bluuebunny/crossref_metadata_2025 huggingface dataset:
Head related transfer function measurements of common PPE
Authors: Ewers Megan , Kincaid Sam , Beltman Marco
Published: September 2021

Due to COVID 19, personal protective equipment (PPE) is now used in everyday life. Such PPE affects communication and perception. This paper provides an overview of the impact of PPE on Head Related Transfer Functions (HRTF's). Spatial acoustic effects of common PPE on human hearing
can be documented to improve and inform field worker safety and communication. After a general description of the measurement process and required tools, we focus on a few methods which contribute significantly to the accuracy and analysis of PPE-based HRTF data. The dedicated setup allows
measuring a full 360 degree map in automated fashion. It includes a special ring setup with 25 speakers, and a precise turn table that is used to adjust the angle of the device under test with respect to the ring. Binaural measurements were performed on a set of common PPE items on a Head
And Torso Simulator (HATS) system, including hard hats, safety glasses, hearing protection, and various face masks. An overview of the data is presented.
Study on the effect of separation and reattachment flow between blades on fan noise
Authors: Kosaka Sho , Sakai Masaharu , Sato Hideaki , Seki Kaori
Published: September 2021

With the growth of the EV/HV market, the main cause of cabin noise has changed from engine driving sound to air conditioner noise. The blower noise is the largest in the air conditioner noise, and the noise reduction is urgent. Separated and reattached flows between fan blades are considered
to be the main sources of blower noise. In the past, we tried to reduce the noise by reducing the separation. This time, the blade shape to further reduce the separation was produced and evaluated. As a result, the noise was greatly reduced, but a new problem was found that there was a flow
velocity condition in which the noise increased despite the small separation. Therefore, we visualized the flow between blades by PIV, investigated the state of separated and reattached flow in detail, and investigated the factors related to noise increase and decrease by measuring noise and
pressure fluctuation of blade surface simultaneously. As a result, it was found that the noise generation condition in the separation reattachment flow between blades is not only the size of separation but also the distance of separation shear layer from blade surface and the strength of vortex
generated in shear layer.
Comparative study of loudspeaker position optimization techniques for multizone sound field reproduction
Authors: Zhao Sipei , Zhu Qiaoxi
Published: September 2021

Mutlizone sound field reproduction aims to generate personal sound zones in a shared space with multiple loudspeakers. Conventionally, loudspeakers are placed to form a regular pattern such as circular, arc or linear array, which are empirical rather than optimal mainly for the convenience
of physical placement. Recently, several algorithms have been proposed to select a fixed number of loudspeaker locations from a large set of candidate positions, such as the sparse regularization (i.e. Lasso and Elastic Net) methods, the Constrained Match Pursuit (CMP) method, the Gram-Schmidt
Orthogonalization (GSO) method etc. Most of these methods were investigated for single-zone rather than mulit-zone sound field reproduction based on the pressure matching techniques. This paper compares the performance of the state-of-the-art techniques for loudspeaker position optimization
in a multizone sound field reproduction system in terms of reproduction error, acoustic contrast and array effort. Simulation results demonstrate that the CMP-LS method shows the best performance in terms of lower MSE and higher AC while the Lasso method needs the lowest AE.
Joint modeling for the analytical estimation of dynamic behaviors of beam-coupled structures
Authors: Park Hansol , Kang Yeon June , Pyo Hee Soo
Published: September 2021

In this study, analytical method is applied for the estimation of dynamic behaviors of beam-coupled structures. Mathematical expressions are given with terms of shape factors, material information and assembly angles of each sub-component. Based on Euler-Bernoulli beam theory, entire
formulation is built with compatibility of system dynamics. The coupled structures are divided into two types, point coupling and mass coupling, related with the properties of coupling points. Point coupling is commonly used assumption that two sub-components are combined with lumped spring
or damping, and mass coupling has undeformable rigid joint which has mass and inertia like welded structures. Dynamic properties of coupled structures are predicted in forms of frequency response functions and spectral responses about given forces. The verification process is conducted for
assessing the accuracy of the estimation formula by using modal frequencies and mode shapes of beam-coupled structures. Extracted modal parameters from experimental modal analysis and finite element method are adopted as reference values for verification.
Subtractive modeling using the reverse condensed transfer function method: influence of the numerical errors
Authors: Dumortier Florent , Maxit Laurent , Meyer Valentin
Published: September 2021

