IMAX Theater Speakers

April 5, 2022 10:31 PM

Back in the 1990s, I saw a number of documentaries and things at the Franklin Institute's domed IMAX theater in Philadelphia. Before they showed the legendary Philadelphia Anthem, they always had someone give an explanation of the theater, and they would show the sound system "through" the screen. Were they actually showing the speakers for real by brightly lighting the area behind, like a one-way mirror effect? Was it just a projected image? If anyone knows for sure, I would be greatly relieved to find out, because this thought has been bugging me for nearly an hour.
posted by DoctorFedora to Technology (12 answers total)

Best answer: I don't have a link for you, but they were definitely real. It's quite normal for a theater screen to be perforated, to allow sound to pass through, and for there to be speakers behind the screen - even in non-IMAX theaters.
posted by kickingtheground at 10:49 PM on April 5, 2022 [5 favorites]

Best answer: The IMAX at Science World in Vancouver did this, too, and it was done by lighting up behind the screen.
posted by foxtongue at 10:52 PM on April 5, 2022 [2 favorites]

Best answer: The IMAX dome at the Des Moines science center did this with lighting behind the screen as well, as recently as 2017.
posted by michaelh at 11:27 PM on April 5, 2022

Response by poster: thank you all for your helpful answers! I always thought it looked weirdly realistic, and at last I know that it was because: it was real
posted by DoctorFedora at 11:34 PM on April 5, 2022 [1 favorite]

Oh they were real!
posted by james33 at 4:53 AM on April 6, 2022

The Museum of Science in Boston did this too, but with Leonard Nimoy reciting "Who Put The Bomp" as various speakers behind the screen were lit up.

Nimoy also narrated the similar short film that would follow it, A New England Time Capsule. I guess there must have been some sort of grant or program for each museum-based omnimax theater to produce a short, introductory film?
posted by RonButNotStupid at 4:56 AM on April 6, 2022 [8 favorites]

check out this youtube video. it explains where the speakers are located at 2:20
posted by radsqd at 5:00 AM on April 6, 2022

MetaFilter: it looked weirdly realistic, and at last I know that it was because: it was real.
posted by wenestvedt at 5:49 AM on April 6, 2022 [7 favorites]

I can confirm that the backlighting to show the speakers at the Franklin Institute was a real thing. Also, that IMAX screen was the worst to see actual movies on. :) Neck pain city!
posted by Geckwoistmeinauto at 6:54 AM on April 6, 2022 [1 favorite]

RonButNotStupid, thanks for the intense nostalgia hit!
posted by lunasol at 7:45 AM on April 6, 2022 [1 favorite]

Don't recall which IMAX I was in but after the show (which began with a similar demonstration) I went up to the screen to check it out and was surprised to note a pattern of regular perforations. There's enough tiny holes (about 2mm diameter) that collectively, at a distance, enough light from behind passes through that your brain receives enough information to see what's behind the screen, when it's illuminated back there. Guessing these holes are there to make the screen weigh less.
posted by Rash at 9:27 AM on April 6, 2022 [1 favorite]

It is fun to know that other Imax theatres do this; we go to the one at the Boston Museum of Science. as you enter and leave, you can see the giant spool of film.
posted by theora55 at 9:55 AM on April 6, 2022 [1 favorite]