Acoustic wave propagation through eco-friendly porous panels at normal incidence

Human and non-human subjects are exposed to micro plastics through drink, food, and air. Micro-plastics propagating through atmosphere are breathable particles during inhalation and exhalation leading to deposition of them in the deep lung via the alveoli of the lungs. Teabags are made of plastics that are not recyclable and biodegradable. Therefore, we intend to remove used teabags from the natural environment by repurposing them to make sound attenuating panels for building and architectural industries, contributing in this way to a sustainable circular economy. The panels were designed and developed from consumed teabags as porous material by filling a frame to investigate acoustics wave propagation through them at normal incidence. Experimental testing was carried out on circular teabag panels in an impedance tube using a transfer function method to determine their sound absorption coefficient and transmission loss. Furthermore, the impedance gun method was used to determine the absorption properties of square panels. Results show that 75 mm thick circular panels give an absorption coefficient higher than 0.8 between 400 and 1600 Hz. Up-to 9.8 dB sound transmission loss of circular panels is obtained at higher frequencies. Absorption coefficients for square teabag panels are very good despite a coincidence-dip seen at 800 Hz. The satisfactory sound absorption and sound transmission characteristics of acoustic panels made of consumed tea bags can make this recycled material a cost-effective solution in the production of sustainable acoustic treatment in indoor spaces. The results suggest that recycling of consumed teabag as the panel could be applied as alternative sound absorbing materials.