Decoupling procedures based on substructuring methods allow to predict the vibroacoustic behaviour of a given system by removing a part of an original system that can be easily modelled. The reverse Condensed Transfer Function (rCTF) method has been developed to decouple acoustical
or mechanical subsystems that are coupled along lines or surfaces. From the so-called condensed transfer functions (CTFs) of the original system and of the removing part, the behaviour of the system of interest can be predicted. The theoretical framework as well as a numerical validation have
been recently published. In the present paper, we focus on the influence of numerical errors on the results of the rCTF method, when the CTFs are calculated using numerical models for the original system and/or the removed part. The rCTF method is applied to a test case consisting in the scattering
problem of a rigid sphere in an infinite water domain and impacted by an acoustic plane wave. Discrete green formulation and finite element method are used to estimate the CTFs. Numerical results will be presented in order to evaluate the sensitivity of the method to model errors and the potential
promises and limitations of the method will be highlighted.
CNN-based multi-class multi-label classification of sound scenes in the context of wind turbine sound emission measurements
Authors: Poschadel Nils , Gill Christian , Preihs Stephan , Peissig Jürgen
Published: September 2021

Within the scope of the interdisciplinary project WEA-Akzeptanz, measurements of the sound emission of wind turbines were carried out at the Leibniz University Hannover. Due to the environment there are interfering components (e. g. traffic, birdsong, wind, rain, ...) in the recorded
signals. Depending on the subsequent signal processing and analysis, it may be necessary to identify sections with the raw sound of a wind turbine, recordings with the purest possible background noise or even a specific combination of interfering noises. Due to the amount of data, a manual
classification of the audio signals is usually not feasible and an automated classification becomes necessary. In this paper, we extend our previously proposed multi-class single-label classification model to a multi-class multi-label model, which reflects the real-world acoustic conditions
around wind turbines more accurately and allows for finer-grained evaluations. We first provide a short overview of the data acquisition and the dataset. We then briefly summarize our previous approach, extend it to a multi-class multi-label formulation, and analyze the trained convolutional
neural network regarding different metrics. All in all, the model delivers very reliable classification results with an overall example-based F1-score of about 80 % for a multi-label classification of 12 classes.
Variance Quantification of Different Additive Manufacturing Processes for Acoustic Meta Materials
Authors: Bopp Manuel , Joerger Arn , Behrendt Matthias , Albers Albert
Published: September 2021

Many concepts for acoustic meta materials rely on additive manufacturing techniques. Depending on the production process and material of choice, different levels of precision and repeatability can be achieved. In addition, different materials have different mechanical properties, many
of which are frequency dependent and cannot easily be measured directly. In this contribution the authors have designed different resonator elements, which have been manufactured utilizing Fused Filament Fabrication with ABSplus and PLA, as well as PolyJet Fabrication with VeroWhitePlus. All
structures are computed in FEA to obtain the calculated Eigenfrequencies and mode shapes, with the respective literature values for each material. Furthermore, the dynamic behavior of multiple instances of each structure is measured utilizing a 3D-Laser-Scanning Vibrometer under shaker excitation,
to obtain the actual Eigenfrequencies and mode shapes. The results are then analyzed in regards to variance between different print instances, and in regards to accordance between measured and calculated results. Based on previous work and this analysis the parameters of the FEA models are
updated to improve the result quality.
Experimental sound power from curved plates using the radiation resistance matrix and a scanning vibrometer
Authors: Bates Trent , Bacon Ian C. , Goates Caleb B. , Sommerfeldt Scott D.
Published: September 2021

Vibration-based sound power (VBSP) methods based on elemental radiators and measurements from a scanning vibrometer have been shown to be accurate for flat plates and cylinders. In this paper, the VBSP method is extended to account for simple curved structures, with a constant radius
of curvature. Data are also presented that suggest the VBSP method is more accurate than the ISO 3741 standard for measuring sound power when significant background noise is present. Experimental results from ISO 3741 and the VBSP methods are compared for three simple curved plate structures
with different radii of curvature. The results show good agreement for all three structures over a wide frequency range. The experimental results also indicate that the VBSP method is more accurate in the low frequency range where the curved plates radiated relatively little and significant
background noise was present.
Acoustic decoupling for structural elements by affixed supports - inherent contradiction or perfect complement? Restrained vibration isolation supports - a critical review
Authors: Wells Adam , Carels Patrick
Published: September 2021

Restrained vibration isolation supports balance efficient isolation performance and stability for the supporting body under present loads. Necessary and beneficially for noise and vibration isolation applications with stringent stability requirements, such as full building isolation
with potential uplift, interior partition sway bracing, curtain walls, elevator rail isolation, and mechanical vibration isolation, the performance of restrained vibration isolators are often misunderstood or oversimplified. This paper investigates the general vibration isolation theory used
to create the analytical model for restrained isolation supports, intricacies of vibration isolation materials which may cause reality to diverge from well-known models, comparison of theory to laboratory testing, and a review of common uses/applications for these types of vibration isolation
solutions, and recommendation to avoid undesired results from common pitfalls associated with restrained isolation supports implementation and installations.
Active Noise Control Algorithm with Saturated Actuator
Authors: Lee Hakjun , Park Youngjin
Published: September 2021

