Search

This paper presents a combined numerical and experimental investigation into the vibroacoustic behavior of a traditional oud. An experimental modal analysis was conducted using impact hammer testing to determine the oud’s soundboard’s dynamic characteristics and frequency response function for up to 400 Hz. Finite element analysis was used to model the oud, incorporating its precise geometry, the wood’s orthotropic material properties, and its interaction with the surrounding air. Validation was performed by matching the numerical and experimental mode shapes and the natural frequencies. Harmonic acoustic analysis examined the oud’s sound pressure level radiation and cavity resonance. Structural–acoustic optimizations were conducted systematically, varying the soundhole’s size, the soundboard’s thickness, and the dimensions of the internal bracing to maximize the acoustics properties while minimizing the structural stress. The effects of these geometric factors on the instrument’s tonal characteristics were quantified. The results provide physical insights into the relationship between the oud’s construction and sound production. The methodology demonstrates a rigorous approach combining simulations and experimentation to comprehensively evaluate and optimize the vibroacoustic behavior of a musical instrument. This fundamental understanding could guide future improvements in the design of ouds. [ABSTRACT FROM AUTHOR]

Uncertainties are significant in the early vibroacoustic development, e.g., of a car body, to prevent costly modifications close to the start of production. First, engineers must know which uncertain parameters are sensitive: Our previous work identified 170 uncertain parameters being sensitive out of a complex finite element model with 1,300 uncertain parameters – a parameter reduction of approximately 87%. Second, engineers aim to find reliable distributions of these sensitive input parameters for finite element simulations. Finding these distributions is very demanding in a large-scale vibroacoustic model with several connecting parameters, as research already acknowledges regarding simplified connections. In this paper, we address this challenge with neural networks. For this, we use data in the frequency domain. Due to the curse of dimensionality, it is difficult to determine the parameter set of 170 parameters with a neural network. Therefore, we examine the influence of the number of parameters on the performance of neural networks. Furthermore, we train a fully connected feed-forward neural network and compare this to a one-dimensional convolutional neural network. The latter exhibits a better performance. Finally, we show how to determine distributions of the analyzed parameters based on artificial measurement data. Due to this process, we can significantly improve our finite element simulations and show how to deal with the challenge of determining uncertain parameters in a large-scale vibroacoustic finite element model based on data in the frequency domain. [ABSTRACT FROM AUTHOR]

The energy efficiency of the building should be understood as the degree of preparation of the building to ensure the comfort of its use in accordance with its intended use with the lowest possible energy consumption of the building. The article presents an in-depth analysis of the possibility of changing the utility function of a historic building in such a way that ensures all aspects of comfort while meeting energy efficiency conditions. Combinatorics methods were used for this purpose. Four possible utility functions were proposed, including the reference state, i.e., the existing state. Five aspects of comfort were considered: thermal comfort, carbon footprint, energy efficiency, noise and vibration. For these five aspects of comfort, boundary conditions were adopted depending on the adopted building class. The selected utility function is therefore the result of comfort, energy efficiency and economic aspects. The purpose of the study was to verify whether the developed methodology for the selection of the utility function for historic buildings, based on combinatorial analyses, would allow the selection of the optimal function from the point of view of energy efficiency, user comfort and environmental impact. The methodology was tested on a historic building located in southern Poland. The new utility function for the analyzed building is to use the historic villa (or some part of it) as an Art Gallery. [ABSTRACT FROM AUTHOR]

In this study, we focus on the prediction of the pressure field scattered from an immersed cylindrical shell partially coated by a soft rubber, impacted by an acoustic plane wave. As the coating covers only a partial portion along the circumference of the shell, the considered system is not axisymmetric. As a result, a spectral (Fourier) resolution of the mathematical problem would induce the coupling of the different circumferential orders, which can lead to prohibitive computing times. To circumvent this issue, the reverse Condensed Transfer Function (rCTF) method has recently been developed to decouple vibroacoustic subsystems initially coupled along lines or surfaces. From an analytical model of the fully coated shell impacted by the acoustic plane wave and a finite element (FE) model of the missing coating material, the rCTF approach predicts the vibroacoustic behavior of the coated shell with a voided section instead of the removed part. This voided section can then be filled by a FE model of the water domain replacing the removed coating material, using the direct CTF approach. The principle of the rCTF approach, some numerical validations, and results for the scattering from the partially coated shell are presented in this paper. [ABSTRACT FROM AUTHOR]

Featured Application: Buildings. This research aims to investigate the impact of incorporating porous materials on reducing noise and vibration in wooden floor panels, and to analyze the vibroacoustic performance of the assembled panel under different types of excitation and boundary conditions, particularly in the lower frequency range. The study begins with an experimental investigation and numerical modeling to determine the mechanical properties of the orthotropic wood material used in the floor panels. Subsequently, a finite element formulation, based on a variational approach, is presented to study the vibroacoustic response of an elastic structure coupled with a porous material exhibiting realistic behavior. The porous material is characterized by two phases: solid and fluid, represented in the formulation through the displacement field for the solid phase and the pressure for the fluid phase. This formulation offers the advantage of reduced computation cost and simplifies the coupling between all domains. To calculate the acoustic radiation of the structure, the Rayleigh integral is employed. Utilizing the proposed numerical approach, a comprehensive study is conducted to analyze the reduction in vibration–acoustic response of the floor with the incorporated porous layer, taking into account different types of excitation and boundary conditions applied to the system. [ABSTRACT FROM AUTHOR]

