Interior Permanent Magnet (IPM) motor. The corresponding methodologies for the mesh and force mapping to the mechanical FEA for the NVH analysis are presented. The NVH test shows that both 2D and 3D FEA can provide reasonable accuracy for the motor eccentricity fault
analysis. The 2D FEA is the most common method used in the design optimization and early performance prediction for electrical. For the 3D FEA, due to the high requirement for the computer hardware and computation capability, it is usually used in the final validation for electrical machines'
performance. The sensitivity of motor performance versus the airgap heights and eccentricities are studied.
A new technology for locating very low frequency and negative signal-to-noise ratio sound sources
Authors: Lu Yazhong , Wu Sean , Yuan Zeyu , He Wen
Published: September 2021

This paper presents a new technology that enables one to locate multiple sound sources with very a large dynamic range simultaneously, including very low frequency and negative signal-to-noise ration sound sources in a non-ideal environment, where there are random background noise and
unknown interfering signals. In particular, spatial resolution of source localization is frequency independent. In other words, spatial resolution remains very high at very low as well as at very high frequencies. The underlying principle of this new technology is a hybrid methodology that
includes a passive SODAR (nic etection nd anging), advanced signal processing and least-squares minimization. Using this technology, engineers will be able to visualize sound sources in both real time and post processing in an adversary test environment. Live videos of sound sources localization
inside a crowd machine shop are shown, where there are unknown background noise, unspecified sound reflections and reverberation, and interfering signals.
Landscape depressions can create silent zones in noise polluted parks
Authors: Van Renterghem Timothy , Thomas Pieter , Botteldooren Dick
Published: September 2021

Excessive road traffic noise exposure in (sub)urban parks hinders its restorative function and will negatively impact the number of visitors. Especially in such green environments, noise abatements by natural means, well integrated in the landscape, are the most desired solutions. Although
dense vegetation bordering the park or raised berms could come first in mind, local landscape depressions are typically underused. In this work, a case-study of a small suburban park, squeezed in between two major arterial roads, is analyzed. The spatially dependent road traffic noise exposure
in the park is assessed in detail by mobile sound pressure level measurements. Local reductions of up to 6-7 dBA are found at landscape depressions of only a few meters deep. It can therefore be concluded that this is an efficient measure and should be added to the environmental noise control
toolbox for noise polluted parks.
High-resolution spectral analysis (HSA) vs. discrete fourier transform (DFT)
Authors: Sottek Roland , Lobato Thiago
Published: September 2021

The Discrete Fourier Transform (DFT) is the standard technique for performing spectral analysis. It is used in the form of the well-known fast implementation (FFT) in almost all areas that deal with signal processing. However, the DFT algorithm has some limitations in terms of its resolution
in time and frequency: the higher the time resolution, the lower the frequency resolution, and vice versa. The product of time (analysis duration) and analysis bandwidth (frequency resolution) is a constant. DFT results depend on the analysis window used (type and duration), although the physical
signal properties do not change. The High-Resolution Spectral Analysis (HSA) method, published at the ASST '90, considers the window influence through spectral deconvolution and thus leads to a much lower time-bandwidth product, correlating better with human perception. Recently, variants
of the HSA have been used for a psychoacoustic standard (roughness). Additionally, HSA is planned for a new model of fluctuation strength. This paper describes the improvements made to the HSA algorithm as well as its robustness against noise, and compares application results for both methods:
HSA and DFT.
Assessing a parallel baffle splitter, an experimental and numerical study on insertion loss and pressure drop
Authors: Escudero Juan , Fuentes Héctor
Published: September 2021

HVAC systems are composed of different noise sources and paths. The non-attenuated propagation of noise through the system has detrimental effects on acoustic comfort of people inside the premises. To mitigate the propagated noise, parallel baffle splitters are used which reduce the
transmitted noise through acoustic coatings. Different methods have been developed to predict the insertion loss of those elements, however, if the input data is not well known these models can lead to deviated results. On the other hand, the use of splitter in HVAC systems produces pressure
drop which can damage the equipment used if that is not well predicted. Different models are available in the literature, which relates dimensional features and design velocity to estimate the pressure drop coefficient. However, models can give overestimated results. In this work an experimental
rig was implemented to assess a splitter installed inside of a test duct. Measurements were performed to estimate insertion loss and pressure drop coefficient, following the guidelines exposed on the ISO 7235 standard. The results were compared with analytic methods. Finally, a numerical method
analysis of the test rig was performed, showing the correlation between these results and the experimental data.
The test bench for the assessment of the impact of wind turbine noise on human performance
Authors: Pleban Dariusz , Szczepański Grzegorz , Radosz Jan , Kapica Łukasz
Published: September 2021

