Sound Insulation Measurements Research Articles

A Design Methodology Incorporating a Sound Insulation Prediction Model, Life Cycle Assessment (LCA), and Thermal Insulation: A Comparative Study of Various Cross-Laminated Timber (CLT) and Ribbed CLT-Based Floor Assemblies

Mass timber is increasingly being employed in constructing low- and mid-rise buildings. One of the primary reasons for using mass timber structures is their sustainability and ability to reduce environmental consequences in the building sector. One criticism of these structures is their lower subjective sound insulation quality. Therefore, acoustic treatments should be considered. However, acoustic solutions do not necessarily contribute to lower environmental impacts or improved thermal insulation performance. This paper discusses a design methodology that incorporates the development of a sound insulation prediction tool (using an artificial neural networks approach), life cycle assessment analysis, and thermal insulation study. A total of 112 sound insulation measurements (in one-third octave bands from 50 to 5000 Hz) are utilized to develop the network model and are also used for the LCA and thermal insulation study. They are lab-based measurements and are performed on 45 various CLT- and ribbed CLT-based assemblies. The acoustic model demonstrates satisfactory results with 1 dB differences in the prediction of airborne and impact sound indices (Rw and Ln,w). An acoustic sensitivity study and a statistical analysis are then conducted to validate the model’s results. Additionally, an LCA analysis is performed on the floor assemblies to calculate their environmental footprints. LCA categories are plotted against the acoustic performance of floors. No correlations are found, and the results emphasize that a wide range of sound insulation can be achieved with similar environmental impacts. Within each acoustic performance tier, the LCA results can be optimized for a floor assembly by selecting appropriate materials. The thermal insulation of floors is then calculated. Overall, a strong positive correlation is found between the total thermal resistance and heat loss against acoustic performance. Designers should be cognizant of the trade-offs between acoustic, thermal insulation, and environmental performance when choosing assemblies with favorable environmental impacts relative to acoustic and thermal insulation ratios.

An advanced nanoparticle reinforced carbon fiber laminates for low frequency sound insulation

Low frequency noise is a common engineering problem in the industrial field. This study utilizes graphite particles to enhance the low frequency sound insulation of carbon fiber laminates significantly. The effects of grasphite particles with different mass and mesh on sound insulation of laminates are investigated by theory and experiment. The analytical model is proposed based on the Galerkin method for the laminates’ motion equations. The effective elastic properties of the samples are calculated using the Halpin-Tasi model and the rule of mixture. Two groups of samples are prepared for sound insulation measurement. The comparison between the theoretical and experimental results shows that the theory can well predict the sound insulation of the nanoparticle reinforced laminates. A significant improvement in low-frequency sound transmission loss of 3–8 dB is achieved without altering the laminates' thickness. However, the mesh variation of the graphite particles has little effect on the sound insulation of laminates.

Effect of reverberation chamber volume on result of qualification procedure for loudspeaker and loudspeaker positions for airborne sound insulation measurements

Measurement of sound insulation from airborne sound is carried out by determining the level of sound power radiated by the test item. In laboratory practice, this translates into measuring the sound level in the transmitting and receiving chambers and measuring the reverberation time in the receiving chamber. When performing these measurements, significant fluctuations in the sound level for low frequencies can be observed, which is related to the occurrence of standing waves inside the chambers. To ensure proper level averaging, as well as repeatability and reproducibility of measurements ISO 10140-5 describes a qualification procedure for sources and source positions. This article presents the effect of increasing the volume of the source chamber on the results of the qualification procedure for sources and source positions for floor airborne sound insulation measurements.

Wall sound insulation measurement in laboratory according to iso 10140-2 standard and sound insulation measurement on the same wall with electrical and telephone sockets

Study related to the measurement of acoustic insulation R to sand and cement block wall with flattening on both sides, which was built inside a Transmission Chamber in accordance with the ISO 10140-2 standard. Subsequently this wall is slotted, placing Conduits, accessories for illumination, electrical and telephone sockets on both sides, finally covering all these installations with products that make it appear that the wall is intact, then the measurement of its acoustic insulation R and Rw is carried out. The results indicate variations that can be very annoying for residents on both sides of the wall, highlighting the lack of sealing into the Conduits, the choice of materials, location of sockets and construction procedures, etc.

