Sound Insulation Performance Research Articles

Lightweight soundproofing meta-panel for two separate broadband noises

We propose a lightweight soundproofing meta-panel, with a multi-scale lattice structure sandwiched between thin membranes, effectively suppressing two separate broadband noises. By adjusting the geometrical parameters, the meta-panel is designed to induce negative effective mass density and negative effective bulk modulus for two distinct target frequency bands: 100–500 Hz and 1000–1500 Hz, thereby achieving high transmission loss that outperforms the mass density law. A meta-panel sample is fabricated via 3D printing technology and we evaluate its sound insulation performance by measuring transmission loss and insertion loss in an impedance tube and an anechoic chamber. Experimental measurements show that the meta-panel can exhibit excellent insulation performance while being significantly lighter in weight (about 5%) compared to a steel plate, and furthermore, it effectively suppresses low-frequency road noise and high-frequency motor noise from an actual electric car.

BIM-based sound insulation performance evaluation of interior walls

As a general contractor, acoustical design confirmation of a project at construction stage is rather limited especially if it is large-scale. Among others, many interior walls of the building projects are found to be improperly designed in terms of sound insulation in that chances are hardly given for the most projects to be intervened by an acoustic expert at their design stage. In many cases, they turn out to be either underperformed or overperformed. This study developed a tool for holistically evaluating sound insulation design of interior walls across the building areas. It was designed on the basis of BIM modeling to be fast-tracked in supporting either the architects or general contractors for a quick and broad design review. Mapping of the information of room use and wall types with their predicted or measured sound insulation data on to a BIM model is set out to compare to the design criteria according to room use and adjacency. The results are simulated on both 2-D and 3-D BIM models, visually presenting the sound insulation performance. A report is instantly generated on performance qualification with the information of wall types, surface areas, etc. It also suggests alternative wall types as necessary.

Improvement of sound insulation on the modular housing

The modular construction method is an architectural technique in which buildings are produced in factories and then assembled on construction sites to complete the construction process. This method has two main advantages. First, since the construction takes place in factories, it can reduce construction waste. Second, it can shorten the construction period on the site. So there is considerable interest in using the modular construction method for the construction of residential buildings. In this study, the purpose of the modular construction method in the case of residential buildings is to improve the indoor sound insulation. For this purpose, first, the sound insulation performance of the walls and floor structures has been predicted through simulations at the design stage. Second, the sound insulation performance of the walls and floor structures has been measured using mock-ups in the factory and compared with the simulation results. Third, the sound insulation performance of the walls and floor structures in the actual completed building has been measured and compared with the performance of the simulations and mock-ups. As a result, we have compared the performance of modular construction from the design stage to the completion of the building. Through this process, we have presented procedures for improving the sound insulation performance of the building and quality management, from the design phase to the post-construction stage.

Sound insulation design using membrane and locally resonant structure

In this study, we propose a design for sound insulation that utilizes a membrane and a locally resonant structure in tandem. A membrane serves as an excellent sound insulation structure in itself, but it can also be used to improve sound insulation performance by changing the dynamic characteristics of the sound insulation panel. In the case of the latter, there is an advantage of improving sound insulation performance in several bands without a large increase in weight. However, because the resonance band occurs at a relatively lower frequency than the anti-resonance band, it is difficult to block noise at frequencies below the anti-resonance band. To address this, we added a locally resonant structure that operates within the associated band. Because the anti-resonance caused by the locally resonant structure occurs at a lower frequency than the resonance, it can compensate for the deterioration band caused by the membrane-cavity. These effects have been verified through a sound transmission loss simulation of the unit structure at the normal and oblique incidence condition. Furthermore, the soundproofing bands of the product (plate and enclosure) were validated through SPL experiments.

Acoustic metaliners for insulating noise in a duct with varying cross-sectional area

We propose a sound-insulating acoustic metaliner for a duct with varying cross-sectional area with consideration of the flow that varies along the direction of flow and is not a fully-developed. The metaliner comprises an array of unit cells based on two different types of Helmholtz resonators and installed on the duct wall to preserve ventilation performance. To consider the effect of flow on the sound insulation performance of the metaliner, we establish an effective impedance model in term of the friction velocity, enabling the consideration for flows that are not fully-developed. The geometrical parameters of unit cells of the metaliner are designed individually considering the flow around each unit cell. The sound insulation performance of the designed metaliners for different flow speeds with the target frequency of 900 Hz is verified experimentally.

