From modern buildings to public spaces are made of concrete, steel, and glass. These materials increase propagation of sound and the reverberation time. Therefore, furniture should be good sound absorbers in such places. The objective of this study was to ascertain acoustic properties of wood-based materials by determining normal acoustic impedance on the surface and sound absorption coefficients. Experiments were carried out on 17 types of wood-based materials commonly employed in furniture design and manufacture. Investigations were conducted based on the transfer-function method. It was demonstrated that for frequencies between 125 and 500 Hz, the highest capability of sound absorption was determined of low surface layer density and high porosity. Honeycomb panels with paper core absorbed better sounds in the range between 1 and 2 kHz. Panels of considerable external surface irregularities were characterized by the most favorable acoustic properties for the frequency of 4 kHz.

ATHENA is the L2 mission selected by ESA to pursue the science theme “Hot and Energetic Universe” (launch scheduled in 2028). One of the key instruments of ATHENA is the Wide Field Imager (WFI) which will provide imaging in the 0.1-15 keV band over a 40’x40’ large field of view, together with spectrally and time-resolved photon counting. The WFI camera, based on arrays of DEPFET active pixel sensors, is also sensitive to UV/Vis photons. Optically generated electron-hole pairs may degrade the spectral resolution as well as change the energy scale by introducing a signal offset. For this reason, the use of an X-ray transparent optical blocking filter is needed to allow the observation of all type of X-ray sources that present a UV/Visible bright counterpart. In this paper, we describe the main activities that we are carrying on for the conceptual design of the optical blocking filter, that will be mounted on the filter wheel, in order to satisfy the scientific requirements on optical load from bright UV/Vis astrophysical source, to maximize the X-ray transmission, and to withstand the severe acoustic and vibration loads foreseen during launch.

Contiones – assemblies during which important Roman politicians discussed the laws proposed at the People’s Assemblies as well as candidates for the offices and presented their opinions to the Roman people – are considered by some scholars as one of the central institutions and rituals of the Roman Republic. Considering the role contiones played in the political life of the Roman Republic, we can ask how many Romans participated in them. In our paper we present results of acoustic analyses of two places at the Forum Romanum that we know were platforms for speakers at contiones: the Rostra and the podium of the Temple of Castores. The main goal of our study was to establish the maximum number of participants that could have heard speeches inteligibly. To do that we used a 3D model of Forum Romanum considering not only the geometry but also the acoustic parameters of materials used to construct the rostra and adjacent constructions. Based on the sound power level of a speaker and possible noise sources, on which the recipients were exposed to, we established areas where speeches could have been heard and understood. This in turn allowed us to estimate the maximum number of recipients.