In recent years, mobility as a service (MaaS) (i.e., a system combining public transport, shared rides, short-term vehicle rentals, and taxis sourced via mobile applications) has become a solution that is increasingly available in smart cities. Along with the development of transport options, the range of vehicles offered as part of this type of service has expanded widely, from buses, taxis, bicycles, and cars to the innovation of electric scooters. The universality of MaaS services has led to a change in communication behavior and, at the same time, to a rapid increase in the number of people using the proposed solutions. Due to this increase, several researchers devoted their dissertations to issues of the management or optimization of websites; however, they ignored the many technical and health aspects. Recognizing a scientific niche area, the research conducted has been devoted to assessing the impact of the vibrations generated by electric scooters upon the user. Research on the vehicles used in MaaS systems has been conducted to learn and analyze the selected design solutions and their impact on the user who utilizes them. The scope of the research included vibroacoustic research and the mathematical modeling of the studied phenomena.

• Establish a vibroacoustic analysis model of a cavity-plate system with connecting nonlinear oscillators (CNOs). • Find that the vibroacoustic responses of the plate-cavity system with CNOs can be accurately predicted by the Lagrange method. • Find that the multi-line spectrum linear and non-linear broadband control modes of CNOs. • The multi-line spectrum non-linear broadband control mode of CNOs motivates multiple frequency components and the targeted energy transfer. • The worsening reason for the vibration control effectiveness of the passive plate of the plate-cavity system with CNOs is found. Nonlinear oscillators have been found to control the vibration of engineering structures. Unfortunately, the studies related to nonlinear vibroacoustic control of the plate-cavity systems by employing nonlinear oscillators are limited, harming the engineering application of nonlinear oscillators in controlling the vibrion and noise of plate-cavity systems. To study the potential application of connecting nonlinear oscillators (CNOs) in the vibroacoustic control of the plate-cavity system, a vibroacoustic analysis model of the plate-cavity system with CNOs is established. According to this work, the vibroacoustic responses of the plate-cavity system with CNOs can be accurately gained by the Lagrange method. The working states of CNOs can be divided into the multi-line spectrum linear and non-linear broadband control modes. Under the above two control modes, the vibration and noise of the plate-cavity system can be both effectively controlled. Especially, the multi-line spectrum non-linear broadband control mode of CNOs can motivate multiple frequency components and the targeted energy transfer phenomenon of the plate-cavity system. There is no doubt that the variation of key parameters of CNOs in a sensitive region can effectively change their working states. Importantly, the introduction of CNOs establishes an additional energy transfer pathway of the plate-cavity system, where an unsuitable parameter combination of CNOs will worsen the vibration control effectiveness of the passive plate. Overall, the application of CNOs can simultaneously suppress the vibration and noise of the plate-cavity system, where a suitable working state of CNOs will strengthen the control effectiveness. [ABSTRACT FROM AUTHOR]

Purpose: In sports requiring multiple short bouts of high-intensity exertion, recovery while off the field is an important part of being an effective competitive athlete. This study investigated the potential of vibroacoustic stimulation to aid recovery from athletic stress.Methods: University of Pittsburgh club and varsity athletes (n = 22) pedaled on a stationary bike strenuously, followed by a period of recovery accompanied by vibration using a wearable transducer. Subjective and physiological (skin conductance responses and cardiac measures) were used to determine the extent of recovery with frontal electroencephalographic (alpha/theta) measures indexing brain reactivity.Results: Vibrations rated as the most calming by each participant were associated with increased high-frequency heart-rate variability, representing parasympathetic tone, particularly in athletes most affected by pedaling. Yet, EEG markers, while related to subjective recovery, were not associated with physiological change.Conclusion: This work provides support for the idea that vibration, which is subjectively rated as calming, could affect physiological recovery from physical stressors, at least for those individuals whose physiology is affected by exertion. This is likely through direct effects on physiology rather than "top down" effects on the brain. [ABSTRACT FROM AUTHOR]

This research aims to investigate the impact of incorporating porous materials on reducing noise and vibration in wooden floor panels, and to analyze the vibroacoustic performance of the assembled panel under different types of excitation and boundary conditions, particularly in the lower frequency range. The study begins with an experimental investigation and numerical modeling to determine the mechanical properties of the orthotropic wood material used in the floor panels. Subsequently, a finite element formulation, based on a variational approach, is presented to study the vibroacoustic response of an elastic structure coupled with a porous material exhibiting realistic behavior. The porous material is characterized by two phases: solid and fluid, represented in the formulation through the displacement field for the solid phase and the pressure for the fluid phase. This formulation offers the advantage of reduced computation cost and simplifies the coupling between all domains. To calculate the acoustic radiation of the structure, the Rayleigh integral is employed. Utilizing the proposed numerical approach, a comprehensive study is conducted to analyze the reduction in vibration–acoustic response of the floor with the incorporated porous layer, taking into account different types of excitation and boundary conditions applied to the system.