Sound insulation properties of embedded co-cured composite damping sandwich panel under arbitrary boundary conditions

The embedded co-cured composite damping structures (ECCDS) are widely used in engineering fields, it is necessary to build a predictive model of the dynamics of the ECCDS panel. In this paper, a method is promoted for the first time that can predict the acoustic-vibration coupling characteristics of the coupled cavity-ECCDS panel-cavity system. This paper innovatively combines the spectral-geometry method (SGM), penalty-function method (PFM), and the energy-generalised variational principle to develop coupling model of the ECCDS panel with two closed cavities. The displacement of the ECCDS panel and the sound pressure in the cavities are expressed as improved Fourier series. The modal parameters of the cavities and the ECCDS panel are obtained by solving the standard matrix eigenvalue problem, and the accuracy of this method is verified by comparing it with the finite element method (FEM) and experiment. On this basis, the sound transmission loss (STL) can be obtained by the sound pressure method. The factors affecting the sound insulation performance of the ECCDS panel are investigated by parametric analysis. The results show that the addition of a damping layer can improve the sound insulation performance of composite panels. This paper provides a reference for the application of ECCDS panels in engineering.

Free Vibration and Sound Insulation of FG-CNTRC Sandwich Plates with Different Cores

The core layer is very important in studying the vibration and noise problems of sandwich structures. The present paper studied the free vibration and sound insulation characteristics of FG-CNTRC sandwich plates with FG-CNT face sheets and different cores including the soft core (epoxy), hard core (aluminum) and porous metal foam core with different porosity distributions. By Hamilton’s principle the dynamic equations of FG-CNTRC sandwich plates are formulated based on the third-order shear deformation theory (TSDT), and the sound insulation expression is given under the excitation of the sound pressure. The theoretical solution of natural frequency and sound insulation are compared with the finite element simulation results and validated. The natural frequency of the square sandwich plate are compared with the rectangular case. The free vibration and sound insulation performance of FG-CNTRC sandwich plates are analyzed and discussed, and parametric studies are performed to evaluate the effects of CNT volume fraction, CNT distribution patterns, CNT orientation angles, porosity coefficient and incident angles on the vibro-acoustic characteristics of the sandwich plate. Some new results are presented to be used as references for the further research.

Damping contribution of viscoelastic core on airborne sound insulation performance of finite constrained layer damping panels at low and middle frequencies

The airborne sound insulation performance of finite sandwich panels is often significantly worsened by resonant transmission components in low and middle frequencies. In this paper, damping contribution of viscoelastic core on sound transmission loss (STL) of finite constrained layer damping (CLD) panels is studied in narrow frequency bands. A fully coupled layer-wise approach is used with a generalized high-order shear deformation hypothesis that accounts for all types of deformations in the core. The influence of several parameters is investigated extensively. Results show that the adverse impact of the first-three odd-odd order modes, namely (1,1), (3,1), and (1,3) modes, as well as some higher-order modes on STL cannot be disregarded. The constrained viscoelastic core plays a crucial role in enhancing, or even eliminating, dips of STL spectrum at resonant frequencies. Additionally, it can considerably counterbalance a relatively broadband reduction of STL caused by the inter-modal coupling in middle frequencies. The damping mechanism can be divided into two aspects: (i) the reduction of modal amplitude by vibration energy dissipation, and (ii) the change of bending modal shapes. CLD treatment is a concise and effective way to achieve stable sound insulation performance.