Among the factors related to the operation of wind farms, wind turbine noise has to be seen as a source of annoyance for both people living and working near wind farms. A method and a test bench to conduct noise annoyance tests of different types of wind turbine noise in laboratory
conditions have been developed. The test bench is based on a multi-channel sound reproducing system using the DANTE network (in which digital acoustic signals are broadcast over Ethernet) and is compiled in the acoustic test chamber. The test bench consists of 19 speakers, including 17 Avantone
MixCube studio monitors and 2 LS600 woofers. During the tests a study subject is assessed in terms of efficiency and performance using a computer-based ALS test from the Vienna Test System. The paper describes the test method, the test bench and the results of the pilot studies carried out
to assess the impact of wind turbine noise on human performance.
Noise and acoustics in complicated rooms with the sound particle method
Authors: Judd Thomas , Weigand Stefan , Schaal Jochen
Published: September 2021

The analysis of noise and acoustics in indoor spaces is often performed with geometrical methods from the ray-tracing family, such as the sound particle method. In general, these offer an acceptable balance between physical accuracy and computational effort, but models with large numbers
of objects and high levels of detail can lead to long waits for results. In this paper, we consider methods to assist with the efficient analysis of such situations in the context of the sound particle diffraction model. A modern open-plan office and a large cathedral are used as example projects.
We look at space partitioning strategies, adaptive placement of receivers in the form of mesh noise maps, and graphics-card-style hardware acceleration techniques, along with iterative modelling methods. The role of geometrical detail in the context of uncertainties in the input data, such
as absorption and scattering coefficients, is also studied. From this, we offer a range of recommendations regarding the level-of-detail in acoustic modelling, including consideration of issues such as seating, tables, and curved surfaces.
"Buy Quiet" with the added benefit of considering all safety, health, and cost factors
Authors: Zechmann Edward
Published: September 2021

Approximately 22 million U.S. workers are exposed to hazardous workplace noise. The industries with the highest prevalence of self-reported occupational HL were Mining (61%), Construction (51%) and Manufacturing (47%). "Buy Quiet" is the most strategic way to reduce noise
exposure. However, there are other safety, health, and cost factors that significantly influence a purchasing decision for equipment. A more holistic approach is needed. The safety requirements procurement standard (SAE AS6228) has extensive guidance for evaluating all the safety, health,
and cost factors influencing a purchasing decision for equipment. The factors are systematically incorporated into a five-year life cycle score. Unfortunately, this standard is underutilized. Publication of SAE AIR6916 and one-page guidance for each tool type will help to address the underutilization.
SAE AIR6916 provides simplified guidance for using the AS6228 standard. One-page guidance documents with example evaluations of life cycle scores will make it easier for additional tools to be evaluated in a consistent and comparable manner. Working with retailers and online shopping websites
is needed to make the life-cycle score information more easily accessible and easy to use for making purchasing decisions. Additional efforts are aimed at making the life-cycle score methodology routinely utilized and adaptable to new applications.
Effect of ceiling and dry-type double floor on heavy-weight floor impact sound in concrete building and CLT building.
Authors: Yamauchi Takashi , Hiramitsu Atsuo , Hirakawa Susumu
Published: September 2021

The air layer between the interior finishes and the structure is used as piping and wiring space. In many cases, ceilings and dry-type double floors are commonly constructed in Japan. However, the effect of the air layer of ceilings and dry-type double floors on the heavy-weight floor
impact sound insulation performance has not yet quantitatively investigated. Therefore, in this study, the same floor and ceiling structures were constructed for concrete and CLT buildings, and the heavy-weight floor impact sound was investigated. As results, it was confirmed that the reduction
amount of the heavy-weight floor impact sound by the ceiling tended to be smaller in CLT buildings than in concrete buildings. However, the trends were similar. Due to the dry-type double floor structure, the heavy-weight floor impact sound level was increased in concrete building and decreased
in CLT building at 63 Hz in the octave band center frequency band. Therefore, it can be said that the dry-type double floor structure can be used to improve the heavy-weight floor impact sound performance in the CLT building.
Road traffic noise disease burden estimates for a model study of varying urban morphology cases
Authors: Forssén Jens , Gustafson Andreas , Pont Meta Berghauser , Haeger-Eugensson Marie , Achberger Christine , Rosholm Niklas
Published: September 2021

