Caracterização do condicionamento acústico de uma sala de aula com o uso de painéis de madeira

Abstract

In indoor environments designed for silence and intellectual activities, the concern about the different acoustical parameters of these spaces is a fundamental topic, which are related to different aspects of the built environment, such as geometry and surface finishes. A built environment might be acoustically treated in different ways in terms of complexity and cost. The insertion of absorbent materials or diffusers is and example of an acoustic solution for that environment. In this context, this research proposes an alternative for the acoustical treatment of a classroom already built through the insertion of wooden composites, panels, which were screwed to the walls. This proposition sought to demonstrate an alternative that was easy in terms of implementation and feasible from the perspective of sustainability. Industrialized wood composites from the south part of Brazil were chosen, sush as the MDF (Medium Density Fiberboard), the OSB (Oriented Strand Board) and the WWCB (Wood-Wool Cement Board) with different thicknesses. The materials were analyzed and characterized through the sound absorption coefficient. In addition, a building material application for OSB and WWCB panels was proposed as an internal coating system of a masonry built with construction and demolition waste (CDW) inside of a reverberating chamber, where the increase in sound insulation provided to the masonry was evaluated. In the already treated classroom, objective acoustic parameters were evaluated, such as the reverberation time, the Definition (D50) and the Speech Transmission Index (STI). In order to complement the analysis, subjective tests were carried out with a sample of men and women to determine the Speech Recognition Percentage Index (SRPI) applied to the classroom environment. Three-dimensional models were built and validated with measurements using an open source software (I-SIMPA), where acoustic simulations showed different schemes of acoustic conditioning along with their objective acoustic parameters. For the sound insulation evaluation, the thesis concluded that the OSB panels might increase up to 4dB the weighted sound reduction index (Rw) of a masonry with CDW blocks. WWCB-type panels increased the STI values at different seats over the classroom. The scenario with the 50.0mm thick panels showed itself as statistically different from the others. Analysis of the sound pressure levels in the classroom environment led to the conclusion that there was no excessive absorption of high-frequency energy, which occurs with many conventional and non-sustainable absorbers, and the subjective tests proved that the WWCB type (50.0 mm thick) improved the speech intelligibility.