Measurements of acoustical parameters in the ancient open-air theatre of Tyndaris (Sicily, Italy)

The emerging field of archaeoacoustics is attracting increasing research attention from scholars of different disciplines: the investigation of the acoustic features of ancient open-air theatres is possibly one of its main themes. In this paper, the outcomes of a measurement campaign of acoustical parameters in accordance with ISO 3382-1 in the ancient theatre of Tyndaris (Sicily) are presented and compared with datasets from other sites. Two sound sources were used (firecrackers and dodecahedron) and their differences were analysed. A very good reproducibility has been shown between the two measurement chains, with differences on average of 0.01 s for reverberation time T20, and less than 0.3 dB for Clarity C50 and C80 and for sound strength. In general, results show that the reverberation time and strength of sound values are relatively low when compared with other theatres because of the lack of the original architectural element of the scaenae frons. When combining this effect with the obvious condition of an unroofed space, issues emerge in terms of applicability of the protocols recommended in the ISO standard. This raises the question of whether different room acoustics parameters should be used to characterise open-air ancient theatres

Influence of scattering coefficient on the prediction of room acoustic parameters in a virtual concert hall.

The scattering coefficient is one of the most important input parameters in room acoustics simulations. Together with absorption coefficient they belong to main descriptors of interior surface properties in the calculation process based on ray or radiosity method algorithms. This paper investigates the influence of scattered sound on the objective room acoustical parameters in the example of a virtual concert hall. Six different alternatives were simulated, where scattering coefficients s = 10, 30, 50, 60, 70 and 90 % respectively, were applied to the interior surfaces of the ceiling, side and rear walls. Analysis has been performed by studying the results of objective room acoustical parameters predicted by simulations done in the software Catt-Acoustic®

Super adsorbent bio-polymer additive to improve hygroscopic and acoustic properties of a conventional lime plaster

The paper introduces a new lime plaster composition, with a Super Bio-Polymeric Adsorbent (SABP), for interior applications to improve hygrothermal and acoustic comfort. Alginate SABP is added to a conventional lime plaster to improve hygroscopic and acoustic performance. The hygrothermal and acoustic properties of the modified plaster are compared with the ones of the original plaster with a preliminary moisture uptake test, the evaluation of the sorption isotherm, the moisture buffering value (MBV), and the acoustic absorption. The results show a significant increase in the equilibrium moisture contents and the MBV (from 0.7 to 6.2 g/(m2 ...%RH)). At the same time, the sound absorption coefficient is slightly improved, increasing 0.1-0.2 at frequencies higher than 500 Hz compared to the reference conventional lime plaster. The paper describes the material characterization: the sorption isotherm and the MBV are obtained using a dynamic vapor sorption (DVS) analyzer. The acoustic absorption is measured using the impedance tube method

Modelling mean radiant temperature in outdoor environments: Contrasting the approaches of different simulation tools

Global warming and increasing urbanization are expected to threaten public health in cities, by increasing the heat stress perceived by the inhabitants. Outdoor thermal comfort conditions are influenced by the material and the geometric features of the surrounding urban fabric at both the urban and building scales. In built environments, performance-aware design choices related to street paving or building façade can enhance outdoor thermal comfort in their surroundings. Reliable estimations of outdoor thermal comfort conditions are required to evaluate and control the micro-bioclimatic influences of different design choices. The mean radiant temperature is the physical variable that has the greatest influence on outdoor thermal comfort conditions during summertime. Since its calculation is complex, the available simulation tools employ different approaches and assumptions to estimate it, and potential users need to be aware of their capabilities and simplifications. This research compares the calculation procedures and assumptions of different performance simulation tools (i.e. ENVI-met, TRNSYS, Ladybug/Honeybee, CitySim, and SOLENE-microclimat) to predict the mean radiant temperature in outdoor spaces, based on the available information in the scientific literature. Their ability to account for different radiative components in both the longwave and shortwave spectra is summarized, and practical information regarding the degree of interoperability with the modelling environments and the level of geometrical detail of the virtual model supported by the tools is provided. This work aims to help potential users in the selection of the most appropriate performance tool, based on the requirement of their projects

Development of advanced multifunctional façade systems: Thermo-acoustic modelling and performance

The development of lightweight a nd multifunctional curta in wa ll systems, which integra te different technological solutions, is a imed at a chieving increa singly higher requirements rela ted to energy efficiency a s well a s indoor environmental quality in nonresidentia l buildings. On one ha nd lightweight a nd thin fa çade elements present several a dvantages (such a s construction time, space, a nd transportation savings, less weight on primary structure etc.), while fa cing the cha llenge of gua ranteeing the required thermal a nd a coustic performance and achieving legisla tive compliance on the other. In the framework of the Horizon 2020 Project Powerskin+ a new concept of multifunctional fa çade, which combines high performance insulation, energy harvesting, heating system, a nd la tent heat storage capabilities is under development. Within the design process of the different sub -modules (opaque and tra nsparent), performance calculations a re carried out by means of existing simulation tools, or a d-hoc developed models for more complex systems. In this study, the authors present the main steps required to a ccelerate the simula tion-based design process a nd the future thermal and a coustic optimization of the novel lightweight a nd multifunctional façade element