Active noise control system has received its attention in various technical field such as headphone, motor vehicle, etc. Meanwhile, filtered-x least mean square (FxLMS) algorithm is conventional linear algorithm used in active noise control system. It assumes that acoustic path from
the noise source and control source to target area are linear. However, in actual system, the secondary path including a D/A converter, an amplifier, and an actuator may exhibits nonlinear distortion like saturation effects. To cope with this nonlinear effects, functional link artificial neural
network (FLANN) has been proposed. FLANN uses nonlinear function expansion filter with FxLMS based control algorithm to control the nonlinear effect. In this paper, noise reduction performance and convergence speed are improved by modifying the conventional FLANN algorithm by decoupling the
linear and nonlinear part of noise signal.
Comparison of Noise Reduction Performance Evaluation Methods for Low-Noise Pavement in Korea- Part
Authors: Kim Byungchae , Kim Hyunjin , Kang Wonuk
Published: September 2021

In Korea, road noise is assessed as a measurement method of exterior noise emitted by road vehicle for management standards by the National Institute of Environmental Sciences. In this method, the noise felt at the actual pickup point is measured as LAeq (the roadside equivalent noise
level). Recently, to clarify the standard for measuring noise on low-noise pavements, the CPX (ISO11819-2; Close-proximity method) was first introduced in the Porous Pavement Guidelines of the Ministry of Land, Infrastructure and Transport. According to ISO, the CPX adopts the side microphone
as a mandatory measurement location, and the rear optional. The side location has been a mandatory due to its high correlation with SPB (ISO 11819-1, Statistical Pass-by method). However, according to our previous study on the correlation evaluation between L and CPX rear microphone noise
level, both noise reduction effect was about 9-12 dB(A) showed a high correlation in Korea where heavy road traffic is common. The following study aims to show the consistent correlation between the L and CPX rear noise level. Furthermore, it is intended to be helpful in selecting the location
of the CPX microphone that can most effectively represent the actual noise on the low-noise pavement in Korea.
Merging science education, citizen science and general population noise exposure data collection in the battle against noise pollution
Authors: Dekoninck Luc , Van Beggenhout Wim , Sterken Mieke
Published: September 2021

Science, Technology, Engineering, Mathematics in education is commonly referred to as STEM. The last decades illustrate that our society is transferring into an ever accelerating technological environment. In parallel, the general public became an important driving force in collecting
citizen science data to trigger legislative pressure and impact on policy makers to accelerate the improvement of their quality of life. That practice is currently extending into the environmental impact of noise related quality of life. This publication suggests to merge those educational
STEM goals, citizen science monitoring and the need for population based noise monitoring data for efficient policy support. The presented educational project can be regarded as a proof-of-concept and can be repeated in different schools and classes every year. This approach has the potential
to acquire abundant noise monitoring data and provides an unbiased population sampling dataset by design. This population driven involvement allows to assess real-life and long-term noise policy impact and could become a fundamental pillar in achieving the overall societal goal of improving
noise related environmental quality of life.
Cardiovascular mortality and transportation noise: a prospective Swiss cohort study
Authors: Vienneau Danielle , Flückiger Benjamin , Saucy Apolline , Tangermann Louise , Schäffer Beat , Wunderli Jean Marc , Röösli Martin
Published: September 2021

Transportation noise from road, rail and air traffic can be detrimental to health and wellbeing. Previous studies, including our own, have shown death from specific cardiovascular diseases (CVD) to be associated with these exposures. Now, with 15 years of follow-up, integrated address
history and noise exposure data for multiple years corresponding to census decades, we conducted an extended analysis of the Swiss National Cohort. Mean exposure in 5-year periods were calculated, and three virtual sub-cohorts were defined (2001-2006, etc.) in addition to the full cohort (2001-2015).
Multi-pollutant (Lden_road, Lden_rail, Lden_air), time dependent Cox proportional hazards models were applied to 4.14 million adults and adjusted for potential confounders and PM2.5. During the 15-year follow-up, there were 277,506 CVD and 34,200 myocardial infarction (MI) deaths. In the full
cohort, there was an increased risk of death for road traffic (1.029 [1.024−1.034] CVD; 1.043 [1.029−1.058] MI per 10dB), railway (1.013 [1.010−1.017] CVD; 1.020 [1.010−1.030] MI) and aircraft noise (1.040 [1.020−1.060] MI). For road traffic noise, Hazard ratios
(HR) were higher in males vs. females and in younger vs. older age groups. HRs were also remarkably consistent with our previous analysis with follow-up until 2008, and were relatively similar across the three virtual sub-cohorts.
Optimization of 3D printed porous materials accounting for manufacturing defects
Authors: Boulvert Jean , Cavalieri Théo , Romero-García Vicente , Gabard Gwénaël , Groby Jean-Philippe
Published: September 2021

