Development of an Empirical Model as a Prediction Tool for the Sound Absorption Performance of Wool/Soy Protein Biocomposites

Finding eco-friendly alternatives to the synthetic materials used for acoustic application in building industry is necessary to address environmental sustainability. Biocomposites of natural fibers combined with a biopolymer matrix emerge as a promising approach. In this study, soy protein biocomposites were prepared with 10, 15, and 20 wt% sheep wool and were added spent coffee grounds by freeze-drying to create fibro-porous biocomposites for acoustic applications. Transmission loss (TL) measurements underlined good behavior as sound insulators, with maximum values around 22 dB at 2500 Hz and even better performance than those of commercial synthetic solutions. The obtained sound absorption coefficients were competitive, as they almost reached unity at medium and high frequencies. Airflow resistivity was determined, and values were higher for the biocomposites with coffee grounds, specifically 14–18 kPa·s·m−2 vs. 5.62–11.6 kPa·s·m−2. Using the input of the measured airflow resistivity, an empirical model using a genetic algorithm was developed as a prediction tool for the sound absorption performance of the samples. All in all, results showcase the feasibility of employing the studied biocomposites as competitive sound insulators and absorbers in building construction industry.