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Impact sound insulation of a lightweight laminate floor resting on a thin underlayment material above a concrete slab
Abstract
Impact noise is a major sound transmission problem in concrete buildings that severely affects the quality of life of residents. The impact insulation of a concrete floor can be improved by the use of floating floor constructions. Commonly, a floating floor consists of an upper panel and a resilient layer, which is in turn laid on the concrete structural slab. Lightweight laminate flooring has become one of the most common floor surfaces in many countries. It is not only used in new dwellings and modern concrete multistorey buildings, but also to replace allergy-causing carpeted floors. However, the improvement in impact sound insulation of lightweight laminated floors has not received much attention. This study aims to report the improvement in impact sound insulation of a typical laminated floor resting on different commercially available thin underlayment materials above a concrete structural slab. Although all the floating floor combinations exhibited different impact sound insulation performance as a function of frequency, the standardized single number ratings described in ISO 717-2 were almost identical. However, environmentally friendly fibrous continuous layers tested in this study reported better impacting sound performance compared with polymeric materials. The force transmissibility-based theory is applied and revised to properly predict the experimental results for this type of floating floor well: an empirical stiffness-dependent formula is derived. In general, the experimental results of the improvement of impact sound insulation are in close agreement with the results obtained with this empirical formula.
... Predicting the vibration transmission properties of materials. [126,127] Neural network model Fitting nonlinear models can take into account the effects of multiple structural parameters but with poor prediction accuracy at low frequencies. ...
... Elastic layer materials contribute the most to improving insulation performance, with increases ranging from 1 to 23.6 dB for concrete floors and 1 to 22.2 dB for timber structure floors. Under the global sustainability concept, studies on sustainable materials, such as wool and recycled textile fibers, for elastic layers have increased, reporting promising results with improvements of 17-18 dB [126]. Surface and cavity materials are mainly applied to timber structure floors, with cavity-filling materials providing up to 15 dB of improvement and surface materials contributing 5-8 dB. ...
The lightweight development trend of modern residential structures reduces sound attenuation in buildings and makes sound propagation paths more complex. Neighbor-induced impact sound has become a significant source of residents’ dissatisfaction with the acoustic environment. To gain a deeper understanding of the characteristics of residential impact sound, reduce its impact on users, and improve the quality of residential buildings, a systematic review of existing research based on PRISMA2020 was carried out. Articles indexed in the Web of Science core dataset and Scopus were searched, with a cutoff date of October 2024. After screening and reviewing, 132 articles were systematically analyzed, categorizing the research on floor impact sound into four aspects, namely impact sound sources, evaluation indicators, prediction methods, and improvement measures. The results show that due to the diversity of real sound sources and differences in living habits, the standard impact sound sources in different countries or regions still need further study. Both subjective and objective evaluations indicate that heavyweight impact sound, particularly low-frequency sound, has the greatest impact on occupants and is the most difficult to eliminate. The physical characteristics of floor impact sound can be predicted using methods such as finite element analysis. However, there are fewer prediction methods for subjective evaluations due to the poor correlation between subjective and objective evaluation indicators. Though different soundproofing measures significantly improve the sound insulation of impact sound, they are still not widely applied due to materials, construction techniques, and time and economic costs. This study provides a reference for research on residential impact sound in China and offers an outlook for future research directions.
... As a result, manufacturers invest in research and development activities, and researchers report on their studies. However, when the literature has been reviewed, the limited number of studies that evaluate the influence of these layers' properties on laminate flooring products has been discovered, and the following are some of the recent studies [1,3,9,10,12,14,17,19,21,22]. The surface roughness of laminate flooring product (melamine resin-saturated paper overlay) has been determined by Kalaycıoğlu and Hızıroğlu [11]. ...
Laminate flooring products are among the essential construction and building materials not only because of their aesthetics, but also their ability to provide energy saving, sound insulation, prevent surface scratches, and minimize maintenance such as periodic varnishing in the case of solid wood flooring, etc. Even though the laminate flooring products are scratch-resistant and easy to install, they must meet the standard requirements. Therefore, optimizing the production parameters of laminate flooring products is of interest in research and development to obtain cost-effective products that not only compete in the market but also represent scientific communities’ studies. In this sense, production parameters such as paper properties, core material type and properties, resin utilization, pressing conditions (pressure, duration, and temperature), etc. come to the forefront. From this point of view, the effect of décor (105, 115, and 125 g/m²) and overlay (90 and 95 g/m²) paper mass on the surface abrasion (SA), abrasion resistance (AR), impact resistance (IR) and cure properties of laminate floor products which have been industrially produced has been figured out. According to the results, SA, AR, IR, and cure values ranged from 3,600–4,800 revolutions, 4.5–5.0, 110–130 N, and class 5, respectively. According to BS-EN 13329 and BS-EN 14323, products meet the requirements. However, the effect of paper masses on properties has been found to be unstable due to oscillations and no changes observed. In the literature, there are scarcely any studies that figure out these parameters and the authors think that the results of this study may provide valuable data for the comparison.
... When the stiffness of the CLT slab was high, the single-number quantity was low and the floor impact sound insulation performance was better. Similar trends are observed in reinforced concrete slabs, where higher rigidity typically results in better floor sound insulation performance (Arenas and Sepulveda 2022;Lee et al. 2023). Therefore, increasing the stiffness of CLT slabs is expected to enhance their impact sound insulation performance. ...
The effects of wood species and panel connections on the vibration and heavy-weight impact sound insulation performance of cross-laminated timber (CLT) slabs were investigated. CLT panels (5-ply, 150 mm thick, 1 m wide, and 4.2 m long) made of larch (Larix kaempferi) and pine (Pinus densiflora) were manufactured with 30 mm thick laminae, considering three types of joints. Three CLT panels of the same species and joint type were connected using spline joints, butt joints, or half-lap joints to form 3 m wide and 4.2 m long slabs for testing. The floor impact sound insulation performance of the CLT slabs was measured according to KS F ISO 10140-3, using the standard heavy-weight impact source, a rubber ball. Additionally, four accelerometers were installed at 400 mm intervals beneath the CLT slabs to analyze the deflections and natural frequencies of the slabs. The results of the experiment indicated that there were no significant differences depending on the wood species and the CLT panel joints. These findings suggest that wood species and joint methods can be flexibly applied in the design of CLT slabs.
... Traditional approaches to floor sound insulation have primarily included floating floors, resilient underlays, and damping compounds or acoustic mortars [33][34][35][36]. A floating floor system can be conceptualized as a simplified mass-spring-damper model, where the mass is defined by the surface density of the floor covering, the spring is represented by the dynamic stiffness of the elastic underlayer, and the system damping is equivalent to the internal friction of the insulating material [37]. ...
Floor impact sound insulation is essential for improving living environments and has become a mandatory requirement for green buildings in Southern China. This study introduces an innovative inorganic sound insulation coating technology for enhancing building floor acoustic performance. Through comprehensive laboratory experiments and field tests, we evaluated inorganic coatings of 3 mm and 5 mm thickness, comparing their performance against traditional methods, including organic coatings and soundproof mortar. Standardized impact sound pressure level measurements, conducted in accordance with the China GB/T 50121 standard, demonstrated significant acoustic improvements. Laboratory testing revealed impact sound reductions of 6–7 dB and 9–10 dB for the 3 mm and 5 mm inorganic coatings, respectively, while field applications of the 3 mm coating achieved an average reduction of 14.3 dB. The inorganic coating exhibited superior performance characteristics compared to both organic coatings and soundproof mortar in terms of sound insulation efficiency, fire resistance, and application feasibility, demonstrating particularly effective attenuation in the mid- to high-frequency range. This investigation presents an innovative, cost-effective, and environmentally sustainable solution for improving floor sound insulation in green buildings.