This innovative study develops a new analytical model to investigate the dynamic responses of asphalt pavements combined with attached mass-spring-damper systems under moving loads. Unlike existing methods that rely on finite element (FE) approximations, an exact solution for the coupled vibroacoustic behavior is proposed using first-order shear deformation plate theory (FSDPT), Hamilton's principle, and Fourier-Laplace transforms. The acoustic pressure is first predicted using Rayleigh integral analysis. Afterwards, the responses are transformed into the time domain using Durbin's numerical inverse Laplace transform strategy. The model utilizes Rayleigh integral analysis to generate innovative predictions of acoustic pressure and uses numerical inversion to accurately determine transient responses in the time domain. The suggested technique has been extensively validated against data from prior research and COMSOL Multiphysics® FE simulations, which confirms its correctness. Parametric analyses provide new insights into the effects of damper and spring coefficients, velocity, and loading frequency on the pavement's vibroacoustic behavior and the time-history response of the attached mass-spring-damper systems. Notably, the model offers fresh theoretical insights into the complex interplay between system parameters and the pavement's vibration and noise patterns. • Higher excitation frequencies increase pavement and mass-spring-damper displacements. • Stiffer springs align mass-spring-damper displacement with pavement response. • Higher observation points reduce sound pressure due to wave spreading. • Sound pressure peaks when excitation matches system's natural frequency. [ABSTRACT FROM AUTHOR]

Buildings are often constructed on a continuous layer of vibration isolation to reduce vibrations and structure-borne noise. There are many vibration isolation products (rubber mats, textiles, polymer foams), but none fulfils all requirements in terms of load-bearing capacity, performance, and cost. In previous work, we have shown that silica aerogel particle beds display a low resonance frequency and correspondingly high vibration isolation performance. Loose silica aerogel granules are not a practical vibration isolation solution. In order to guide the future development of dedicated vibration isolation products based on aerogels, we determine the vibro-acoustic properties of a variety of existing commercial and R&D stage mesoporous composites, that have been developed for thermal insulation applications. The sample set includes monolithic aerogels (polyurethane), silica aerogel composites (aerogel – fibers, aerogel impregnated foams, aerogel bound with polymer foam), glued fumed silica-fiber boards, and nanoporous polymer foam composite boards. The silica aerogel and fumed silica composites display low resonance frequencies (down to 8 Hz for 40 mm, strongly dependent on composite type) and a low dynamic stiffness and loss factor over a wide range of static loads. The polymer aerogel, nanoporous foam and polymer-bound silica aerogel granule board all display higher resonance frequencies, consistent with their higher static stiffness. Although optimized for thermal insulation rather than vibration isolation, many of the tested silica aerogel and fumed silica composites are competitive with the best vibration isolation products on the market in terms of vibration isolation performance. The diversity of materials tested informs on which approaches, materials, and materials combinations are most promising to target vibration isolation. • Vibroacoustic properties of 8 types of mesoporous materials tested. • All materials have a low loss factor and are not effective vibration dampers. • Silica aerogel and fumed silica composites have very low resonance frequencies. • Silica aerogel and fumed silica composites are excellent vibration isolators. [ABSTRACT FROM AUTHOR]

A 49‐year‐old male with severe low back pain (LBP) showed multilevel disc bulges with spinal stenosis. After 18 novel low‐frequency sound wave treatments, initial VAS pain score of 9.5 reduced to 2.5 and the Rolland‐Morris score of 13 reduced to 3. MRI showed some resolution of L3–L4 and L4–L5. [ABSTRACT FROM AUTHOR]

The prevalence of dementia is increasing with the ever-growing population of older adults. Non-pharmacological, music-based interventions, including sensory stimulation, were reported by the Lancet Commission in 2020 to be the first-choice approach for managing the behavioural and psychological symptoms of dementia. Low frequency sinusoidal vibration interventions, related to music interventions through their core characteristics, may offer relief for these symptoms. Despite increasing attention on the effectiveness of auditory music interventions and music therapy for managing dementia, this has not included low frequency vibration. This scoping review, following the JBI methodology guidelines, was conducted to investigate participants’ responses to both sound and mechanical vibration, the characteristics of the delivered interventions, methodological challenges, and the specifics of the research experiments reported. An extensive search was conducted in BMC, CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, ERIC, MEDLINE (OvidSP), Pedro, ProQuest Central, PsycINFO, Scopus, and Web of Science. Current Controlled Trials, Clinical Trials, and Google Scholar were also searched as well as a hand search in relevant journals. Studies on adults with all types of dementia, investigating tactile low frequency sound or mechanical vibration in any context were considered. Data from eight full-length studies (three RCTs, two quasi-experimental, two case reports, and one qualitative) were extracted using the data extraction table developed by the authors and were included in the analysis and critical appraisal. Issues in quality related to, for example, control groups and blinding. Few studies addressed participants’ subjective responses to the interventions. Reporting on the intervention characteristics was unclear. It appeared more frequent sessions led to better outcomes and home-based interventions potentially addressing the issue of access and feasibility. Future research should include neuroimaging to measure and confirm the hypothesised mechanism of cerebral coherence. Standardised reporting of intervention characteristics is also needed to ensure replicability of the experiments. Higher quality research is needed to investigate the impact and effect of low frequency vibration for the symptoms of dementia and compare outcomes in meta-syntheses. [ABSTRACT FROM AUTHOR]

