Normalized Impact Sound Pressure Level Research Articles

Effect of polyvinyl alcohol on the mechanical and sound properties of recycled rubber mortar

Recycled rubber mortar is a novel green construction material which alleviates the environmental impact of waste rubber tires and greatly improves the sound insulation performance. Existing cement mortar with high rubber content exhibits poor mechanical properties, limiting its application in construction field. In this study, polyvinyl acetate (PVA) was introduced to modify recycled rubber mortar and the effect of PVA contents on its fluidity, flexural, compressive, impact strengths, and drying shrinkage was analyzed. To improve the analytical accuracy, analytic hierarchy process (AHP) was used to select the optimal mix proportion. The results indicate that PVA has positive effects on the mechanical properties of recycled rubber mortar. Further, comparing the trend of the normalized impact sound pressure level with an increase in frequency and the weighted normalized impact sound pressure level revealed that mixing 50 % recycled rubber particles and 8 % polyvinyl acetate effectively improved the sound insulation performance of cement mortar. These findings can promote the application of recycled rubber mortar in housing construction projects and having environmental benefits.

Sound insulation of slabs in dwellings

The well-being and sleeping quality of people in dwellings depends on appropriate sound insulation efficiency of building structures. In individual apartments, airborne sound is produced by people talking and music playing, and impact sound is produced by people walking and falling of various objects on the floor. The inter floor slab separating the individual dwellings is intended for airborne and impact noise insulation, so special attention is paid to its design and installation. Since the composition of this structure is primarily determined by the structural requirements, the improvement of the sound insulation performance is mainly carried out by developing the damping interlayer materials. The stone wool plate has been modified reducing the fiber intertwining to obtain a more uniform fiber directivity, thus reducing its dynamic stiffness. Therefore, the aim of this study was to investigate the sound insulation efficiency of inter floor slabs with a new modification of stone wool damping interlayer in comparison with currently used mineral wool products. The experimental measurements in 50-5000 Hz frequency range were performed in construction site (real structures), the single-number quantities – weighted standardized level difference (DnTw) and weighted normalized impact sound pressure level (L‘nW) with living adaption term (C) were determined and compared. The research results demonstrated that the modified stone wool with reduced fiber intertwining and lover organic content used for damping interlayer enables to improve living sound insulation of inter floor slab comparing with existing stone wool materials.

The effect of suspension systems on the sound insulation of suspended ceilings: A finite element analysis

It has been shown via laboratory measurements that the airborne and impact sound insulation of a concrete floor structure with a suspended plasterboard ceiling can be improved by using elastic ceiling suspension systems. The weighted airborne sound reduction index R w was increased by 7dB and the normalized impact sound pressure level L n,w was decreased by 15 dB when using elastic ceiling hangers as opposed to fixed hangers. In order to study the effect of elastic ceiling hangers on sound insulation further and to make it easier to compare different suspension systems especially in the low frequency range, a calculation model applying the finite element method (FEM) and parametric calculation methods was created. The calculation model was validated using measured data. The calculation results were then used to predict the improvement of sound insulation achieved with the different suspended ceilings. Additionally, the calculation model was used to examine the phenomena around the performance of the different ceiling hangers. The calculation results confirm the observations made from the laboratory measurements; switching from fixed ceiling hangers to elastomer ceiling hangers improved the performance of the suspended ceiling by more than 10 dB, with significant improvements beginning from the low frequencies.

Suitability of standardized single-number ratings of impact sound insulation for wooden floors – Psychoacoustic experiment