Measurement of sound reflection and sound insulation of installed noise barriers using the SOPRANOISE quick method

This paper presents the preliminary results of a study on the new possibilities emerging from the analysis of measurements on installed noise barriers following the quick method designed in the frame of the SOPRANOISE project. Measurements of sound reflection and sound insulation were done in laboratory on a full-scale acoustic barrier and on an acoustic barrier installed along the Brennero motorway in northern Italy. The measurements were carried out using the SOPRANOISE quick system device, designed and engineered to provide a fast and lightweight version of the Adrienne method (i.e., EN 1793-5 and EN 1793-6), and then checked by applying the standardized Adrienne method, using instrumentation and procedures validated during the round-robin test performed in the frame of the QUIESST project. The preliminary results of the measurements are presented.

Computational prediction of impact sound insulation of a timber floor excited by an ISO standard tapping machine

During the last decades, researchers have actively developed procedures to predict impact sound insulation of timber slabs and floors using the finite element method (FEM). Since the simulations have mainly been performed in the low frequencies, a full understanding of their suitability for research and development (R&D) purposes has not yet been created. The object of the study reported in this paper was to determine the applicability of a modern FEM simulation procedure for predicting the normalised impact sound pressure level Ln of a full timber floor, when information provided by material manufacturers is used as input data. Force excitation caused by the ISO standard tapping machine was determined utilizing explicit time integration and FEM. The modelling of sound radiation itself was performed in a frequency domain FEM analysis. The models of a timber floor in its construction stages were constructed before the laboratory measurements of impact sound insulation so that the set-up corresponded to a simulated R&D task. Based on the prediction results, the applied procedure was considered suitable for R&D purposes and needs for further studies were identified.

Sound insulation characterisation of innovative natural ventilated façade in the context of living lab installations

Building acoustic standards like EN 14351 and ISO 10140 regulate the measurement of sound insulation of transparent elements, with indications of the test sample dimensions, test conditions, and criterions of adaptations of the results to different on-site conditions. However, given the research on innovative transparent building envelope including internal ventilation as double skin facades, these methodologies present limitations related to the characterization of the high variability of operating conditions in real in-field conditions. To this aim the acoustic performance could be explored with more flexible methods inside the multi-domain context of Living Labs, which present an opportunity for multiple characterizations and testing costs reduction. This work investigates the possibility of using the sound-intensity probe method to evaluate the airborne sound insulation of a transparent building element with internal ventilation. For this purpose, a comparative measurement campaign has been performed on the same building element installed in two Living Labs. The results show good compatibility between the different measurements and scales supporting the application of this methodology for comparative studies in the perspective of innovative building components measurements, and the application in Living Labs.

Towards a simplified model for partially open windows - connecting acoustic and thermal comfort

Traditionally, the internal environmental quality (IEQ) aspects of acoustic and thermal comfort have been considered and designed separately. However, where occupants rely on opening or closing windows to achieve these dimensions, they are not independent in use. To consider both simultaneously, it is crucial to have a simple model of a partially open window that can predict both acoustic and thermal conditions internally. CIBSE TM59 defines the assessment method for adaptive thermal comfort. In the thermal model the ventilation performance of open windows can be described with an "Equivalent Area" (EA). We propose to use the EA to calculate the facade sound insulation based on a simple assessment according to Annex D of ISO 12354-3, i.e. as a facade element with an area of EA and zero sound insulation. This study presents field measurements of sound insulation according to ISO 16283-3 with road traffic sound sources, to evaluate the acoustic uncertainty of using the EA to calculate internal sound levels. Results show encouraging correlation between measurements of element-normalized level difference, Dn,e,w + Ctr and calculations based on the EA. This model is considered adequate for acoustic design purposes, and represents a significant simplification compared with previous proposals.

