Search Results (846)

Traffic-induced noise pollution is a significant environmental issue, driving the development of advanced noise-reducing pavement materials. Semi-dense graded asphalt mixtures (SDAMs) present a promising compromise, offering enhanced acoustic properties compared to conventional dense-graded asphalt mixtures while maintaining superior durability to porous asphalt mixtures. However, the mechanism underlying the relationship between the energy dissipation characteristics and noise reduction effects of such mixtures remains unclear, which limits further optimization of their noise reduction performance. This study designed and prepared semi-dense graded noise-reducing asphalt mixtures SMA-6 TM, SMA-10 TM, and SMA-13 TM (SMA TM represents noise-reducing SMA mixture) based on traditional dense-graded asphalt mixtures SMA-6, SMA-10, and SMA-13, and conducted tests for water stability, high-temperature performance (60 °C), and low-temperature performance (−10 °C). Subsequently, energy loss parameters such as loss factor and damping ratio were calculated through dynamic modulus tests to characterize their energy dissipation properties. The mechanism linking the energy dissipation characteristics of semi-dense graded asphalt mixtures to noise reduction was investigated. Finally, the noise reduction effect was further verified through a tire free fall test and a close-proximity (CPX) method. The indoor test results indicate that the semi-dense mixtures exhibited a trade-off in performance: their dynamic stability was 11.1–11.3% lower and low-temperature performance decreased by 4.2% (SMA-13 TM) to 14.1% (SMA-6 TM), with moisture stability remaining comparable. Conversely, they demonstrated superior damping, with consistently higher loss factors and damping ratios. All mixtures reached peak damping at 20 °C, and the loss factor showed a strong positive correlation (R² > 0.91) with energy dissipation. Field results from a test section showed that the optimized SMA-10 TM mixture yielded a significant tire–road noise reduction of 3–5 dB(A) relative to the SMA-13, while concurrently meeting key performance criteria for anti-water ability and durability. This study establishes a link between the energy dissipation in SDAM and their noise reduction efficacy. The findings provide a theoretical framework for optimizing mixture designs and support the wider application of SDAM as a practical noise mitigation solution. Full article

Due to increasing demand for the exploration of marine resources, underwater optical wireless sensor networks (UOWSNs) have emerged as a promising solution by offering higher bandwidth and lower latency compared to traditional underwater acoustic wireless sensor networks (UAWSNs), with their existing routing protocols facing challenges in energy consumption and packet forwarding. To address these challenges, this paper proposes an energy-partitioned routing protocol based on an advancement function (EPAR) for UOWSNs. By dynamically classifying the nodes into high-energy and low-energy ones, the proposed EPAR algorithm employs an adaptive weighting strategy to prioritize the high-energy nodes in relay selection, thereby balancing network load and extending overall lifetime. In addition, a tunable advancement function is adopted by the proposed EPAR algorithm by comprehensively considering the Euclidean distance and steering angle toward the sink node. By adjusting a tunable parameter α, the function guides forwarding decisions to ensure energy-efficient and directionally optimal routing. Additionally, by employing a hop-by-hop neighbor discovery mechanism, the proposed algorithm enables each node to dynamically update its local neighbor set, thereby improving relay selection and mitigating the impact of void regions on the packet delivery ratio (PDR). Simulation results demonstrate that EPAR can obtain up to about a 10% improvement in PDR and up to about a 30% reduction in energy depletion, with a prolonged network lifetime when compared to the typical algorithms adopted in the simulations. Full article