... [10][11][12] Of course, the noise vulnerability of the box-frame system includes the issue of noise level, which many studies have addressed. [13][14][15] However, it is not just the problem of noise level; the ambiguity of the impact source also acts as a factor that aggravates residents' annoyance. Noise source ambiguity refers to a phenomenon when residents hear a noise, and they find it challenging to identify the source's actions or location. ...
This study investigated impact source ambiguity in box-frame multifamily buildings, prevalent in densely populated areas, by examining the transmission of heavy-impact noise and its relationship with junction attenuations across five floors. Contrary to the decline in noise levels with increased distance from the impact source, our findings uncover an intriguing deviation in the behaviour of vibration response levels. Surprisingly, vibrations are often intensified, rather than diminished, with distance. Notably, upon examining each room, instances where non-structural or thin concrete walls exhibited the highest vibration responses were frequently observed. Such instances were particularly prevalent in rooms not directly adjacent to the impact source. This trend markedly impedes residents’ ability to pinpoint the origin location of impact noises. This study reveals an unexpected weakening and reversal of distance attenuation in vibration, linked to the increasing number of valid flanking paths as the junction distance grows. The findings suggest that increasing slab thickness for noise insulation may unintentionally complicate source identification due to diminished junction attenuation in thicker horizontal components compared to vertical ones. To enhance acoustic comfort in such housing, this study recommends minimizing valid flanking paths through improved junction design, addressing an often-overlooked issue of source ambiguity of floor noises.
... In this regard, as mentioned above, further research is necessary to account for the loss mechanisms linked to the actuator for a proper determination thereof. Even though other approaches can be also found in the literature, such as the equations derived by Segovia et al. [21], a modified dynamic stiffness calculation method for rubber isolators [22], or empirical formulas for lightweight laminate floors [23], the proposed approach was shown to be a simple and straightforward procedure for the determination of the dynamic stiffness of resilient materials. ...
Dynamic stiffness is a parameter of great importance for the assessment of the sound insulation properties of resilient materials commonly used under floating floors in dwellings. This work proposes a simplified approach that relies on an electro-mechanical circuit model for the determination of this parameter using a two-degree-of-freedom system of masses and springs. Unlike the method described in the standard ISO 9052-1, the proposed approach uses a single electrodynamic actuator both as an impulser and vibration sensor, thus reducing the instrumental requirements and yielding a more stable arrangement. By measuring the input electrical impedance of the mass-loaded actuator when coupled to a slab–material system it was possible to retrieve the mechanical mobility function thereof and thus obtain the dynamic stiffness of the material. Several materials were tested following the proposed approach, with results showing good agreement when compared to those obtained following the standardized procedure. In general, the preliminary research encourages the use of the proposed approach for characterization purposes.
... Indeed, if the vibration induced by the impacts from daily activities can be sufficiently isolated, the vulnerability of wall-slab structures to the propagation of floor impacts might not be significantly highlighted. The floating floor system is a common vibration isolation method used for sound insulation against floor impacts [12,13]. It features a resilient layer placed between the walking surface and the structural slab, which plays a significant role in dampening vibrations [4]. ...
This research examines the application of periodic materials in wall–slab structures to mitigate impact noise and vibration propagation, a prevalent issue in multifamily housing. Traditional methods, such as floating floors, have proven insufficient in addressing low-frequency impact noises and in facilitating the identification of noise origins, leading to increased resident annoyance. Periodic materials, known for their effectiveness in controlling plane waves in civil engineering, were applied to the intermediate slab of a wall–slab experimental setup. The research involved assessing the attenuation of noise and vibration over distance before and after the application of periodic materials by measuring indoor sound pressure levels and the natural vibration amplitude of the structure’s members upon impact. The results showed that periodic materials not only facilitated distance attenuation but also significantly diminished noise and vibration throughout the structure, without the side effects of vibration amplification seen in prior civil engineering applications. This indicates a practical advancement in using these materials, offering a novel approach to sound insulation and enabling more precise impact source localization. Ultimately, this study contributes to improving urban living by suggesting a method to enhance acoustic comfort in multifamily housing, underlining the importance of further exploration in architectural applications of periodic materials.
... The use of elastic materials as anti-impact foils (floating floors) has been common practice in construction since the second half of the 20th century. In this line of research, there are studies on the use of GTR to improve the performance of building solutions with regard to impact noise [115,116], but there are few with regard to airborne noise [117,118]. ...
The current European standards demand more energy-efficient, comfortable, and sustainable buildings and encourage the incorporation of recycled materials in building construction. Timber buildings are successfully competing with traditional building materials in addressing these challenges; however, one of the weaknesses of timber systems is their limited sound insulation capacity. One material that can fit into the sustainability aims of timber construction and improve its acoustic performance is recycled ground tyre rubber (GTR), which, on top of this, is a serious environmental problem. This paper presents research on the use of GTR materials combined with timber systems in order to improve their acoustic performance. Three different types of GTR products (granulate, rolls, and sheets) of different thicknesses and densities are selected and are combined with different sound-absorbing materials (mineral wool, cellulose, and wood fibre) inside a lightweight timber sandwich system. In this study, the first qualitative approach, the acoustic performance of the different resulting systems is compared based on the sound pressure level difference measured in a custom-made reduced-size transmission chamber. Secondly, the sound reduction index of four selected specimens is measured in an accredited sound transmission laboratory. The results show that, for all the lightweight timber systems included in this research, introducing a GTR layer improves the acoustic performance of the system.
... The constitutive model has been successfully applied to several thin-component floating floors [5,6], with accuracy and reliability, and it has been exploited in advanced impact sound insulation investigations, design and applications [15][16][17][18][19][20]. Nevertheless, for floating floors with thick or heavy resilient layers, the transmissibility models of Eqs. ...
The floating floor technology in buildings is increasingly used to achieve national acoustic and thermal insulation requirements, combining different compositions of materials and components with proper technical features. However, the analytical models nowadays available do not allow to estimate with the due accuracy the actual acoustic performance of floating floors with a thick or heavy resilient layer from involved material properties. The physical model presented in this paper, based on the vibration transmissibility theory, improves the prediction of the effect of a floating screed on the impact sound insulation, as a function of frequency, by taking into account the thickness-resonance wave effects in the resilient layer. The model is based on the exact analytical solution of the one-dimensional wave equation in elastic media. Theoretical results are compared with existing computational models and with experimental data of impact sound insulation.
... Hence, floating floors are commonly used to reduce floor impact sounds caused by walking and running. The floating floor typically consists of a resilient material layer, and studies have been conducted to predict the level of heavy-weight impact sound reduction provided by various resilient materials [9,10]. Kim et al. discovered that the dynamic stiffness of resilient materials is related to heavy-weight impact sound reduction [11]. ...
In this study, factors influencing the heavy-weight floor impact sounds were analyzed in situ while considering 59 households in a residential building with identical plans and floor structures. A formula to calculate the contribution of the Li,Fmax of each frequency band to the LiA,Fmax was suggested and the main frequency range was determined as 95% of the LiA,Fmax. Further, a hierarchical cluster analysis was conducted on the Li,Fmax, derived for the main frequency range for a rubber ball and a tire each. As a result, the similarity between heavy-weight floor impact sounds in households located on the same floor was found to be higher than that between sounds in households located on different floors. This difference may be attributed to the fact that the households on the same floor share the same floor slab.
