Acoustic characterisation of hosiery factory waste materials

Hosiery factory by-products quite often cannot be recovered and are considered waste materials. Such elements are in the form of fabric, wool having different densities or pellets. This research aims to characterise these materials from an acoustic point of view, determining their sound absorption and their sound transmission loss, for possible applications as noise control material. The measurements were performed using a four-microphone impedance tube. Three different samples were tested in the form of pellets, yarn wool, and stockings waste. It was found the yarn-like samples have fair sound absorption performances, especially in the medium-high frequency range, while no sample of the tested thickness turned out to be suitable for real sound insulation applications due to the low density of the material.