Similar spec projectors that are a comparable age to this projector have noise levels of between 21dB and 45dB, and the average noise level is 32dB. At only 22 decibels, the PT-AT6000E has a fairly quiet noise level compared to most of the other projectors that were released more than two years ago.
We compared this projector to all the other 22dB noise level data projectors and we think the Optoma HD83 (£1,999.99) which has better reviews is also worth considering.
If you don't mind having a louder noise level then you might want to look at the Epson EH-TW6100W (£1,599) (32dB and cheaper).
What does "noise level" mean?