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The article deals with the actual problem of non-destructive quality control of products and semi-finished products of transport engineering by the method of acoustic emission. The results of evaluating the possibility of applying the method to control castings from titanium alloys are given, and positive results are obtained. The results of a comprehensive study of the dependence of the parameters of acoustic emission signals with the quality of elastic elements for critical purposes are presented. The results obtained unambiguously confirm the relationship between the signal parameters and the state of the microstructure of the material of the elastic element, and, as a consequence, its operational resistance. [ABSTRACT FROM AUTHOR]

Sound package development in the transportation industry has taken a very different role in the past two decades. Instead of relying totally on measurements, acoustic engineers are relying on various numerical methods to characterize the acoustic performance of materials as well as predicting the interior noise levels and other products in the transportation industry. In doing these analyses, often one needs some measured data of different variables such as thickness and airflow resistance properties of an insulation material, and insertion loss properties of materials used for sound blocking purposes. This paper presents an overview of different standards and specifications that are often followed to measure and estimate these required input values. Results obtained using different methods are not always comparable with each other and therefore have the potential to obtain an incorrect conclusion. The paper provides some case studies of inconsistent results because of that. [ABSTRACT FROM AUTHOR]

As acoustical engineers, we are often asked to develop community noise-related guidelines, regulations, laws, ordinances, and project specifications. This paper will describe the ingredients needed to develop a robust and defensible construction noise specification that is both enforceable and effective. It will be based on the author's past and current experiences developing such specifications, including those used for the Big Dig project in Boston, FHWA's construction noise handbook, the New York City construction noise regulation, as well as dozens of large-scale construction projects across the country. The goals of proactive and reactive noise control and the difference between a performance-based versus a prescriptive-based specification will be explained, community noise criteria will be suggested, and examples will be provided for important clauses in such a specification. Lastly, a listing of "lessons learned" over the decades are provided. [ABSTRACT FROM AUTHOR]

The initial construction cost of barriers has led to considerable interest by local Transportation agencies and the Federal Highway Administration (FHWA) to assess alternatives such as short noise barriers. Many agencies have found that the utilization of short concrete safety barriers as a noise mitigation strategy is highly beneficial. However, not much evaluation data is available to satisfy the FHWA noise requirements or to satisfy the Noise Reduction Design Goal [1]. This paper presents a review of the utilization of short concrete noise barriers as a noise abatement strategy. The study reviews the relevant research, methodologies, tools, and technologies that have been used in evaluating the reasonableness and feasibility of this strategy. Various modeling techniques that can realistically model the insertion loss of short concrete noise barrier were also reviewed. A few proprietary short noise barrier systems were also evaluated for their reasonableness and feasibility. The study reveals the state of the practice survey of DOTs with respect to the adoption and implementation of short noise barriers. [ABSTRACT FROM AUTHOR]

Floating floor systems are part of state-of-the-art modern building technology. They are an efficient option to improve the acoustical performance of buildings and can be part of box-in-box systems installed in high-performance spaces. There are many types of high-performance floating floor types, one of which is a jack-up system that guarantees that the floor is decoupled from the structural floor. With these systems, once the concrete has cured, the isolated slab is raised off the structure to the required void depth using pre-cast boxes. These boxes allow for easy adjustment of the final floor height and, if the use of the room or load conditions change in the future, can also allow the replacement of the isolators inside them. Replaceable and inspectable acoustical floor systems are perceived as systems with lower sound insulation (airborne noise) than traditional floating floor or non-replaceable jack-up systems. To measure airborne sound reduction and impact noise isolation of replaceable jack-up systems and confirm factors that can influence its performance, CDM Stravitec invested in a testing campaign, where measurements were made considering many variables, such as: concrete floating slab thickness; bearings type, air void depth, steel lid installed on top of each box and insulation material installed in the air void. This paper will present the findings of the test campaign. [ABSTRACT FROM AUTHOR]