For a model set of 31 different building morphologies in an urban setting, road traffic noise exposure has been calculated and analysed. For five of the building morphologies also vegetation surfaces on facades and roofs were studied. Facade exposures were analysed for both smaller
(single-sided) flats and larger (floor-through) flats, considering the direct exposure from the roads as well as the non-direct exposure at noise-shielded positions like inner yards, applying a noise mapping software in combination with a prediction model for the non-direct exposure. Using
noise indicators Lden and Lnight, the disease burden, in terms of DALY (Disability-Adjusted Life Years) per person, was estimated and analysed, via predictions of annoyance and sleep disturbance. The resulting effects of varying the building morphology and adding vegetation are shown and discussed,
including effects of a bonus model for flats having additional facade elements with lower noise exposure.
Soundproof Window - Natural Ventilation
Authors: Ávila Ferreira Vinícius
Published: September 2021

Expansion of brasilians cities worsen noise pollution in these places, forcing people to maintain their doors and windows closed. Domestic environment enclosing lead to necessity of air conditioning system, however the frequent use of the equipment may cause many health problems, such
as respiratory difficulties and spread of diseases , not to mention high costs with energy. Considering these facts, there is the need of soundproofing windows with air supply , that allows passage of air without noise passage, guarantee a well-ventilated environment, with thermic and acoustic
comfort without the use of acclimatisation systems . we have developed two prototypes with significant opening that allows air supply (passage) (0,35m2) and noise reduction (Rw+Ctr) reaching 8 to 10 dB. In the first study, we considered people inhabiting really noisy surrounding areas, who
has already installed a regular window. In this particular case, we developed a soundproofing window air supply that can be installed over the existing one. A second study considered new constructions to focus the environment where the person sleeps and then elaborate a soundproofing window
air supply for bedrooms.
Monitoring trends in road surface impact on rolling noise emissions
Authors: Botteldooren Dick , Van Hauwermeiren Wout , Filipan Karlo , De Coensel Bert
Published: September 2021

Road surfaces degrade over time due to heavy traffic and weather conditions, which negatively influences both driving comfort and acoustic properties. In addition, the lifetime of a road surface can be increased by performing cost-effective incremental maintenance and this maintenance
becomes more expensive when the damages are more severe (cracks, potholes). Current methods such as CPX are performed in a standardized way (using designated equipment and tightly controlled measurement conditions), however budget constraints limit frequent monitoring of surfaces. Therefore,
continuous monitoring using ordinary passenger vehicles could be helpful to observe trends in rolling noise emissions and road evenness. Hence, we deployed designated sensor boxes in a number of vehicles that are on the road for other purposes. In addition, advances in calibration of different
devices using de-noising autoencoders alleviate the effect of various measurement conditions such as driving speed, braking, accelerating, and temperature. As our innovative methodology has now been on the road for several years, trend analysis becomes possible.
An experimental methodology to study engine gear rattle problems
Authors: Donmez Ata , Kahraman Ahmet
Published: September 2021

Gear induced noise represents a major part of overall automotive drivetrain noise. Gear rattle noise is caused by strongly nonlinear dynamic behavior of the gear pair, primarily due to external torque of speed fluctuations under lightly loaded conditions. Such loading conditions cannot
be generated by using the conventional gear dynamics test set-ups that employ power recirculating gearbox arrangements or conventional electric motors. In this paper, a new test set-up is introduced to emulate the actual torque/velocity fluctuations of the input and/or output members of a
gear train through three-phase synchronous servo-motors. In addition to establishing backlash boundaries, a pair of absolute encoders are used to measure the relative motions of the gears as well as their impacts along the drive and coast sides flanks or gears. Torsional vibratory behavior
of a gear pair is presented at different backlash values under several input/output fluctuation conditions along with the companion sound pressure measurements.
Operable partitions - a life of experiences, observations, and testing plus comments on standards
Authors: Stewart Noral
Published: September 2021

Experiences testing operable partitions since 1986 will be reviewed including typical performance and various problems observed with both the partitions and surrounding structures. ASTM standards E557 on proper building preparation for an operable partition and E336 for the measurement
of field performance will be discussed, including the 2005 revision of E336 as it affects evaluation of operable partitions.
Automated Material Parameter Calibration for an Electric Motor Stator
Authors: Pasha Hasan , Lee Gil Jun , Zhang Henry , Hale Steve , Kottalgi Santosh
Published: September 2021

