ATTENUATION OF NOISE IN THE CABIN OF A REGIONAL AIRCRAFT BY METAMATERIAL TRIM PANELS

Interior noise has always been an issue for aircraft manufacturers, even if only recently has it received equal importance to other design requirements. Passengers are increasingly concerned about cabin comfort, which they consider high priority for medium and long flights. In order to reach the challenging interior noise target set for the new generation small aircraft 80 OASPL dB, 70 dBA, 56 dBSIL3, a noise reduction plan must address and accurately identify noise sources. The main goal of this work is to evaluate acoustic comfort, by analysing sound pressure levels, in the cabin of a regional turboprop subjected to multiple broadband noise components, that simulates the noise generated inside the aircraft with monopolar sources. Sandwiches with metamaterial core are employed as trim panels of the cabin for improving sound absorption through the fuselage and the averaged interior noise level at seated person ear height is numerically evaluated with the Finite Element commercial software, Actran®. In particular, this work aims to show the higher acoustic performances of innovative passive Noise & Vibration technologies, such as acoustic metamaterials, with respect to classical soundproofing solutions.