Structural engineers can reduce the embodied carbon (EC) in building design, often by minimizing structural material. Concrete floors contain considerable EC and are thus the subject of ongoing research. Previous studies that have evaluated the EC for different concrete floor systems often exclude important design considerations such as fire resistance, acoustics, and vibrations. In response, this study assesses how design requirements for fire resistance, sound insulation, and walking vibration affect the EC of eight concrete floor systems. A parametric analysis was conducted to calculate EC when varying the floor span, structural design parameters (concrete strength, loads, deflection limits), and the requirements for the three secondary objectives. The EC increased as the secondary objective requirements increased from a 1-hr to 4-hr fire rating, although the lower ratings considered are more typically found in building codes. Satisfying walking vibration requirements had the smallest effect on EC (an increase of up to 14%), while fire-resistance rating and sound insulation were found to increase EC up to 55% and 62%, respectively, compared to floors meeting minimum structural requirements. While less material-efficient floor systems such as reinforced concrete flat plates had higher EC (up to an average of 400 kgCO2e/m2), these systems often performed favorably across all secondary objectives. All results are presented in design charts to inform building engineers of low-carbon design solutions while balancing other design requirements.
Impact sound transmission in concrete slabs is a persistent challenge in building acoustics, particularly in residential and commercial environments. This study introduces a novel floating floor design utilizing polyurethane cushions of various 3D shapes and sizes to mitigate impact noise. The aim is to improve acoustic performance across a wide frequency spectrum while maintaining flexibility and practicality in installation. Two floating floor configurations—fully-filled and half-filled systems—were experimentally tested on twenty-two specimens under controlled laboratory conditions. Fully-filled systems achieved significant impact sound reductions of up to 6.8~dB, delivering consistent performance in mid to high frequencies and low frequencies when appropriately configured. In contrast, half-filled systems were effective at controlling low-frequency noise but demonstrated limitations at higher frequencies due to resonance sensitivity and variability in configurations. Parametric studies revealed that optimizing polyurethane cushion properties, such as elastic modulus and height, enhanced overall impact sound performance. Additionally, incorporating lightweight concrete layers significantly improved low-frequency insulation. Fully-filled systems consistently outperformed conventional methods, delivering comprehensive and reliable sound insulation. However, half-filled systems require further refinement for broader acoustic applications. This research highlights the critical role of cushion material properties, structural configurations, and multi-layer designs in effective impact sound control, providing a solid foundation for next-generation floating floor systems tailored to advanced acoustic insulation needs.
This study investigates the dynamic stiffness and damping characteristics of three polyurethane materials—PM, PS, and PST—using a comprehensive vibroacoustic testing approach. The aim is to examine material parameters such as dynamic stiffness, Young’s modulus, critical damping factor, and the influence of sample irregularities on the accuracy of measurements. The study employs both experimental testing, in which cuboidal and cylindrical polyurethane samples were subjected to sinusoidal excitation, and finite element modeling (FEM) to simulate the test conditions in sample without irregularities. Results indicate that sample contact surface irregularities (even as low as ~0.04 mm) significantly impact the measured dynamic stiffness, with the effect intensifying for materials with higher Young’s modulus values (above 5 MPa). Furthermore, cylindrical samples demonstrated more stable and repeatable measurements compared to cuboidal samples, where surface irregularities were tested in a more controlled environment. The findings underscore the need to consider sample geometry and irregularities in dynamic stiffness assessments to ensure better material evaluations. This work contributes valuable insights for the accurate modeling and testing of materials used in vibration isolation and sound insulation contexts.
La madera contralaminada es un producto industrializado de madera que ha incrementado exponencialmente su uso en la industria de la construcción debido a su eficiencia estructural, su ligereza, su carácter sostenible y su competitividad económica. Así, en los últimos años, se está utilizando este producto para la construcción de edificación colectiva (edificación en altura) en toda Europa, desarrollando un nuevo sistema estructural y constructivo eficiente y de alta calidad. Sin embargo, el uso de estos sistemas constructivos ligeros empleando madera contralaminada, en comparación con los sistemas pesados tradicionales, no presentan un buen comportamiento de aislamiento al ruido de impacto en los suelos de sus construcciones colectivas. Para alcanzar aislamientos similares a los sistemas tradicionales, en el diseño de las estructuras de madera se incorporan nuevos materiales elastoméricos, la mayoría con un coste elevado, en colaboración con materiales de mayor densidad (mortero/hormigón) o multicapa (aislantes acústicos específicos). Este estudio investiga la introducción de materiales elásticos fabricados a partir de neumáticos fuera de uso (NFU), con propiedades elásticas semejantes a los elastómeros actuales, como alternativa para mejorar el comportamiento acústico de estas construcciones ligeras. Para ello, se realizan ensayos en laboratorio de la reducción de transmisión del ruido de impacto sobre especímenes de tamaño reducido, con distintos espesores de manta de NFU, sobre una base de panel mixto de madera contralaminada (CLT) y hormigón. Los resultados muestran mejoras de aislamiento a ruido de impacto (>8 dB) en todos los casos estudiados (mantas de NFU de 4 mm, 10 mm y 20 mm) por encima de los 160 Hz. También se alcanzan mejoras de aislamiento por encima de los 250 Hz al sustituir parcialmente (15%) árido por granalla NFU en la dosificación de la losa de hormigón. La introducción de este tipo de materiales (neumáticos fuera de uso) en la industria de la construcción como aislantes acústicos permite reutilizar, de forma controlada, un material que actualmente genera graves problemas medioambientales por su incontrolado almacenamiento y escaso volumen reciclado. Así mismo, contrarresta las limitaciones acústicas de los productos derivados de la madera, como los paneles mixtos CLT-hormigón, e incrementando las ventajas de sostenibilidad de estos sistemas constructivos de madera.
In the realm of civil construction, there is an increasing demand for sustainable technological advancements aimed at improving the technical quality and comfort of buildings. This shift in perspective has generated heightened interest in innovative solutions that positively influence a building’s acoustic performance. This research is dedicated to developing unique floor screed systems utilizing Construction and Demolition Waste (CDW). The evaluation specifically focuses on their impact on noise levels within construction systems, aligning with current standards. The primary goal is to measure the normalized impact sound pressure level (L
) in various flooring systems within individual units. To achieve this, 30 square-meter samples were designed to create alternative flooring systems using CDW, incorporating materials such as rubber chips, expanded clay, and an air-entraining additive. Common floor coverings, including ceramic, porcelain, wood laminate, vinyl, and granite, were applied over these cementitious screeds. In addition to L
measurements, the proposed floor screeds underwent impact sound insulation calculations within CYPE AcouBAT software, utilizing a 3D model representing a typical Brazilian residential building. The findings indicated that all flooring systems employing alternative materials demonstrated acoustic performance comparable to traditional construction solutions. The most favorable outcomes were observed with mortar having a mix ratio of 1 : 1.25 : 0.64 : 0.20 : 0.91 (cement : CDW sand : natural sand : expanded clay : water-binder ratio) in weight units, achieving a compressive strength of about 14.5 MPa with a weighted reduction of impact sound pressure level (
L
) equal to 23 without covering and 32 with a glued laminated flooring. Simulated weighted normalized impact sound pressure level in the field (L
) reached 47 dB within the typical building, falling below the recommendation set by the National standard for a superior level (
55 dB). In addition to their soundproofing capabilities, these custom-designed flooring systems offer substantial environmental advantages by repurposing CDW.
Multi-family homes have been constructed traditionally using heavy materials like concrete/steel and bricks. Wooden structures are a promising substitute for typical heavyweight constructions. However, floor impact noise has been identified as the most annoying noise source in South Korea. Here, we have studied the effect of floorboard installation on impact sound changes before and after installing the floorboard on the floor of a wooden building. We used standard tapping and bang machines in this study to generate lightweight and heavyweight impact sounds. The changes in noise from lightweight and heavyweight impact sounds were estimated on the upper layer (UL) and lower layer (LL) floors before and after the installation of the plywood floorboard (PFB). The average of the octave band center frequencies at 125, 250, 500, 1000, and 2000 Hz from the lightweight impact before installation of PFB was 84.08 dB (UL) and 50.54 dB (LL), respectively, while 84.04 dB (UL) and 41.90 dB (LL) after the installation of the surface decorated PFB. Similarly, the heavyweight impact sound before installing PFB was 73.26 dB (UL) and 42.16 dB (LL), respectively, while after installation of PFB, impact sound appeared at 71.58 dB (UL) and 42.48 dB (LL). The results exhibited that lightweight impact sound could be reduced by about 8.6 dB on the LL. These results could entice the researcher or building engineer to design wooden floorboards for a comfortable building environment. This study is new because it compares the impact sound of the floor before and after it has been constructed.
