The printer is very loud, thats true!
All fans are not the silenced at all. In front of the hotend is an 30mm one (little, fast - that one will not be quit), 40mm on the side and two 60mm under the printer.
The most noise comes from the 60mm in the PSU. The main problem here is, that the fan is getting louder if more power is needed from the printer. So, in peak you'll always have 100% in prints because of balancing the temps.
I did some tweak with another PSU from another printer with a temp-resistor behind the fan. If the PSU temp is getting up to 65°C, the fan will start but not under this temp. Than, you hear it only a view seconds and all is quiet after that again. I like to do this a lot, becaus as an technical electrician its easy to do.
But in this case, I'll try something else first - changing the fan by another brand with a lower db ratio.
But hey @creality - why don't you use fans with the lower db but same flow ratio like the one from Nocuta.at?
I'll bet, a little bit more on the selling price will not let people think the printer is to expansive.
Prusa does the same with there fans and gets enough outcome.