Pipe exits into cryogenic systems, such as an exit of a venting or sensor tube inside a cryogenic storage tank, can affect spontaneously occurring acoustic oscillations, known as Taconis oscillations. The amplitude which such oscillations will reach is dependent on losses at the pipe exit that prevent resonant oscillations from growing without bound. Consequently, being able to accurately determine minor losses at a pipe exit is important in predicting the behavior of these oscillations. Current thermoacoustic modeling of such transitions typically relies on steady-flow minor loss coefficients, which are usually assumed to be constant for a pipe entrance or exit. In this study, numerical simulations are performed for acoustic flow at a pipe exit, with and without a wall adjacent to the exit. The operating fluid is cryogenic hydrogen gas, while the pipe radius (2 and 4 mm), temperature (40 and 80 K), and acoustic velocity amplitudes (varying in the range of 10 m/s to 70 m/s) are variable parameters. The simulation results are compared with one-dimensional acoustic models to determine the behavior of minor losses. Results are also analyzed to find harmonics behavior and a build-up of mean pressure differences. Minor losses decrease to an asymptotic value with increasing Reynolds number, while higher temperatures also reduce minor losses (10% reduction at 80 K versus 40 K). A baffle sharply increases minor losses as the distance to pipe exit decreases. These findings can be used to improve the accuracy of oscillation predictions by reduced-order thermoacoustic models. Full article

The vaporization of urea–water solution (AdBlue) plays a critical role in the performance of selective catalytic reduction (SCR) systems for modern diesel engines. This study presents mathematical models describing the vaporization of AdBlue droplets under ultrasonic excitation generated by a magnetostrictive effect, focusing on both film and volumetric regimes. The models rigorously incorporate heat and mass transfer equations, including acoustic cavitation effects induced by ultrasound. The influence of magnetostrictive-induced atomization and combined inductive preheating on droplet detachment and SCR catalyst efficiency was analyzed. Additionally, the impact of ultrasound frequency and amplitude on thermal vaporization efficiency and reactive mixture formation was investigated with the aim of enhancing NOx emission reduction. Model validation against literature data confirmed the practical applicability of the proposed approach, offering valuable insights for optimizing ultrasound-assisted AdBlue injection systems. Full article

Passenger comfort in executive-class aircraft demands rigorous control of noise, vibration, and harshness. This study describes the development of a detailed, high-fidelity coupled structural–acoustic finite element model of the Piaggio P.180 passenger cabin, aimed at accurately predicting interior cabin noise within the low- to mid-frequency range. A hybrid discretization strategy was employed to balance computational efficiency and model fidelity. The fuselage structure was discretized using two-dimensional shell elements and one-dimensional beam elements, while the interior cabin air volume was represented using three-dimensional fluid elements. Mesh sizing in both the structural and acoustic domains were determined through analytical wavelength estimates and numerical convergence studies, ensuring appropriate resolution and accuracy. The model’s reliability and accuracy were validated through comprehensive modal analysis. The first three structural modes exhibited strong correlation with available experimental data, confirming the robustness of the numerical model. Subsequent harmonic response analyses were conducted to evaluate the intrinsic noise reduction characteristics of the P.180 airframe, specifically within the frequency range up to approximately 300 Hz. Full article

The basic tone of the human voice is generated in the larynx, which is reinforced by and derives its distinctive features from the resonance of the oral and nasal cavities An inappropriate ratio between oral and nasal resonance results in a more nasal timbre of the voice, which is referred to as nasality (hypernasality). Nasality is often present in hearing-impaired patients, and various studies have shown that hypoacusis, including partial deafness (PD), causes voice disorders as a result of disturbed control over the complex process of voice production. This study describes our investigation of nasality in 20 adult Polish patients with post-lingual partial deafness. The results show that PD patients developed more nasality in their voices when compared with individuals in the control group. Observations made 9 months after cochlear implantation for partial deafness indicated a reduction in nasality, with the changes in acoustic parameters achieving statistical significance. Background/Objectives: This study aimed to assess whether partial deafness (PD) causes changes in nasal resonance in adult patients and whether partial deafness cochlear implantation (PDCI) influences the level of nasality. Methods: Voice samples from 20 patients attending the Institute of Physiology and Pathology of Hearing in Warsaw with partial deafness were analyzed and compared with samples from 20 individuals with normal hearing. Voice samples from the same patients were comparatively analyzed at 9 months after cochlear implantation. The level of nasality was assessed using the FFT (Fast Fourier Transform) for acoustic analysis, as well as subjective description by two experienced medical professionals (a medical doctor and a clinical acoustician). Pearson analysis was then performed to determine the correlations between the objective and subjective assessments. Paired two-sample t-tests for means were conducted for statistical analysis. All patients of the Institute of Physiology and Pathology of Hearing in Warsaw declared their deliberate consent to all necessary diagnostic and therapeutic procedures upon admittance. Results: The results show that post-lingual partial deafness causes nasality in adult patients when measured both objectively (p = 0.0001) and subjectively. The average objective level of nasality was 21 dB (SD 4.5), while the subjective level was an average grade of 1.25. The level of nasality presented a positive correlation with the duration of partial deafness. The assessment performed 9 months after cochlear implantation showed a reduction in nasality, achieving 17 dB (SD 4.2) in the objective measurement (p = 0.0002) and a grade of 0.5 when assessed subjectively. Pearson analysis showed a weak correlation between the objective measurement and subjective assessment (r = 0.2). Conclusions: Post-lingual partial deafness causes nasality in adults in a manner that is positively correlated with the duration of hearing impairment. Partial deafness cochlear implantation reduced nasality after 9 months of observation, as shown both objectively (MDVP) and subjectively (perceptual assessment). However, the correlation between the objective and subjective results is rather weak; therefore, objective acoustic methods (e.g., MDVP) should preferably be used for a more credible assessment, while the subjective method may only serve as a rough and general tool in everyday clinical use. Full article