Research on insect biotremology has resulted in a burgeoning body of literature over the past few decades. Despite this, several biases and knowledge gaps have been proposed, but not quantified. Therefore, a systematic literature review and meta-analyses were carried out to summarize the temporal trends and test for biases regarding taxa, developmental stages, and research topics reported in scientific papers spanning 75 years. The survey tracked 831 papers, which exhibited exponential growth since the 1990s and covered 17 insect orders. Among these studies, 70.4% were associated with adaptive behaviors, while the remaining (29.6%) focused on applied entomology and sensory organs. Three main biases were detected: (i) a prevalence of studies on Hemiptera, Hymenoptera, and Coleoptera, (ii) a focus on adults, and (iii) a preponderance of studies on reproductive behaviors. Considering only adaptive behaviors, the likelihood of studies with adults was 3× higher than for juveniles. Studies documenting receiver response were 2× higher than not. Still, few insect orders (9 of 17) included reports on vibrations used in an adaptive context, while studies reported in the remaining orders focused on mechanisms of vibration production or vibration characteristics. The results of this study highlight knowledge gaps worthy of future investigations. In particular, further research is necessary on the role of vibratory sensing and communication in juveniles (eggs, larvae, pupae, and nymphs), testing hypotheses on the adaptive roles of vibrations in a broader range of taxa, characterization of vibratory landscapes, and research on sensory receptors. [ABSTRACT FROM AUTHOR]

The prevalence of dementia is increasing with the ever-growing population of older adults. Non-pharmacological, music-based interventions, including sensory stimulation, were reported by the Lancet Commission in 2020 to be the first-choice approach for managing the behavioural and psychological symptoms of dementia. Low frequency sinusoidal vibration interventions, related to music interventions through their core characteristics, may offer relief for these symptoms. Despite increasing attention on the effectiveness of auditory music interventions and music therapy for managing dementia, this has not included low frequency vibration. This scoping review, following the JBI methodology guidelines, was conducted to investigate participants’ responses to both sound and mechanical vibration, the characteristics of the delivered interventions, methodological challenges, and the specifics of the research experiments reported. An extensive search was conducted in BMC, CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, ERIC, MEDLINE (OvidSP), Pedro, ProQuest Central, PsycINFO, Scopus, and Web of Science. Current Controlled Trials, Clinical Trials, and Google Scholar were also searched as well as a hand search in relevant journals. Studies on adults with all types of dementia, investigating tactile low frequency sound or mechanical vibration in any context were considered. Data from eight full-length studies (three RCTs, two quasi-experimental, two case reports, and one qualitative) were extracted using the data extraction table developed by the authors and were included in the analysis and critical appraisal. Issues in quality related to, for example, control groups and blinding. Few studies addressed participants’ subjective responses to the interventions. Reporting on the intervention characteristics was unclear. It appeared more frequent sessions led to better outcomes and home-based interventions potentially addressing the issue of access and feasibility. Future research should include neuroimaging to measure and confirm the hypothesised mechanism of cerebral coherence. Standardised reporting of intervention characteristics is also needed to ensure replicability of the experiments. Higher quality research is needed to investigate the impact and effect of low frequency vibration for the symptoms of dementia and compare outcomes in meta-syntheses.

A patient presenting with low back pain received 18 treatments of FDA‐approved low‐frequency vibro‐percussion wave stimulation known as Khan Kinetic Treatment (KKT). Following KKT, he demonstrated improvement in pain, function, quality of life, sleep, and trunk range of motion with no adverse events. [ABSTRACT FROM AUTHOR]

Internal combustion engines take up the major position in the power facility market and still encounter some challenges; one key issue is liner cavitation erosion. The impact vibration between piston and cylinder generates pressure fluctuation on the wet liner surface and leads to the occurrence of cavitation in the case that coolant pressure falls below its vapor pressure. Piston slap methodology has been improved by considering the dynamic characteristics of the piston. Water coolant passage acoustic features were investigated and the Helmholtz effect between cylinders was confirmed. In order to address the cavitation erosion potential of the engine cylinder, acoustic pressure in the cooling water passage was investigated by boundary element method analysis with the acceleration of the cylinder liner which was obtained from the piston slap program. This study revealed that a certain acoustic mode of the cooling water passage had a dominant effect on the amplitude of water coolant dynamic pressure induced by liner vibration. Measures of eliminating the acoustic mode are believed to be able to suspend pressure fluctuation and furthermore the potential of cavitation. [ABSTRACT FROM AUTHOR]

This work proposes a novel two-dimensional (2D) graded core with anti-tetrachiral cells and evaluates the numerical vibroacoustic response of sandwich panels with these particular cores. First, a homogenization scheme is utilized to model the sandwich structure, followed by a modal analysis of the homogenized model in the frequency range of 0–200 Hz. The results have been compared with those obtained from an exact and full-scale finite element model of the sandwich structure. A general good agreement has been observed for the first six natural frequencies. Next, the radiated sound power level in the frequency band of 0–200 Hz is calculated and minimized for different geometry parameters of the sandwich structure. A hybrid design optimization approach using method of moving asymptotes and genetic algorithm is used. The optimized 2D gradient configurations show a significant 78% reduction of the normalized radiated sound power level and a 15% increase of the fundamental frequency, compared to the baseline sandwich panel configurations. [ABSTRACT FROM AUTHOR]

