“…As a technical solution to reduce the noise generated by clean agent discharge, silent nozzles-often also referred to as acoustic nozzles-have been developed. Since modifying the nozzle outlet does not appear to fully address the challenge, given that SPL was proven to be largely independent of nozzle shape [7], adding sound absorptive layers to the nozzle outer surface has become the most employed approach [3,12,13], with the insertion of horizontal plates also being recommended to make the released flow rate and pressure as balanced as possible in multiorifice nozzles [12,14]. Currently, the open literature presents relatively few studies that focus on the design of such nozzles and on assessing their acoustic performance, especially when compared with that exhibited by standard nozzles under the same discharge conditions.…”