Wooden floors usually have worse impact sound insulation (ISI) at low frequencies than concrete floors having the same rating level. Rating level is usually expressed by single-number quantities (SNQs), such as weighted normalized impact sound pressure level Ln,w. Psychoacoustic research among wooden floors is very limited although a controlled laboratory experiment is the strongest method to point out the most adequate SNQs to be declared for the floors. The purpose of our study was to determine how four standardized SNQs of ISO 717-2, Ln,w, Ln,w + CI, Ln,w + CI,50, and LiA,Fmax,V,T, and a recently proposed SNQ, Ln,w + CI,25, are associated with the annoyance of natural impact sounds transmitted through wooden floors. Fifteen floors were built in the laboratory based either on cross-laminated timber (heavy) or open box wood (light) slabs. Different coverings and suspended ceilings were applied on these slabs. The ISI was tested within 25–3150 Hz using both tapping machine and rubber ball. Thereafter, five natural impact sounds were recorded for each floor: rubber ball drops, steel ball drops, walking, jumping, and chair pushing. Fifty-two people rated the annoyance of these 75 recorded natural impact sounds in psychophysics laboratory. Annoyance was best associated with Ln,w for all the five impact sound types. That is, measurement of ISI within 100–3150 Hz is sufficient from subjective point of view. All four SNQs based on tapping machine explained annoyance better than the SNQ based on rubber ball. Our results can significantly guide the future research, development, and regulations of wooden floors.

Relationship between the normalized impact sound pressure level (NISPL) and the transmission loss (TL) of a floor ceiling assembly

The relationship between the normalized impact sound pressure level (NISPL) and the sound transmission loss (TL) of a floor ceiling assembly has been understood since 1963 (Heckl, and Rathe) and confirmed in 1971 (Ver), both for concrete based buildings. This concept has even made its way into ISO 12354-2. This paper will analyze approximately eight hundred floor/ceiling assemblies that Pliteq has measured in the lab to see if this relationship holds for other types of assemblies and where it might fall short. In a related topic, there has been discussion at ISO to create a delta sound reduction index (R) and normalized impact sound level (Ln) for added ceilings similar to the Delta IIC for floor coverings. The Ln/R are similar to the TL and NISPL in ASTM. The same data set will be queried to see if this is a valid approach for real world constructions in North America.

Sound insulation of lightweight wooden floor structures: ANN model and sensitivity analysis.

The artificial neural networks (ANN) approach is applied to estimate the acoustic performance for airborne and impact sound insulation curves of different lightweight wooden floors. The prediction model is developed based on 252 standardized laboratory measurement curves in one-third octave bands (50 - 5000 Hz). Physical and geometric characteristics of each floor structure (materials, thickness, density, dimensions, mass, and more) are utilized as network parameters. The predictive capability is satisfactory, and the model can estimate airborne sound better than impact sound cases especially in the middle frequency range (250 - 1000 Hz), while higher frequency bands often showed high errors. The forecast of the weighted airborne sound reduction index Rw was calculated with a maximum error of 2 dB. However, the error increased up to 5 dB in the worse case prediction of the weighted normalized impact sound pressure level Ln,w. A feature attribution analysis explored the essential parameters on estimation of sound insulation. The thickness of the insulation materials, the density of CLT material and the concrete floating floors and the total density of floor structures seem to affect estimations the most. A comparison between wet and dry floor solution systems indicated the importance of the upper part of floors to estimate airborne and impact sound in low frequencies. Keywords: airborne sound, impact sound, insulation, prediction model, artificial neural networks

Prediction of Sound Insulation Using Artificial Neural Networks—Part I: Lightweight Wooden Floor Structures

The artificial neural networks approach is applied to estimate the acoustic performance for airborne and impact sound insulation curves of different lightweight wooden floors. The prediction model is developed based on 252 standardized laboratory measurement curves in one-third octave bands (50–5000 Hz). Physical and geometric characteristics of each floor structure (materials, thickness, density, dimensions, mass and more) are utilized as network parameters. The predictive capability is satisfactory, and the model can estimate airborne sound better than impact sound cases especially in the middle-frequency range (250–1000 Hz), while higher frequency bands often show high errors. The forecast of the weighted airborne sound reduction index Rw was calculated with a maximum error of 2 dB. However, the error increased up to 5 dB in the worse case prediction of the weighted normalized impact sound pressure level Ln,w. The model showed high variations near the fundamental and critical frequency areas which affect the accuracy. A feature attribution analysis explored the essential parameters on estimation of sound insulation. The thickness of the insulation materials, the density of cross-laminated timber slab and the concrete floating floors and the total density of floor structures seem to affect predictions the most. A comparison between wet and dry floor solution systems indicated the importance of the upper part of floors to estimate airborne and impact sound in low frequencies.

