At only 26 decibels, the Optoma HD25e has a fairly quiet noise level compared to most of the other projectors of a comparable type and age to this data projector. Similar spec projectors that are a comparable age to this multimedia projector have noise levels of between 26dB and 37dB, and the average noise level is 31dB.
It may also be worth considering one of the alternative 26dB noise level projectors currently available including because of its better review score, the Optoma HD25e.
If you don't mind having a louder noise level then you might want to consider the EH200ST (£726) (31dB), or the H100 (31dB) both from Optoma.
What does "noise level" mean?