Noise engineering is not a new field of study, but statistics showed that experts in the field are on a decline. Observing that motivation and curiosity are among the hallmarks of any workforce development pipeline, the study developed an experiment-centric pedagogy to detect and measure noise from pollution using low-cost hands-on devices with the aim of motivating learners. The study design was a pre- and post-test method. The learners were enrolled in a transportation course and the noise detection and measurement strategies course module was used for the study. Motivated Strategies Learning Questionnaire was adopted for the study. Learners' response to the use of technological tools incorporated in learning was predominantly positive revealing that the learners' gain extensively. More so, significant improvement was observed in the task value and expectancy component of leaners (p<0.05) and overall, there was an increase in their motivation at the posttest. Significant improvement in academic performance of learners was also observed at post-test (p<0.05). It is therefore posited that there is need for effective engagement with learners with similar low-cost hands-on to lead to better understand and motivation that can lead to development of workforce in noise engineering. [ABSTRACT FROM AUTHOR]

In today's automotive industry, sound package design and optimization is important considering the mounting need for weight reduction and achieving targeted sound absorption and sound transmission loss values. The present paper relates to dual layered light weight (LW) fire resistant (FR) Polyurethane (PU) foam-based composite for engine room insulation, referred herein as Ωμ2 foam comprising of two layers of foam having different densities and flexibility. The composite consists of one layer of semirigid FR PU foam acting as a carrier with sound absorptive property and another layer consisting of flexible FR PU foam acting as higher acoustical absorptive property. This concept is intended for enhancement of acoustical performance by the synergistic effect of dual foam layers besides being FR and LW material, specially designed for passenger vehicles' engine compartment insulations such as firewall/dash panel, bonnet/hood liner insulation and other diverse applications in commercial vehicles. The paper presents material properties and in-depth comparative assessment of sound absorption properties of dual layer (Ωμ2) LW FR PU foam with respect to conventional materials like single layer light weight semi-rigid PU foam and resinated cotton shoddy felt, etc. [ABSTRACT FROM AUTHOR]

While traditional finite element based vibro-acoustic analysis of structures is done on stationary structures, in many occasions the structure under investigation is actually moving. To perform accurate finite element analysis on the vibro-acoustic performance of such structures requires the evaluation of a time-varying system, leading to several challenges, such as the selection of a strategy to update the mesh to the new configuration and an adequate time integration scheme that does not introduce large numerical artifacts. Additionally, the time-varying nature leads to an increase in computational complexity. In this paper a modeling strategy based on cut finite elements (cutFEM) is introduced that aims to tackle these challenges. The cutFEM approach can be seen as a fictitious domain approach in which the source is moving over a static mesh, cutting through elements where the actual source is located, using a level set description. The key advantage of this approach is that no re-meshing and/or mesh morphing is required. It is shown how both implicit and explicit time integration schemes can be used to propagate the solution while the source is moving. Additionally, several model order reduction strategies are compared to speed up the online evaluation of the reduced order model. [ABSTRACT FROM AUTHOR]

The Danish standard DS 490:2018 "Akustik - Lydklassifikation af boliger" *1, translated to "Acoustics - Acoustic Classification of Dwellings" relates to many acoustical parameters, and "Noise from ventilation" is now being tested in real life in the Danish "Voluntary sustainability classification" (called FBK *6). The Danish building regulation *2 state a sound level limit in dwellings from all kinds of technical systems at 30 dB(A), equal to the Acoustical class C, comparable with the limit in several countries. Research shows *3 that 30 dB(A) does not ensure acoustic satisfying comfort for all people. The FBK has chosen to lower the noise limit to 25 dB(A), equal to acoustical class B. We need to improve the ventilation systems to reach such lower level of sound emission, and we must be able to measure it implemented in dwellings. This paper describes some methods and in situ experience fighting background noise problems caused by activities and equipment around and in the dwelling, as well as in the measurement systems. A proposal for measuring closer to the ventilation armature and convert data to the prescribed position larger distance is described ant tested. The goal is: Measure and document low noise without a high cost in time and money, which could be a barrier for implementing lower noise levels in dwellings. [ABSTRACT FROM AUTHOR]

