Patrizio Fausti

An Intercomparison of Laboratory Measurements of Airborne Sound Insulation of Lightweight Plasterboard Walls

This paper describes the results of the European Inter-Laboratory Test (ILT) program, conducted for the determination of repeatability and reproducibility values for the laboratory measurements of airborne sound insulation of walls. A total of 24 laboratories took part in this ILT, 21 belonging to the European Community. Two test structures were constructed; a double lightweight wall and a single lightweight wall, both built of plasterboard. The sound reduction index values were measured. The main result of the ILT was the significant difference obtained for the reproducibility value, R, for the double lightweight wall with values up to 12 dB at middle-high-frequencies. On the contrary, the reproducibility value for the single wall was very similar to the tentative values indicated in Annex A of ISO 140–2. Good agreement between laboratories was found for both structures in the computed repeatability values, r.

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.

An Investigation into the Reproducibility Values of the European Inter-Laboratory Test for Lightweight Walls.

In an inter-laboratory test programme (ILT) for the measurement of airborne sound insulation of lightweight walls, reproducibility values of up to 12dB were obtained from the sound reduction index measured in 21 participating laboratories. These high reproducibility values were for a test structure composed of lightweight plasterboard panels, forming a double wall, mounted on separate metal ‘C’ channels. This paper presents possible reasons for the large reproducibility values for the double wall using experimental investigations and theoretical models using Statistical Energy Analysis (SEA). Whilst the sound reduction index(SRI) does take into account the different test wall areas and reverberation times of the respective laboratories involved, some factors which may influence the measured SRI values are not. It is suggested that the principle factor which may have effected the SRI values of this test programme for the double wall was the lining material of the test aperture in the various laboratories which can provide a flanking transmission path between both sides of the double wall. Other factors are discussed which may also play a contributory role in causing differences in the measured SRI values such as sill/reveal size, aspect ratio, panel-channel connections and workmanship.

Thermal and acoustic performance expectations on timber buildings

In recent years, building technologies have been developed in order to improve comfort and energy saving. European institutions and single countries firmly invite individuals to choose high energy-saving strategies in order to decrease carbon emissions and energy consumption. Examples could be found in thermal insulators added to façades and improvement of glazing performance. At present, two technologies are the most used in construction realization: traditional (concrete, masonry or in general heavyweight structure) or wood (timber, crosslam or in general timber lightweight structure). Designers, scientists and builders have their own opinions on these two topics, but good insulation performance are achievable with both of them. Nevertheless, for lay people as well as for designers, wooden structures seem more comfortable, reliable and insulated. Therefore, an international survey was realized in order to investigate what individuals expect from these two different construction technologies in terms of insulation performance. Results indicate that timber buildings stereotypes are confirmed for acoustic and thermal insulation and show how scientific communication may help to deal with new or untraditional constructions.

Acoustics of opera houses: A cultural heritage

An important part of contemporary Italian musical culture has developed inside historical opera houses. An outstanding opera repertory was especially conceived to match these places, both from the architectural and the acoustical points of view. But, while extensive attention is devoted to architectural and historical aspects, the acoustical characteristics of an opera house, that is, the set of listening attributes which make such a place unique among all spaces for music, are still nowadays hardly recognized as being paramount. In fact they can be rightly considered a relevant cultural heritage in Italy and can thus be called acoustical heritage. This new kind of heritage calls for accurate study and attention, both from the scientific and social points of view. To preserve the heritage for future generations, it is necessary to know it precisely and to elaborate means of accurate description. A project with the participation of international specialists has been established to agree on a standardized p...

Sound Transmission between Rooms with Curtain Wall Façades: A Case Study

Curtain walls have reached good performances in terms of façade sound and thermal insulation, as well as solar protection. Nevertheless, the sound insulation performance of the partition between adjoining rooms with continuous curtain wall façades is often reduced by the presence of direct and flanking transmission through the junction with the façade itself. In this work, flanking and direct structural transmissions are analysed with reference to the joints of the mullion of the curtain wall with lightweight plasterboard partitions. Airborne sound insulation and vibration measurements were made in two adjacent rooms affected by the acoustic problems determined by the curtain wall joint. Traditional acoustic measurements, carried out according to EN ISO 16283–1, highlighted problems in sound insulation between rooms, but without any indication on different sound transmission paths through the wall. Vibration measurements were made for every part of the system (frame columns and beams, window panes, plasterboard wall, plasterboard false ceiling, etc.) to better understand the sound transmission paths in these kinds of structures. In this paper the results of this analysis are presented. Moreover, taking into account previous works and measurements made in this research field, different solutions for curtain wall structures are analysed and technical suggestions are given to improve airborne sound insulation between rooms separated by partitions mounted up to metal frames.

Predicting sound radiation efficiency and sound transmission loss of orthotropic cross-laminated timber panels

In the last decades, new materials and new technologies which satisfy sustainability and energy efficiency demands have been developed for the building construction market. Lightweight structures are becoming increasingly popular, but it has been shown that they cannot provide satisfactory sound insulation to meet the regulation requirements. Therefore a proper acoustic treatment needs to be specifically designed, considering both airborne and structure-borne sound sources. Cross-laminated timber (CLT) elements, for example, have had great success in the last twenty years, both in Europe and North America. CLT plates, due to their peculiar sub-structure, very often exhibit an orthotropic behavior: they have different stiffness properties along their two principle directions. In this paper two prediction models to evaluate the radiation efficiency, due to mechanical excitation, and the sound transmission loss of an orthotropic CLT plate are presented. The main purpose of these simplified models is to provi...

Predicting sound radiation and sound transmission in orthotropic cross-laminated timber panels

In the last decades, new materials and new technologies which satisfy sustainability and energy efficiency demands have been developed for the building construction market. Lightweight structures are becoming increasingly popular, but it has been proved that they cannot provide satisfactory sound insulation. Therefore a proper acoustic treatment needs to be specifically designed, considering both airborne and structure-borne sound sources. Cross-laminated timber (CLT) elements, for example, have had great success in the last twenty years, both in Europe and North America. CLT plates, due to their peculiar sub-structure, exhibit an orthotropic behavior; they have different stiffness properties along their two principle directions. This paper investigates prediction models for orthotropic plates designed to evaluate sound radiation due to mechanical excitation, and sound transmission due to acoustic excitation. Particular attention is paid to the influence on sound radiation of non-resonant vibration, or ne...

Noise generated from large construction sites: Measurements and possible mitigations

In this study, the issue of noise arising from the activities of large construction sites is analysed. The problem is particularly significant when the sites are close to protected natural areas or to residential areas and also when the duration of the construction works is very large. The case of the construction of a mobile barrier system, known as the MoSE, for the safeguard of the city of Venice from intruding tidal waters, is here reported. Since the early beginning of the construction activities, in April 2005, noise emission monitoring was conducted in order to evaluate possible effects on the presence of bird communities in the surrounding areas and also to evaluate the noise disturbance in some of the residential buildings close to the sites. During the monitoring activity, it was possible to measure the noise levels, the noise spectra and spectrograms in real-time and occasionally even the audio signal for particular activities was recorded. The analysis of data collected in different periods de...

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...