Hey sunnyvale
Heres what vortex said about the 4" & 6" fans.4" is 172 cfms,0.65 amps,80 watts,weight 6.8lbs,RPMS 2500,dBA49 .The 6" fan is 449 cfms,0.80amp, 100watts,weight 11.3lbs,RPMS 2600, dBA 49.You can also get a speed controler
and slow down the fan too. Slower fan speed the less dBA{ noise}.Put a20" box fan in the same room on 2 setting and you wont here it at all.I would put one of those talking gagits on the door of the cab that when you step close to the cab it would start makeing noise,Like that BILLY BASS thing looks like a fish singing.How many times do want to here that annoying dam fish sing.
A fan a singing fish no detection.