The loss factor of a structure is significantly improved by using constrained damping treatment. For a mass efficient design, the damping material is to be applied at suitable locations. The studies reported in literature use the modal strain energy distribution in the viscoelastic material or the strain energy distribution in the base structure as tools to arrive at these suitable locations for the damping treatment. It is shown here that the regions identified through the above criteria need not be suitable for certain bending modes of vibration. A new approach is proposed in which the strain in the viscoelastic material and the angle of flexure are shown to be more reliable in arriving at the locations for the damping treatment. Providing damping layers at identified locations using these parameters results in significant loss factors with minimal added mass.
With increasing demand for quieter residential environments, impact sound insulation for floating floors is gaining importance. However, existing methods for estimating the performance of heavy impact sound insulation are limited by their inability to comprehensively analyze various types of floating floors, as well as difficulties mathematically determining the input force of the reference source for heavy impacts. To overcome these limitations, this study proposes empirical models for estimating the sound insulation performance of floating floors under heavy impacts. The proposed models are then validated; the model with the highest accuracy exhibits an average estimation error of 2.73 dB at 50–630 Hz. The proposed models exhibit better accuracies than existing analytical models for frequencies below 100 Hz, where the estimation errors of the analytical models were large. Thus, the proposed models may help reduce errors in analytical estimates or when estimating a single numerical quantity for sound insulation rating during the design stage of multifamily housing.
This paper presents a comprehensive review on different theoretical elastic and viscoelastic foundation models in oscillatory systems. The review covers the simplest foundation models to the most complicated one and fully tracks the recent theories on the topic of mechanical foundations. It is fully discussed why each theory has been developed, what limitations each one contains, and which approaches have been applied to remove these limitations. Moreover, corresponding theories about structures supported by such foundations are briefly reviewed. Subsequently, an introduction to popular solution methods is presented. Finally, several important practical applications related to the linear and nonlinear foundations are reviewed. This paper provides a detailed theoretical background and also physical understanding from different types of foundations with applications in structural mechanics, nanosystems, bio-devices, composite structures, and aerospace-based mechanical systems. The presented information of this review article can be used by researchers to select an appropriate kind of foundation/structure for their dynamical systems. The paper ends with a new idea of intelligent foundations based on nanogenerators, which can be exploited in future smart cities for both energy harvesting and self-powered sensing applications.
Eco-materials employed to reduce noise are used either independently or as components of complex composite materials, which are a growing area of research. These eco-materials have the potential to be used as high-performance sound-absorbing noise isolators in a number of applications in areas such as transportation, architectural, industrial, and construction. Public concern about the environmental impact of transportation is leading to reduced fuel consumption and the use of recycled materials. These are clearly related to the reduction of weight, extending durable years. Currently, the concept of “green” building materials is used in practice in several European countries. In addition, public awareness and concern about the negative effects of pollution have led consumers to favor environmentally friendly materials, less contaminating processes, and recycled products. This chapter discusses eco-materials produced for the specific purpose of reducing noise. After an introduction to the subject, a section is devoted to the assessment of sustainable materials. Then, the fundamentals of the sound absorption, airborne sound insulation, and impact sound insulation properties of acoustical eco-materials are presented. The following section reviews common acoustical eco-materials, including those using natural fibers instead of synthetic ones, recycled fibers and surplus materials, advanced mix and composite eco-materials designed to provide better performance and produce lightweight materials that help in reducing fuel consumption and greenhouse gas emissions to the atmosphere, and, finally, green walls and roofs used on top of some buildings. All these eco-materials provide an alternative to chemical building materials, polymers, and other artificial non-sustainable materials.
This study investigates several factors that have not been specified in the standard for dynamic stiffness, compressibility, and long-term deformation; these factors can be used to evaluate the acoustic and physical performances of resilient materials. The study is intended to provide basic data for deriving the factors that need to be additionally reviewed through the standards. Since magnitude of dynamic stiffness changes with an increase in loading time, it is necessary to examine the setting of the loading time for a load plate under test conditions. Samples of size 300×300 mm, rather than 200×200 mm, yielded more reliable results for compressibility measurement. Since the test to infer long-term deformation of resilient materials after a period of 10 years in some samples showed variation characteristics different from those specified in the standards, it is recommended that the test method should be reviewed through ongoing research.
Acoustical performance and mechanical properties of different types of resilient underlayer, used in floating floors, are investigated on the basis of apparent dynamic stiffness measurement, compressibility and compressive creep and of laboratory measurement of the reduction of transmitted impact noise. Determining and quantifying resilient underlayers properties with time, on the basis of evaluation of thickness under load and behaviour under compression, is the aim of this study. The measurement and analysis methodologies of the macroscopical mechanical behaviour, although in first approximation, allow useful knowledge of acoustical performances of resilient materials used under floating floors.
This paper reports an investigation of a new kind of material and its acoustical performance. The potential of recycled materials made from rubber fluff for reducing impact noise was assessed according to EN ISO 140-8:1997. The performance of these materials was compared to those of some commercially available underlays.
The disposal of used tyres is a significant environmental problem in developed countries. The production of acoustic materials from rubber crumbs can therefore represent a valid alternative to incineration or to the disposal of used tyres into landfill. The goal of the paper is to analyze and optimize the manufacturing process of impact sound insulating materials made of recycled tyre granules mixed with binders. Several prototypes were manufactured in laboratory by means of the developed process and tested in order to evaluate their dynamic stiffness. The influence of grain size, binder concentration and density of the sample was investigated. Thanks to the measured values of the viscoelastic properties, it was possible to model the new materials and to estimate the indexes of impact sound reduction ! Finally, the prototypes showing the best properties were produced in bigger size and tested in two overlapping reverberating rooms according to the standard ISO 140-8. Results confirm that the materials manufactured through the developed process have satisfactory acoustic properties, comparable to the ones of commercially available materials.
This paper describes a procedure for evaluating the reduction in impact sound pressure level of
floating floors by measuring the apparent dynamic stiffness of the resilient layer, according to
International Standard EN 29052-1. The impact sound pressure level experimental data, obtained
according to International Standard UNI EN ISO 140-8, was compared with estimates obtained
from dynamic stiffness measurements. Results confirm the effectiveness of the empirical model.
Two questions are addressed. The first concerns the decrease in layer thickness over time. The
second concerns the relationship between damping ratio and performance
The Nelder{Mead simplex algorithm, rst published in 1965, is an enormously pop- ular direct search method,for multidimensional unconstrained minimization. Despite its widespread use, essentially no theoretical results have been proved explicitly for the Nelder{Mead algorithm. This paper presents convergence properties of the Nelder{Mead algorithm applied to strictly convex functions in dimensions 1 and 2. We prove convergence to a minimizer for dimension 1, and various limited convergence results for dimension 2. A counterexample of McKinnon gives a family of strictly convex functions in two dimensions and a set of initial conditions for which the Nelder{Mead algo- rithm converges to a nonminimizer. It is not yet known,whether the Nelder{Mead method,can be proved to converge to a minimizer for a more specialized class of convex functions in two dimensions. Key words. direct search methods, Nelder{Mead simplex methods, nonderivative optimization AMS subject classications. 49D30, 65K05 PII. S1052623496303470
To explore the relationships between thermal, acoustic, luminous environments and human perceptions, i.e., individual factor comforts, individual factor satisfactions, and the overall satisfaction, this investigation conducted a controlled laboratory test with 216 different environmental conditions. The main, crossed, and interaction effects of multiple environmental factors on individual factor perceptions were investigated first, and the results indicated ranges for the neutral temperature, sound level and illuminance. It implied that temperature had crossed effect on acoustic and visual comfort, and both sound level and illuminance had crossed effect on thermal comfort. In addition, thermal, acoustic and visual comfort were also affected by the temperature × illuminance interaction. Subsequently, it was discovered that the individual factor satisfactions showed a one-vote veto tendency but not an absolute veto power over the overall satisfaction. The effect of acoustic satisfaction on overall satisfaction was the greatest, followed by thermal satisfaction and visual satisfaction. This study also classified the environmental conditions under typical overall environmental acceptable rates and quantified the relationships between human comforts and human satisfactions by using the conditional probability. This method implied that machine learning and probability theory, which have seldom been used in this field of research, could be alternative analytical methods in the future.