Open-cell materials are well-known for their low price, low weight, and broadband acoustic behavior. They form one of the most used class of acoustic treatments but suffer from a lack of versatility when made by conventional manufacturing processes. Recent advances in additive manufacturing
allow to produce porous materials having a controlled microstructure. In this way, the design of treatments including porous materials is not limited to a catalog of existing media. The macroscopic behavior is governed by the micro-geometry of the porous medium, which can be estimated by numerical
models. Then, acoustic treatments can be optimized numerically using predicting models and minimization algorithms. However, additive manufacturing induces defects often too complex to be accounted for numerically. In this presentation, a method allowing to obtain the parametric model of the
intrinsic behavior of a 3D-printed porous material is presented. The corrected model is used in the optimization of several porous treatments; namely, graded porous materials, folded porous materials and metaporous surfaces. These treatments are versatile and display remarkable properties.
They provide quasi-perfect absorption at several frequencies that can be out of reach of standard porous treatments in normal or oblique incidence. Experimental validations confirm the relevance of the proposed design processes.
A flow and acoustic facility for characterization of liner and meta-acoustic surfaces under grazing flow condition
Authors: Yi Wei , Guo Jingwen , Fang Yi , Qu Renhao , Zhong Siyang , Zhang Xin
Published: September 2021

The Hong Kong University of Science and Technology (HKUST) has designed and assembled a new facility, a grazing flow tube, for aeroacoustic characteristics measurement of acoustic liners, e.g. transmission loss, impedance, etc., under a high-speed grazing flow. The cross-section of
the test section of the tube has a dimension of 50 mm × 50 mm, and the grazing flow speed can be up to 0.3 Ma. A settling chamber, a long-enough flow development section and a multi-stage anechoic termination are adopted to ensure the high-quality flow field and acoustic field. This
paper presents the detailed designs of the key components of the facility, as well as the calibrations of the velocity profile in a series of cross-section surfaces of the duct along the streamwise direction and sound pressure distributions in the axial and circumferential directions. Pitot
tube, Hotwire and PIV are used to obtain the flow field measurement results. The overall performance of the diagnostic facility is verified by comparing the impedance results of acoustic liners acquired from an impedance tube under the static condition and the theoretical variation of axial
wavenumber with Ma number under the grazing flow.
Explainable machine learning: A case study on impedance tube measurements
Authors: Stender Merten , Wedler Mathies , Hoffmann Norbert , Adams Christian
Published: September 2021

Machine learning (ML) techniques allow for finding hidden patterns and signatures in data. Currently, these methods are gaining increased interest in engineering in general and in vibroacoustics in particular. Although ML methods are successfully applied, it is hardly understood how
these black box-type methods make their decisions. Explainable machine learning aims at overcoming this issue by deepening the understanding of the decision-making process through perturbation-based model diagnosis. This paper introduces machine learning methods and reviews recent techniques
for explainability and interpretability. These methods are exemplified on sound absorption coefficient spectra of one sound absorbing foam material measured in an impedance tube. Variances of the absorption coefficient measurements as a function of the specimen thickness and the operator are
modeled by univariate and multivariate machine learning models. In order to identify the driving patterns, i.e. how and in which frequency regime the measurements are affected by the setup specifications, Shapley additive explanations are derived for the ML models. It is demonstrated how explaining
machine learning models can be used to discover and express complicated relations in experimental data, thereby paving the way to novel knowledge discovery strategies in evidence-based modeling.
Audio recording analysis in an urban park of the city of Milan (Italy)
Authors: Benocci Roberto , Bisceglie Alessandro , Angelini Fabio , Zambon Giovanni , Brambilla Giovanni , Roman H. Eduardo
Published: September 2021

A noise monitoring campaign has been performed in an urban park of Milan (Italy) called Parco Nord. The area of study is a large peri-urban park in the northern part of the city, characterized by wooded land rich in biodiversity and exposed to different sources and degrees of anthropogenic disturbances, such as road traffic noise and artificial light. The acoustic environment is rather complex due to the contemporary presence of different noise sources, leading to the difficult task of discriminating them in audio data. Due to these multifactorial characteristics, we evaluated different eco-acoustic indices in the attempt to derive a methodology to evaluate the potential of sound ecology indicators to discriminate the different types of sounds present in medium-large urban parks. Time series of about two-week recordings have been transformed into eco-acoustics indices and statistically analysed. The results show a redistribution of recordings into each cluster associated with different sound components and different period of the day. This allowed the identification of different degree of biophonic and/or anthropogenic activities throughout the day.
Partial discharge monitoring using deep neural networks with acoustic emission
Authors: Gourishetti Saichand , Johnson David , Werner Sara , Kátai András , Holstein Peter
Published: September 2021