This paper deals with analyzing the nonlinear vibration of an isotropic cracked plate interacting with an air cavity. A part-through surface crack with variable orientations and positions is considered and modeled using the modified line spring model. In the first step, based on the Von Karman theory, the governing equation of the nonlinear vibration related to the cracked plate–cavity is presented. Then, by employing the Euler equation along with the Galerkin method, the coupling effect between the fluid–solid media inside the enclosure is eliminated. In the next step, the variational iteration method (VIM) is introduced as an appropriate method for nonlinear analysis of the mentioned system. To this end, the convergence of the nonlinear coupled natural frequencies with high precision is proved by performing four iterations of VIM. Finally, the effect of the length, angle, and position corresponding to the crack as well as the cavity depth on the frequency ratio is inspected for various boundary conditions by plotting three and four-dimensional backbone curves. It is revealed that the crack angle is the most effective parameter on the frequency ratio. [ABSTRACT FROM AUTHOR]

In this paper, a numerical approach able to evaluate the sound power emitted by a non-cavitating flexible marine propeller blade is proposed. With asymptotic expansions and order of magnitude analysis, two main phenomena are identified: the so-called propulsion and vibroacoustic phenomenon. The propulsion phenomenon is nonlinear and models the lift generation along the blade. It creates a pre-stress and a pre-strain on a deformed configuration on which the blade vibrates and emits sound waves. The vibroacoustic phenomenon is linearized and has no retroaction on the first static phenomenon. This simplified model allows to solve the fully coupled fluid–structure system in order to compute the radiated noise of a pre-stressed blade. • Lift generation and small vibrations are partially decoupled for marine propeller. • Propulsion phenomenon is solved using a simple iterative solver. • Vibro-acoustic phenomenon is solved using monolithic FEM-FEM formulation. • Blade deformation significantly changes lift generation. • The pre-strain and pre-stress on a blade have an impact on its vibrations. [ABSTRACT FROM AUTHOR]

The present approach considers hybrid control strategy to reduce the amount of transmitted sound through a multilayered doubly curved sandwich shell equipped with piezoelectric layer and shunt circuit. The construction is composed of some piezoelectric actuator and sensor layers as an active controller as well as resistance–inductance shunt circuit as passive controller. In addition, a layer made of isotropic material is also sandwiched as a core. Firstly, in order to obtain the electromechanical equations of curved shell integrated with piezoelectric layers, Hamilton's principle, and shear deformation shallow shell theory are employed. After presenting the sound transmission loss of structure, the reliability of the formulation is checked by the aid of previous outcomes. In the following, the piezoelectric layers coupled with shunt circuit are employed to inspect the influence of these patches on the control of transmitted sound through structure. The results indicate that the shunt circuit is able to enhance the sound transmission loss at resonant frequency with no need source of energy. Since in designing the engineering structures, the transmitted noise control is important especially in the resonant frequency, the influence of using several parallel shunt circuits with each piezoelectric layer is also examined. It is shown that increment of the number of parallel shunt circuits implies substantial reduction of transmitted sound to the structure in the resonant frequency. Finally, the solution process is followed to study the effect of active control on the acoustic transmission. Then, it is found that employing the simultaneous active and passive controllers not only cause to reduce the transmitted noise in the resonant frequency but also make to improve the behavior of sound transmission loss in entire range of frequency. [ABSTRACT FROM AUTHOR]

In swarming season, honeybee queens emit two kinds of queen piping signals: tooting and quacking. These signals are considered to be important for swarming, and honeybees distinguish between the two signals through differences in their temporal structures. In this study, we revealed that the piping signals of two honeybee species, Apis cerana and Apis mellifera, had different temporal structures. The tooting of A. cerana consisted of almost one long syllable, while that of A. mellifera was constructed from several syllables. The quacking of both species comprised around 50 short syllables, but the duration and period of the syllables of A. cerana were about half those of A. mellifera. The findings provide new insights that reveal the mechanisms of signal discrimination and the functions of the signals. [ABSTRACT FROM AUTHOR]

Introduction: One of the essential components of the process of prenatal care is the assessment of the fetal health, for which there are several tests. Recently, in some studies, vibroacoustic stimulation and halogen light have also been evaluated as a test for the evaluation of fetal health. This study was conducted with the aim of systematically summarizing recent studies on the effect of stimulation with vibroacoustic and halogen light on the fetus. Materials and Methods: In this review study, in order to retrieve relevant national and international studies published from 1990 to 2017, the researchers extensively searched the following databases: magirin, irandoc, SID، Google scholar, Scopus, PubMed, and science direct. English keywords included “vibroacoustic” and “halogen light”. The papers that had the highest similarity with our review title were entered into the study, and the results were reported. Results: Finally، 15 papers that investigated the effect of halogen light and vibroacoustic stimulation were studied. There was a correlation between fetal heart rate، fetal health assessment, and stimulation with vibroacoustic and halogen light (P