This study focuses on the compression behavior of hemp shiv layers for bio-based floating floor applications.
An experimental campaign was performed to measure the instantaneous and creep behavior of different hemp shiv. The effect of humidity was also taken into account.
A model was developed to assess both instantaneous and creep behavior of the shiv layer. The model validity ranges from a compressive stress of 0 to 5 kPa and with moisture ratio up to 20% in mass. It was used to define the maximum acceptable initial height of the shiv layer to guarantee a limited long-term deformation. These modeling and experiments lead to recommendations for application.
Composite sandwich panels have been increasingly considered in structural applications due to their lightweight, high strength, environmental resistance, and ease of assembly. Yet, since transmission loss phenomena are usually governed by mass, their low weight renders composite sandwich panels potentially inefficient in terms of acoustic performance, a subject that has received little attention in the past. This paper presents experimental, numerical and analytical investigations about the acoustic performance of composite sandwich panels used in building construction. Standard airborne and impact sound transmission tests are performed on a full-scale composite sandwich panel, designed for structural application in building floors, and their acoustic performance is compared with the applicable code requirements. In the numerical study, a finite element model is developed to simulate the airborne sound transmission. The analytical study assesses the applicability of the reciprocity theorem to such panels. The obtained results confirmed the overall low acoustic performance of lightweight composite sandwich panel floors and pointed out the need for additional sound insulation measures. The numerical simulations presented good agreement with the experimental data, following the overall development of the experimental transmission loss curve, and predicting the dip associated with the coincidence effect. The application of the reciprocity theorem to the sandwich panel floors was validated with the experimental results and allowed for an accurate prediction of the impact sound pressure level based on the numerical results of the airborne sound reduction.
This research concerns the study of composite boards made from polymer-based materials that include rice husk and recycled rubber granules, to see if they can mitigate vibrations and improve the impact sound insulation of floor solutions in buildings. The influence of the composite mix, mass density and board thickness on the overall performance was studied experimentally. First, the composites were studied under static compressive loading. Then, the behaviour under dynamic loads was evaluated through transmissibility tests for frequencies ranging from 20 to 200 Hz with five different static loading scenarios, from which the dynamic transfer stiffness and transmissibility curves were determined. The ability of the proposed composite boards to improve the impact sound insulation of floors was also assessed experimentally, in adjacent vertical acoustic chambers. The composite boards were tested as the top layer of the system and as part of a floating floor. For the latter, a thin slab was built above the tested specimen. The results indicate that composites produced from rice husk and recycled rubber granules can help to mitigate vibration in building solutions. Thicker samples whose rubber content was higher and apparent density lower showed higher vibration isolation capacity for a wide range of frequencies. Moreover, it was found that rice husk and rubber boards were able to improve the impact sound insulation of floor solutions. Composite boards with higher rubber content were found to perform better as floor coatings.
Exposure to noise is proven to have important repercussions on human comfort and health conditions. In recent decades, efforts to increase awareness among users have focused on highlighting the benefits of an appropriate acoustic indoor environment. In addition, given the significant increase in complaints about noise, the control, reduction, and limitation of sound transmission have become important issues to be considered in acoustic retrofit work in buildings. Much of the housing stock was built in a period characterized by the limitation or absence of standards, and renovation interventions should be geared towards existing buildings. However, despite the major potential to improve quality of life, only a handful of countries consider old buildings in their national Building Codes and regulations. The main aim of this work is to develop a comparative study of the acoustic requirements for indoor sound insulation between dwellings of existing buildings established in current building regulations around the world. The analysis of the documents concludes that the usual difference between requirements for new and existing buildings is 5 dB, both for airborne sound insulation and impact sound insulation. To this end, this paper provides the basis for discussion regarding future cooperation for the optimization of acoustic regulations for old buildings.
In building acoustics, it is necessary to conduct both objective and subjective evaluations in a holistic sound
quality assessment. However, there is a huge variety in a selection of psychological tools. This arouses the
concern about reliability and validity of the tools. Although various perceptions can be affected by environmental
sounds, the underlying structure of acoustic perceptual influences was recently investigated by the researchers
in their systematic review study. This is a first study aiming at the development of a valid and reliable
subjective scale to quantitatively assess the three fundamental perceptual dimensions of sound via the investigation
of its psychometric properties. Nine semantic differential questions in the psychoacoustics perception
scale (PPS) covered the assessments about the subjects’ responses to the general judgement (Evaluation (E)),
energy content (Potency (P)), and temporal and spectral content (Activity (A)) of sound. The reliability test
results (Cronbach’s αs > 0.80) indicated the acceptable internal consistencies of the items in the E, P, and A
factors. The construct validity in characterizing the structure of perceptual influences was confirmed by the
goodness-of-model-fit indexes in the confirmatory factor analysis (CFA, N ¼ 128) for the factorial structure of the
hypothetical EPA model behind the PPS. The further invariant tests verified the invariances of the model across
gender except the error variance of the E factor. A total EPA score, representing the joint attribution of the
factors, was a significant predictor of the other perceptions. The concurrent validity of the PPS to the modified
dental anxiety scale (MDAS), a well-developed psychometric tool, was also supported by the result that the E
factor was a significant predictor of the MDAS score.
Viscoelastic layers under floating floors are often used to reduce impact sound. A standardized dynamic stiffness test is routinely used to estimate the performance of a layer as an impact sound isolator. During the test, a material sample is placed between a load plate and a motionless rigid foundation. In this work, equations that provide a useful analytical description of the standardized test are derived. The new analytical approach is linked with the analysis of multilayer elastomeric bearings. The new approach leads to simpler analytical solutions as compared with those of previous studies, which makes them easy to translate into computer codes. The obtained expressions are almost independent of the shape of the boundary and are only dependent on static values such as the area and moments of inertia of the contour. Taking advantage of the new closed-form solutions, it is shown that, under certain restrictions, the analytical approach may be used to experimentally estimate the elastic parameters of a flexible material using a harmonic (frequency-dependent) analysis. It is reported that results obtained using the proposed approach are in good agreement with those obtained using a commercial finite element software.
An effective way to reduce impact sound in buildings is to install a floating floor consisting of a floating slab separated from the structural slab by a continuous viscoelastic layer. Although a considerable amount of work has been reported on nanomaterials in the past decades, the impact sound reduction performance of polymer/clay nanocomposites has not been specifically addressed in the literature. In this paper, we report the synthesis and characterization of a nanocomposite made of thermoplastic polyurethane (TPU) with laponite clay filler and its potential use for reducing impact sound in floating floor technology. Samples were prepared with laponite content ranged between 0.5 and 10 wt% for each nanocomposite synthesized using a solvent solution mixing process. The characterization of the nanocomposites confirmed that the clay content in the TPU matrix has significant impact on the viscoelastic properties. In particular, the incorporation of 5–10 wt% laponite clay in the TPU matrix increased mechanical damping and reduced dynamic stiffness as compared to the pristine TPU. The experimental results were compared with a constitutive model that extends the Cremer-Vér model. The results predicted a considerable improvement of the impact sound insulation at the resonance frequency when the nanocomposite is used as a continuous viscoelastic layer supporting the floating slab. These results were attained without significantly increasing the total weight of the floating layer.
