Research at Stanford University proved lip-sync error present in every home theater is undermining "our impression of the characters and story". And, contrary to popular belief, HDMI 1.3 does not really correct it.
Read the Stanford research (at www.felston.com/research
or at www.Pixelinstruments.tv
)and see how this impossibility of nature causes its negative impact even when you don't consciously notice it.
Viewers described the characters as "less persuasive", "more agitated", etc. – the same way we describe people who don't look us in the eye. I'll make the connection below.
In the real world you can't hear a sound before you see the action that created it. To the contrary, you will see the action – lip movement for example – and the sound will follow, delayed about 1 millisecond per foot the sound travels.
This space time relationship is violated in home theaters when delays from video and audio processing allow sound to arrive too soon or too late. Since we can't reconcile this physical impossibility, we avoid it, subliminally looking away from the characters' lips and faces. This hides the problem but causes the same negative impression as if the characters "were not looking us in the eye".
Most A/V receivers can add a fixed audio delay to offset a display's video delay but that doesn't solve the problem since lip-sync error is not fixed. It often varies more from program to program and DVD to DVD than its fixed component coming from your display.
And, this widely misunderstood "automatic lip-sync correction" feature of HDMI 1.3 does nothing more than "automatically" set a fixed delay as instructed by the display during the EDID handshaking. Ironically, rather than "correcting lip-sync", this can actually make it "worse" when audio arrives delayed.
The only way to really correct lip-sync and eliminate its disruption is to fine tune a variable delay while focusing on the lips. Alchemy, Felston and Primare make remote controlled digital audio delays which allow on-the-fly adjustment without image disturbance for this purpose. I use Felston's third generation DD740.
When doing that your display's video delay becomes an asset and can offset audio that arrives delayed which sometimes does happen. As another member pointed out the largest component of lip-sync error often comes from video (and sometimes audio) delays within the broadcast chain or even DVD encoding and "automatic lip-sync correction" is actually impossible since there is no watermark in the video and audio to define when it was "ever" in sync.
I use a Felston DD740 and spend a few seconds at the start of every program and DVD focusing on the lips and tweaking lip-sync until it is perfect. That's the only way to eliminate the subliminal disruption documented at Stanford since they clearly point out that while most people won't notice 40 ms lip-sync error its negative impact on viewer perception is still there.
To eliminate it you have to force yourself to look at the lips because our natural tendency is to look away to avoid this impossibility of nature. In reality HDMI 1.3's misnamed feature (as well as the fixed delay in most AV receivers) does us a disservice since it helps mask the problem (making it easier for us to avoid) but usually leaves over 40 ms uncorrected and still undermining our impression of the characters and story. What could be worse? Isn't that what cinema is all about - our impression of the characters and story?