For accurate prediction of E-motor noise and vibration performance at the design stage, it is important to model the E-Motor stator structural behavior with high fidelity. Orthotropic material properties have been widely used in practice to simulate laminated steel in the stator. In
these models, material constants are calibrated to match natural frequencies of critical modes such as oval/triangle/square modes. Typically, identifying accurate material properties is a manual, time-consuming process, involving lots of trial and error. This study presents an automated workflow
to calibrate the material properties for the stator with Ansys Mechanical and optiSLang. The developed workflow can track natural frequencies and corresponding mode shapes of critical modes, and adjust material constants automatically to find best material parameters for the given frequencies.
It can rotate the mode shapes and find the orientation that gives best match to the measurements based on modal assurance criteria (MAC). This workflow has shown a good correlation between simulation and test in terms of natural frequencies and corresponding mode shapes for the stator of a
switched reluctance motor (SRM). Such an automated workflow enables the fast, efficient material calibration process, therefore accurate electric powertrain NVH simulations.
Control of low frequency noise from an environmental test facility
Authors: Smith Malcolm , Quaranta Erika
Published: September 2021

Environmental test chambers are used in the automotive industry to verify the resilience of vehicles. In just a few hours it is possible to take a car from mid-winter in the artic, via a high mountain range, to mid-summer in a desert. Powerful ventilation systems are used to change
the temperature, pressure and humidity of the air in the chamber, and the variable speed blowers are a major source of low frequency noise, which can cause significant disturbance at neighbouring properties if there are gaps in silencer performance. This paper details a study to assess the
attenuation requirements for a system to meet a standard criterion for low frequency far-field noise levels, and to select a reactive silencer system to achieve that specification under all circumstances. The system used standard silencer components where possible, but needed to take account
of long pipe runs through the facility, with tailpipe resonances being a particular issue, and was further constrained by space and loading limits for the building. Design layouts were verified using the Actran FE code, taking account of interactions with existing silencers and transfer functions
to the far-field, in order to have very high confidence of a successful outcome.
A case study in the measurement of door sound isolation with ASTM test standards
Authors: Ono Christopher , Beiler Todd , Clausen Devin
Published: September 2021

The use of the door transmission class rating in lieu of the apparent sound transmission class rating has yet to gain traction within building codes and specified project requirements. This paper presents a case study involving performance requirement testing conducted at a university's
media facility, in which sound insulation properties were a critical design and construction focus. Both test methods described in ASTM E2964 and ASTM E336 were performed where a door was the test partition. Door transmission class ratings were presented in comparison to apparent sound transmission
class ratings for the same partition. Testing was performed in a variety of situations, including scenarios both inside and outside of the minimum requirements of testing standards. Our analysis considers the effectiveness of the recently adopted ASTM E2964 in comparison to the methods of
the ASTM E336. We also consider some of the subtle differences between the two test methods and how they may impact the testing of certain adjacencies.
A basic study on estimating location of sound source by using distributed acoustic measurement network
Authors: Ikemi Itsuki , Harada Kazunori , Sugahara Akiko , Hiraguri Yasuhiro
Published: September 2021

The sounds from childcare facilities are often a cause of noise problems with neighbors, however since the sound power levels of children's play and other sounds in child-care facilities have not become clear, evaluation methods have not been established, making countermeasures difficult.
In order to evaluate the noise, it is necessary to model the location of the sound source and the sound power level. We have been developing a sound source identification system that uses multiple Raspberry Pi-based recording devices to estimate the location of a sound source and sound power
levels. By using GPS for time synchronization, the system can be distributed and placed without connecting cables, which is expected to expand the measurement area significantly. As a method of estimation, the arrival time difference is calculated by cross-correlation from the signals input
to each recording device, and the sound source location is estimated from the calculated arrival time difference and the location information of the device. The effectiveness of this system was verified in an anechoic room and outdoor fields.
Attenuation of Torsional Vibration in the Drivetrain of a Wind Turbine using a Centrifugal Pendulum Absorber
Authors: Lee Hyeongill , Han Youkyung , Kim Byeongil
Published: September 2021

The drivetrain of wind turbines consists of many complicated rotary elements such as planetary gear, parallel gear train, bearing etc. The drivetrain of the wind turbine are studied with many different modeling techniques in several works. However, the things come to complicated when
considering a complete drivetrain of a wind turbine. In this study, the transfer matrix method will be utilized to analyze the torsional vibration of a sample wind turbine drivetrain. Each element in the drivetain of the sample wind turbine is modeled with a specific transfer matrix and the
matrix for the whole drivetrain is derived by serial multiplications of individual matrices. Dynamic characteristics of the drivetrain are investigated with derived matrix. Then, the application of a centrifugal pendulum absorber(CPA) to the drivetrain to attenuate the torsional vibration
in the system is studied. The transfer matrix for the CPA introduced in the previous study is used to determine the optimal configuration and location of the CPA. The CPA shows good performance on the torsion vibration reduction for the drivetrain of the sample wind turbine.
On the performance sound design of a stringed instrument by the control of the stiffness and mass of the component part
Authors: Morisaki Ryoma , Terashima Osamu , Miyajima Toshiro
Published: September 2021