Metamaterials, characterized by engineered microstructures rather than chemical composition, are transforming civil infrastructure through their unique ability to achieve frequency-selective wave attenuation and programmable mechanical responses. This review provides a comprehensive overview of the applications of acoustic and mechanical metamaterials within civil engineering contexts. Acoustic metamaterials demonstrate significant potential for mitigating noise pollution in environments such as high-rise buildings, urban public areas, and transportation infrastructure by substantially enhancing sound insulation and noise reduction capabilities. Meanwhile, mechanical metamaterials, exhibiting advanced properties including shape memory, exceptional stiffness, and programmable functionality, offer novel strategies for improving structural resilience and seismic performance. Additionally, this article explores emerging opportunities in energy harvesting and adaptive infrastructure integration. Despite these advancements, critical challenges related to scalability, durability, and seamless integration with the existing infrastructure persist. Addressing these issues in future research will facilitate the advancement of sustainable, adaptive, and high-performance metamaterial solutions for modern civil infrastructure. Full article

To address the problem of low-frequency broadband vibration and noise encountered in engineering, a method for expanding the low-frequency band gap of locally resonant acoustic metamaterials is proposed based on the multi-mode coupling effect. A computational method for the band gap characteristics of second-order multi-mode acoustic metamaterials has been derived. By incorporating the vibrational modes obtained from band structure calculations, a systematic investigation of the formation mechanisms of multiple band gaps was conducted, revealing that the emergence of these multiple band gaps stems from the coupled resonance between elastic waves and distinct vibrational modes of the local resonator units. Furthermore, the influence of design parameter variations on the bandgap was investigated, and the strategy of realizing low-frequency multi-order bandgaps by increasing the order of local resonance units was examined. Finally, vibration tests were conducted on the second-, third-, and fourth-order multi-mode coupled acoustic metamaterials. The results demonstrated that these materials exhibit an expanded vibration band gap within the low-frequency range, and the measured frequency response aligns closely with the theoretical calculations. This type of acoustic metamaterial offers viable applicability for controlling low-frequency broadband vibrations. Full article

To address the challenges of low diagnostic accuracy arising from the non-stationary and nonlinear time-varying characteristics of acoustic signals in rolling bearing fault diagnosis, as well as their susceptibility to noise interference, this paper proposes a fault diagnosis method based on a Weighted Average Algorithm–Feature Mode Decomposition (WAA-FMD) and a Local–Global Adaptive Multi-scale Attention Mechanism (LGAF)–Swin Transformer. First, the WAA is utilized to optimize the key parameters of FMD, thereby enhancing its signal decomposition performance while minimizing noise interference. Next, a bilateral expansion strategy is implemented to extend both the time window and frequency band of the signal, which improves the temporal locality and frequency globality of the time–frequency diagram, significantly enhancing the ability to capture signal features. Ultimately, the introduction of depthwise separable convolution optimizes the receptive field and improves the computational efficiency of shallow networks. When combined with the Swin Transformer, which incorporates LGAF and adaptive feature selection modules, the model further enhances its perceptual capabilities and feature extraction accuracy through dynamic kernel adjustment and deep feature aggregation strategies. The experimental results indicate that the signal denoising performance of WAA-FMD significantly outperforms traditional denoising techniques. In the KAIST dataset (NSK 6205: inner raceway fault and outer raceway fault) and the experimental dataset (FAG 30205: inner raceway fault, outer raceway fault, and rolling element fault), the accuracies of the proposed model reach 100% and 98.62%, respectively, both exceeding that of other deep learning models. In summary, the proposed method demonstrates substantial advantages in noise reduction performance and fault diagnosis accuracy, providing valuable theoretical insights for practical applications. Full article