The Effect of Soundscapes and Lightscapes on the Perception of Safety and Social Presence Analyzed in a Laboratory Experiment

The present study evaluates the effect of soundscape and lightscape variations on the perceived safety and perceived social presence in a pedestrian area through laboratory experiments. Thirty-one participants were presented with nine different virtual scenarios, in which the same underpass was reproduced under different soundscape and lightscape conditions. The participants were asked to assess each scenario considering 10 items related to perceived safety and perceived social presence. A principal component analysis allowed the 10 items to be reduced to two principal components, namely “perceived safety” and “perceived social presence”. A two-way repeated measures ANOVA analysis was conducted to assess the effect of modifications of both the soundscape and lightscape on the two components. The obtained results showed that the soundscape had an effect on both the perceived safety (p < 0.05) and perceived social presence (p < 0.05), while the lightscape variations implemented in this experiment only had a statistically significant effect on the latter (p < 0.05). The results of such studies may be of interest for public design and management as they may be conducted by means of non-intrusive and cost-effective techniques

Ergun-Wu equation: a novel approach for the determination of physical parameters in low/medium porosity materials

The experimental determination of effective porosity and tortuosity in medium/ low porosity materials (typically ≤0.5) is still a challenge debated in metrology. In this paper is proposed a semi-empirical approach to the problem, based on the implementation of a new resistive model and accurate experimental input data. The empirical model is based on the recent redefinition of Ergun's equation (Wu et al., 2008) and on the geometric model for tortuosity (Yu et al., 2000). On the basis of measured quantities, such as the airflow resistivity and the average pore diameter, it is possible to determine the average effective porosity and the average tortuosity of the material in a defined range with a proper confidence level. In this work is also addressed the problem of a suitable determination of the average pore diameter and a definition of an average equivalent pore diameter in fibrous materials is also propose

Ergun-Wu equation: a novel approach for the determination of physical parameters in low/medium porosity materials.

The experimental determination of effective porosity and tortuosity in medium/ low porosity materials (typically ≤0.5) is still a challenge debated in metrology. In this paper is proposed a semi-empirical approach to the problem, based on the implementation of a new resistive model and accurate experimental input data. The empirical model is based on the recent redefinition of Ergun’s equation (Wu et al., 2008) and on the geometric model for tortuosity (Yu et al., 2000). On the basis of measured quantities, such as the airflow resistivity and the average pore diameter, it is possible to determine the average effective porosity and the average tortuosity of the material in a defined range with a proper confidence level. In this work is also addressed the problem of a suitable determination of the average pore diameter and a definition of an average equivalent pore diameter in fibrous materials is also proposed

Ergun-Wu equation: a novel approach for the determination of physical parameters in low/medium porosity materials.

The experimental determination of effective porosity and tortuosity in medium/ low porosity materials (typically ≤0.5) is still a challenge debated in metrology. In this paper is proposed a semi-empirical approach to the problem, based on the implementation of a new resistive model and accurate experimental input data. The empirical model is based on the recent redefinition of Ergun’s equation (Wu et al., 2008) and on the geometric model for tortuosity (Yu et al., 2000). On the basis of measured quantities, such as the airflow resistivity and the average pore diameter, it is possible to determine the average effective porosity and the average tortuosity of the material in a defined range with a proper confidence level. In this work is also addressed the problem of a suitable determination of the average pore diameter and a definition of an average equivalent pore diameter in fibrous materials is also proposed

Effective scale of microstructure of fibrous permeable materials

Microstructure properties of fibrous permeable materials, such as effective porosity, pore size and tortuosity, and related transport phenomena, is of great importance to many practical and industrial application, as well as in several manufacturing process-es. Several resistance models, based on Darcy’s law and Forchheimer’s equation, were derived through the last decades to predict the behavior of fluid flow and permeability in fibrous materials. In existing resistance models the effective scale of microstructure (also called specific surface area or pore size), is assumed as the hydraulic diameter of the capillary in Hagen-Poiseuille law, from Carman geometrical model. Nevertheless, the disordered nature of fibre arrangement suggests the existence of different relation-ships, linked to the transport phenomena within the fibre network. In this work a new approach is proposed in order to evaluate the effective scale of microstructure (in terms of pore size) of fibrous permeable materials