Enhanced sound absorption performance of porous ceramics with closed-pore structure

To enhance the sound absorption performance of porous ceramics at low-to-medium frequencies, a novel porous ceramic with closed-pore structure was prepared through the addition of silicon carbide (SiC), which foamed at high temperature. The porous ceramic with closed-pore structure exhibited a better combination property than those without such pore structure. The results revealed a 69.6% improvement in the average sound absorption coefficient of porous ceramics with closed-pore structure compared to those without closed-pore structure at 200–1600 Hz. Furthermore, the sound insulation performance of porous ceramics with closed-pore structure exhibited a 150% improvement at 160–1600 Hz. Moreover, these ceramics featured a high open porosity from 65% to 82% when combined with sufficient compressive strength of 1.21–5.13 MPa and low thermal conduction of 0.126–0.198 W/m∙K, indicating a considerably promising combination of properties for noise control and reduction in corrosive environments at high temperature. These results indicated that the porous ceramic had sufficient strength, low thermal conduction, and good sound absorption performance, which was expected to be applied as the building insulation and acoustic damping material. Besides, this study provides a new method for enhancing the sound absorption performance of porous ceramics at low-to-medium frequencies.

The sound insulation performance of light wood frame construction floor structure based on phononic crystal theory

The development of timber structures worldwide is rapid and promising. Acoustic insulation is an important metric to measure the quality of occupants' living conditions. Therefore, to effectively improve the harm caused by low-frequency noise of the wood structure floors that people are concerned about, this paper combines the structural characteristics of the light wood frame construction floor with the phononic crystal structure with excellent sound insulation performance and carries out the impedance tube test through the simulation calculation results of COMSOL software. Impedance tube tests and field test studies were also carried out on a two-story light wood frame construction floor in Nanjing, China, to obtain a phononic crystal structure building cover with good sound insulation performance … The conclusion of the study shows that: the G8-40 phononic crystals structure obtained by COMSOL simulation matches with its impedance tube test results, and the effectiveness of its sound insulation performance has been verified by the airborne sound insulation field test; the phononic crystals structure floor has excellent sound insulation performance in the low-frequency band, which can significantly improve the user's living comfort needs and has good engineering application value.

Study of Gap Flow Effects on Sound Transmission Through a Micro-Perforated Sandwich Cylindrical Shell Excited by a Plane Wave

This paper presents a theoretical model to study sound transmission through a micro-perforated double-walled sandwich cylindrical shell with emphasis on the potential of internal gap flow to improve the sound insulation performance. This model adopts Donnell’s thin shell theory to govern the shell motions and a simplified model based on Biot’s theory to describe sound propagation in the porous lining. The mean acoustic particle velocity model with the grazing flow effect is applied to define the coupling condition between the fluid medium and the perforated shell. Transmission loss (TL) through the configuration with one gap flow is numerically calculated using the mode superposition method when subjected to an oblique plane wave in the presence of an external mean flow. Results reveal that the gap flow in the opposite direction to the external flow would elevate the mid-frequency TL. Gap depth has a complicated effect on TL since it influences the aerodynamic damping of the gap flow and sound dissipation in the porous layer. The average TL in 20–20[Formula: see text]000[Formula: see text]Hz is then optimized with a genetic algorithm, and an increase of 17.82 dB is finally achieved. The possibility of tuning the structural sound insulation performance by the gap flow has been verified.

Effects of Impact Sound Insulation of Floor Covering on the Properties of Wood Organic Resilient Material

近年來樓板緩衝材多以玻璃棉、橡膠墊或發泡類等工業化之產品為主，在製程或回收利用上亦須依賴大量能源之供應。因此，本研究在地球永續與循環經濟之課題下，以栓皮櫟（Quercus suber）樹種作為研究對象，利用木栓層（Cork layer）組織特性，開發木質有機緩衝材，並搭配複合木地板之面材進行樓板衝擊音隔音性能之探討。研究結果顯示，在栓皮櫟樹皮顆粒使用比例為30 %時，衝擊音降低量預估值達22 dB，較10 %及20 %之比例條件佳，且低頻衝擊音降低量數值較常見之橡膠發泡與PU發泡佳，顯示本研究之木質有機緩衝材除符合生態綠建材之原則外，亦可提升建築樓板之隔音性能。In recent years, glass wool, rubber, and foam were the main materials used in floor resilient material, which consume a lot of energy in the process of recycling. Under the topic of earth sustainability and circular economy, in this study, we took Quercus suber as the research object, and use the organizational characteristics of the Cork layer to develop wood organic resilient material. We discussed the floor impact sound insulation performance of laminate wood flooring and wood organic resilient material. The result showed when using 30 % cork oak, the impact sound reduction value of the floor covering was 22 dB. The impact sound insulation performance of low frequencies of wood organic resilient material was better than rubber and foam. The wood-organic resilient material produced in this study was in line with ecological green building materials and improved the sound insulation performance of building floors.