Eco-materials employed to reduce noise are used either independently or as components of complex composite materials, which are a growing area of research. These eco-materials have the potential to be used as high-performance sound-absorbing noise isolators in a number of applications in areas such as transportation, architectural, industrial, and construction. Public concern about the environmental impact of transportation is leading to reduced fuel consumption and the use of recycled materials. These are clearly related to the reduction of weight, extending durable years. Currently, the concept of "green" building materials is used in practice in several European countries. In addition, public awareness and concern about the negative effects of pollution have led consumers to favor environmentally friendly materials, less contaminating processes, and recycled products. This chapter discusses eco-materials produced for the specific purpose of reducing noise. After an introduction to the subject, a section is devoted to the assessment of sustainable materials. Then, the fundamentals of the sound absorption, airborne sound insulation, and impact sound insulation properties of acoustical eco-materials are presented. The following section reviews common acoustical eco-materials, including those using natural fibers instead of synthetic ones, recycled fibers and surplus materials, advanced mix and composite eco-materials designed to provide better performance and produce lightweight materials that help in reducing fuel consumption and greenhouse gas emissions to the atmosphere, and, finally, green walls and roofs used on top of some buildings. All these eco-materials provide an alternative to chemical building materials, polymers, and other artificial non-sustainable materials.
This study aimed to investigate whether different acoustic and non-acoustic factors have effects on the subjective responses to floor impact noise made by upstairs neighbours in multi-story residential buildings. An on-site evaluation was conducted in four different apartment complexes with 100 residents from each site (N = 400). All the buildings had a box-frame-type structure with reinforced concrete slab floors with different thicknesses; two sites used 150 mm slabs, another used 180 mm, and the last used 210 mm slabs. The participants responded to a questionnaire which measured annoyance, anger, and empathy as their subjective responses to floor impact noise. The questionnaire also asked about socio-demographic, personal, and situational variables. Outdoor noise measurements were carried out for 24 h on the top of the buildings at each site in order to assess any masking effect of ambient noise on the subjective responses to the indoor noise. Results showed that the subjective responses were significantly affected by noise sensitivity and house ownership. Those who had higher noise sensitivity or those who were house owners reported higher annoyance and anger towards floor impact noise. Outdoor noise did not have any masking effect on the responses but those who lived in higher ambient noise levels reported higher annoyance and anger to the indoor noise. The subjective responses were not solely understood by slab thickness; however, slab thickness contributed to predicting the subjective responses with other variables. These findings imply that it is limited to fully explain the subjective responses to floor impact noise without other acoustic and non-acoustic factors such as noise sensitivity.
Resilient materials are used to reduce vibration transmission in buildings, e.g. in floating floors designed to decrease the impact sound pressure level in the room below the floor. The performance of a floating floor can be estimated in advance knowing the dynamic stiffness per unit area of the resilient material, which is usually measured on a small sample according to ISO 9052-1. Thus, the reliability of results from ISO 9052-1 measurements is crucial. However, the published standard gives few indications on the measuring equipment and suggests measuring the resonance frequency of the fundamental vertical vibration of the test specimen and of the load plate by using either sinusoidal, white noise or pulse signals, considered as equivalent. In this work, a measuring apparatus following the ISO 9052-1 specifications with some hardware and software improvements is described. Then the scanty specifications about the excitation signal are complemented introducing two robust alternatives, compatible with the ISO 9052-1 prescriptions: the ESS (Exponential Swept Sine) and MLS (Maximum Length Sequence) signals. The two newly proposed signals are validated measuring the dynamic stiffness per unit area of different resilient materials, whose resonance frequency is estimated using the same measuring equipment and four different excitation methods: hammer generated impulses, white noise, ESS and MLS. The comparison shows that ESS and MLS signals, already in use since many years for other kinds of acoustic measurements, are viable alternatives to traditional techniques and may have advantages in term of repeat-ability, dynamic range, cleanness of the frequency response and background noise immunity.
The civil construction sector is one of the areas that most generates waste and consumes raw materials. To mitigate this environmental damage, is possible to use waste from other sectors to reduce raw mate- rial or by minimizing the generation of waste with materials of satisfactory durability. One of the main points to be evaluated is how such materials behave to the loads application and other mechanical stres- ses, and how it affects their acoustic performance. These mechanical tests usually are performed only in industrial materials. Still, the search for building performance is increasingly based on the sustainability, safety and habitability. Habitability requirements include acoustic performance, which is vital in build- ings because its absence could cause stress, insomnia, hearing loss and other problems. So, this article proposes the use of EVA waste and rice husk in subfloors to decrease impact noise, replacing natural fine aggregates in the contents of 25, 50 and 75%. Compressive creep, dynamic stiffness and impact noise tests were performed. The results show that the use of both natural and artificial waste can represent gains in the efficiency of impact noise acoustic insulation for subfloors when used in larger proportions.
Floating floors have a high potential for reducing disturbance by impact noises in dwellings, since it greatly reduces the vibrations transmission through structures. The acoustical performance of a floating floor is quantified in terms of improvement of impact sound insulation ΔL. The improvement of impact sound insulation of a floating floor is a key parameter for the calculation of structure-borne sound insulation in buildings. Indeed, once ΔL is known, it is possible to evaluate the impact sound insulation, in in situ conditions, for several base floors of different building technologies and materials. ΔL can be directly determined on the basis of standard laboratory measurements, but it can be also estimated from elastic and inertial properties of involved materials, such as stiffness and mass. In this paper a constitutive model for the estimation of floating floors improvement of impact sound insulation is presented. As it will be shown, the constitutive model proposed based on force transmissibility theory, allows to accurately estimate the acoustical behavior of a floating floor, as a function of frequency, with a simple single function. Theoretical assumptions, experimental evidences and comparisons with previous computational models (e.g., Cremer-Vér model) allow to confirm both validity and effectiveness of the proposed model.
The number of high-rise residential buildings being constructed in countries with high population density is increasing in response to the need to utilize small areas. In Seoul, which is the densest of the Organization for Economic Co-operation and Development (OECD) countries, high-rise buildings have become more common in response to the considerable population increase. To diminish floor impact sound, resilient materials are generally applied between the concrete slab and the finishing mortar. Floor impact sound is affected by various characteristics of resilient materials such as dynamic stiffness, thickness, etc. Many experimental studies have been conducted to evaluate the impact sound reducing capacity of the materials, and have indicated that the dynamic stiffness of resilient materials has a close relation with the floor impact sound reduction. In most cases, a resilient material having lower dynamic stiffness has better floor impact sound reduction capacity. However, the dynamic stiffness of soft resilient materials could be changed under long-term loading and this could result in an increase of floor impact sound. The variation of the dynamic stiffness of 8 of the most widely used resilient materials under four different loadings were monitored for more than 500 days. The test results indicated that the dynamic stiffness of the resilient materials for floor impact sound increased with time, and that the variation of the dynamic stiffness was affected by loading time, weight of loading, and material properties. In addition, the proposed formula predicted the dynamic stiffness of resilient materials subjected to long-term load with reasonable agreement.
IntroductionAirborne Sound InsulationImpact Sound InsulationAcoustical Requirements in Building CodesReferences
Building multi-dwelling units is one of the practical engineering solutions to housing shortage in urban areas with high population density. However, noise from upstairs is a major issue. The use of resilient materials in floating floor structures is recognized as an effective method to reduce such noise. In general, soft materials are considered as better resilient materials due to their superior performance in impact sound reduction. However, it is often overlooked that the sound reduction performance of soft resilient materials is susceptible to being degraded over time when subjected to a long-term load. In this study, the long-term performance of eight resilient materials is evaluated by monitoring their dynamic stiffness for 270 days under the two sustained load conditions: 250. N and 500. N. According to the experimental study, the dynamic stiffness increases consistently with loading time for all resilient materials. This leads to a decrease in the sound reduction performance. More rapid reduction in the dynamic stiffness and hence in the sound reduction performance is observed when a larger sustained load is applied. A greater decrease in the sound reduction performance is found in soft resilient materials.