Sound insulation of access floors on CLT

The acoustic performance of access floors resting on concrete slabs has been long investigated. When such flooring solutions are used on lightweight construction systems, estimates of impact sound insulation improvements cannot be transferred without relevant loss of accuracy. To gain understanding on such behaviour, an experimental campaign has been carried out at the Building Envelope Lab of the Free University of Bozen-Bolzano on 16 access floors mounted on a 200 mm CLT slab. Three different panels (calcium silicate, encapsulated calcium silicate and encapsulated chipboard panels), two different pedestals (standard and resilient), and three flooring solutions (bare, carpet tiles, acoustic carpet tiles) were studied. Impact sound insulation measurements were carried out using both the tapping machine and the rubber ball as source. The results discuss in detail the outcomes of the measurement campaign as well as the relation between the two impact sources chosen.

Application of Cadna/A software to the prediction of traffic noise on residential envelope sound insulation

The primary issue influencing residential structures' interior sound insulation environments is urban traffic noise. When choosing sound insulation for residential windows and doors, it is essential to consider the influence of road traffic noise. In conjunction with the examples, a three-dimensional simulation prediction model is created early on using Cadna/A software, and it is configured in accordance with the measured data of the road environmental noise to predict the sound pressure level of the outer surface of the residential building's enclosure structure at various locations and floors. This serves as a foundation for choosing the residential building's interior sound-insulated windows and doors as well as for the building's construction. In order to confirm that interior doors and windows are structurally sound-insulated, sound insulation measurements of typical residential sample buildings are made later in the building process.It offers some reference value for using Cadna/A in the assessment and forecasting of traffic noise's impact on the soundproofing of residential building envelopes.

House FIRSTLIFE in student contest and in Living Lab

Abstract The paper comments on selected measurements and observations related to the FIRSTLIFE house demonstration unit, which was prepared by the team of the Czech Technical University for the international competition Solar Decathlon Europe 21/22 with its final at the Solar Campus in Wuppertal, Germany. The paper comments on the measurement results obtained during the competition in the field of building physics (thermal and moisture comfort, measurement of air permeability, measurement of sound insulation of the perimeter wall and dynamic co-heating test). The second part of the paper describes selected follow-up activities. For the purposes of the Living Lab, eight of the competition houses remained on the Solar Campus for at least another 3 years. This allowed long-term monitoring and targeted experiments to be carried out and some of the earlier measurements to be repeated under different climatic boundary conditions. For this phase, additional sensors were added in the Czech house, such as a meteorological station and temperature and heat flow sensors in the perimeter wall. Part of the data comes directly from the building management system. The paper comments on first results from Living Lab period.

Soundbox-based sound insulation measurement of composite panels with viscoelastic damping

Sound transmission loss (STL), an essential index for assessing the sound insulation performance of composite laminated structures, typically relies on experimental methods to measure. The soundbox method (SBM), a straightforward technique for measuring the STL, is sensitive to microphones’ positions. Within the framework of the Chebyshev-Ritz method, a semi-analytical vibro-acoustic model extended to composite laminated panels with viscoelastic damping (VED) is proposed for the first time. Based on the developed simplified layer-wise theory, the panel is modeled using three layers: the top face layer, the VED layer, and the bottom face layer. A closed cavity is added to the model as the soundbox enclosure used in actual measurements. By employing the Hamilton's principle, the governing equation for the coupling system is derived, and the vibration and internal acoustic responses of the coupling system are calculated. A discretization strategy is introduced to address the frequency-dependent properties of the VED layer, avoiding the need to reconstruct the stiffness matrix at each frequency. To obtain the STL of the panel, sound pressures at external measurement points are calculated based on the Rayleigh integral. The proposed model is validated against numerical results from finite element analyses. The influences of the microphone position inside and outside the cavity on the measured STL are studied. Furthermore, parametric studies over the microphones' positions are performed to enhance the SBM-based evaluation of the composite panel's sound insulation performance. The optimal locations for two internal microphones and one external microphone are recommended. Finally, experimental studies are carried out to guide the implementation of the SBM.