In this work, we investigate the potential of considering a non-uniform material distribution in the design of panel partitions, in order to achieve a superior vibroacoustic performance close to a given target frequency. In order to achieve this goal, we apply numerical topology optimization to find the optimal material thickness distribution for both single and double panels. Two formulations of the optimization problem are employed: in the first one, we suppress the resonance dips in the sound transmission loss by simply pushing the system eigenfrequencies far away from the target frequency. In the second formulation, we directly maximize the sound transmission loss of the system at the target frequency. In the iterative design process, the panels are modelled by mechanical plate finite elements. For double panels, the vibro-acoustic coupling between the panels and the internal air cavity, which is modelled analytically, is accounted for. The sound insulation properties are evaluated by transmission loss computations through hybrid Deterministic-Statistical Energy Analysis (Det-SEA) simulations. The method is applied considering different target frequencies in the audible range and focusing on practically relevant design cases. For both single PMMA panels and double glazing panels, it is demonstrated how a non-uniform thickness distribution allows for significant transmission loss improvements close to the target frequency, that are in the range of 5-15 dB with respect to uniform panels with the same mass. [ABSTRACT FROM AUTHOR]

This conference paper deals with computational methods to determine the wavenumber spectrum of acoustic data measured by a phased microphone array. Such problems occur e.g. within the analysis of pressure fluctuations due to a turbulent boundary layer on a surface such as a wind-tunnel wall or the skin of an aircraft. The problem is closely related to the deconvolution of dirty beamforming maps in wavenumber domain, which seeks to determine the wavenumber spectrum by removing the influence of the shift-invariant point spread function from the beamforming result. Firstly, we recall how this task can be formulated as a minimization problem and then discuss a specific solver for this problem, provided by the framework of the generalized FISTA algorithm. The resulting method includes regularization with L1 and L2 penalties as well as a nonnegativity constraint. By exploiting convolutional structures, the computation can be further accelerated. Finally, the presented algorithmic framework is demonstrated with numerical examples. [ABSTRACT FROM AUTHOR]

A sketch is an important tool that architects use to visualize and formulate design decisions. The sketch process is a crucial stage where design iterations and decisions can be made fast, easy and abundant. Sketching facilitates idea spawning, design assessment, modification and communication. This exploratory study focuses on qualities with Virtual Reality that can be used for sketching sound in the architectural design process. The study was influenced by Contextual Inquiry Interviews and used trained architects as respondents. The main result of this study is a summary of the pros and cons on how Virtual Reality work today and discusses how to develop a test bed for future research. One of the main cons, as of now, is the bulkiness of the equipment and the fact that it is not intended for sketching sound, yet. Computing speeds and acoustic rendering is another issue on the technical side. A possible benefit of using Virtual Reality is that it gives architects the possibility of incorporating sound in the architectural design process, thus making it an integral part of the practice. [ABSTRACT FROM AUTHOR]

This work aims at studying the mechanical and acoustic behaviours of a new bio-based porous epoxy resin obtained by a "green" adapted combination of the cationic photopolymerization and the porogen leaching technique. This new kind of material generally possesses interconnected complex morphology and it would be useful to consider this feature in a model. In this study, the effective properties of the material were estimated by using the asymptotic homogenization method. Four types of ordered pore arrangements together with systematic variations of the porosity and the pore size have been studied. Based on the results of these investigations, a subtle relation between the microstructure and mechanical/acoustic properties has been established. The estimated equivalent dynamic density and equivalent dynamic bulk modulus were compared with experimental results obtained by conducting the three-microphone impedance tube testing. The processing parameters of material elaboration could be adjusted so that the obtained porous material would possess the best sound absorption performance. [ABSTRACT FROM AUTHOR]

The dynamic and acoustic behaviour of the railway wheel is defined by its numerous vibration modes and natural frequencies. The modes whose contribution to the rolling noise radiation are predominant generally have 2 or more nodal diameters and appear above 2 kHz. The vibration due to these modes is decoupled from the rest of the wheelset, allowing the wheel to be treated separately. The error produced in the wheel noise prediction by this treatment appears at the low and medium frequencies and is negligible since the wheel emission occurs mainly at the high frequency range. However, given the dynamic coupling between the wheel and track, the changes in the dynamics of the former affect the latter, whose radiation is predominantly in the low and medium frequency range. Therefore, in order to correctly study both elements, it is necessary to include the contribution of the rest of the wheelset in the wheel response. In this work, this contribution is introduced through an analytical approach considering the rigid body motion of the wheelset and a benchmarking against an equivalent numerical formulation is carried out for validation purposes. In addition, the inertial effects associated with the rotation under straight circulation conditions are considered. [ABSTRACT FROM AUTHOR]

