First things first. Fan noise on the Viewsonic is very reasonable. Let me rephrase that. It's really impressive. When in Movie or ViewMatch mode, it's quieter than a lot of home theater projectors!!! It's really mostly the sound of the air you mostly hear, rather than the fan itself. Even in the brighter mode
The PLED-W800 projector has two small (OK, very small), rear facing speakers. While they can provide reasonable volume, you can't expect sound quality to be a whole lot better than a typical laptop. At least this Viewsonic provides some audio controls. Basically they offer three audio modes:
Standard, which would probably be best for a presentation that has different types of audio.
Speech mode: Mutes the highs a bit to bring out the range of vocals.
Entertainment: It's very bright sounding (more highs), but is probably your choice for watching TV or a loud movie. I find it a too bright (a bit tinny) for serious music listening, but then I would never really listen to music on something like this, I'd output the sound to something a whole lot better, even if just a decent boom box, or small powered speakers.
The projector does have a stereo audio output jack. It would have been nice if the PLED-W800 supported Bluetooth, so it could wirelessly work with some very impressive, yet very small speakers that are available, and which many of us already own.
Like every other projector I've reviewed, Viewsonic's PLED-W800 "flunks" one design feature. Yes there's a stereo audio out, but when you plug in external speakers, or output to a stereo or home theater sound system, the speakers cut out.
It's a shame. if you had the option of outputting the sound, and leaving the speakers on, that would allow you to add a small powered sub-woofer, which would balance the sound, and give you something actually rather respectable for watching an action flick like Casino Royale, or Transformers, and even give you that room shaking low end that is completely missing on every projector with internal speakers.
Finally, if you crank the internal speakers all the way up, (10), if the content audio is particularly loud, you will get a bit of distortion though still certainly usable.