Chronic pain is a widespread issue accompanied commonly by depression and anxiety. Chronic pain has been shown to alter brain processing within the emotional and reward circuits, pointing towards a possible link between pain and comorbid mood disorders. Pain relief may be achieved by alleviating depressive and anxious symptoms. Relaxation is important for pain relief and eliciting relaxation through music listening is shown to relieve pain, depression, anxiety, and discomfort among others. In addition to auditory stimuli, Vibroacoustic treatment – the tactile application of low frequency sinusoidal sound vibration, plus music listening and therapeutic interaction – has been shown to be beneficial for relieving these symptoms. Although the combination of music listening and low frequencies has been previously explored, the role of the music listening within the vibroacoustic treatment context is unknown. A single-case, mixed method crossover study was conducted with a client suffering from chronic pain and comorbid mood disorders, four sessions with music listening, and four sessions without. Quantitative outcomes showed the client was more relaxed, less anxious, and had less pain after the music sessions. Qualitative findings showed that the client at first could not relax without the music listening because of her severe anxiety, but learned to use music as a distractor from her thoughts to relax, but also that silence was equally important for her; these hinged on her making the choice based on her needs, which had previously been difficult for her.

In this research, the application of the method in microphone array to the sound quality of the violin soundboard will be evaluated by the vibro-acoustic properties of the bamboo. The appropriate methods in corresponding process are composed of bamboo physical properties, texture, soundboard processing, surface geometry procedures and soundboard thickness which further establish the sound characteristics of handmade violin. To create the best sound quality of violin, the properties of Taiwan Moso bamboo species, sound quality and processes have to be combined. The acoustic features, fine aesthetics and sound quality of violin will be highlighted. Furthermore, this research will predict the performance of sound quality by integrated the factors as the vibro-acoustic of the bamboo soundboard, processes and the sub-assembly structure etc. However, the entire evaluation of violin sound quality will be recorded via the analysis, vibroacoustic characteristics, bamboo histological, processing technology and matched combination. Therefore, the sound characteristics and current status of violin (such as moisture content, dimensional stability) are monitored by the microphone array measurement to establish the reference of handmade violin quality by bamboo. The bamboo violin tones are periodic which the harmonics are more consist and coupling to correlate the bright and clear sound performances. The wooden violin acoustic has richer anharmonic and overtones which the peaks and overtones are correlated to create the better loudness and thickness sound performances. Further study about the sound performance of violin which is made by the combination of bamboo and wood for more advanced explanations about timbre characteristics. [ABSTRACT FROM AUTHOR]

Acoustical investigation of a thin plate having a part–through surface crack surrounded by an air enclosure is studied in this paper. The enclosure comprises five rigid walls and a flexible plate based on the Kirchhoff plate theory. It is also assumed that the crack is located at an arbitrary position and orientation with a specific length. Accordingly, partial differential equation related to the coupled cracked plate–cavity system is presented. In order for the partial differential equation (PDE) to be solved, firstly, the sound pressure inside the cavity is estimated by a suitable number of the plate modes. Then, the coupled PDE decomposes to some ordinary differential equations in the time-domain by employing the Galerkin method for three different boundary conditions. In addition, the linear natural frequencies are obtained in vacuo and coupled conditions for an uncracked plate and then, a similar procedure is performed for a cracked plate. Furthermore, comparing the results with available data in the literature shows the reliability and accuracy of the present work. Finally, the influences of the crack angle, crack length, crack position, and cavity depth on the natural frequencies are investigated. [ABSTRACT FROM AUTHOR]

Alternative fuels appeared soon after the first internal combustion engines were designed. The history of alternative fuels is basically as long as the history of the automotive industry. Initially, fuels whose physicochemical properties allowed for a change in parameters of the combustion process in order to achieve greater efficiency and reliability were searched for. Nowadays, there are significantly more variables; in addition to the above mentioned parameters, alternative fuels are being sought that will ensure environmental protection during vehicle operation and improve the ergonomics of use. This article outlines the results of the authors’ own comparative tests of vibrations of a vibroacoustic character. Based on a popular engine model, the vibration–acoustic responses of a system powered by two types of fuel, namely, diesel and biodiesel (B10), are compared. The research consists of comparing vibrations in both time and frequency domains. In the case of the time domain, the evaluation was performed with vibrations as a function of engine torque and speed. In the case of frequency analysis, the focus was on changes in the frequency response for the tested fuels. The research shows that the profile of vibroacoustic vibrations changes in the case of biodiesel power supply in relation to standard fuel. The vibration profile changes significantly as a function of speed and only slightly in relation to the engine load. The results presented in this article show different vibroacoustic responses of an engine powered by diesel and biodiesel; the change is minor for lower speeds but significant (other harmonics are dominant) for higher speeds (changes in the dominant harmonic magnitude of up to 10% at a crankshaft speed of 3000 rpm).