The occurrence of partial discharge (PD) indicates failures in electrical equipment. Depending on the equipment and operating conditions, each type of PD has its own acoustic characteristics and a wide frequency spectrum. To detect PD, electrical equipment is often monitored using various
sensors, such as microphones, ultrasonic, and transient-earth voltage, whose signals are then analyzed manually by experts using signal processing techniques. This process requires significant expertise and time, both of which are costly. Advancements in machine learning, aim to address this
issue by automatically learning a representation of the signal, minimizing the need for expert analysis. To this end, we propose a deep learning-based solution for the automatic detection of PD using airborne sound emission in the audible to the ultrasonic range. As input to our proposed model,
we evaluate common time-frequency representations of the acoustic signal, such as short-time Fourier, continuous wavelet transform and Mel spectrograms. The extracted spectrum from the PD signal pulses is used to train and evaluate the proposed deep neural network models for the detection
of different types of PD. Compared to the manual process, the automatic solution is seen as beneficial for maintenance processes and measurement technology.
Case Study: Floating Jack-Up Slabs for Multi-Story Cinema in Manhattan
Authors: Hunt Bradlay , Sassmannshausen Florian
Published: September 2021

A review of a uniquely designed floated jack-up concrete slab to isolate fourteen movie theaters on multiple floors within a multi-use building. The jack-up boxes were engineered and custom tailored to increase airborne sound transmission loss performance while achieving a very high
vibration isolation efficiency specified. Field test results were obtained to validate the floating jack-up concrete's acoustical performance.
Acoustic survey at Genova (Italy) Aquarium aiming at characterizing the acoustic of tropical marine environment
Authors: Zambon Giovanni , Bisceglie Alessandro , Confalonieri Chiara , Lavorano Silvia , Benocci Roberto
Published: September 2021

An acoustics survey has been performed at Genova (Italy) Aquarium aiming at characterizing the acoustic environment of tropical underwater habitats. Mid-term (5-7 days) and short-term measurements (10-20 min) within different fish tanks containing tropical habitats have been chosen
for a preliminary analysis. Eco-acoustic indices and statistical-related acoustic indices have been applied to derive information on the population activity and determine the bio-acoustic richness. Such approach will be used to compare environments with different degree of disturbance and
derive information on the environmental quality of both artificial and natural habitats
Performance evaluation on multi-channel Wiener filter based speech enhancement for unmanned aerial vehicles recordings
Authors: Li Yameizhen , Yen Benjamin , Hioka Yusuke
Published: September 2021

Recording speech from unmanned aerial vehicles has been attracting interest due to its broad application including filming, search and rescue, and surveillance. One of the challenges in this problem is the quality of the speech recorded due to contamination by various interfering noise. In particular, noise contamination due to those radiated by the unmanned aerial vehicles rotors significantly impacts the overall quality of the audio recordings. Multi-channel Wiener filter has been a commonly used technique for speech enhancement because of its robustness under practical setup. Existing studies have also utilised such techniques in speech enhancement for unmanned aerial vehicle recordings, such as the well-known beamformer with postfiltering framework. However, many variants of the multi-channel Wiener filter have also been developed over recent years such as the speech distortion weighted multi-channel Wiener filter. To address these recent advancements, in this study we compare the performance of these variants of techniques. In particular, we explore the benefits these techniques may bring forth in the setting of audio recordings from an unmanned aerial vehicle.
Characterizing noise barriers: SOPRANOISE half-term progress report
Authors: Clairbois Jean-Pierre , Garai Massimo , Bartolomaeus Wolfram , Chudalla Michael , Strigari Fabio , Conter Marco , Fuchs Andreas
Published: September 2021

SOPRANOISE targets simplified assessment of the in-situ intrinsic acoustic performances of road / railway noise barriers. This paper presents its half-term progress. The research is divided in 5 Work Packages, the scientific ones being WP2 to WP5.WP2 is about establishing a state of
art (SoA) of the intrinsic performances characterization: it is now finished and presented in 2 other papers by Conter and Fuchs. WP3 is about in-situ inspection tools: based on a review / questionnaire, an inspection protocol has been developed allowing simplified assessments mainly based
on visual inspections and characterization of possible defects; WP3 is now in its final testing phase. WP4 is about designing a brand new "quick and safe methods" that could take place "in between" the inspection tools and the standardized EN1793-5 and 6; the research and
development phases of WP4 are now finished, while its validation along highways is now scheduled. Finally, WP5 is about the use of noise barriers in the European market and the final report: a synthesis on the physical behavior of noise barriers and the physical significance of the test methods
has been done, as well a SoA on the effective use of noise barriers; the results will be presented.
Effect of sound source movement at low Mach number on radiated noise level
Authors: Makino Yusuke , Takano Yasushi
Published: September 2021

