The Sandbox
As we said, Dolby itself feels that 5.1-channels are a sweet spot for surround audio. But the limits of what can be done with surround audio are being tested in what Dolby calls its "Sandbox." There are 24 speakers in this room -- 16 at ear level encircling the listener, a smaller ring of 6 above that, a single "voice of God" speaker is on the ceiling directly above the listener, and a subwoofer. Simply put, the goal of this setup is to be able to create sound anywhere in the upper hemisphere within a theater. The speakers are not perfectly arranged, to better mimic the varying speaker-listener interactions across a theater setting.

After doing some white noise pans, we were convinced that this array of 24 speakers can create a much more spatially continuous soundfield than a conventional 5.1 or 7.1-channel setup. Not a big surprise, right?

But here's the interesting part -- the Sandbox uses 5.1-channel encoding to upmix (expand) to 24-channels, and the results are stunning. The implications for this are pretty exciting -- a 5.1-channel mix that is compatible with everyone's existing surround sound setup can be upmixed to as many as 24-channels for dramatically better surround performance. As with our Pro Logic IIz demo, we didn't notice any ill effects, even when the original material was sourced from a 2-channel vinyl record -- and we believe our host's claims that improper 24-channel upmixing can make the listener seasick, change the tonality, or collapse the soundfield. Thankfully, we didn't lose our lunch, and we heard a dramatically improved sense of ambiance while the tonality of the sound made it immediately recognizable as the original 2-channel stereo recording.

Sure, finding room for 24 speakers is daunting at best and would push even our nonexistent sense of decor to the limits, but it's good to know that with some clever technology like that Dolby showed us in its Sandbox, we won't have to carry around audio files containing 24 discrete channels to create a holographic soundstage. And hey, with the onslaught of in-wall speakers, maybe this kind of sound will be possible in the living room one day. Until then, we'll be eager to see this technology find its way into the cinema space.

http://www.engadgethd.com/2009/07/08/engadget-goes-behind-the-dolby-logo/


I HAVE BEEN TALKING ABOUT DOING THIS WITH THE TACT.

Typical "magazine" hyperbole. "It's good to know...we won't have to carry around audio files containing 24 discrete channels". The advantage of more discrete channels (such as 10.2) is real and any attempt to "create" that with a 5.1 mix is and will be a faint imitation at best. Having said that, I'm certainly excited by the potential of using more speakers with existing mixes if it can be pulled off decently, just as long as it's understood it's a faint imitation of the real thing, and that we very much do "need to carry around that file with 24 discrete channels" if we want to experience truly moving to more discrete channels. 10.2 would be a nice number for high-end home theaters.

I guess it's only a matter of time before we get in-floor surround speakers installed in the floor to mimic the sounds of insects on the ground, creaking of wood when walking on it and the fall leaves rustling on the ground. :D

we won't have to carry around audio files containing 24 discrete channelsThat sort of thinking won't fly with typical audiophiles that are recent converts to surround sound (recent = discrete multi-channel era). They're more likely to be slaves to the delivery medium (2 channels played back over 2 speakers, 5.1 channels played back over 5.1 speakers, etc) than be comfortable with the notion of scaling the number of channels in the source to the number of speakers in their set-up. So if 24 speakers are used for playback, then 24 discrete channels are expected in the source. Otherwise, some of those channels won't be "real" (whatever that means).

Folks who have been listening to surround sound prior to the discrete multi-channel will probably be more comfortable with the idea of scaling channels to speakers. They've lived with it and many of them, at least on these forums, tend to use modern surround sound technologies on a regular basis. So the idea of playing back 5.1 sources over 10 or 24 speakers won't be new to them.

Sanjay, I think it's more likely that hyperbole "won't fly" with knowledgeable people, I doubt very much it will have anything to do with when someone started listening to surround sound. I've listened to all manner of surround sound including those which "extract" information to create extra surround channels. Some of they work quite well depending on your tastes, they just do not compare to true discrete channels. The only thing I really take issue with here is the hyperbole in the report, if they had have said "we found it superior to 5.1, we were glad to learn that until the future brings additional discrete channels we may see technologies that approximate it" I'd have no issues with it.

Some of they work quite well depending on your tastes, they just do not compare to true discrete channels.No one is claiming they do, any more than claiming that video scaling is a substitute for true hi-def content. The idea is to use it when you don't have more discrete channels, not instead of discrete channels. But some people aren't comfortable with derived channels. For them, it's discrete or nothing. I doubt very much it will have anything to do with when someone started listening to surround sound.My experience has been different. Folks that were listening to surround sound during the quad era seem to be more comfortable with using matrix processing for surround sound (2-ch -> 5.1) or even to supplement discrete multi-channel (5.1 -> 7.1 or 9.1). By comparison, more recent converts to surround sound often express disdain for anything matrixed derived, labelling those as "fake" channels with "made up" content.

It doesn't matter whether the results are good or bad, the very idea of scaling the number of source channels to a greater number of speakers is an anathema to their beliefs. Look in some of the PLIIz threads for people who refuse to use height speakers until sources have discrete height channels. Can you imagine how these same folks would feel about extracting 24 channels?

And then there are people who say that 4 channels correctly done beat any >= 7.1 system...
http://www.ambiophonics.org/papers/LLRG-TactManual.pdf

I think I recall you posting some interest in ambiophonics some time back. Have you ever had an opportunity to evaluate it?

And then there are people who say that 4 channels correctly done beat any >= 7.1 system...Heck, they say that a 4-speaker set-up provides "better side imaging" than even a 10.2-speaker layout. They're claiming that a phantom image at your side, with one ear in acoustical shadow, will localize better than a hard source that's physically at your side. You buy that?

I think I recall you posting some interest in ambiophonics some time back. Have you ever had an opportunity to evaluate it?

I tested with stereo and the results depend on the source and the parameters you set. It can be very nice but also (way) off. I think it's not mature for the general case since unwanted side effects are hard to control.

Heck, they say that a 4-speaker set-up provides "better side imaging" than even a 10.2-speaker layout. They're claiming that a phantom image at your side, with one ear in acoustical shadow, will localize better than a hard source that's physically at your side. You buy that?

It depends what you listen to I would say based on results with stereo. 5.1 material is not mixed for this system so I have my doubts. But I have not listened to 4.1 ambiophonic yet. My back speakers are too far apart to make it work and I don't fancy 'remodelling' the back of my home cinema.

Great, I can hang a B&W 800D on the ceiling directly above my head... Voice of God channel does sound cool though...

Great, I can hang a B&W 800D on the ceiling directly above my head... Voice of God channel does sound cool though...
This would need IB at the very least! Anyone know what dynamics are involved?

Why don't we have a recording where every single instrument has it's own speaker/channel? Or for video, we can have every single animal, person and moving thing have it's own speaker/channel. At the first day of filming just hand out microphones to every thing that moves or makes a noise. And just think, you can boast to your neighbors, "I have 3,686 channels in discreet high-rez format!" But then again, why not put the channels inside our head? We can become walking, discreet high-rez intertainment beings. ;)

But then again, why not put the channels inside our head? We can become walking, discreet high-rez intertainment beings. ;)

Yeah but the government would surely grab the opportunity to intrude on peoples thoughts.