Study of Acoustic Prototypes Based on Plastic Cap Waste

This paper presents the initial prototypes of solutions designed using plastic caps, seeking acoustic applications for both airborne sound insulation and the acoustic conditioning of rooms. Plastic caps are a waste product from the packaging sector and they constitute a major waste problem, given that, if they are not attached to the packaging, they get lost during the recycling cycle and end up in landfill. Finding an application for this waste that can provide acoustic improvements is a sustainable alternative. This paper shows the results of airborne sound insulation measurements obtained in a scaled transmission chamber and sound absorption measurements obtained in a scaled reverberation chamber for different combinations of single and double plastic caps and combinations with thin sheets of sustainable materials, such as jute weaving, textile waste, hemp felt and cork board. Tests have shown that obtaining sound reduction index values of up to 20 dB is possible with plastic cap configurations, or even up to 30 dB is possible at some frequencies with combinations of caps and certain eco-materials. With regard to the sound absorption coefficient tests, close to unity absorption values have been achieved with the appropriate configuration at frequencies that can also be selected. The results indicate that these panels can be eco-solutions for airborne sound insulation as lightweight elements, or they can be used for the conditioning of rooms, tailoring the sound absorption maximums to the desired frequencies.

Advancing sustainable construction through comprehensive analysis of thermal, acoustic, and environmental properties in prefabricated panels with recycled PET materials

Acoustic and thermal insulation materials play a crucial role in the construction industry as they ensure high-performance applications. This study analyzes three recycled insulations (two derived from PET and one is EPS with graphite additives) for innovative prefabricated panels. A multiphysics, multiscale, and multiobjective approach was developed to analyze the performance of the individual materials and three prototype prefabricated panels incorporating them, combined with numerical analysis enabling the thermal transmittances assessment of a full-scale panel. Thermal investigations were conducted at both small and large scales to assess their performance. Additionally, acoustic sound insulation measurements at both scales and a LCA analysis were carried out. Thermal conductivity of the insulation layer ranges from 0.026 to 0.043 Wm−1K−1. Furthermore, the sound transmission loss exhibits a positive trend with increasing frequencies, reaching approximately 10 dB after 1600 Hz for the 15 cm thick PET insulation. EPS performs exceptionally well at low frequencies, with sound insulation peaks reaching almost 40 dB around 400 Hz. At the large scale, the weighted sound reduction index showed a 3.5 dB increase compared to the reference. The environmental assessment emphasized that 80 % of global warming potential comes from material extraction, stressing the importance of using recycled materials.

Sound Transmission Loss in Light Steel Framing Walls With Vermiculite and Recycled-pet Fiber

Due to the demand for multifamily constructions, there is an increasing need for buildings with enhanced acoustic comfort. This study evaluated the acoustic performance of facade walls in the Light Steel Framing (LSF) construction system, using recycled-PET (Polyethylene Terephthalate) fiber and vermiculite board according to ISO 10140:2021 (Acoustics – Laboratory measurement of sound insulation of building elements). Experimental tests on sound transmission loss (STL) were conducted on LSF walls, comprised of two plates (a fiber cement board and an OSB (Oriented Strand Board) separated by an air gap. Four different internal cavity configurations were considered herein: a prototype without any material inside the wall; the second configuration with only recycled-PET fiber inside; the third configuration with solely vermiculite board inside; and the last model with both recycled-PET fiber and vermiculite board inside the wall. The ‘composite’LSF wall with two sound absorbing materials inside, achieved the value of STL equal to 37 dB. It complies with the minimum requirements of the Brazilian Standard NBR 15575-4 (ABNT, 2021) for facades. Furthermore, this study introduces a new approach for LSF walls which considers the introduction of vermiculite boardin between the external boards.

