Here's what I've got. My PS3 is hooked up to my 1080p LCD PC monitor (a Dell S2409W) via HDMI. In turn, the monitor is hooked up to my PC speakers via the line out port. The problem I'm having is that it takes time for it to recognize that there's a sound signal - rather, it defaults to mute, slowly rises in volume, and then cuts off again when there's no sound. So there's no lovely bootup blurb, and the click-click-click of scrolling menu options is muted entirely if I scroll slowly. For another example, the company logos when I played a DVD (yeah, I don't have much of a Blu-Ray library yet) have no sound; the movie plays fine, unless I pause, in which case the sound turns off again and the movie is muted for a few seconds when I press play again. Does anyone know just what the hell is going on here? Do I have a bad HDMI cable? Is my monitor being persnickety about its sound I/O? Is there some obscure setting on my PS3 that I haven't turned on or off yet?
I'm not sure what the correct term is, but it sounds like the sound times out. A lot of devices turn output off during pauses of sound in order to minimize any noise/interference coming out of the speakers when it's supposed to be silent. My theater system does this, the LCD display on it will actually show the speakers disappearing when there has not been sound for 2-3 seconds. Though mine is quick to cut the channels back on so I don't really loose anything.
Certainly does sound like the sound processor, not the console. If the lead were bad, you wouldn't get sound. You stated it happens when there's no sound, so it sounds like it's gating as a 'security measure'. Perhaps you might need to invest in an amp with HDMI?
We had this problem with a TV at work, we found that playing around with the sound settings helped as some TVs have an auto volume setting which when turned off solved the problem.