Neglecting turbulent scattering when modeling sound propagation in an upwardly refracting atmosphere leads to the prediction of unrealistically low sound pressure levels. Engineering models then typically impose a distance independent constant value for the sound pressure level relative to free field propagation. However, such an approach neglects the strong temporal variability in the sound pressure level observed in the acoustic shadow zone due to the scattering phenomenon. A modeling framework is presented to account for the effect of such scattering contributions, showing that the level variations might be as large as 20 dB in such zones. An approach to feed the model with the necessary turbulence input data is discussed as well. The engineering type scattering model further shows to be in line with more advanced but highly time-consuming predictions of outdoor sound propagation in upwardly refracting and scattering atmospheric boundary layers. This work contributes to more accurately predicting long-term sound pressure levels outdoors, also in situations where low levels might be of interest, e.g. near wind turbines. [ABSTRACT FROM AUTHOR]

This paper presents an efficient method to predict underground railway-induced vibrations. The method uses the finite element method (FEM) to model the railway tunnel structure and the singular boundary method (SBM) to model the wave propagation in the surrounding soil. The FEM mesh and the distribution of SBM collocation points at the tunnel/soil interface are generated using an automatic meshing strategy. The presented method is one of the main components of VIBWAY, a user-friendly prediction tool to address railway-induced vibration problems. This paper presents three calculation examples in which the soil response due to forces applied on the tunnel structure are computed in terms of transfer functions. The results obtained for each one of the calculation examples are compared with those computed using a model based on a 2.5D FEM-BEM approach. The presented comparisons show that the proposed approach is a suitable strategy for predicting underground railway-induced vibrations, both in terms of accuracy and computational efficiency. Moreover, the use of an automatic meshing strategy and the SBM formulation not only eases the implementation of the approach but it also makes it easier to use, which is one of the key features of the VIBWAY tool. [ABSTRACT FROM AUTHOR]

The two transverse motions of the string in planes parallel and perpendicular to the soundboard are believed to contribute to some of the characteristic effects of piano tones. In this work we aim to model the coupling between a single string and soundboard, considering the two transverse motions. A stiff string model is coupled to the bridge of the soundboard. Modelling approaches are presented in both frequency and time domain, using mobility coupling and state-space equations, respectively. For time domain modelling, the soundboard mobilities are approximated by lumped elements, springs and dampers in this case. In the frequency domain model, the mobilities of the elongated string, detached from the bridge, corresponding to the transverse response to a transverse force, are the same in both directions and the coupling between them is neglected, while the soundboard mobilities are represented by a 2 matrix. The state-space model has the benefit of allowing inclusion of the non-linear hammer excitation. Although the frequency domain model can represent the linear characteristics of the coupling and give an insight into the importance of the cross-terms of the coupled mobility, it is the time domain model that is able to represent typical features of the interaction. [ABSTRACT FROM AUTHOR]

Tranquil environments are considered quiet, peaceful places where people can get away from everyday life, and for many years the University of Bradford's Tranquillity Rating Prediction Tool (TRAPT) has been used to successfully predict the perceived tranquillity of outdoor spaces as a function of their auditory and visual modalities. The Warren, Hull, established 1983, is a citywide free project for marginalised and vulnerable young people aged 14-25 that helps to encourage and support them to take control of their lives and futures by engaging them in all of the decision-making that has impact upon the strategic and day to day running of project. Staff at The Warren have noticed that the young people often gather around a large public fountain to socialise and relax; the same fountain is due to undergo major work in 2022 and will be sectioned off from the general public for months. This paper addresses the challenges associated with bringing tranquillity indoors via considered and experimental application of the TRAPT to indoor spaces, and via empowerment of the young people to introduce tranquil auditory and visual changes to multiple spaces in The Warren. [ABSTRACT FROM AUTHOR]