This study investigates the difference of performance sounds of an electric guitar with a metal pickguard. The sounds of the open strings of the guitar are measured, showing that the damping time becomes shorter than that obtained with a commonly used plastic pickguard. Further, it
was also found that the sounds of the 1 and 2 strings were distinct and those of the other strings were slightly suppressed when the metal pickguard was used. Therefore, the metal pickguard is effective in making sharp, clear, and distinct sounds. We changed the material of the pickguard from
plastic to copper. In the experiments, simultaneous measurements of the vibrational acceleration of the peg, pickguard, and output voltage of the guitar with a constant plucking force of the strings were performed. It was found that the profile of the RMS value of the vibrational acceleration
of the pickguard changed when the copper pickguard was used. Moreover, the vibrational modes of copper the pickguard were different than the others. In conclusion, it was determined that the sound quality is affected by the vibrational characteristics; thus, it can be adjusted by varying the
means by which the pickguard is attached to the guitar body.
Investigating the relationship between train speed and ground vibrations using random forest machine learning models
Authors: Klein Schaarsberg F.L.H. , de Niet A.C. , Zandberg H. , Dijkgraaf Gerrit Jan
Published: September 2021

In the Netherlands, concerned citizens have proposed reducing train speed as an effective measure to mitigate annoyance caused by railway-induced vibrations. In the present study the relationship between train speed and other influencing parameters (e.g. axle load, wheel roughness),
and ground vibrations was investigated using measurements, at different locations, of ground vibrations caused by the passage of regular freight trains and a test train at different speeds. Measurements have been analysed using multivariate regression models and a random decision forest model.
The prevailing uncertainties have also been measured using normalized mean deviation between the model predicted value and the actual value. A comparison of results demonstrates that a 'trained and tested' random forest model has certain predictive advantages: i) mean deviation between predicted
and actual value is found to be the lowest with random forest model; ii) the random forest model considers all available parameters in the dataset, thus simulating the real situation more closely. However, the model is very location-specific and must therefore be used with caution. In general
it is observed that a decrease in train speed results in the reduction of measured vibration levels.
Generative Adversarial Neural Network for Unsupervised Bearing Fault Detection
Authors: Kim Gyuwon , Lee Seungchul
Published: September 2021

Detecting bearing faults in advance is critical for mechanical and electrical systems to prevent economic loss and safety hazards. As part of the recent interest in artificial intelligence, deep learning (DL)-based principles have gained much attention in intelligent fault diagnostics
and have mainly been developed in a supervised manner. While these works have shown promising results, several technical setbacks are inherent in a supervised learning setting. Data imbalance is a critical problem as faulty data is scarce in many cases, data labeling is tedious, and unseen
cases of faults cannot be detected in a supervised framework. Herein, a generative adversarial network (GAN) is proposed to achieve unsupervised bearing fault diagnostics by utilizing only the normal data. The proposed method first adopts the short-time Fourier transform (STFT) to convert
the 1-D vibration signals into 2-D time-frequency representations to use as the input to our (DL) framework. Subsequently, a GAN-based latent mapping is constructed using only the normal data, and faulty signals are detected using an anomaly metric comprised of a discriminator error and an
image reconstruction error. The performance of our method is verified using a classic rotating machinery dataset (Case Western Reserve bearing dataset), and the experimental results demonstrate that our method can not only detect the faults but can also cluster the faults in the latent space
with high accuracy.
Reduced order model analysis to identify possible aerodynamic noise sources of small axial fan: POD and CNN
Authors: Obayashi Wataru , Aono H. , Tatsukawa T. , Fujii K. , Takemi K.
Published: September 2021

This paper reports computational analysis of location and strength of sound source of the noise generated by a small axial fan widely used as an air-cooling system. High-fidelity Navier-Stokes simulations with high-resolution compact scheme are conducted with an implicit Large Eddy
Simulation (LES) method on a HPC system and the resultant large-scale data confirms existence of unsteady vortex structures and their interactions around the impellers, boss and casing of the fan. To identify location and strength of the sound sources, reduced order model analysis is conducted
for the distribution of pressure fluctuations in space and time. Snapshot POD (Proper Orthogonal Decomposition) analysis both in time and in circumferential direction, together with conventional FFT analysis, identifies location and strength of the sound sources. In addition, Convolutional
Neural Network (CNN) is attempted, which shows more physical mode decomposition and separates some of the important features shown in the snapshot POD analysis. The study shows that the two data-mining techniques considered here identify possible aerodynamic noise sources of the axial fan
clearly in comparison to those in the previous studies.
Relationship between noise-induced annoyance and age based on data of previous literatures
Authors: Ni Ke , Huang Yu
Published: September 2021

