Influence of screw spacings on sound reduction index in lightweight partitions

In this paper measured sound reduction index data for lightweight partitions with gypsum board layers attached to the frame with two different screw spacings are presented. Data are used to show the effect of screw spacings and to quantify the effect on sound reduction index. The results show that screw spacing had a great effect in double walls where each gypsum board layer was attached to each side of a timber frame.     

Experimental sound insulation performance of double frame partitions with slits

In this paper the influence of slits on sound reduction index of double steel frame partitions with and without mineral wool in the cavity was examined. It was shown that the sound insulation of the partition is strongly dependent on the relative position of the slits on each steel frame. As could be expected, the reduction in sound insulation due to slits is lower in partitions without mineral wool in the cavity, since the effect of slits is more important in the case of partitions with high sound insulation.     

Influence of air layers and damping layers between gypsum boards on sound transmission

In this paper the influence on sound reduction index of a thin air layer between gypsum board layers of lightweight partitions has been examined. It has been shown that the air layer between gypsum boards causes a decrease in sound reduction index due to mass-air-mass resonance. When the thin air layer is filled with a damping layer, the sound reduction index is increased for frequencies around the critical frequencies. Predictions show similar effects to those measured.     

Criticism of statistical energy analysis for the calculation of sound insulation: Part 2-double partitions

The theory of statistical energy analysis has been applied to the problem of estimating the transmission loss of a single finite panel. This theory was extended to the problem of a finite double-leaf partition structure.This paper deals with the degree of agreement of the measured values with the theoretical results of the sound insulation of double partitions according to this theory.In addition, the advantages and disadvantages of this method compared with classical methods are discussed. A comparison between the method of statistical energy analysis and classical methods for the calculation of the sound insulation of double partitions is given.     

The effect of the structure-borne sound transmission between panel and stud via screw connections for a double leaf partition

In additional to the screw connection affecting the sound transmission characteristics of the panel-stud partition,the spacing of screws is also considered as a factor in predicting the sound insulation of the partition.It can be modeled either as a series of independent point connections,or as a line connection depending on the screw spacing.For small screw spacing,the connection between panel and stud can be treated as a line connection,from which a higher sound transmission effect can be achieved.Whilst for a larger screw spacing,it can be treated as an independent point connection,from which a lesser sound transmission through the partition can be achieved accordingly.The distinction between these two kinds of connection is also related to the frequency.Usually,half bending wavelength of a panel will be treated as a distinct frequency.Experimental results of double leaf partition with diverse screw spacing significantly demonstrated their influences on sound reduction.Some prediction methods for partitions with different screw spacing are also reviewed in this paper.It should be noted that the impact of screw spacing effecting on the sound insulation of partitions of wood stud and light-weight metal stud is different.     

A review of the metal stud stiffness on the sound insulation of gypsum-board partitions

For the sound insulation of a double-panel partition,the stud between two leaves creates a vibration transmission path,which can often be more critical and more important in the mid-frequency range than the airborne path through the cavity.Owing to the fact that partitions with light-weight steel studs are commonly used in building construction,studies on the sound insulation effect of such studs have been conducted.Especially,a model,initiated by Gu and Wang(1983),has been widely studied during the past decades.In the model,the steel stud is considered as an elastic spring with its cross-section stiffness in the sound insulation index prediction of such a partition.Experimental results of different stud profiles have been reported from different testing laboratories and more information has been gained to understand the stiffness effect of the stud on the sound insulation of the double-leaf partitions.In this paper,the authors have given this subject a thorough review and have concluded that a critical problem needs further investigation on the determination of the stiffness of the connecting elements in the double-leaf partitions.     

Criticism of statistical energy analysis for the calculation of sound insulation—Part 1: Single partitions

Crocker and Price⁴ employed the method of statistical energy analysis to calculate the sound insulation of single and double partitions. This paper deals with the degree of agreement between the results obtained by this method for sound insulation of single partitions and measured values.In addition, the advantages and disadvantages of this method compared with classical methods are discussed. A comparison between the statistical energy analysis method and classical methods for the calculation of the sound insulation of single partitions is made.     

The influence of slits on sound transmission through a lightweight partition

In this paper the influence on sound reduction index of the length and the depth of sound leaks at the perimeter of lightweight partitions was examined. It was shown that the most important decrease on sound reduction index is caused by the first slit between lightweight partition and one of the structural members. When the length of the slit is increased, the decrease on sound reduction index is less significative. Calculated results show the same effects as measured ones.     