Paper and cardboard, made with recovered fibers obtained by recycling, are an attractive, sustainable material. Recovered paper and cardboard are mainly used for packaging purposes, even if, in recent years, various researches focused on the possibility to develop new products and proposed alternative applications. This paper presents new designs of acoustic absorbers made of partially recycled cardboard, in order to reduce the environmental impact of the materials usually used for the acoustic correction on indoor environments. Some of these new designed absorbers are porous and make use of the visco-thermal absorption effects in the pore space. Other absorbers are based on the Helmholtz resonator principle. Computer modeling software was used to predict the performance of the absorbers; in particular, different options of cardboard-based panels and paperboard tubes were investigated to identify the solutions with the best acoustic performance. A real-size prototype of a sandwich panel was then experimentally characterized in laboratory. The absorption coefficient spectrum of the prototype was measured according to the procedure indicated in the ISO 354 standard. The results show that the measured acoustic absorption coefficient of the material made using cardboard was higher than the one of traditional gypsum absorbers, giving in particular an increase of the acoustic absorption at mid and high frequencies in the order of 40%. A Life Cycle Assessment analysis was also performed to evaluate the environmental advantages of these materials. The environmental impacts of the production of the cardboard-based panel were compared with the impacts of conventional acoustic materials. The analysis highlighted a potential reduction of both energy demand and greenhouse gas emissions during the production process of the cardboard-based acoustic materials. The estimated CED and GWP values result 10% and 34% respectively lower than the impacts of a conventional gypsum board.
The vibroacoustic behavior of a commonly used floating floor installed in an actual multifamily housing unit was investigated to determine the factors that influence impact sound transmission at low frequencies. A finite element vibration model of the floor structure and an experimental sound field against a rubber ball impact were analyzed in combination. The results indicated that, in addition to isolation of the impact energy above the system’s natural frequency, the aspect of coupled and decoupled wave fields of the floating floor influences the impact sound transmission. The coupled wave field below the natural frequency is dominated by the bending wave field of the base slab and exerts a strong influence on the sound field, in which the sound field is dependent on the modal space and impact location of the coupled motion. The decoupled wave fields generated in the floating plate or the base slab above the natural frequency may disturb the vibration isolation. The non-rectangular acoustic cavity is considered to mitigate the influence of axial room modes on the impact sound field.
The installation of damping materials between a concrete slab and a form concrete layer was led to the disappearance of considerable impact noises by those materials to reduce floor impact noises in multi-dwelling houses. However, those damping materials currently used are mainly manufactured from organic materials with lower density and dynamic stiffness such as EPS, EVA, etc. These products generate a floating structure due to heterogeneous material layers and cause problems such as resonance and amplification of certain frequencies. Accordingly, this study manufactured mineral damping materials using mineral binders and applied the manufactured mineral damping materials to a floor structure, depending on physical properties such as density, dynamic stiffness and remnant strain among others, in a bid to analyze the characteristics of heavyweight impact noises and evaluate the reduction effects of floor impact noises. As a result of our experiments, both density and dynamic stiffness tended to increase due to the high specific gravity of raw materials if the powder types were applied when the mineral damping materials using mineral binders in the powder type and liquid type were manufactured, while the characteristic with the high strength development depending on the hydrated characteristics and acceleration of raw materials. Remnant strain appeared inversely proportional to both density and strength development ratio, great noise reduction was shown from materials with high density and strength of heavyweight impact noises and low remnant strain, and the correlation of dynamic stiffness with impact sound reduction was considered low.
1. A floor and its covering are considered as an infinite isotropic plate in which cylindrical flexural waves are excited by the blow of a hammer. The elastic layer is considered as having springiness without side coupling. In the common mats made of glass or slag wool the spring is provided by the enclosed air.2. The spectrum of the sound excited by a blow on the bare floor is first calculated.3. When the floating floor is struck bending waves of two types are produced which at high frequencies approach those proper to the individual plates. As in the main floor the type of the greatest wavelength is greater and better radiated than the other type, it is possible to compare its spectrum with that of 2. and deduce the improvement ΔL.4. Below the frequency at which the inertia resistance of the impinging mass (iωm 0) exceeds the driving point impedance Z 01 of the free floating floor and above the natural frequencyf 1 = 1÷2π√K/dm 1,of the floating floor on the layer of air, the approximate formulaΔL = 40 log (f/f 1) holds.Neither the impact mass nor the properties of the main floor nor the flexural stiffness of the floating floor come into the final formula. Increasing the mass of the floating floor or the air space between the two floors would produce improvement, as was to be expected. Only interleaves possessing the compressibility of air can produce improvement over the whole gamut.
In the present study, the effects of resilient isolators and viscoelastic damping materials on reducing heavyweight floor impact sounds from reinforced concrete structures were investigated using FEM simulations and in situ measurements. At first, the dynamic properties of the materials were measured using a beam transfer function method to include the properties in an FEM simulation. As a result, the damping materials provided a higher loss factor and dynamic elastic modulus than the resilient isolators. Subsequently, FEM simulations and in situ measurements were conducted to investigate the effects of the interlayers on the characteristics of floor impact sounds and vibrations. The results indicated that the impact vibration acceleration level and floor impact sounds at low frequencies were significantly decreased owing to the installation of damping materials, whereas the impact sound pressure levels at low frequencies were increased as a result of the use of resilient isolators.
This paper is concerned with the analysis of the dependence of low frequency impact sound transmission through floating floor systems on in situ matched resonances. The evidence for the floating floor matched resonances has been found previously considering laboratory and numerical tests for one concrete slab and floating floor with varying resilient layers. In the present paper, considering laboratory and field tests for concrete slabs and floating floors with different plan configurations, this evidence is strengthened as differences between laboratory and field measurements of the impact sound level were negligible for the bare concrete slab but not with the floating floor installed. These results were also confirmed numerically. The analysis indicates that the dependence of low frequency impact sound transmission through floating floor systems on in situ matched resonances should be considered in addition to the conventional single degree of freedom models in order to improve accuracy.
The impact noise reduction provided by floor coverings is usually obtained in laboratory, using the methodology described in the standard EN ISO 140-8, which requires the use of standard acoustic chambers. The construction of such chambers, following the requirements described in the EN ISO 140-1, implies a significant investment, and therefore only a limited number exists in each country. Alternatives to these standard methodologies, that allow a sufficiently accurate evaluation and require lower resources, have been interesting many researchers and manufacturers. In this paper, one such strategy is discussed, where a reduced sized slab is used to determine the noise reduction provided by floor coverings, following the procedure described in the ISO/CD 16251-1 technical document. Several resilient coverings, floating floors and floating slabs are tested and the results are compared with those obtained using the procedures described in the standards EN ISO 140-8 and EN ISO 717-2.
Most recent European acoustic design codes and regulations establish a maximum value for impact sound insulation on pavement slabs. These requirements demand the implementation of technical solutions such as floating floors, with the introduction of a resilient layer under the finishing pavement layer. Technical solutions such as floating concrete slabs (placed over synthetic foam or natural fibers layers), or floating pavements (like wooden floors built over synthetic foam layers) became quite common on recently built constructions. A possible alternative solution to floating pavements is the use of lightweight soft layers, applied over the structural concrete slab. These lightweight materials may present high quality results on the reduction of impact sound transmission. In the present work, lightweight mortar slabs were tested, and the impact sound insulation for different materials was quantified. Different types of cement mortar containing expanded polystyrene, expanded cork and expanded clay granulates were compared. The acoustical performance of these solutions was evaluated through laboratory tests, using an acoustic chamber with small dimensions, which allows comparing several solutions, on similar test conditions, in an expedite way. The influence of the type floor covering used over the lightweight mortar layer was also analysed. Different types of materials were tested.