Many studies have investigated subjective responses to noise, but few concerned about the influence of age on the annoyance (discomfort) caused by noise. It is difficult to get a quantitative model featuring the relationship between noise-induced annoyance and age from one or several
laboratory studies due to relatively small samples and limited age groups. This paper investigated recent studies (published after the year 2000) on noise-induced annoyance by the literature review method. We classified the studies according to their employed noise types and summarized the
quantified subjective values and the ranges of age. The quantitative values of annoyance obtained from variable rating scales were transferred to a uniform scale and normalized. A probability density function then figured out the corresponding annoyance of a certain age under the small sample
-distribution assumption. A predicting model of noise-induced annoyance from the age of 7-55 was proposed, which fitted previous data well.
Subjective responses between real impact sound and rubber ball im-pact sound
Authors: Jeong Jeongho
Published: September 2021

By the recent COVID-19 situation, people stay more time in their home and abatements on noise between neighbouring units are increasing. Heavy/soft impact sound is one of the major noise sources in high-rise apartment buildings. Standardized heavy/soft impact source is known for having
the most similar physical and subjective characteristics with real impact sound such as a child running, jumping and an adult walking. The single number quantity on the rubber ball was standardized. A classification scheme for rubber ball impact sound needs to be standardized. Several studies
on subjective responses were conducted on rubber ball impact sound in various situations. In this study, subjective responses on the rubber impact sound and real impact sound were compared. The subjective experiment was conducted in the listening chamber which is furnished similarly to the
typical living room of Korean apartment buildings. In the experiment, rubber ball impact sounds recorded in the real apartment building and real impact sound recorded in the mock-up building were presented through a sub-woofer and multi-channel loudspeaker system. Subjective responses were
collected with an 11 points SD scale.
Experimental study of smart sound absorber using multimode electromechanical coupling control in the low-frequency range
Authors: Liu Xiang , Wang Chunqi , Huang Lixi , Wu Keming
Published: September 2021

To construct a smart sound absorber in the low-frequency range with a wide control band, a piezoelectric ceramic (PZT) shunted with multiple resonance circuit is attached onto a micro-perforated panel (MPP) to perform as a smart sound absorber. The absorption can be controlled by the shunt circuit parameters conveniently. This smart micro-perforated panel (MPP) is investigated experimentally to explore the feasibility and design procedure in practical use. Based on the coupling among the acoustical, electrical, and mechanical fields, the proposed broadband sound absorber can achieve good acoustic performance on subwavelength scales. The electrical response of the shunt circuit is tested with a Network Analyzer. The acoustic performance of the smart sound absorber is measured in an impedance tube with the two-microphone transfer function method. The experimental results validate that the shunt circuit can resonate with the PZT patch at multiple frequencies, and hence improve the sound absorption of the smart absorber at these frequencies.
Progress on consumer and industrial product noise control and technology transfer: summaries of the 2015 and 2016 TQA workshops
Authors: Maling George , Akay Adnan , Wood Eric W.
Published: September 2021

Progress on consumer and industrial products noise reduction, was a Technology for a Quieter America (TQA) workshop and International INCE symposium hosted by the National Academy of Engineering (NAE) held in October 2015 . The workshop consisted of two major parts, consumer products
at home and commercial and industrial products. The former included appliances, waste disposers, leaf blowers, Information Technology Equipment and automotive interior noise. The second half of the workshop included such industrial products as air moving devices, industrial power generation
equipment generator sets, compressor noise, transformer noise and valve plus gear noise. It also included national and international noise emission standards for consumer and industrial products. The technology transfer workshop was hosted by NAE in October 2016. The workshop covered four
areas; an overview of technology transfer in the United States, government programs, technology transfer from universities, and panel discussions on a variety of topics. Government agencies which participated included NASA, the National Science Foundation, the Small Business Administration,
the Federal Aviation Administration, the Office of Naval Research (ONR), and the Naval Research Laboratory.
Monte Carlo method for uncertainty evaluation of noise annoyance prevalence
Authors: d'Avila Villela Ricardo Luís
Published: September 2021

When a decision-making process relies on the information provided by a measurement or simulation result, the right decision demands a good quality result, in other words, a low uncertainty result. In order to establish public policies for environmental noise control, it is essential
to identify the impact of each type of noise pollution (e.g. road, aircraft and rail transportation noise) on the population affected. One of the noise impact metrics that can be used is the number of highly noise annoyed people in a region whose estimated value is obtained from the corresponding
exposure-response function and noise and population density maps. However, an estimated value of the noise impact metric with high uncertainty makes it difficult to realize the actual severity of the problem and its priority in relation to other public health issues. In this work, a Monte
Carlo simulation method is used to assess the uncertainty of a noise impact metric result, namely the number of people highly disturbed by road noise in a city. This article also presents a sensitivity analysis of uncertainty sources that allows quantification of the main uncertainty components,
which supports improvements in noise impact metric results.
Effect of junction type on the vibroacoustic response of a system of plates
Authors: Treszkai Marcell , Feszty Daniel
Published: September 2021

