Diffusing pressurized gas with minimum noise

Problem:

I need to diffuse pressurized dry air (about 4-6 bar) in to a room, while creating minimal noise. The inner diameter of the tube is about 8 mm. Without a proper nozzle, there are bond to be vortexes and eddies screaming.

• Is there any kind of nozzle design already exist for this purpose ? For example, a firearm suppressor ?

• If possible, the nozzle should have minimum resistance to achieve maximum flow.

Thanks in advance !