Assessing the low-frequency measurement procedure for the measurement of impact sound insulation using the rubber ball

ISO 16283-2 includes a procedure for measuring field impact sound insulation at low frequencies using a tapping machine to improve the repeatability, reproducibility, and relevance of results in the 50, 63, and 80 Hz one-third octave bands in small receiving rooms (volumes less than 25 m3). However, the low-frequency measurement procedure with excitation from a standardized rubber ball was not included because the link between measurements of Li,Fmax from the central region and corners had not been established at the time of writing. This paper assesses the use of the low-frequency measurement procedure with a rubber ball source through measurements of Li,Fmax in a vertical transmission suite at the Building Research Institute (Japan). It also provides analysis of the modal sound field in the receiving room due to rubber ball excitation of the concrete slab. The results indicated that the low-frequency measurement procedure was beneficial in this 60 m3 room to estimate the room average sound pressure level below 80 Hz. Future work could therefore evaluate the low-frequency procedure in the field with different room volumes and floor constructions.

Need for a new test method for determining the acoustic performance of road traffic noise reducing devices

Noise reducing devices such as sound barrier walls are common ways to mitigate traffic noise problems in residential areas next to arterial roads or railways. The basic performance of noise reducing devices is sound insulation and absorption. However, the existing measurement methods are not adequate for characterizing sound insulation and absorption performances of noise reducing devices. The sound insulation measurement method is different from the actual installation condition of the noise reducing devices that transmit the sound to the free field, and the sound absorption coefficient measurement method does not include the transmitted sound energy. This study raised the problem of the current acoustic performance measurement method of noise-reducing devices and arises the need for a new measurement method to complement it.

Effects of sound insulation and light reflection of desktop partitions on subjective impression during conversation

In recent years, transparent desktop partitions have often been placed in public spaces to prevent the spread of COVID-19. Moreover, to clarify the view during conversation, surface materials with low light-reflectivity are developed for the partitions. In this paper, we conducted sound insulation measurements for partitions with four different materials, and two psychological experiments in order to examine the audio-visual effects on the ease of conversation. First, in non-visual conversation between two persons, better subjective evaluation of speech transmission was confirmed for partitions with lower surface density which have less insertion loss. However, in normal audio-visual conversation, the low light-reflective partitions got higher evaluations of not only visual but also auditory impressions, regardless of sound insulation performance. In addition, subjective evaluations among different materials varied in the quiet condition more remarkably than in the noisy condition.

Investigation of alternative methods for measuring and evaluating airborne sound insulation

The reproducibility of airborne noise insulation testing is poor, as documented by various interlaboratory studies. This is compounded by the definition of Sound Transmission Class (STC), the dominant single-number rating used in North America, which over-emphasizes the wall performance at and around the 125 Hz third-octave band. Small variations in performance at these frequencies can result in substantial changes in STC rating. To address these concerns, changes to both the measurement method and the single number ratings may be appropriate. For the former, the authors have begun an investigation of measuring the vibro-acoustic characteristics of walls, including measuring the vibration on the surfaces of the separating assembly and the flanking assemblies. This may result in increased precision of sound insulation measurements. For the latter issue, the authors have performed statistical evaluation of published wall sound insulation tests to clarify the effects of idiosyncrasies in the definition of STC and investigated whether different rating methods may better describe the performance of wall assemblies.

Effect of Diffusing Elements in a Reverberation Room on the Results of Airborne Sound Insulation Laboratory Measurements

The main problem in the measurement of airborne sound insulation is the measurement of the sound power radiated by the barrier, in practice performed by measuring the sound pressure level and the acoustic absorption in the receiving room. Large variations of the sound pressure level in a reverberation room indicate the presence of dominating strong standing waves, so that it becomes necessary to install diffusing elements. In ISO 10140, the limits have been defined in which the reverberation time at frequencies at and above 100 Hz should be included. Sometimes, however, in the case of rooms with a large volume, obtaining the required parameters is difficult and sometimes even impossible. It should then be checked whether the measured sound insulation depends on the reverberation time. The paper presents the results of sound insulation measurements at various reverberation time lengths in subsequent stages of diffusing elements installation in the receiving room. An analysis of diffusing materials amount and arrangement influence on the uniformity of the sound pressure level distribution and reverberation time in the room as well as the value of the measured sound insulation was carried out. Uncertainty of sound insulation measurement with partial uncertainties was adopted as a criterion supporting the assessment of the obtained results.