How sound interacts with different projection screens

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ScareDe2

Enthusiast
New member here.

I basically know about two type of projection screens: perforated (or acoustically "transparent" ?) and... non perforated, or full PVC ? According to recent readings, sound is either "absorbed, reflected, refracted, diffused or diffracted, or transmitted." And they give a value, right? You have the NRC value (Noise Reduction Coefficient) that if close to 1 means 100% of the sound is absorbed. I don't think a projection screen has a good NRC but I am confused about the acoustically transparent screens used in theaters. I know they serve in case you want to position the speakers behind the scene, but what about the sound from the outside that impacts the screen? Is it 100% going thru without any kind of reflection? Is there any value known to describe how sound waves behave when they impact a theater screen?

Thanks.

Edit: Just to provide a little more meat to my question, here can we read from stewartfilmscreen (no association): All AT (acoustically transparent) screens, regardless of technology type, will impact sound slightly. Each type will have a different effect, but the overall issue is one of attenuation of sound; reduction of sound volume in certain frequency ranges. This can be overcome by using an EQ but can require accurate data from the screen manufacturer or testing by the integrator to ensure proper audio quality.

Now I am curious, more in details, what is the effect it has, overall? What are the targeted frequencies here? They say it impacts sound just slightly, but contradict this further by proposing the use of EQ to achieve proper audio quality? What does "slightly" means, then?
 
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shadyJ

Speaker of the House
There are response comparisons out there that do show the effects of acoustically transparent screens. Here is a technical paper that deals with cinema screen effects. For the kind of screens that you are talking about, the screen seems to attenuate very high frequencies a bit, but the audible effect is pretty much negligible.
 
S

ScareDe2

Enthusiast
There are response comparisons out there that do show the effects of acoustically transparent screens. Here is a technical paper that deals with cinema screen effects. For the kind of screens that you are talking about, the screen seems to attenuate very high frequencies a bit, but the audible effect is pretty much negligible.
Highly appreciated.
 

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