Originally Posted by Skylinestar
Does that mean the dialog voice should be higher than the center of the screen?
It seems all the LCR are placed about 2/3, closer to the top of the screen. Does that mean the sound should come from the upper half of the screen? I'm not a pro in cinematography. Does that means majority of action are framed above the center of the screen?
I'm only going to relate what is done at the professional/commercial cinema and why. You will have to decide whether the logic is sound and should be applied at home.
You don't have to be a pro cinematographer/camera operator to understand the logic behind the 2/3rds screen height placement of the acoustic center of speakers. It's not based on "action." It's based on people/dialogue localization. Think about a medium closeup. Where is the actor's head? In the top third. Even in a tight closeup where the actor's mouth will be nearer the bottom of the screen, you have to consider that much of the human voice comes not only from the mouth, but resonates through the sinuses and eminates from our faces near the mouth/nose. Therefore the 2/3rds screen height still works. But remember that all the sound also does not come from your tweeter/horn (unless you have a Tannoy model or JTR 212). The acoustic center of your speaker, as perceived from your viewing distance, will be (as described in the Dolby document) somewhat central between the tweeter and mid-range component(s). I would contend then that there is a "circle of perception" on the screen of the voice of each LCR that is maybe 1.5' in diameter, not a pinpoint. That's up for research, but that's my theory FWIW. Speakers with good directivity index will still localize highly precisely.
The image/graphic from Dolby is a little misleading in terms of scale of the size of the screen and each LCR stack. That would be like us using a little Bose satellite for LCRs.
Most of us have speakers that occupy a much larger piece of real estate behind the screen, so placing them such that the acoustic center is just above the center of the screen is pretty easy to achieve. I contend that the benefits are strong. Ear level for me at home would put the LCRs near the bottom of the screen. I would find that much more distracting when the speaking actor's head is some 40" above that (in trigonometry maybe 3-4 degrees higher than where the sound is coming from)...not good...at least for me and any professional cinema. Same goes for mixing stages (which are not giant cinemas).
On the other hand, that scale relationship we have at home between speaker size and screen size makes it quite easy. If the acoustic center of LCRs are at least at 1/2 screen height, then it will be indiscernible from 2/3rd screen height...ie "close enough."
One last comment: Since most of us will have a slight look-up angle from our seating position, the higher speaker location is "along" our viewing sightline. Even if the LCR is near the top of the screen or above it, the distraction will be less than if the LCR is too low or below the screen. And all of this is based on listening in a dark room so that there are no visual distraction cues about speaker locations. Of course that is a moot point if you're using an AT screen.
So, I guess that what I'm saying is that if I'm going to make the investment in a fine AT screen like Chris's, I'm gonna get ALL the benefit. Edited by Cam Man - 12/3/13 at 7:11am