15 research outputs found
OPTISOUNDWOOD: UN PROGETTO MULTIDISCIPLINARE PER LO SVILUPPO DI MANUFATTI A BASE DI LEGNO INNOVATIVI
Progressive Impedance Method for the classical analysis of of acoustic transmission loss in multilayered walls.
Sound transmission through hollow brick walls
Hollow bricks and blocks are one of the most common forms of material used for wall construction found in Central and Southern Europe. The principle purpose of the perforations (holes) is to increase the thermal insulation properties. As a result of these perforations the block gross density is reduced significantly and these block walls have high anisotropy. Consequently, the acoustical insulation properties are influenced detrimentally in comparison to solid blocks. Due to the large thickness of some of these types of hollow block thick wall effects can occur such as bending shear waves and thickness resonances. These further reduce the sound insulation at high frequencies. This paper describes the characteristic features of sound transmission through hollow walls. For this study several different types of wall were built of varying thickness and materials and the sound reduction index was recorded. The effects of additional plaster layers is also discussed. It is suggested that the material properties of the block's complex web structure may strongly influence the sound reduction index at the low and high frequencies
La statistical energy analysis come strumento progettuale aplicato all'acustica edilizia (Statistical Energy Analysis as a prediction design tool in building accoustics).
La statistical energy analysis come strumento progettuale aplicato all'acustica edilizia (Statistical Energy Analysis as a prediction design tool in building accoustics).
Metodo delle impedenze progressive nello studio classico dell'isolamento acustico di pareti multistrato
Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal
SOUND ABSORBING SYSTEMS MADE OF WOOD CROSS SECTIONS PAIRED WITH VOID CAVITIES - A FIRST INVESTIGATION
This study investigates the possibility of exploiting the porous structure of wood for absorbing sound. With this aim, the following system is proposed: 1) the cross section of wood should be exposed to sound waves so that these can activate the vibration of air inside the wood pores; 2) the cross section should be cut to have small thickness to realize a thorough open cell absorber; 3) a void cavity should be left on the back to activate the absorption effect. This setup has been conceived to absorb sound by Helmoltz resonance. To preliminary assess the effectiveness of the system, cross sections of poplar wood were cut 1 mm thick and paired with rear void cavities 15, 30 and 50 mm thick. The normal sound absorption coefficient α was determined through the impedance tube method. Multiple absorption peaks and several α values higher than 0.6-0.7 (αmax=0.99) were measured in the medium-low frequency range. Building on these results, further studies are envisaged to model the acoustic behavior of the system and to set the technical aspects relevant to its feasibility in practice