Heating, ventilation and climatization systems are necessary to keep indoor environments warm, cool and clear with high-quality air. Architects and constructors usually consider the aerodynamical and acoustical parameters (ventilation rate, airflow direction, sound pressure level, sound power level) that are connected with the appropriate selection of some elements of the system such as - fans, ducts, angles, air valves, silencers, diffusers, and exhaust elements (grid). Ceiling swirl diffusers in HVAC systems are important because they create a swirl to supply air to rooms where people are and allow mixing flow ventilation in the comfort zone, but also they are the source of the noise. In this work, an aeroacoustic study of square ceiling swirl diffusers with six prototype manually adjustable air control blades in two positions, fully opened and by 45 angles, was performed. The objects were installed on the plenum box with a side entry without the damper. The prototype blades using the 3D printer were used to find the one with lower noise parameters which are set out by measuring according to ISO 5135.