The rising demand for lower noise emissions of car ancillary units due to electrification and higher customer expectations regarding driving comfort results in the need for more silent car components. Hydraulic driven car components in particular are often identified as a major source of noise in the system. Therefore, it is mandatory to investigate the noise sources inside the hydraulic system. In this work, a combined CFD-FEM approach is applied to estimate the flow-induced noise radiation of a mechanically driven transmission pump. To achieve this goal, the mapping procedure to hand over the pressure field from the CFD to the FEM mesh must be valid. For this purpose, the error during the mapping process is evaluated and different parameters, which influence the mapping results, are analyzed. Additionally, the impact of the time step size and the length of the time signal on the frequency resolution of the force signal is investigated to get an appropriate excitation force for the vibroacoustic simulation. Subsequently, a force analysis and a structural FEM simulation are performed to identify which flow phenomenon contributes most to the excitation of the pump housing. Specific locations in the pump with high loads are pointed out. In a final step, the results of the vibroacoustic model are compared to acceleration and sound pressure level measurements of the pump performed in a hemi-anechoic room.

Abstract Sound waves due to vibro-thermal excitation propagating through a binary mixture of rarefied gases in a gap between source and receptor are investigated by applying the McCormack model to the Boltzmann equation. The sound waves are induced by mechanical vibration and temperature variation of one plate, while the other plate being fixed at a constant temperature, acts as a receptor of sound waves. The oscillatory gas mixture flow is considered as fully established and all its macroscopic quantities depend on time harmonically. The discrete velocity method is used to solve the coupled kinetic equations in wide ranges of both rarefaction and oscillation parameters. The former is defined as the ratio of the distance between the plates to the equivalent free path, while the latter is the ratio of the intermolecular collision frequency to sound frequency. Analytical solutions in the free molecular and hydrodynamic regimes have been obtained too. Two mixtures, namely, Helium Argon and Helium Xenon, are considered with a molar fraction equal to 0.1, 0.5 and 0.9. The amplitudes and phases of all macroscopic characteristics of the gas mixture flow are calculated as functions of the rarefaction and oscillation parameters so that the free molecular, transitional and hydrodynamic regimes are covered. The results are compared to those obtained in the limit of a single gas in order to investigate the influence of the molar fraction and molecular masses of species on the problem solution. The reciprocal relations between cross phenomena are obtained and verified numerically. Highlights • Numerical solution of a linearized kinetic model to the Boltzmann equation. • Sound propagation through a binary gas mixture due to vibration and thermoacoustic. • Calculation of all the non-equilibrium macroscopic characteristics of the mixture. • Analysis of the influence of the receptor and molar fraction of species on the solution of the problem. • Verification of the reciprocal relation between heat flux and pressure difference. [ABSTRACT FROM AUTHOR]

MODal ENergy Analysis (MODENA) is an energy-based method, which is proposed to deal with vibroacoustic problems. The performance of MODENA on the energy analysis of a mechanical system under spatially correlated excitation is investigated. A plate/cavity coupling system excited by a pressure field is studied in a numerical example, in which four kinds of pressure fields are involved, which include the purely random pressure field, the perfectly correlated pressure field, the incident diffuse field, and the turbulent boundary layer pressure fluctuation. The total energies of subsystems differ to reference solution only in the case of purely random pressure field and only for the non-excited subsystem (the cavity). A deeper analysis on the scale of modal energy is further conducted via another numerical example, in which two structural modes excited by correlated forces are coupled with one acoustic mode. A dimensionless correlation strength factor is proposed to determine the correlation strength between modal forces. Results show that the error on modal energy increases with the increment of the correlation strength factor. A criterion is proposed to establish a link between the error and the correlation strength factor. According to the criterion, the error is negligible when the correlation strength is weak, in this situation the correlation strength factor is less than a critical value. [ABSTRACT FROM AUTHOR]

We designed a vibrotactile vest and The Humming Wall, a vibroacoustic interactive furniture set in an urban environment to interact with each other. We developed the vibrotactile patterns in the vest as a form of vibrotactile language to convey information to the wearer. In addition, we designed a set of interactive movements on The Humming Wall that would trigger patterns on the vest and elicit sensations and encourage body movements onto the wearer’s body. We invited people to interact in pairs at The Humming Wall, with one at the wall and one wearing the vest (they later swapped roles). Actions by the one at the wall, such as swiping or knocking on the wall were repeated on the vest wearer’s body. In addition, participants could ‘feel’ (vibroacoustically) and hear their own heartbeats and breath rates at the wall. We conducted a field trial with 39 participants over a 5-week period. Participants wearing the vest (and their pair) completed a set of tasks. We logged use and responses, recorded all activities on video and conducted post-experiment interviews and questionnaires. The results depicted the participants’ experience, communication and connection while wearing the vibrotactile vest and interacting with the wall. The findings show convincing, strong and positive responses to novel interactions between the responsive vibroacoustic environment and the vibrotactile vest. This work constitutes the first field trial with people ‘working’ in pairs with a vibrotactile wearable responding to and driving vibroacoustic displays with an interactive vibroacoustic environment. [ABSTRACT FROM AUTHOR]

The paper presents results of systematic computational and experimental investigations of rotordynamic induced vibrations and noise of turbochargers. The proposed solution approach is based on a combination of a virtual turbocharger and finite element method calculations of structural or acoustic domains. The virtual turbocharger is a computational model enabling simulations of rotordynamics in the time domain by multibody dynamics software. Structural vibrations and emitted noise of the turbocharger are computed by finite element method based on excitation forces calculated by the virtual turbocharger. The solution approach is proposed to rapidly calculate vibroacoustic behaviour of newly designed turbochargers in a development phase. Main results are applied on a turbocharger of diesel engine of heavy-duty vehicle. [ABSTRACT FROM AUTHOR]