Impact sound pressure values - Field measurements for different configurations of concrete slabs on the ground

The presentation will summarize and discuss values of field measured normalized impact sound pressure level L'n,w measured sideways with different configurations of concrete slabs on ground within buildings. All results are adjusted to receiving room volume of 100 m3 and with thickness of concrete slab 80-100 mm. Measurement on continuous concrete slab on expanded polystyrene gives L'n,w between adjoining rooms of 74 dB. Different principles of splitting have been investigated to evaluate the effect on L'n,w. The configuration where only the concrete slab is split (and with a plastic film between the concrete base and the upper layer of expanded polystyrene), gives L'n,w of approximately 66 dB which is 8 dB lower than for a continuous bare concrete slab. When both the concrete slab and the upper layer of expanded polystyrene are split, measurements show L'n,w of 58-61 dB for the case of no flooring, which is 13-16 dB lower than for a continuous concrete slab (no split). When both concrete slab and all layers of polystyrene are split down to continuous foundation measurements show L'n,w of 55 dB. The situation with concrete slab and all layers of polystyrene split and with no foundation beneath gives L'n,w of 46 dB. Consequences for airborne sound and R'w will be discussed as well for the above mentioned configurations.

Application of Sound Insulation Technology in Floating Floor

In this paper, the sound insulation performance of the floating floor is studied from the perspective of its structural application. The field test shows that the sound insulation improvement value of the dry laying method is higher than that of the wet sticking method. At the same time, the influence of the construction technology of the floating floor on the load and net height of the building structure is summarized and compared. Finally, the weighted standardized impact sound pressure level of the field test is higher than the normalized impact sound pressure level measured in the laboratory This universal phenomenon is analyzed. This paper puts forward the construction technology of dry laying method of floating floor with sound insulation mat, which can provide reference for the construction of sound insulation mat laying on reinforced concrete floor and the design of building structure.

Advanced lightweight steel floor towards high sound insulation and fire resistance

Industrialized lightweight buildings have great advantages associated with lower indirect costs, minimum construction wastes and faster construction processes. However, their main weaknesses lie in their acoustic performance and fire resistance. This paper develops and assesses a novel lightweight steel floor with high fire resistance and high acoustic performance for buildings. Acoustic measurements through laboratory tests were carried out according to ISO 10140:2010 and ISO 717:2013. Fire resistance was tested according to EN 1365–2:2000. The results demonstrate that using an appropriate structural and resilient layer through an optimized design, insulating the floor surface from the surrounding structure, separating structural systems between layers, minimizing flanking transmissions through resilient strips and joint sealing between boards, a Weighted sound reduction index of Rw (C; Ctr) ≥ 65 (−6; −14) dB, and a Weighted normalized impact sound pressure level of Ln,w (CI) ≤ 49,9 (4) dB can be achieved, along with a fire resistance of REI45.

Comparative analysis of resilient and dense materials in lightweight construction for impact sound attenuation

Resilient underlayments are commonly utilized as a primary method of reducing footfall noise in architectural acoustics. Although resiliency is a large component of a partition’s footfall performance, as well its ability to achieve higher AIIC ratings through ASTM E1007 AIIC testing, adding resiliency alone does not always address all of the frequencies which cause disturbances due to footfall. Particularly in lightweight construction, the density of the configuration is also a critical component of a successful solution. Due to the lack of sufficient mass in lightweight construction materials, successful treatment for impact noise disturbances in lightweight conditions becomes more difficult to achieve. This paper compares data with different flooring configurations in mock-up ASTM AIIC testing conditions in order to evaluate advantages and disadvantages of ANISPL (Absorption Normalized Impact Sound Pressure Level) performance in different frequencies. Resiliency and density are added in varying combinations in a wood frame construction in order to better understand their relationship to AIIC ratings and a partition’s success in impact noise insulation.