A Study on Floor Impact Sound Insulation Performance of Cross-Laminated Timber (CLT): Focused on Joint Types, Species and Thicknesses

A Study on Floor Impact Sound Insulation Performance of Cross-Laminated Timber (CLT): Focused on Joint Types, Species and Thicknesses

Damping characteristics and sound transmission loss of finite composite plates with frequency dependent constrained viscoelastic interlayer

This paper proposes a sublaminate layer-wise finite element modeling method to accurately evaluate the damping and sound insulation characteristics of composite constrained layer damping plates. It incorporates the frequency-dependent property of viscoelastic interlayer into fully coupled structure-acoustic interaction equations, and employs the generalized high-order displacement hypothesis with tailored polynomial series expansion. The method is applicable to various boundary conditions and material layer combinations. Validation is conducted using numerical and experimental data. Parametric study identifies optimal thickness and stiffness for maximizing modal loss factor. Additionally, sound insulation performance is examined in narrow frequency bands, highlighting the damping enhancement of viscoelastic interlayer.

Revealing the Sound Transmission Loss Capacities of Sandwich Metamaterials with Re-Entrant Negative Poisson's Ratio Configuration.

Due to the influence of mass law, traditional lightweight sandwich structures have struggled to surpass solid structures in sound insulation performance. To this end, we propose an acoustic metamaterial structure with a sandwich configuration based on the re-entrant negative Poisson's ratio (NPR) structure and systematically investigate its sound transmission loss (STL) performance under incident plane wave conditions. We used the acoustic impedance tube method to experimentally study the sound insulation performance of the re-entrant NPR sandwich structure under free boundary conditions, and then established an acoustic analysis simulation model based on COMSOL Multiphysics software, which verified that the results obtained by the experiment and the numerical simulation were in good agreement. The results show that the sandwich structure exhibits excellent sound transmission loss performance in the studied frequency range (250-4000 Hz), and the overall sound insulation performance exceeds the curve of the mass theorem, basically achieving more than 20 dB when the sandwich thickness is 2 cm. Finally, we conduct parametric studies to establish a correlation between the geometric design of NPR sandwich structures and their sound transmission loss performance. The research shows that the changes of the length of the ribs, the distance from the ribs to the center of the unit, and the length of the upper wall and the lower wall have a significant impact on the sound insulation performance of the re-entrant NPR sandwich structure, while the change of the wall thickness basically will not affect the sound insulation performance of the sandwich structure. This research can provide practical ideas for the engineering application of noise suppression designs of lightweight structures.

Lightweight stiffness-dominated acoustic metamaterial barrier for low-frequency sound

In this study, we experimentally demonstrate a class of lightweight acoustic metamaterial barriers that block low-frequency sound. The acoustic metamaterial barrier is composed of a thin rubber membrane coated over a stiff honeycomb plate. Our findings, combined with high-fidelity finite element simulations, demonstrate that the sound insulation performance of the acoustic metamaterial surpasses the mass law in three distinct frequency ranges: (a) the stiffness law dominates insulation up to 140 Hz, (b) degeneracy and destructive superposition of high-order natural modes dominate within the frequency range of 300–500 Hz, and (c) destructive interference between high-order resonance and membrane resonance dominates in the frequency range of 800–1200 Hz. Notably, our study highlights the potential of high-order shear vibration of the periodic structure for the resonant bending waves of the honeycomb cell that coincide with the wavelengths of longitudinal sound waves in air, thereby offering new design guidelines for lightweight acoustic metamaterial barriers. This study reports for the first time the coincidence of high-order and membrane resonance modes within the honeycomb cell by employing an accurate finite element model and experimental validation.