Many engineering structures consist of plates being periodically stiffened or loaded. Examples can be wooden joist floors, dry walls with wooden or metal beams, or metamaterials for increased sound insulation. Even though some of these structures are well known and thoroughly studied in the past, there lack prediction models that can handle both the finiteness and periodicity in a simple and accurate manner. In two previous attempts, the periodicity of the structure have been tried to be incorporated in a variational technique based on integral-differential equations of the fluid loaded plate, based on [J. Brunskog, JASA 132, 1482-1493, 2012]. These attempts have not worked well: they show a poor fit with measured data. In this paper, this issue is investigated again, and a different tactics is used to incorporate the periodicity, using space harmonics. In this way, the paper try to explain the previous misfit and improve the model. [ABSTRACT FROM AUTHOR]

The Acoustics, Ventilation, Overheating: Residential Design Guide[1] ("The AVO Guide") was launched by the Association of Noise Consultants and Institute of Acoustics in January 2020. It provides a methodology for assessing the adverse effect due to break-in of external transport noise through façade openings provided for the purpose of mitigating overheating. Figure 3-2 of the AVO Guide indicates qualitatively how the SOAEL (Significant Observed Adverse Effect Level) is expected to vary with the duration for which the 'overheating condition' occurs. However, no quantitative guidance regarding the dependence on duration is given. This study describes how the methodology used in the WHO Night Noise Guidance for Europe 2009[2] to evaluate outside-to-inside level difference can be extended to provide a quantitative definition of the SOAEL for transport noise affecting passively cooled residential bedrooms at night. A quantitative version of the AVO Guide Figure 3-2 is derived and presented. Comparison is made between the SOAEL values presented here and the duration/frequency independent values suggested in the recently published Approved Document Part O[3]. Commentary is provided regarding the urgent need for better availability of relevant information on the frequency of occurrence of window openings for residential buildings in use, as opposed to data generated by the dynamic thermal models produced to show compliance with CIBSE TM59[15] and/or Approved Document Part O. [ABSTRACT FROM AUTHOR]

In my laboratory, a new noise localization method, 'Double nearfield acoustic holography (DNAH) method' is being developed. This method aims for mechanical noise source localization of the low frequency noise under 100Hz. Formerly, the experimental results of speaker tests in laboratory environment is presented (4)(6). It shows the better experimental results compared with the conventional near-field acoustic holography method as a low frequency noise sources localization method. In this paper, the experimental results of low frequency noise localization for a motor scooter using DNAH method are presented. As an example of mechanical product, a 50cc scooter's low frequency noise are measured by DNAH method, and by conventional near-field acoustic holography (NAH) method. The experimental results are compared with the results of conventional holography method. By these experiments, it is proved that the developing DNAH method can detect the low frequency noise source location of mechanical products, even if the sound frequency is lower than 100Hz. [ABSTRACT FROM AUTHOR]

Under the CNR (Italy) and RSE (Scotland) joint scientific cooperation agreement, the project deals with the development and enhancing understanding of the technical clashes and engineering solutions required to deliver net-zero outcomes across diverse construction systems both in new build and retrofit. This paper relates to the comparison between the two research groups about the acoustic and energy standards and low carbon measures in force in both countries. The sound insulation requirements and energy efficiency for residential buildings are mandatory in both Scotland and Italian building regulations. Sound insulation performance compliance is undertaken via on-site testing after completion of construction works. Importantly the specification for energy efficiency changes (and improvements) to the fabric of buildings often clash in terms of the material properties and performance functions for sound insulation. Thus, it is critically important for the specification changes in building materials for energy efficiency do not negatively impact noise and vibration sound insulation and vice versa. This can lead to non-compliance resulting in noise disturbance complaints by building occupants or loss of performance for energy efficiency. The paper characterizes some of the regulatory factors, clashes in material outcomes and recommends the importance of multi-factor knowledge across building performance measures. [ABSTRACT FROM AUTHOR]