Modelling of junctions is one of the most challenging tasks in vibroacoustics, especially for Statistical Energy Analysis (SEA), where the results heavily depend on the damping (DLF) and coupling loss factors (CLF). Also, it is an interesting question to determine that to what extent
does the DLF or CLF contribute to the overall vibroacoustic characteristics of a structure? The aim of this paper is to investigate via measurements and SEA simulations the effect of the ratio of DLF and CLF on the response of a system for various junctions, such as riveting, bolting, line
and point welding, between two steel plates. Loss matrices are determined experimentally by the Power Injection Method in the 200-1600 Hz frequency range. The simulation was performed in the ESI VA One software by using its analytical CLF formulations and compared to experimental data. For
the reference case, a bended plate structure was considered, representing an ideal junction between two subsystems. This was equipped with damping foils to ensure the same weight and then compared to the results from other joints. Results showed that increasing the CLF could be more effective
than focusing on increasing the DLF.
Use of masks inside the classrooms
Authors: Sukaj Silvana , Trematerra Amelia , Ciaburro Giuseppe , Iannace Gino
Published: September 2021

To counter the transmission of Covid -19 it is mandatory to wear face masks. Medical face masks (surgical or other medical devices) are used to control the spread of infection by reducing the airborne dispersion of the viral load-carrying saliva droplets emitted from the mouth when
talking, sneezing or coughing. The use of the mask can cause fatigue, difficulty in breathing and reduced speech understanding. In school classrooms, the use of masks makes verbal communication very difficult by reducing speech understanding and this can affect both the learning level of pupils
and cause vocal dysfunctions in teachers who incur an overload of the speech apparatus. To investigate the effects of using the mask in learning environments, tests were carried out with pupils of a primary school. The students were given dictations by a teacher according to two configurations:
with and without a mask. Subsequently, the texts written by the children were analyzed to assess the presence of possible errors in the understanding of the dictation administered with and without a mask.
Subjective hearing sensation of process variations at a milling machine. How reliable will chatter marks be detected?
Authors: Trautmann Florian , Knöfel Björn , Drossel Welf-Guntram , Troge Jan , Freund Markus , Penter Lars , Anders Damian
Published: September 2021

Intuition enables experienced machine operators to detect production errors and to identify their specific sources. A prominent example in machining are chatter marks caused by machining vibrations. The operator's assessment, if the process runs stable or not, is not exclusively based
on technical parameters such as rotation frequency, tool diameter, or the number of teeth. Because the human ear is a powerful feature extraction and classification device, this study investigates to what degree the hearing sensation influences the operators decision making. A steel machining
process with a design of experiments (DOE)-based variation of process parameters was conducted on a milling machine. Microphone and acceleration sensors recorded machining vibrations and machine operators documented their hearing sensation via survey sheet. In order to obtain the optimal dataset
for calculating various psychoacoustic characteristics, a principle component analysis was conducted. The subsequent correlation analysis of all sensor data and the operator information suggest that psychoacoustic characteristics such as tonality and loudness are very good indicators of the
process quality perceived by the operator. The results support the application of psychoacoustic technology for machine and process monitoring.
Learning effect of active learning coursework in engineering acoustics course
Authors: Hioka Yusuke , Kingan Michael , Dodd George
Published: September 2021

This paper reports the learning effect achieved by a newly developed coursework for an engineering acoustics course offered to fourth year and postgraduate engineering students at the University of Auckland, New Zealand. The course teaches fundamental knowledge that acoustical engineers need and which underpins a variety of sub-disciplines in acoustics including: fundamental physics of wave propagation, building and room acoustics, electro-acoustics, audio signal processing, and the psychology of hearing. The coursework incorporated practical active learning activities and was developed in order to help students gain understanding of complex concepts related to the room acoustics measurement and analysis. The coursework also has the goal of providing students with an introduction to some of the practical tasks which are typical of a practising acoustical engineering in New Zealand. The learning effect was measured by comparing students' performance in a quiz that was run before students commenced working on the coursework and that in the final examination and by investigating common mistakes students made in the report which was the required deliverable of the coursework. Overall, the new coursework successfully improved students' understanding of the material which it covered.
Development and application of an integrated virtual thermal-acoustic manikin design used inside an office space
Authors: Conceição Eusebio , Conceição Mª Ines , Lúcio Mª Manuela , Gomes João
Published: September 2021

