I tried to capture the different noise levels with my Sony HX5 but auto gain sadly ruined it. They were all equal.
My last one before the Epson was a ACER P1265 and this one is quoted 24 to 28-31 dB.
Epson quotes the EH-TW3200 with 22 to 28 dB. but for my ears the Epson is quite a bit louder than the ACER.
The Epson in the lowest noise setting: Cinema, ECO, Iris off and not Ceiling Mount produces still a bit more noise than the Acer in Eco mode.
So I question the 22 dB according to my hearing and some similar forum posts. I think something in the 26 dB area is more correct.
The noise increases in several levels.
Ceiling Mount and x.v Color or Cinema brings on a few rpm and a tiny bit of noise more but still in a quite acceptable range.
Living Room and Dynamic are a fraction louder but no difference in mounting.
Turning off the Eco mode (normal setting for Dynamic) more than doubles the noise.
If you activate the Auto Iris you get a very noticeable mechanical noise what is louder than the projector on max power and brightness.
To understand the dB value it is important to know that dB doubles in intensity every 3 steps.
So 28 dB is 4 times a s loud as 22 dB.
My Epson EH-TW3200 is mounted one meter directly over my head, so the exhaust blows above me. If you have the projector close behind or next to you, it is a good idea to hear before you buy in case you want the Epson not only for movie watching and you find noise irritating.
I would rate the Epson EH-TW3200 from 26 to 34 and with Auto Iris up to 40 dB.
In normal viewing environment no problem, but if it is dead quiet like viewing pictures a bit more noisy than I would like.