多孔弹性介质三层夹心板的隔声性能研究

应用Biot关于流体饱和多孔弹性介质的声传播理论,采用传递矩阵的分析方法,就复合多孔弹性材料夹心三层板在不同结构情况下的隔声性能进行了理论研究和实验分析,并与同等条件下双层夹心板的隔声性能进行了比较。数值计算和实验结果均表明,与双层夹心板相比,三层夹心板在中高频段隔声性能有明显优势,但低频段隔声性能有一定程度上的下降。研究还表明不同结构的复合三层夹心板在隔声效果上也各有特色。     

Effectiveness of T-shaped acoustic resonators in low-frequency sound transmission control of a finite double-panel partition

Double-panel partitions are widely used for sound insulation purposes. Their insulation efficiency is, however, deteriorated at low frequencies due to the structural and acoustic resonances. To tackle this problem, this paper proposes the use of long T-shaped acoustic resonators in a double-panel partition embedded along the edges. In order to facilitate the design and assess the performance of the structure, a general vibro-acoustic model, characterizing the interaction between the panels, air cavity, and integrated acoustic resonators, is developed. The effectiveness of the technique as well as the optimal locations of the acoustic resonators is examined at various frequencies where the system exhibits different coupling characteristics. The measured optimal locations are also compared with the predicted ones to verify the developed theory. Finally, the performance of the acoustic resonators in broadband sound transmission control is demonstrated.     

An empirical model for the equivalent translational compliance of steel studs

The effect of the resilience of the steel studs on the sound insulation of steel stud cavity walls can be modeled as an equivalent translational compliance in simple models for predicting the sound insulation of walls. Recent numerical calculations have shown that this equivalent translational compliance varies with frequency. This paper determines the values of the equivalent translational compliance of steel studs which make a simple sound insulation theory agree best with experimental sound insulation data for 126 steel stud cavity walls with gypsum plaster board on each side of the steel studs and sound absorbing material in the wall cavity. These values are approximately constant as a function of frequency up to 400 Hz. Above 400 Hz they decrease approximately as a non-integer power of the frequency. The equivalent translational compliance also depends on the mass per unit surface area of the cladding on each side of the steel studs and on the width of the steel studs. Above 400 Hz, this compliance also depends on the stud spacing. The best fit approximation is used with a simple sound insulation prediction model to predict the sound insulation of steel stud cavity walls whose sound insulation has been determined experimentally.     

含空气层与多孔材料的复合结构隔声特性研究

基于高速列车减振降噪需求,本文应用Biot提出的多孔弹性介质声传播理论,采用传递矩阵法理论推导了典型分层结构的隔声量计算公式,给出了空气层与多孔材料对分层复合结构隔声特性的影响。将传递矩阵与遗传算法相结合,对特定中低频段内的复合结构隔声特性进行了优化。研究结果表明:空气层和多孔材料有助于分层复合结构隔声量的提高,特别是空气层对低频隔声有很好的促进作用,另外空气层与多孔材料的分配情况也影响着隔声效果。含有空气层的复合结构在提高隔声量的同时降低了结构的总体重量,实现了高速列车隔声材料低能耗和轻量化的设计目标。     

Sound insulation of double-leaf walls - Allowing for studs of finite stiffness in a transfer matrix scheme

In a recent paper by the present author the effect of finite structural connections on the sound reduction index of double walls was predicted by modifying a model based on the transfer matrix technique. However, the model did not include any means to account for the flexibility of the studs; they were assumed to be of infinite stiffness. Based on data for the effective stiffness of flexible steel studs, the model is extended to take account of this flexibility. A number of comparisons are performed, mainly with the measured sound reduction index of lightweight double walls with gypsum boards. Cases include walls with cavity filling as well as with empty (air-filled) cavities. In the latter cases, the energy losses of the cavity are simulated using a model of a porous layer with a minute flow resistivity. Predicted results compare favourably with measurement results. It is assumed that different basic types of studs, i.e. other than the TC-type simulated here may successfully be included in the model.     

Effects of an air-layer-subdivision technique on the sound transmission through a single plate

Many studies on the sound transmission through a single plate have been carried out theoretically and experimentally. The transmission-loss characteristics, in general, follow mass law. Therefore, increasing mass of a plate is a fundamental measure to improve the insulation performance. This method, however, has limitations and might not be a reasonable alternative in current standards. Furthermore, the transmission loss at the critical frequency of coincidence is deteriorated significantly even if the mass is rather large. In this paper, the effect of the air-layer-subdivision technique is studied in detail from the viewpoint of the sound transmission problem of a single plate. An analytical model of an infinite single plate with a subdivided layer is considered and the improvement of the transmission loss is estimated. The limitations of the technique are clarified with some parametric studies. In order to validate the predictions, an experiment was carried out. The transmission loss of a glass board with the air layer subdivided by acryl partitions was measured in the experiment. They were in good agreement with the theoretical ones near and above the coincidence.     

Sound intensity investigation of the acoustics performances of high insulation ventilating windows integrated with rolling shutter boxes

High sound insulation ventilating windows (HSIVW) were recently proposed for noise control in buildings close to motorways or railways, where noise barriers are not effective or too expensive. These windows are characterized by good insulation performances and at the same time allow airflow through the window itself; such a performance matches summer indoor ventilation and refreshment needs.In the last years at the Acoustics Laboratory of the University of Perugia various prototypes were tested and their acoustic and airflow performances were assessed, also verifying the influence of filtering systems in the aerator.In the present paper a lot of experimental data are presented and in particular the results of a recent campaign, aimed at testing windows samples integrated with insulated rolling shutter boxes are presented. Sound reduction index R and single number sound reduction index R_w are evaluated, considering different exercise conditions; acoustic intensity measurements and analysis have also been performed, in order to verify the parts of the window which need to be optimized.     