The low frequency vibro-acoustic characteristics of a massive floating floor with continuous resilient layer are investigated with experimental measurements and numerical simulations using a hybrid FEA–SEA method. The results of the study indicate the occurrence of the in situ resonance of the floating floor system, which could be explained by the frequency matching between bending modes of the floating plate and the vibration isolator. The in situ frequency-matched resonance is considered to result in a sharp rise of the low frequency transmissibility of the vibration isolator and the impact sound. The difference between the in situ and the apparent natural frequency of the vibration isolator is assumed to be due to a reduced mass behavior of the floating floor in association with the base floor. It is inferred in the present work that contributing factors in the in situ frequency-matched resonance such as floating plate dimensions, elastic properties of the plate, and the location of an impact might affect the conventional regime of the single degree-of-freedom vibration isolation model for floating floors. The influence of floating plate dimensions on the occurrence of the in situ frequency-matched resonance might be considered as one of the factors affecting the differences in the low frequency impact sound of massive floating floors between laboratory and field measurements.
Expressions giving the velocity level difference between bottom and top plates are derived. Calculated and measured values are compared. The frequency dependence of the level difference is found to be between 25 and 40 dB/decade. The slope of the curve depends on the material parameters for the floor. Radiation ratios and reduction indices for some floating‐deck constructions are also discussed.
This paper describes a procedure for calculating the impact‐noise level of a bare stiff structural floor when excited with a standard tapping machine. Calculations are also given for the improvement in impact noise isolation achieved by adding to the structural floor (a) an elasticsurface layer, (b) a locally reacting floating floor, and (c) a resonantly reacting floating floor.
Airflow resistivity is a physical parameter which characterizes porous and fibrous sound absorbent materials.
It is well-known that such property allows the evaluation of the acoustic behaviour of sound absorbent
materials in various fields of application, including automotive noise mitigation, architectural
acoustics and building acoustics. In structure-borne sound insulation, airflow resistivity is essential for
the evaluation of the dynamic stiffness of porous and fibrous resilient insulating materials used as underlay
in floating floors.
However, an inconsistency between the dynamic stiffness and the airflow resistivity test conditions can
be recognized. In order to evaluate dynamic stiffness of a resilient material, a static load of about 2 kPa is
applied, while in airflow resistivity determination this condition is not explicitly required. As a result, the
density of analyzed material, in dynamic stiffness and airflow measurements, is different. Since these two
quantities are correlated, it is necessary to measure materials under the same conditions of applied static
load.
In this work the effects of static load (or density after compression) in airflow resistivity determination
of various porous and fibrous resilient materials are investigated, and the consequent influence on
dynamic stiffness is discussed. A simply empirical relation between density and airflow resistivity is also
put forth.
The main focus of this paper is to propose an harmonization among requirements of the Standards in
order to prevent significant errors in dynamic stiffness determination and incorrect evaluations of the
acoustic behaviour.
An experimentally validated analytical model has been developed in order to investigate the effect on impact sound transmission at low frequencies of location of the impact, type of floor, edge conditions, floor and room dimensions, position of the receiver and room absorption. The model was developed in order to allow rapid repeated calculations necessary for a parametric survey, described in a companion paper. The analytical model uses natural mode analysis to predict the sound field generated in rectangular rooms by point sound sources and the point excitation of homogeneous rectangular plates with different edge conditions. A floor-room model of the sound field generated in a room by a vibrating floor also has been derived. Laboratory and in situ measurements confirm that the models can be used to estimate impact sound transmission at low frequencies. The approach applies to homogeneous simply supported base plates of uniform thickness with homogenous floating floors, which again were experimentally validated in the laboratory and in situ.
Installing resilient materials between the slab and the Ondol layer is known as the most popular method of reducing floor impact sound in Korean apartments. The Ondol layer is made up of lightweight concrete and mortar constructed on the upper part of the resilient material, and is a typical heating system used for all types of residential buildings in Korea. In Korea, lightweight impact sound and heavyweight impact sound are considered when evaluating the floor impact sound. The resilient materials used can be categorized according to dynamic stiffness. Resilient materials with a low dynamic stiffness reduce the lightweight floor impact sound level. In this study, to examine the relationship between dynamic stiffness and heavyweight impact sound level, the dynamic stiffness and floor impact sound level of 51 resilient materials were measured. The impact sound level of each of these resilient materials, whose dynamic stiffness was measured, was measured before and after installation, and the level difference (ΔL) was analyzed. The measurement results show that, if the dynamic stiffness of single-layered resilient materials is known, the dynamic stiffness of multi-layered structures of resilient materials can be predicted. Also, as the dynamic stiffness of resilient materials decreased, the heavyweight impact sound level also decreased, and there was a correlation between the dynamic stiffness and the heavyweight impact sound.
This paper reports an investigation of the impact sound insulation performance of a range of materials made from recycled carpet tiles and provides a comparison with the performance of some commercially available acoustic underlays. The impact testing is carried out using a specially designed rig. It is demonstrated that good quality acoustic materials can be successfully manufactured from a granulated mix of industrial carpet waste. The effects of the grain to fibre (G:F) mass ratio, binder concentration and particle size distribution on the acoustic performance is investigated. It is shown that the optimum G:F ratio should be close to the mass ratio of the backing material to the pile material in many types of commercial carpet tiles (60:40). Sieving the granular waste and producing samples containing a single class of particle size does not enhance the impact sound insulation performance. These are important findings, which should ensure an efficient, cost-effective, full-scale manufacturing process. A formulation has been developed which yields samples with optimum impact sound insulation capability. This optimised sample compares favourably with the commercial underlays tested on the impact rig. The dynamic mechanical properties of the developed underlays have also been investigated to provide a better understanding of their influence on the impact sound insulation.
In this paper, vibration reduction in ship cabins by using floating floor is studied. Two theoretical models are developed and predicted insertion losses of floating floors are compared to experimental results, where measurements are done in the mock-up built for simulating typical ship cabins. The floating floor consists of upper board and mineral wool, which is in turn laid on the deck plate. The first model (M–S–Plate Model) is that upper plate and mineral wool are assumed as a one-dimensional mass–spring system lying on the simply supported elastic floor. The second model (Wave Model) is that mineral wool is assumed as elastic medium, in which longitudinal wave propagates. The comparisons show that M–S–Plate model is in good agreement with experimental results, while mass–spring model on the rigid floor behaves very poorly in the low frequency ranges, particularly near the natural frequency associated with mass–spring system. On the other hand, the wave model significantly underestimates the insertion loss. It is found that including elastic behavior of the deck plate is essential in improving accuracy of the insertion loss prediction for low frequency range below 100–200 Hz.
A method is described for the minimization of a function of n variables, which depends on the comparison of function values at the (n + 1) vertices of a general simplex, followed by the replacement of the vertex with the highest value by another point. The
simplex adapts itself to the local landscape, and contracts on to the final minimum. The method is shown to be effective and
computationally compact. A procedure is given for the estimation of the Hessian matrix in the neighbourhood of the minimum,
needed in statistical estimation problems.
Impact-noise rating of various floors
- Mariner
T. Mariner, H.W.W. Hehmann, Impact-noise rating of various floors, J. Acoust. Soc.
Am. 41 (1967) 206-214, https://doi.org/10.1121/1.1910319.
Zur meβmethodik der Trittschalldämmung
- Gösele
K. Gösele, Zur meβmethodik der Trittschalldämmung, Gesundheitsingenieur 70
(1949) 66-70.