Estimativa de incerteza em ensaios de ruído de impacto: posição dos equipamentos em medições em campo

A precisão metrológica em ensaios em campo de acústica de edifícios é uma questão atual, com necessidade ampla discussão sobre as variáveis envolvidas que podem gerar dúvidas nos resultados. Nesse contexto, este trabalho analisa as incertezas de medições de ruído de impacto em campo. O foco do trabalho é a análise da influência do posicionamento dos equipamentos. As medições foram realizadas conforme as normas ISO 140-7 e ISO 140-14 em duas salas sobrepostas, separadas por uma laje de concreto maciço de 10cm de espessura. Foram consideradas dois grupos de variações no posicionamento da máquina de impactos e do microfone: distâncias mínimas das paredes definidas nas normas ISO e pontos centralizados no piso. As variações no posicionamento dos equipamentos geraram 64 resultados de níveis sonoros na sala de recepção, divididos em quatro grupos de resultados, a partir das medições na faixa de frequência entre 100 e 3.150 Hz. Para as análises foram utilizados os métodos da norma ISO 12999-1 e do Guia RELACRE/Portugal que expressam de formas diferentes as incertezas de medições acústicas em edificações. Os resultados são apresentados na forma de exemplos de aplicação em sistemas pisos ensaiados anteriormente, com diferentes comportamentos acústicos e consequentemente, com valores distintos de níveis de ruído de impacto padronizados ponderados corrigidos pela incerteza estimada. Neste estudo foi evidenciada e quantificada a influência do posicionamento dos equipamentos nos resultados de ensaios de ruído de impacto em campo.

Measurements of structure-borne sound from building service equipment by a substitution method—Round robin comparisons

A pilot project has been performed with a round robin comparison (inter-laboratory test), where a modified heavy-duty washing machine has been circulated for tests among 6 laboratories. The main goal of this pilot project was to find out whether a simple substitution method could be applied to estimate the structure-borne sound pressure level of some typical building service equipments. First, the vibration levels of a heavy low mobility test floor are measured when a machine with high internal mobility operates on this floor. Then, the vibration levels are measured at the same positions on the same floor when a standardized tapping machine (ISO 140-7) operates in the same positions as the test machine. The differences between the vibration level are then calculated. The difference may be used to compare the performance of different machines at one site or to estimate the sound pressure level in other buildings with heavy floors. In its simplest form, this can be made in the same way as for floorings, i.e., first calculating the normalized impact sound pressure level (EN 12354-2) and then subtracting the vibration level difference of the actual machine compared to the tapping machine. It remains to apply this method in the field and to compare estimated sound pressure levels with measured.

Impact Sound Pressure Level Performances of Basic Beam Floor Structures

In order to obtain reliable estimations of the impact sound insulation between rooms, it is necessary to know the acoustic performance of each element composing the floors. The contribution of the flanking transmissions, the attenuation of floating floors and the weighted normalized impact sound pressure level of the basic structure need to be determined in order to apply the simplified calculation method according to the EN ISO 12354-2 standard. With the aim of verifying the range of validity of the calculation method proposed by the EN ISO 12354-2 standard for typical basic beam floor structures, a research based on on-site measurements was conducted. This paper provides an analysis in terms of spectrum trend, predicted average weighted normalized impact sound pressure level and reduction of impact sound pressure level obtainable with a generic floating floor typology. The study can represent a starting point for a correct estimation of the impact sound insulation in new buildings and renovation plans.

The prediction of the vibration reduction index Kij for brick and concrete rigid junctions

Abstract The vibration reduction index, K ij , is related to the transmission of the vibrational power over a junction between structural elements. Two empirical models are proposed to evaluate K ij , on the basis of statistical evaluations of numerous in-field tests carried out on rigid junctions between floors made by concrete beams and ribbed slab with brick blocks and brickwork walls, a type of junction that is frequently encountered in Southern European and Mediterranean buildings. These models can be applied in order to calculate the sound insulation properties, such as the normalized impact sound pressure level, L n ′ , and the apparent sound reduction index, R ′, of walls and floors in buildings. The first model allows the single number value of the vibration sound reduction index of a junction to be calculated, on the basis of the real properties of the materials that constitute the junction. A new quantity, the “essential” mass per unit area, was introduced to implement the model. The second model provides an estimation of the K ij as a function of frequency, subdivided between BB-junction, as ribbed slab with brick blocks floor–brick wall, and CB-junction, i.e. concrete beam–brick wall.

