Sustainable Sound Absorbers to Improve Acoustical Comfort in Atria: A Methodological Approach

Resource-efficient buildings are one of the most important challenges of the construction industry, which could be achieved by limiting the extraction of natural resources and by replacing them with industrial residues. The present work proposes innovative panels made from textile wastes as an efficient solution for making the semi-open atrium in the Polytechnic University of Bari, acoustically suitable for use as an area of study. Several measurements were carried out in the atrium under empty and occupied conditions in order to characterize the sound field of the space (i.e., the reverberation time and the sound pressure level) and the actual sound sources (i.e., the sound power level of the students occupying the space). The on-site measurement results were useful to calibrate a geometrical acoustic model implemented in CATT-Acoustic software and used to predict the effect of the proposed treatments. About 700 m(2) of absorbent panels were distributed, leading to a predicted reduction in the reverberation time from 2.4 s to 1.4 s at 500 Hz, and consequently to an estimated 3 dB reduction in sound pressure level, resulting in a reduction in the background noise level due to speech. Furthermore, as a consequence of the "Lombard effect", a decrease in the background noise level will likely reduce the sound power level of the speakers by 2 dB, with an expected overall reduction of 5 dB.