Change in A-weighted sound pressure level or Noise level of radiated sound due to sound sources moving at low Mach number at the same speed along a straight track is discussed in this paper. When a sound source move, frequency and amplitude modulation is observed in the radiated sound
field. Without their modulation, the noise level at a receiving point is determined only by distance and A-weighted sound power level of each sources. Solution of modulated frequency and amplitude of radiated sound can be obtained by using the Duhamel's efficient calculation. The modulated
frequency and amplitude increase for approaching sources and decrease for receding sources. The difference of maximum noise level,and the equivalent sound level during the sources passing-by, with or without considering the modulation, increases monotonically with respect to source velocity,
and independent of distance from the track. This difference increases as dominant frequency band of the sources decreases due to A-weighting below 1 kHz.
Assessment of digital image correlation vibrometry in the presence of thermal flow disturbance
Authors: Homma Kenji , Braunwart Paul R. , Clavette Patrick L.
Published: September 2021

Digital Image Correlation (DIC) is an image-based method for measuring displacement and/or stain on the surface of a structure. When coupled with a stereo pair of highspeed cameras, DIC can also capture three-dimensional dynamic deformation of a structure under vibratory loading. However,
high frequency and small amplitude displacement typically associated with structural vibrations mean that extra care is required during measurement and data processing. It becomes more challenging when thermal disturbances are present in the optical path, for example from a heated air flow,
which introduces extraneous noise due to disturbances in the refractive index. In the present study, a simple composite plate was vibrated under a shaker excitation and stereo DIC measurements were performed. The obtained vibratory displacement results were compared against accelerometers
and a laser Doppler vibrometer. Heated air flow was introduced in front of the plate to observe the effects of thermal disturbances on the DIC measurements. Although the contributions from the thermal disturbances were clearly visible in the DIC displacement data, it was shown that the vibratory
deflections of the structure could still be extracted by post processing of the DIC data.
Gauge repeatability and reproducibility study of airborne sound isolation measurements
Authors: Dong Wayland , Wong Devin , LoVerde John
Published: September 2021

A gauge repeatability and reproducibility study (GRR) uses analysis of variations (ANOVA) on an appropriately designed experiment to separate and quantify the components of the overall uncertainty. The authors have previously presented results of GRR studies of the measurement of airborne
and impact insulation of floor-ceiling and demising wall assemblies in several apartment buildings, in which the uncertainty in the measurement method and the variability of the nominally-identical assemblies were compared. The results of two additional GRR studies on measurements of airborne
noise isolation of wood stud demising walls are presented. The first study, like previous studies, evaluates the components of variance attributable to operator, repeatability, and part. The second study uses a fixed operator and part, and evaluates the variance due to loudspeaker type, position,
and level on the measured noise reduction. The measurement standard (ASTM E336) gives limited guidance on the type and location of the loudspeaker used on the source side, and this study can inform whether changes in the standard with regards to the loudspeakers could reduce the uncertainty
in measurement.
Optimization of metamaterials with complex neck shapes for aircraft cabin noise improvement
Authors: Kone Tenon Charly , Ghinet Sebastian , Panneton Raymond , Grewa Anant
Published: September 2021

More frequently, recent low-frequency noise control techniques commonly implemented in aerospace and ground transportation as well as in building applications are based on acoustic metamaterial concepts. The technologies proposed in the literature, using layered porous materials with
embedded Helmholtz resonators (HR), exhibited considerable potential when tuned at tonal, multi-tonal or narrow frequency bands. Our recent investigations have shown that the acoustical performance of these metamaterials can be further improved by the use of resonators with complex shaped
necks. These necks can be designed and optimized to minimize the HR resonance frequencies (small form factor) and maximize the sound transmission loss (STL) performance. This paper presents the developed design optimization method for HRs with complex neck shapes recessed within the HR cavity.
The HRs were embedded in a layer of porous material. The implemented approach was based on the transfer matrix methods (TMM) in series and in parallel coupled to a multi-objective optimization. Complex optimum neck shapes were obtained allowing for a shift towards the low frequencies of the
resonator resonance with a good STL performance. Moreover the STL calculated using the TMM approach were observed to be in excellent agreement with the finite element method numerical results.
Metamaterial plate with an arrangement of different resonators
Authors: Pisicchio Zanoni Giovanna , Serpa Alberto Luiz
Published: September 2021

Local resonant metamaterials have been widely studied for vibration suppression in the last 20 years. They produce band gaps, which are frequency regions where the wave is not allowed to propagate. They are an alternative to reduce vibration levels at lower frequencies when compared
to phononic crystals, which require larger periodic cells to create band gaps at lower frequencies. The most common configuration for a local resonant metamaterial is a periodic cell of a known structure with one attached resonator. In this study, a plate with a periodic cell using two different
resonators is analyzed. Some configurations of mass and stiffness for the two resonators will be discussed to pursue the best compromise between a wider band gap and a more considerable vibration attenuation. The dispersion relation for the proposed metamaterial unit cell will be calculated
using the Wave Finite Element Method to evaluate these configurations. The frequency response function for a finite structure with the proposed arrangement will also be calculated using the Finite Element Method to compare the results.
Broadband noise mitigation using coupled Helmholtz resonators: a numerical study
Authors: Krasikova Mariia , Melnikov Anton , Krasikov Sergei , Baloshin Yuri , Slobozhanyuk Alexey , Marburg Steffen , Powell David , Bogdanov Andrey
Published: September 2021

