Beyond 7.1

Movie theaters are always eager to find new ways to drag consumers off their living-room sofas and into the multiplex. In recent years, this has become more difficult as big-screen HDTV and home surround sound can often exceed the movie-going experience. Apart from sheer screen size, consumers have less and less incentive to spend $12 a head, or more, just for the seat—never mind the cost of refreshments.

Imax and 3D theaters have helped, but they command even higher prices. The next big thing for theater owners may be what promoters have dubbed 3D sound. Instead of the theaters' current complement of 5.1 or 7.1 channels, 3D sound gives you more—many more. Several companies are working on such systems, but Imm Sound, based in Barcelona, Spain, appears to be ahead of the game, currently sporting 30 theaters worldwide, with more on the way.

Only two of those theaters are in the U.S.: one in Las Vegas, NV (opening soon) and another in Glendale, CA, just outside Los Angeles. On April 17, Imm Sound presented a demo to a number of press and technical personnel at the Pacific Theaters Glendale 18 in the Americana shopping complex, and I was there.

Imm Sound's system consists of 23.1 audio channels (!) distributed around the theater—at different heights, side and rear surrounds, and even directly overhead as seen in the photo above. Several of the channels in the Glendale 18 auditorium consisted of a cluster of more than one speaker, aimed for wider angular distribution. Such clusters count as only one of the 23.1 channels, however, so the system we heard actually had more than 23 full-range speakers.

The company expects that producers who opt for this system will mix their soundtracks with 23.1 discrete channels. But since that's unlikely for all future films, the system is also compatible with standard 5.1 and 7.1 soundtracks. Using proprietary algorithms, it upconverts these conventional mixes to make use of the 23.1 available channels. For theaters that cannot or will not invest in a full 23.1 array of speakers, smaller arrays can be used. But Imm Sound considers 14.1 to be the smallest package that can retain most of the benefits offered by the system.

Needless to say, such soundtracks are compatible only with digital projection in which the audio is stored on a server along with the picture. I doubt it's possible to include a 23.1 soundtrack on actual film.

For a discrete 23.1-channel production, sound mixers will be able to use many of the tools currently available to them, supplemented by processors from Imm Sound. An iPad may also be used to better visualize where the mixer wants to position various sounds.

The mix is not produced by directing the sound to specific speaker channels. Rather, the mixer directs each sound to the location in the auditorium where he or she wants that sound to originate, and these locations are encoded in the mix. The Imm Sound processor decodes them in a way that sends the sound to the speaker or speakers that will produce the desired effect. Since theater setups will necessarily vary somewhat in the number of channels, layout of the speakers, and size and shape of the auditorium, each theater's Imm Sound processor can be programmed to account for these differing parameters.

After a brief technical discussion, we were treated to several short demos, both discrete mixes and upconverted 5.1 and 7.1 soundtracks. There was significant edginess to some of the sound—likely due to the mixes themselves, the theater's speakers and equalization (probably set for a full house rather than a small audience), and excessive volume (a plague in Los Angeles theaters—and I listen to my own home theater loud!).

But the main subject of the demo was directionality and immersion, and the results from the discrete Imm Sound mixes were astonishing. I'm not sure this type of sound will be necessary or even desirable for many movies—it's so effective it can be distracting—but for today's popular action and animated flicks, it will surely put more of those proverbial asses in the seats.

The upconversion demos were satisfactory, but I'd have to hear them side-by-side with basic 5.1 or 7.1 to determine if the benefit is worth the extra bucks theaters will surely charge. And that's an important issue. It's akin to the created-in-3D vs. converted 3D conundrum. Given good production quality, audiences will definitely hear what they are paying for with a discrete Imm Sound mix. But with an upconversion—which will comprise most of the material available to the system for the foreseeable future—I'm not so sure. In any case, the first film to be produced with a full 23.1-channel upmix will be The Impossible.

The presenters also dropped hints about the system being available for home use. But that raises a slew of questions. How much will it cost? (The processor itself appears to be affordable.) Can all those extra channels be carried on today's best home sources without reverting to lossy compression? (Doubtful, with 3D's demands already here and 4K on the horizon.) And how soon after those 23.1 speakers are installed will the divorce papers be served?!

Rob Sabin's picture

Thanks for the cool report, Tom. It reminded me that I recently had another opportunity to demo and get an update on the latest developments in the progression of Multi-Dimensional Audio (MDA) at SRS Labs in Irvine. (Latest press release is linked below). I wrote about MDA in our August issue last year and here. Conceptually, instead of a movie being mixed in 5.1 or 7.1 or whatever, the mixing engineer works from the hundreds or thousands of of stem recordings assembled for the movie and simply places each sound in a three-dimensional space for any given moment in time. Metadata describing the sound's position and volume is generated by the system and stored. This in essence becomes the permanent mix, and once that data exists, it's as simple as pushing a button to get a 5.1, 7.1, or 23.1 channel discrete mix from the data. All of sudden, the movie gets "mixed" once, and the information is used to accommodate any sound system in place now or invented in the future. If the mixing engineer wants a sound above your head, the metadata describes that, and if the playback system can accommodate it, all you do is tell the renderer what kind of system you have and where the speakers are.

The demos of this have absolutely amazed me. At this point, they've got the software more or less working for the mixing and the rendering, and SRS is hoping some studio will come on board and mix a major film in MDA as proof of concept. If they can get the studios mixing in this new format, it'll encourage more of these "xtreme theater" chains, because every movie mixed in MDA can be readily adapted for more exciting, realisitic, discrete playback in these theaters without having to go back to the stems and start from scratch or upconvert from a 5.1 or 7.1 mix that has already sacrificed information containing critical cues that could be rendered more realistically on a bigger playback system. And who knows how this will affect what can be one with home systems? If you've got an 11-channel receiver, all of a sudden, you can actually have a discrete and three-dimensional 11.1 mix from all your software instead of some approximation of what Dolby or Audyssey thinks they ought to put into height or width channels...

SRS Labs Successfully Completes Development of Multi-Dimenisional Audio Specification 1.0.

Jarod's picture

Ive been on IMM Sounds website the last few months reading about this so its great to finally hear a listeners account, especially by Tom's trained ears. I wonder how this would stack up against Barcos Aura 3D sound?

Scott Wilkinson's picture

There's also Dolby Atmos, a similar system that I hope to hear soon.

Scott Wilkinson's picture

BTW, here's more info about Barco Auro 3D sound:

Jarod's picture

Thanks for the heads up. Actually just been reading up on Dolby Atmos over on the AVS forums. Really excited about these technologies. I think that the Atmos' panning array tech alone would be very effective in and of itself.

limabird's picture

I appreciate the idea of improved directional sound, but why just 1 sub channel? I certainly don't want to hear muddy lows bouncing all over the place, but when a director wants a big boom to come from behind, why shouldn't the low frequencies be a little more directional too? Certainly this is exceedingly difficult with say 20-40hz, but I feel like the somewhat standardized (as per THX) cutoff of 80hz still leaves subs somewhat directional. I don't want to loose the ability of the sub to cleanly reproduce that sound, but why not give the director the ability to take advantage of that directionality by having 3 or 4 low frequency channels? The processor could also take advantage of the extra subs to equalize problems in the theater's acoustics.