Depends on a few things. Is this for your PC or HTPC? Also depends on the case it is in; for instance, if it has many ports for air to flow in and out, noise will travel outside the case.
In general, 34db is tolerable and you shouldn't notice it while watching tv, movies, music. If you have it muted and your system is on, you probably will notice the slight hum from the fan depending on how close you are to your case.
I have the BenQ MP610 projector which is rated at 29dB (not much lower than the projector you're looking at). In a quiet room, I can hear it, but it's drown out once the movie begins. I'm sitting about 5 ft away from the unit. For the most part, you're not going to notice it unless you're right next to it.
The scale at the bottom of this page puts 34 dB at just above a whisper.