Across all the similar spec multimedia projectors that were launched around the same time as this projector the noise levels range from 29dB to 48dB. At 39 decibels, the NEC PA572 has a quite loud noise level compared to most of the other comparable spec multimedia projectors that are a similar age to this projector.
There are a number of other 39dB noise level projectors currently available which you might want to consider including the NEC PA522 (£1,999) which is cheaper.
Alternative projectors with a louder noise level that you might want to look at include the PT-EX800ZLE (£2,828.40) (37dB), or the PT-EW730 (37dB) both from Panasonic.
What does "noise level" mean?