Acoustic treatments with innovative panels produced from olive oil wastes

In the Mediterranean region, placing olive tree is a common practice. Historically, these trees were cultivated along the coasts of Magna Graecia, and today the European community is the largest global producer of olive oil. Spain accounts for 42% of production, followed by Italy with 17% and Greece with 11%. Olive oil has been traditionally extracted for food, cosmetics, medicine, and, in ancient times, also for lighting. One significant by-product of olive cultivation is the waste generated from cut tree trunks and foliage. This study aims to describe the possibility of utilizing these waste materials for sound absorption applications. The proposed system for the acoustic absorption involves triturating small trunks into particles ranging from 1.5 mm to 4 mm. The absorption coefficients were measured for samples with varying thicknesses, providing insights into the potential of these materials for sound absorption. This approach highlights a sustainable pathway for repurposing agricultural waste. Moving from the Delany-Bazley model, this study compares the impedance tube results with the theoretically predicted ones. Finally, using a least-square fit procedure based on the Nelder-Mead method, the coefficients that best predict both the acoustic impedance and the propagation constant laws are reported.