I used to have a darkroom guide (I think the title was _Do it in the Dark!_--you know, a 70s thing) with a gratuitous photo of one of those Beseler 4x5" enlargers with the Dichro head and the ventilation hose, proclaiming it the coolest, fanciest thing one could possibly have in the darkroom.

The reason for the hose is to isolate the vibration from the fan, and keep the head from vibrating.