Appliances-sones to decibels & subjective ratings
I was researching the "quietness" of various kitchen range hoods and found this great reference:
dBA = 33.2 * LOG10(Sones) + 28
It also gives you an idea of subjectively how loud things are. For example, 30 dB = a theater, no talking; 40 dB = residential area at night; 50 dB = quiet restaurant inside; 70 dB = busy traffic at 16 ft.; etc.
So the Electrolux island hood I was looking at is rated at 73.8 dB, which makes it pretty noisy in my mind, compared to the Futuro Futuro brand many hoods of which are rated at 0.5 - 3.5 sones (up to about 45 dB. Of course correct installation is everything and I wonder if the Futuro rates theirs including their "silent kit". But at least it's more information that makes it easier to compare.