Control valves are the main throttling resistance components in industries such as chemical engineering, nuclear power, aerospace, hydrogen energy, natural gas transportation, marine engineering, and energy systems. Flow-induced vibration fatigue failure is a common failure mode. To provide engineers and researchers with a reference for reliable design analysis of control valves and to predict and prevent potential failures, this article reviews and categorizes vibration-induced failure in control valves by integrating numerous engineering cases and research articles. The vibration failures of control valves are mainly divided into categories such as jet flow, vortex flow, cavitation, and acoustic cavity resonance. This paper reviews control valve vibration research from three aspects: theoretical models, numerical simulations, and experimental methods. It highlights the mechanisms by which internal unstable flow, jet flow, vortex shedding, cavitation, and acoustic resonance lead to vibration-induced fractures in valve components. Additionally, it examines the influence of valve geometry, component constraints, and damping on flow-induced valve failures and summarizes research on vibration and noise reduction in control valves. This paper aims to serve as a reference for the analysis of vibration-induced failures in control valves, helping identify failure mechanisms under different operating conditions and proposing effective solutions to enhance structural reliability and reduce the occurrence of vibration failures. Full article

This paper proposes a robust blind algorithm for direction of arrival (DOA) estimation in challenging acoustic environments. The method introduces a novel Time Difference of Arrival (TDOA) consensus framework that effectively identifies and filters outliers using Median and Median Absolute Deviation (MAD) statistics. By combining this consensus approach with whitening transformation and Lawson norm optimization, the algorithm achieves superior performance in noisy and reverberant conditions. Comprehensive simulations demonstrate that the proposed method significantly outperforms traditional approaches and modern alternatives such as SRP-PHAT and robust MUSIC, particularly in environments with high reverberation times and low signal-to-noise ratios. The algorithm’s robustness to impulsive noise and varying microphone array configurations is also evaluated. Results show consistent improvements in DOA estimation accuracy across diverse acoustic scenarios, with root mean square error (RMSE) reductions of up to 30% compared to standard methods. The computational complexity analysis confirms the algorithm’s feasibility for real-time applications with appropriate implementation optimizations, showing significant improvements in estimation accuracy compared to conventional approaches, particularly in highly reverberant conditions and under impulsive noise. The proposed algorithm maintains consistent performance without requiring prior knowledge of the acoustic environment, making it suitable for real-world applications. Full article

This study presents an acoustic membrane design utilizing a thin foil sound resonance mechanism to enhance sound absorption and insulation performance. The membranes incorporate single-layer and double-layer structures featuring parallel foil square wedge-shaped coffers and a flat bottom panel, separated by air cavities. The enclosed air cavity significantly improves the sound insulation capability of the acoustic membrane. Parametric studies were conducted to investigate key factors affecting the sound transmission loss (STL) of the proposed acoustic membrane. The analysis examined the influence of foil thickness, substrate thickness, and back cavity depth on acoustic performance. Results demonstrate that the membrane structure enriches vibration modes in the 500–6000 Hz frequency range, exhibiting multiple acoustic attenuation peaks and broader noise reduction bandwidth (average STL of 40–55 dB across the researched frequency range) compared to conventional resonant cavities and membrane-type acoustic metamaterials. The STL characteristics can be tuned across different frequency bands by adjusting the back cavity depth, foil thickness, and substrate thickness. Experimental validation was performed through noise reduction tests on an air compressor pump. Comparative acoustic measurements confirmed the superior noise attenuation performance and practical applicability of the proposed membrane over conventional acoustic treatments. Compared to uniform foil resonators, the combination of plastic and steel materials with single-layer and double-layer membranes reduced the overall sound level (OA) by an additional 2–3 dB, thereby offering exceptional STL performance in the low- to medium-frequency range. These lightweight, easy-to-manufacture membranes exhibit considerable potential for noise control applications in household appliances and industrial settings. Full article