In this study an integrated virtual thermal-acoustic manikin design used inside ventilated and occupied office spaces is developed and applicated. The component of the virtual thermal manikin evaluates the internal airflow and occupants' thermal, thermo-physiology and clothing systems
and calculates the thermal comfort and the indoor air quality levels. The component of the virtual binaural manikin evaluates the direct and indirect sound and calculates the reverberation time. The space geometry with complex topology is developed using a Computer Aid Design (CAD), while
the occupants' geometry is made using geometric equations. The grid generation, in the surrounding space surfaces and around the external occupants' surfaces geometry, is used to calculate the radiative heat exchanges and the sound propagation. In this study, performed in an office room occupied
by eight persons and equipped with personalized ventilation system, the thermal comfort level, the air quality level and the space reverberation time is evaluated and discussed. In accordance with the obtained results the values are, in general, in accordance the actual standards.
An investigation on the methods of noise countermeasures for safeguarding Intangible Cultural Property-Attempt of noise compatibility planning rooted in the local community -
Authors: Ueda Mari
Published: September 2021

In the Ogino area of Atsugi City, where the Kanagawa Institute of Technology is located, Japanese drums are being practiced and the arts are inherited in order to perform at events such as Japanese festivals. It may be reported. Therefore, in Atsugi City, when the main purpose is to
practice Japanese drums, the practice place is restricted, such as not being able to obtain permission to use the facilities of the city. In order to solve such a problem, we performed acoustic measurement of Japanese drums and clarified their acoustic characteristics. It was confirmed that
the sound near the drum due to the repellent impact of the Nagado daiko has a lot of energy even in the low frequency component of 200 Hz or less, and the magnitude of the radiated sound SEL increases as the sound is hit harder. It is also difficult for local governments to take physical noise
countermeasures for membranophones from a cost perspective. Therefore, the ultimate goal of this research was to obtain a solution to the noise problem by social measures to continue the succession activities of traditional musical instruments such as Japanese drums, which are difficult to
take measures against physical noise. Launched and operated a website to understand the current state of noise complaints and to collect the voices of local residents regarding the sound of drums according to the lifestyle and situation of each individual as part of the Noise Compatibility
Planning attempt. We built the system.
Evaluation of additively manufactured stacks for thermo-acoustic devices
Authors: Biswas Samarjith , Krawczyk Zack , Manimala James M.
Published: September 2021

The thermo-acoustic effect provides a means to convert acoustic energy to heat and vice versa without the need for moving parts. This is especially useful to construct mechanically-simple and robust energy harvesting devices, although there are limitations to the power-to-volume ratio achievable. The mechanical and thermal properties as well as geometry of the porous stack that forms a set of acoustic waveguides in thermo-acoustic devices are key to its performance. In this study, we evaluate various additively manufactured polymer stacks against more conventional ceramic stacks using a benchtop thermos-acoustic refrigerator rig that uses air at ambient pressure as its working fluid. Influence of stack parameters such as material, length, location, porosity and pore geometry are examined using experiments and correlated to simulations using DeltaEC, a software tool based on Rott's linear approximation. Structure-performance relationships are established by extracting scaling laws for power-to-volume ratio and frequency-thermal gradient dependencies. It is found that additively manufactured stacks can deliver performance comparable to ceramic stacks while being more affordable and customizable for thermo-acoustic transduction applications.
Impressions and interpretations of vehicle horn sounds with acoustic characteristics of speech
Authors: Takada Masayuki , Goto Kanji
Published: September 2021

In Japan, vehicle horns have been used as a means of communication between drivers, and frequently aroused psychological negative reactions in hearers. If horn sounds have acoustic features of speech, they possibly help communication between drivers, and improve hearers' negative impressions.
To investigate such hypotheses, psychoacoustical experiments were conducted using synthesized horn sounds with acoustic characteristics of Japanese speech "abunai", which implies a dangerous situation. Spectral features and temporal envelopes were extracted from the speech stimulus
and the similar one with swapped syllables, and were reflected in horn sounds. Two experiments were carried out to examine the effects of acoustic characteristics of horn sounds on the perceived quality and interpretations of the intention behind another driver's horn use. Stimuli with spectral
characteristics of the speech and those of swapped syllables were evaluated as being less unpleasant and more safe than the original horn sound. On the other hand, many responses of 'caution' and 'danger' were obtained for the stimulus with spectral characteristics of the speech. Results suggested
that the horn sound with spectral characteristics of the speech improved from the original horn sound in the perceived quality, and correctly communicated the intention behind another driver's horn use.