Estimation method for parameters of construction on predicting transmission loss of double leaf dry partition

For improving sound insulation of a double leaf dry partition, each leaf is often consisted of more than one panel. Previous study on predicting a transmission loss of double leaf partition, treats with the leaf varied just two kinds of panels and restricted to a leaf having same kind and same thickness. These restrictions are unfit for variety of current building materials and constructions. This study makes a prediction formula for a transmission loss of the double leaf partition with laminated leaves by a theoretical analysis and an experiment, and will discuss the predicted value with measured value in previous studies and catalogs.     

Analytical evaluation of the acoustic insulation provided by double infinite walls

The acoustic insulation provided by infinite double panel walls, when subjected to spatially sinusoidal line pressure loads, is computed analytically. The methodology used extends earlier work by the authors on the definition of the acoustic insulation conferred by a single panel wall. It does not entail any simplification other than the assumption that the panels are of infinite extent. The full interaction between the fluid (air) and the solid layers is thus taken into account and the calculation does not involve limiting the thickness of any layer, as the Kirchhoff or Mindlin theories require. The problem is first formulated in the frequency domain. Time domain solutions are then obtained by means of inverse Fourier transforms using complex frequencies.The model is first used to compute the sound reduction provided by a double homogeneous brick wall, with identical panels, when illuminated by plane sound waves. The results are then compared with those provided by the simplified method proposed by London, which was later extended by Beranek (London-Beranek method). The limitations of the simplified London-Beranek model, namely, its applicability only to double walls with identical mass, subjected to plane waves, and its failure to account for the coincidence effect, are overcome by the method proposed.Time signatures are produced to illustrate the different sound transmission mechanisms. Several types of body and guided waves are originated, giving rise to a complex dynamic system with multiple reflections within the solid and fluid layers and the global resonance of the system. The effect of the cavity absorption is considered by attributing a complex density to the air filling the space between the two wall panels. Absorption attenuates the dips of insulation controlled by the cavity resonances. Several simulations are then performed for different combinations of wall and air layer thickness to assess the influence of this variable on the final acoustic insulation. The influence of the air cavity on sound reduction was found to be dependent on the frequency. At low frequencies a better performance was achieved for thicker air layers, while at higher frequencies a thinner air layer is preferable. The use of wall panels with different mass resulted in the wall performing better, particularly for high frequencies.     

Potential solutions to improved sound performance of volume based lightweight multi-storey timber buildings

Lightweight building systems in general suffer from poor sound insulation, especially in the low frequency region. Since no reliable mathematical models that can predict the impact sound pressure level exists, the lightweight building design is to a high extent based upon previous experience and upon measurements. A special difficulty is related to experimental measurements since the variation among identical units must not be neglected. A modern volume based lightweight wooden building concept has here been tested by numerous well controlled measurements, in laboratory as well as in more field like conditions. The volume construction technique offers new possibilities and challenges to improve sound insulation in light weight timber construction. The main purpose was to investigate how different constructional solutions in the floor, like plaster board, mineral wool, elastic glue, dividing board, floating floor etc., affect the sound insulation. Many of the tested modifications resulted in only marginally changed impact sound pressure level but parameters that substantially can improve the sound insulation were found in using elastic glue to mount the floor boards, to install extra board layers and to use floating floors.     

钢结构装配式住宅墙板连接方式对隔声性能的影响*

为提升其隔声性能,通过有限元法数值分析,比较了不同位置墙板的连接方式对房间隔声性能的影响。结果表明：(1)侧墙墙板柔性连接处理对侧向传声的抑制作用显著,当侧墙墙板采用柔性连接后,房间的隔声量在低频段平均可以提升3 dB左右;(2)公共隔墙墙板的柔性连接对房间低频段隔声量提升不明显,甚至在160 Hz、400 Hz、500 Hz等频率下隔声量有所降低。最后,基于模拟分析结果对装配式墙体连接方式提出了改进策略。     

Acoustic insulation capacity of Vertical Greenery Systems for buildings

Vertical Greenery Systems (VGS) are promising contemporary Green Infrastructure which contribute to the provision of several ecosystem services both at building and urban scales. Among others, the building acoustic insulation and the urban noise reduction could be considered. Traditionally vegetation has been used to acoustically insulate urban areas, especially from the traffic noise. Now, with the introduction of vegetation in buildings, through the VGS, it is necessary to provide experimental data on its operation as acoustic insulation tool in the built environment. In this study the acoustic insulation capacity of two VGS was conducted through in situ measurements according to the UNE-EN ISO 140-5 standard. From the results, it was observed that a thin layer of vegetation (20–30 cm) was able to provide an increase in the sound insulation of 1 dB for traffic noise (in both cases, Green Wall and Green Facade), and an insulation increase between 2 dB (Green Wall) and 3 dB (Green Facade) for a pink noise. In addition to the vegetation contribution to sound insulation, the influence of other factors such as the mass factor (thickness, density and composition of the substrate layer) and type of modular unit of cultivation, the impenetrability (sealing joints between modules) and structural insulation (support structure) must be taken into account for further studies.