My rack is enclosed. That's the only thing that makes it tolerable to begin with. I'll probably donate it to my company if I can get rid of it.
It's a 42U APC rack and it has an AC unit in it that doesn't work any more.
I don't think I like those Antec Enclosures that don't have 3 5.25" bays for me to stick my SuperMicro drive bays in.
Maybe I should just buy generic chassis and try to customize.
It is possible, that the excessive noise is because the AC doesn't work! In an enclosed rack w/o air conditioning, the temps can get rather excessive requiring all those small fans, in all your machines, to whirr at very excessive RPMs to produce adequate cooling. One simple test may be to simply leave the front and back doors open for a while. If the fans slow down, then maybe if you repaired the AC (depending on how loud it is) then the noise would be much improved.
It may be that my solutions are ineffective. I really don't know how loud everything is, nor do I know your particular sensitivities to noise. What was it like before the AC died? Have you added lots of small 1u machines (using 40mm-80mm fans) to your rack and thereby increasing the amount of noise.
In general, I have found that most rack-mount equipment is very loud to start with and that the manufacturers, and the end users, really don't care: there just are outright much more important matters. You may find that getting normal computer/server cases that have as an option a rack-mount accessory may help. At least there you are dealing with cases that, at least to some extent, both the end user and the manufacter care about noise.