Room requirements for laboratory measurement of transmission loss and impact sound insulation.

Laboratory measurement of transmission loss (ASTM E90) and impact sound insulation (ASTM E492) have one thing in common: measurement of the sound power radiated into the receive room by the specimen under test. In E90 the reported quantity, transmission loss (TL), is the difference between the incident and transmitted sound power, whereas for E492 the reported quantity, normalized impact sound pressure level (NISPL), is a direct measure of the radiated sound power of the floor. A derivation of the TL and NISPL equations using a statistical energy analysis (SEA) framework shows that the ASTM equations are based on the assumption of power balance and statistical sampling of the sound field. This SEA framework is used to define the acoustical conditions of the receive room (number of modes in each frequency band, the average loss factor in each band, and hence the modal overlap factor), which are then related to the physical properties such as room shape, volume, absorption, etc. The conditions necessary for...

Effect of the frequency spectrum trend on the determination of the weighted normalized impact sound pressure level for floor structures

The most common floor constructions in Italian buildings are composed of two parts: the structural one, made of concrete beams and perforated bricks, and the floating floor. The results of the in situ measurements of the impact sound pressure level, realized on the structural part of the floors, show a frequency spectrum trend that increases with the frequency. The spectrum is also characterized by many peaks and dips at the high frequency range that strongly influence the determination of the weighted normalized impact sound pressure level, also for structures with similar mass and geometry. The frequency trend of the beam and brick structures is completely different from the characteristic spectrum of homogeneous concrete slabs or lightweight structures. Considerations on how those differences can influence the obtainable results in terms of the reduction of impact sound pressure level referred to the same floating floor typology, the spectrum adaptation terms and the other acoustic quantities described...

Prediction of the impact sound transmission from lightweight stairs in buildings based on a simplified laboratory characterisation

Based on a simplified laboratory characterisation of lightweight stairs the normalized impact sound pressure level in buildings can be predicted using parts of EN 12354. For the characterisation an approach is followed where the stair is treated as an active component with respect to an external excitation (e.g. by the tapping machine). The laboratory characterisation was performed for a timber stair and the normalized impact sound pressure level was predicted for different building situations. The various transmission paths via the separating and flanking walls were investigated and compared to the prediction according to EN 12354. Within the presentation the proceeding will be outlined and the restrictions are discussed. By comparison of measured and calculated values some references for the accuracy of the method are obtained.

Vibration reduction of thermal break balcony connections

In energy efficient buildings concrete balconies have to be thermally insulated from the concrete floor to reduce heat loss and to increase surface temperature. This thermal break is obtained by polystyrene in combination with high-strength concrete thrust-force bearings and an arrangement of stainless steel straight and bent bars to act as tension and shear reinforcement. The acoustic performance of such thermal break units was investigated under laboratory conditions. Therefore the vibration level difference at different junctions between balcony and the thermal isolated concrete floor as well as the normalized impact sound pressure level of the floor when the balcony is excited with the standard tapping machine are measured. The influence of the number of tension and shear steel bars and the type of thermal insulating material was studied on typical sized balconies connected to small test floors. The vibration isolation at low frequencies was determined using modal testing.

Technical Note: Controlling the Impact Sound Insulation of Concrete Slab Floors

This paper investigates the impact sound attenuation of a concrete slab floor with different covering as topping layers. The basic covering is an extruded polystyrene foam board, reinforced with fiberglass mat and painted with special cementatious mortar. The concrete slab floor was tested with extruded polystyrene foam board of different thicknesses, foam board with thin rubber surfaces, and foam board with a thin rubber layer adhered to ceramic or vinyl tiles. Also, multi layers of extruded polystyrene foam board have been tested as a topping to the tested floor. The weighted normalized impact sound pressure level and weighted reduction of impact sound pressure level have been determined and used for comparison between the tested samples.