This paper describes the vibroacoustic behavior of sandwich panels with a novel core topology made from 2-dimensionally gradient auxetic hexagonal honeycombs. The 2D gradient core enables a tailoring of localized mechanical properties of the sandwich structure in different regions of the panel. A homogenized finite element modeling has been used to initially determine the mechanical properties of the structures. The natural frequencies and the radiated sound power level of the sandwich plate with the homogenized properties have been calculated and verified with those obtained from a full-scale detailed model of the sandwich structure. The geometry of the 2-dimensionally gradient auxetic core has been then optimized using two different techniques in order to minimize the radiated sound power level over the frequency range of 0 to 200 Hz. The optimized design of the 2-D gradient core shows a remarkable reduction of the radiated sound power level for the sandwich structure when taking into account the mass of the panels. The results of this study provide new insights about the vibroacoustic behavior of hexagonal auxetic sandwich structures with complex core geometry. [ABSTRACT FROM AUTHOR]

We designed a vibrotactile vest with physiological monitoring that interacts with a vibroacoustic urban environment, The Humming Wall. We structured vibrotactile patterns and built a vibrotactile language to convey information and to interact towards and from the vibroacoustic environment in order to elicit sensations and encourage particular body movements. The patterns were structured to emulate calming and activating sensations and to guide or warn the vest wearer. In addition, actions such as swiping or knocking on the wall were replicated on the vest for the vest wearer, and participants could ‘feel’ (vibroacoustically) and hear their own heartbeats and breath rates at the wall. A field trial with 39 participants was conducted over a 5-week period in an urban park. Participants wearing the vest completed a set of defined tasks. We logged use and responses, videoed all activities and conducted interviews and questionnaires post-experiment. The results depicted the participants’ experience, engagement and impressions while wearing the vibrotactile vest and interacting with the wall. The findings show convincing, strong and positive responses to novel interactions between the responsive vibroacoustic environment and the vibrotactile vest. We found compelling evidence to support further exploration into vibrotactile and vibroacoustic solutions for improving health and well-being. The work presented demonstrates the capacity for health and well-being solutions with multiple use cases. Additionally, this work constitutes the first field trial with a vibrotactile wearable responding to and driving vibroacoustic displays with an interactive vibroacoustic environment. [ABSTRACT FROM AUTHOR]

Composite panels, by virtue of their outstanding mechanical properties, have found various applications in different sectors like aerospace and transportation. Under certain assumptions like Kirchhoff–Love and Mead–Markus hypotheses, certain high-order differential equations can be used for vibroacoustic modeling of composite panels. However, for accurate modeling, updating parameters is an essential stage. Herein, we aim to theoretically and experimentally review this stage. For this purpose, a hybrid updating method is proposed, incorporating hierarchical functions, inhomogeneous wave correlation approach, and least squares optimizations. Then various laboratory measurements, including Laser Doppler Vibrometry measurements as well as sound pressure levels, are analyzed. The measurements were performed for a thick composite (sandwich) panel, and a thin composite (laminate) one, along with two isotropic (steel and aluminum) plates for additional validation. The experiments indicate the ability of the hybrid approach to adjust parameters and precisely model vibroacoustic behaviors of the panels. Furthermore, the proposed hybrid method can be used in studies whose goal is accurate vibroacoustic modeling for psychoacoustic issues and perceptual validations, which is also one of the future targets of this research. • A hybrid updating method for vibroacoustic modeling of composite panels is proposed. • The updating method is adapted for the corresponding 4th and 6th order problems. • The hierarchical functions are used for analytically formulating the problems. • The hybrid method utilizes the IWC technique and total least square optimization. • Laboratory experiments were performed, validating the proposed hybrid method. [ABSTRACT FROM AUTHOR]

• A hybrid method to estimate the radiated noise from sparsely-instrumented vibrating casing structures is demonstrated. In a complex structural system, such as a gearbox or a motor, with partially or completely unknown set of excitation forces, the exact prediction of the vibrations of a casing encapsulating the complex system, is not possible, especially at high frequencies. For the spatial recording of the complete vibration field on the casing, it would be necessary to scan the casing surface using several vibration sensors, especially at higher frequencies. Such a high-resolution rate of sensors or recording points on the casing surface is rarely achievable in industrial tests. Moreover, usage of several optical scanning devices to scan the vibration field from every possible direction is very expensive, cumbersome and mostly ineffective. Therefore, a novel technique is developed here, which enables the calculation of the participation factors of the casing eigenmodes using a reduced number of vibration sensors on the casing, with the aim to estimate the radiated noise levels generated by the vibrating casing. This technique is based on a Compressed Sensing approach which solves an under-determined system of equations. The calculated participation factors of the eigenmodes are then used as inputs into a Finite Element Method (FEM) to calculate the radiated noise levels. The noise predictions are then compared to the measurements to achieve enough confidence level in this method for its industrial usage. [ABSTRACT FROM AUTHOR]