The Vivitek DH913 has one of the louder noise levels (39 decibels) amongst similar spec projectors of this age. The average noise level of 15000:1 contrast ratio projectors that came out around the same time as this projector is 35dB, and the noise levels range from 29dB to 40dB.
There are a number of other 39dB noise level projectors currently available that you might want to consider including the Vivitek DX831 (£839.08) which is cheaper.
If you are not bothered about having a louder noise level then you might want to look at the Optoma EH415ST (£1,045.87) (40dB).
What does "noise level" mean?