Aircraft, air conditioning systems, and air diffusers that may be used to create a quiet, comfortable environment within an aircraft cabin are disclosed. The systems and apparatuses are configured to flow air at a rate that meets and/or exceeds the FAA minimum requirement of 0.55 lbs/min (about 250 g/min) per occupant. In use, even at higher flow rates, the systems and apparatuses are configured to create a quiet cabin experience, by contributing little to ambient cabin noise. Thus, the systems and apparatuses may be used to provide fresh air at a comfortable rate and a comfortable noise level.