For the first time I downloaded 2 demos from the PS store (Ninja Gaiden Sigma, Dark Sector). When I load up either, there is no audio. Video is fine and the games are playable.

Has anyone else experienced this? If so, is there a fix?

I tried several searches for an answer but saw none.

I have the 80 gb PS3 connected via HDMI to a Vizio 37" 768p LCD. Full version games I own (DMC4, Lair, Uncharted) do not exhibit any audio problems, nor do Blu Ray discs.

I don't have either demo but I wonder if they're outputting DTS instead of DD.

Most EA sports demo's also gave me this issue. I only have DD through optical to my old receiver,
but if I used hdmi audio through TV was ok, so DTS vs DD is the likely issue.

Most PSN demos are 2-channel PCM only. Double-check that your XMB sound settings are set to allow those outputs and make sure your output destination (receiver or TV or whatever) is set to receive a simple 2-channel signal.

I had same problem. Some demos had no sound while others were fine. I was going CRAZY trying to figure out what was wrong. it turned out to be in my system sounds menu. I had a box checked and when i unchecked it all was good. Can't remember which one it was but uncheck formats that your speakers dont support. Let us all know.

If your having problems with sound, hit the "select" key and see what type of audio it is outputting.

Then go into your audio settings and make sure you have specific audio format selected (I believe AAC or something like it is common on trailers).

-Splints