Earlier this week I was doing maintenance on one of the home cinemas that we built and consequently look after, maintenance generally consists of checking the all-in-one remote works properly, that all the sources are configured correctly and that everything just works as it should.
We often do a sound test to make sure that all the surround sound channels are working correctly (for example this one was set to multi channel stereo instead of Dolby Surround Sound). I distinctly remember thinking as I was running through the sound checks, going through the surround sound channels how quiet the projector was.
The reason being that we designed this projector to be inside a hush box, by placing the projector into a box you quieten it down, hence called a hush box. These have their ins and outs - obviously they are quieter and often give a tidier look to the projector install, on the flipside they don't circulate air as well, are harder to get to and work on the projector through.
Still if you are looking at a projector based home theatre it's something to think about if you don't like to see or hear a projector just hanging overhead.