A comparative study on the performance of PLA and PET acoustic perforated panels

Abstract

The growing demand for high-performance low-frequency sound absorbers in architectural acoustics requires sustainable alternatives to conventional sound absorbing materials. The present study investigates the acoustic performance of Micro-Perforated Panels (MPP) made from organic and inorganic 3D printed thermoplastics utilizing Fused Deposition Modelling (FDM). Following this gap in the literature, the research compares biodegradable polylactic acid (PLA) based (MPP1) and recycled polyethylene terephthalate (PET) based (MPP2) MPPs as sustainable alternatives to classroom settings. To compare with conventional materials from previous literature, inhomogeneous MPP configurations were manufactured for each material type. Their sound absorption coefficients (α) were tested with ISO 10534-2:2023 using an impedance tube and were evaluated in a classroom simulation based on ODEON Room Acoustics Software Version 18.0 to assess their impact on reducing Reverberation Time (RT30) and increasing Speech Transmission Index (STI) scores. The results indicated that both materials demonstrated similar α values in mid to higher frequencies, while MPP2 performed better in lower frequencies. Subsequently, the measured and simulated measurements of RT30 in the classroom in Bilkent University showed that the room is acoustically undertreated. The introduced materials in the simulation indicated that treatment with MPP1 reduced RT30 from 1.25s average to 1s, and treatment with MPP2 reduced RT30 to 0.85s. The STI results increased from 0.51 to 0.6, improving from “fair” to “good” speech intelligibility scores. Overall, the findings highlighted the potential of recycled and biodegradable MPPs to serve as a viable alternative to sustainable sound-absorbing materials in university classroom settings. For future studies, recycled sound absorbers could replace conventional sound absorbers in architectural acoustics.