In this work we investigate a periodic structure in the frequency range from 20 Hz to 5500 Hz designed for broadband noise insulation. The considered unit cell consists of a simple structure: a pair of polymer pipes with slits carved along the axes, representing two coupled Helmholtz resonators. In order to develop a design with a broad band gap, we analyze the eigenmodes of the infinite two-dimensional structure considering their symmetry and interaction. This analysis is supported by parametric optimization of the resonator geometry. The obtained band diagram is compared with numerically determined transmission coefficient of a finite structure based on the same unit cell. The number of unit cells of the finite structure is chosen to be sufficient for demonstration of insulating properties and stop band formation. Furthermore, we analyze how the transmission coefficient is linked to the pressure field distribution inside the resonators. Owing to the simplicity of the geometry, the obtained results may become a basis for development of budget-friendly passive systems for broadband noise insulation within the audible range of frequencies.
The impact of the cracks in the window
Authors: Ávila Ferreira Vinícius , de Moraes Edison Claro
Published: September 2021

When we talk about the acoustic insulation performance of a building facade, we know that its weakest link is the frame that makes it up. We soon know that great performance on the part of this component is necessary so that the facade assembly can obtain high levels of insulation.
Although there are several lines and models of frames, each with two unique characteristics and varied acoustic performance, they have a similarity in their result curve. where at high frequencies it becomes a decisive point for your result. In this work, we will analyze the vulnerable points
of a typology of mitering, focusing on its cracks and the impact that each one has on its result; as well as measures that can be taken so that the frame can acquire great acoustic performance, without changing the profile lines or glass thickness.
Impact of lamination on acoustic performance
Authors: Ávila Ferreira Vinícius
Published: September 2021

When we speak of laminated glass, it has several variations of lamination. either increasing the number of laminations between glasses or the thickness of the lamination. But how much does this really impact your acoustic performance? In this work we will analyze different types of
lamination and understand the difference in the performance curve of each one and how much this impacts on its result, whether global or at a certain frequency.
Occupant noise exposure in a fitness classroom setting
Authors: Didier Madeline , Jarta Gina
Published: September 2021

Fitness facilities characteristically place an emphasis on the health and wellness of their occupants. Very loud amplified speech and music in group fitness rooms creates energetic spaces at the expense of the health and wellness of participants' hearing. The authors measured spectral
sound pressure levels from fitness programs and occupants in over 20 group fitness classes (cycling, dance, strength training, and yoga) at facilities throughout the United States. Measurements occurred over durations varying from 10 minutes to a full hour. Variables considered include class
type and the athletic club where the classroom is located. This paper discusses the overall findings from these noise surveys with an emphasis on noise exposure and statistical levels. This paper also includes a discussion of noise management and recommendations for best management practices
to help achieve energetic spaces that are protective of hearing health and wellness.
A multibody dynamic model for predicting operational load spectra of dual clutch transmissions
Authors: Ozdemir Enes Timur , Sarikaya Bahadir , Inalpolat Murat , Lee Hyun Ku , Kim Moo Suk
Published: September 2021

In this paper, a generalized nonlinear time-varying multibody dynamic model of dual clutch transmissions (DCT) is presented. The model consists of clutches, shafts, gears and synchronizers, and can be used to model any DCT architecture. A nonlinear clutch model is used to determine
the transmitted power to the transmission at any speed and clutch temperature. The clutch can be a single- or multi-plate clutch and can operate in a wet or dry-clutch configuration. A combined kinematic and powerflow simulation enables calculation of gear, shaft, bearing and clutch quasi-static
loads as well as gear mesh frequencies following a duty cycle as the input. For the corresponding Linear-Time-Invariant (LTI) system model, natural frequencies and mode shapes are obtained by solving the eigenvalue problem. The modal summation technique is used to determine the steady state
forced vibration response of the system. For the corresponding NTV system, Newmark's time-step marching based integration is used to determine both the steady state and transient forced vibration response of the system. The DCT model is exercised using a common transmission architecture operating
at several different operating conditions. The resulting impact of changing operational conditions on gear and bearing loads as well as dynamic transmission error spectra are demonstrated.
Broadband sound absorbers of multilayered micro-slit panels using Bayesian probabilistic inference
Authors: Hoeft Michael , Fackler Cameron J. , Xiang Ning
Published: September 2021