Investigation of sound transmission through a finite length cylindrical shell in the presence of an exterior turbulent boundary layer

This paper studies sound transmission through a thin cylindrical shell of finite length. The structure is subjected to an exterior turbulent boundary layer (TBL) excitation and the boundary conditions of its two ends are considered as simply-supported. The classical shell theory (CST) is employed to derive wave propagation in the cylindrical shell, and the Corcos model is applied to describe pressure fluctuation due to TBL. According to the existence of two axial and radial modes, a complete convergence study is presented. To examine sound transmission through the structure, a comprehensive parameters study is provided on the resulting power spectral density (PSD) of the kinetic energy. To validate the results of the present method, the statistical energy analysis (SEA) method is used. For this purpose, modeling is performed by SEA in VA One software, which shows the high accuracy of the results of the present method. The analytical predictions suggest that the sound insulation performance of such a finite length structure is enhanced considerably by increasing the thickness of the shell in a broad-band frequency range. Similar effects on sound transmission are observed for Young’s modulus and density of the shell particularly in the low and high-frequency ranges, respectively. Whereas, enhancing the turbulent pressure and freestream velocity adversely affects sound radiation into the structure.

Broadband low-frequency sound insulation of double-panel metastructures with a perforated lattice truss-core sandwich plate

Lattice truss-core sandwich plates have drawn increasing attention owing to their excellent mechanical properties and multifunctional characteristics, but they are insufficient in low-frequency sound insulation because of their lightweight feature. To improve the sound transmission loss (STL) of such lightweight sandwich plates while without greatly increasing the structural complexity and the total mass, one faceplate of the sandwich plate is perforated so that the sandwich core can be utilized as an acoustic cavity. A homogenous plate is further introduced to construct a double-panel metastructure together with the perforated sandwich plate. For ease of analysis and design of the double-panel metastructure, a semi-analytical method is developed by combining an effective medium theory of the acoustic domain and a dynamic homogenization method of the sandwich plate. The feasibility of the developed method for efficient STL prediction under different incident angles is verified by comparing with the conventional finite element method. Numerical results show that the double-panel metastructure exhibits a remarkable sound insulation performance within a broadband low-frequency range, owing to the fact that the acoustic domain enclosed by the double-panel metastructure has an unusual equivalent bulk modulus. Then, a parametric study is conducted to reveal the sound insulation capacity and provide a guideline for tuning the STL of the double-panel metastructure. Finally, the actual sound insulation capacity of the double-panel metastructure is validated by experimental measurements of large-scale specimens.

Sound insulation mechanism and prediction of membrane-type acoustic metamaterial with multi-state anti-resonances by weighted-kNN

In this study, we present a swing-arm type membrane-type acoustic metamaterial (MAM) with multi-state anti-resonances. The designed structure is lightweight and can achieve excellent sound insulation in a wide frequency range of 100–1000 Hz. Through the analysis of sound transmission loss and anti-resonance mode, the sound insulation principle of MAM is obtained. Besides, the orthogonal experiment presents the order of the main factors affecting the sound insulation performance. Based on the relative bandwidth as the classification criterion, k-nearest neighbor with analytic hierarchy process and K-Fold cross-validation is utilized to predict different levels of sound insulation.

Monitoring and performance evaluation of a green wall in a semi-arid Mediterranean climate

Green walls are gaining popularity as a sustainable cladding solution for buildings, offering various advantages for the built environment and human well-being. However, there is a lack of research on plant selection guides and field data in semi-arid Mediterranean climates, limiting our understanding of green wall potential. To address these gaps, this study assesses the hygrothermal and sound insulation performance of a modular living wall in a semi-arid Mediterranean climate and develops a plant-selection guideline for green wall applications. The experiment involves a comparative assessment between the modular living wall and a bare-wall-reference facade. Measurements of air temperature, relative humidity, and sound pressure were taken, along with thermal imaging, to record the surface temperatures of the experimental facades. Results reveal that the modular-living wall significantly decreased dry-bulb air temperature (up to 8 °C) and reduced sound pressure by up to 5.1 dB. Additionally, relative humidity in the air cavity behind the modular living wall consistently increased by 6.6%, with a maximum absolute humidity differential of 8.6 g/kg. Thermal imaging showed a surface temperature difference of up to 27 °C, with foliage having a higher leaf-area-index proving more efficient in reducing the surface temperature of the green wall.Overall, the modular living wall effectively protected building walls from high solar radiation and temperatures, resulting in reduced energy requirements for space cooling. However, proper irrigation and plant health maintenance are necessary. This study fills important research gaps, providing valuable insights into the potential benefits and performance of green walls in semi-arid Mediterranean climates.