Análise da absorção sonora de painéis e baffles a base de resíduos de politereftalato de etileno (PET)

Abstract

In most buildings, used for varied purposes, the quality and acoustic performance tend to be neglected, reaching in incompatible levels of comfort for users, where, many times, corrections can often become costly and unfeasible. In this way, the acoustic treatment of rooms aims to control the sound behavior in enclosed environments to comply with the defined requirements by the use of each space. The path travelled by the sound waves from the source to the receiver modifies the original characteristics of the emitted sound mainly by the geometry, materials, elements and objects that compose the room. For rooms where their original composition does not provide adequate comfort, materials with sound absorption capability can be added, reducing the sound energy reflected to the sound field. Within the field of materials with sound absorption capacity are the fibrous materials, which can be made of PET synthetic wools, that is a highly used material, non-renewable and with a huge recycling potential. These wools can be mounted in the form of panels, baffles or pads, where the mounting type, in relation to the reflective surface, has a great impact on their sound absorption spectrum. Therefore, this work aims to verify the influence of the density and mounting type of PET based wools used in the form of panels and baffles in their sound absorption capacity. For this, sound absorption tests were performed in a reverberation room (ISO 354:2003) using PET wool samples as panels, with and without airgaps of 5 and 10 cm, and baffles, with a height of 50 cm and mounted with 25, 50, 75 and 100 cm of spacing between rows. When installed as panels, the higher the density of the wools the greatest was the sound absorption coefficients, and the increase of the airgap resulted in higher sound absorption capacity in the low frequency range with smaller results in the mid and high frequency range. And for the baffles, the greatest wool densities also resulted in the highest results. Besides that, an increase in the sound absorption coefficients was evidenced, in practically all the frequency bands analyzed, when the distance between the rows of baffles was increased.