People’s perceptions of architectural spaces are shaped by multiple senses, including vision and hearing. While vision has received extensive attention, hearing is often overlooked in architectural design, with a primary focus on sound insulation and noise reduction rather than on using acoustics to enhance spatial experience. Therefore, this study aims to investigate the impact of acoustic environments on two key spatial perceptions: Spaciousness and transparency. Two laboratory experiments were conducted with 60 participants. Thirty subjects evaluated 96 audiovisual stimuli for perceived spaciousness, and another 30 subjects assessed 128 audiovisual stimuli for perceived transparency. The results indicate that sound type significantly affects perceived spaciousness, while sound type and sound pressure level (SPL) significantly influence perceived transparency. Reverberation time (RT, T60) had no effect on either spatial perception. Interaction analysis further revealed that sound type affects transparency across different space sizes and window proportions, while SPL only influences small spaces and standard window proportions, with transparency decreasing as SPL increases. Mediation analysis showed that the effects of sound type on both spaciousness and transparency are partially mediated by subjective spatial perceptions, such as building environment preference and alignment with the outdoor environment. These findings emphasize the importance of integrating acoustic considerations into architectural design, which can enhance spatial experiences and provide valuable insights for future design practices. Full article

Traditional sound-absorbing materials, which are intended to address the issue of low-frequency noise control in automobile air-conditioning duct mufflers, have limited noise reduction effects in small spaces. Because of their straightforward structure and excellent controllability, acoustic metamaterials—particularly Helmholtz resonators—have emerged as a research hotspot in low-frequency noise reduction. However, existing technologies have issues such as restricted structural scale, narrow absorption frequency bands, and conflicts with ventilation requirements. To address these, this paper proposes a new type of Helmholtz perforated and tortuous-characteristic duct muffler for the unit cell of acoustic metamaterials. Through the innovative structural design combining a perforated panel with a multi-channel tortuous cavity, the length of the channel is changed in a limited space, thereby extending the sound wave propagation path and enhancing the dissipation of sound wave energy. Meanwhile, for the muffler, acoustic theoretical modeling, finite element simulation, and parametric optimization methods are adopted to systematically analyze the influence of its key structural parameters on the sound transmission loss (STL) of the muffler. Compared with the traditional folded-channel metamaterial, the two differ in resonance frequency by 38 Hz, in transmission loss by 1.157 dB, and in effective bandwidth by 1 Hz. This research provides theoretical support and design basis for solving the problem of low-frequency noise control in ventilation ducts, improves low-frequency broadband sound absorption performance, and promotes the engineering application of high-efficiency noise reduction devices. Full article

This study presents a semi-empirical approach to generalizing the acoustic radiation generated by serrated airfoil configurations, based on small-scale aerodynamic/acoustic experiments and functional regression techniques. In the context of passive noise reduction strategies, such as leading-edge and trailing-edge serrations, acoustic measurements are performed in a controlled subsonic wind tunnel environment. Sound pressure level (SPL) spectra and acoustic power metrics are acquired for various geometric configurations and flow conditions. These spectral data are then analyzed using regression-based modeling techniques—linear, quadratic, logarithmic, and exponential forms—to capture the dependence of acoustic emission on key geometric and flow-related variables (e.g., serration amplitude, wavelength, angle of attack), without relying explicitly on predefined nondimensional numbers. The resulting predictive models aim to describe SPL behavior across relevant frequency bands (e.g., broadband or 1/3 octave) and to extrapolate acoustic trends for configurations beyond those tested. The proposed methodology allows for the identification of compact functional relationships between configuration parameters and acoustic output, offering a practical tool for the preliminary design and optimization of low-noise serrated profiles. The findings are intended to support both physical understanding and engineering application, bridging experimental data and parametric acoustic modeling in aerodynamic noise control. Full article