Abstract: Noise reduction in face masks and helmets reduces ear damage and improves communication by reducing noise in demand regulators with air diffuser perforated plates, screens or open cell foam and by providing muffling chambers. Insertable earmuffs are slid into voids formed in interior padding. Oral-nasal masks are isolated from helmet padding. Various layered helmets shells and padding reduce internal noise.

Abstract: Reduced noise abrasive blasting assemblies and systems are described. The new assemblies and systems are comprised of standard blast hose, accelerator hose, couplings and nozzle. The improved abrasive blasting system maintains abrasive particle velocity while decreasing the exit gas velocity and consequently decreasing sound production. This is accomplished through an acceleration section with reduced inner diameter and sufficient length to provide the necessary abrasive particle velocity. The new system maintains the productivity and efficiency of conventional abrasive blasting systems but with greatly reduced acoustic noise production and reduces operator fatigue due to the lower weight of the carried portion of the system.