Micro-perforated panel absorbers can typically achieve either visual transparency or broadband absorption, but not both. This paper assesses the potential of Multilayer Micro-Slit panels to maintain both of these characteristics simultaneously. Micro-slit panels are similar to micro-perforated
panels, and can similarly achieve high absorption coefficients without fibrous backing materials. The arrangement of slits are better suited to visual transparency than perforated holes because it provides more unobstructed panel per perforated area. However, these types of absorbers are limited
to a narrow frequency bandwidth of effective absorption. By combining several panels into a multilayer assembly, broadband absorption becomes possible. The inherent complexity stemming from optimizing the parameters for multiple layers to meet a given design criteria necessitates the use of
the Bayesian framework. This probabilistic method rapidly hones in on the best parameters of each individual layer so that the overall composite meets the design goal. Furthermore, Bayesian inference implemented cyclically alongside panel fabrication and testing allows for corrections of fabrication
tolerances while assessing visual transparency.
Societal obstacles to Selling and Buying Quiet
Authors: Nelson David
Published: September 2021

The desire for a quieter environment, office, or workplace is nearly universal. The technology exists to accurately measure noise emission and estimate the health, functional, and financial impacts on hearing conservation, speech interference, and residential or workplace comfort. Several
useful methods for labelling of noise emission have been proposed over the years. Government regulations for certain classes of equipment are already in place in some countries. Why then after several decades of concerted effort is "Selling and Buying Quiet" not commonplace? It may
be that the fault lies neither with the quality of the engineering work nor the existence or lack of regulation. Instead, a complex of societal factors including confusion, misinformation, denial, and cognitive dissonance effectively undercut any program. This paper will discuss the societal
factors opposing the success of "Selling and Buying Quiet", as experienced by the author, along with some possible approaches for increasing the recognition of noise control engineering in the future.
Passive control of the flow-induced noise from a rectangular cylinder using porous walls
Authors: Nishikawa Reon
Published: September 2021

A noise reducing technique for the flow-induced noise using a porous material was studied experimentally and numerically. In the experiment, flow-induced noises emitted from three types of rectangular cylinders were measured in a low-noise wind tunnel. One cylinder was made of four
aluminum plates and others were made of two or three aluminum plates. Measurement results show that the frequency of the distinct tonal noise was different among three cylinders, that frequency was higher for using porous material. It was also found that the sound pressure lelvel of the noise
was also different and that of the cylinder using two porous material plates was 25 dB smaller at maximum. Velocity field of the wake of cylinders were examined by the PIV measurement and that showed that time and space scale of separated vortices around cylinder were smaller for using two
porous material plates. It is assumed that the change of aerodynamic sound was caused by that change in velocity field. In the numerical simulation, we could simulate changes of the emitted noise and the wake of the cylinder by applying the slip boundary condition of the velocity to the wall
of the cylinder.
The effects of acoustical ceiling panel type and penetrations for services on vertical sound isolation inside buildings
Authors: Madaras Gary
Published: September 2021

Attenuation of sound transmitting between rooms oriented over one another inside buildings is studied. Transmission loss and sound transmission class were measured by an independent, accredited, acoustics laboratory with and without a variety of modular acoustic ceilings suspended under
a baseline concrete floor structure. Ceiling panel material types include stone wool, fiberglass and mineral fiber. Ceilings were tested with and without the presence of service penetrations for supply air diffusers, return air grilles and light fixtures. Some ceilings were also scanned with
a sound intensity probe and the resulting color sound maps are used as a supplemental method of evaluating both isolation and absorption performance of the individual components of the ceiling systems. Results show that while the effects of ceiling panel type on absorption performance, and
thus room acoustics, is substantial, the material type and weight of the ceiling panels do not substantially affect the overall isolation performance of the floor-ceiling assembly.
Elastic wave propagation in metamaterial rods with periodic shunted piezo-patches
Authors: Miranda Edson J.P. de , Nobrega Edilson D. , Oliveira Leopoldo P.R. de , Dos Santos José M.C.
Published: September 2021

The wave propagation attenuation in low frequencies by using piezoelectric elastic metamaterials has been developed in recent years. These piezoelectric structures exhibit abnormal properties, different from those found in nature, through the artificial design of the topology or exploring
the shunt circuit parameters. In this study, the wave propagation in a 1-D elastic metamaterial rod with periodic arrays of shunted piezo-patches is investigated. This piezoelectric metamaterial rod is capable of filtering the propagation of longitudinal elastic waves over a specified range
of frequency, called band gaps. The complex dispersion diagrams are obtained by the extended plane wave expansion (EPWE) and wave finite element (WFE) approaches. The comparison between these methods shows good agreement. The Bragg-type and locally resonant band gaps are opened up. The shunt
circuits influence significantly the propagating and the evanescent modes. The results can be used for elastic wave attenuation using piezoelectric periodic structures.