The Next Step in Surround Sound
My first “beyond 5.1″ experience was in January 2000 at the Alexis Park Hotel in Las Vegas. My colleague from the USC Immersive Audio Lab, Tomlinson Holman, was in the small room next door explaining why more channels are needed. This was followed by a demonstration of the world’s first 10.2 system to a few members of the press.
The world of sound had come a long way from the introduction of the first stereo LP in 1957. But in fact, with 10.2 we were moving back in time. It was in the late 30s that researchers at Bell Labs had looked into the question of how many loudspeakers are needed to reproduce a seamless, realistic sound scene. The answer at the time was discouraging: it turned out to be an infinite number–not exactly a high SAF (spouse approval factor) idea. Two channel stereo, however, was the only way to deliver sound to the consumer and it was limited by the LP groove that had two sides. Certainly better than mono, it didn’t come close to delivering an immersive experience.
The audio industry made great progress since 1957 and in the 1990’s we saw the introduction of 5.1 channel surround sound. Combined with the emergence of the DVD as the delivery medium, 5.1 surround became widely accepted in consumer homes because it created better sound immersion to match our growing video displays.
But since the 90s, the industry misdirected its focus to more esoteric endeavors: high sampling rates and higher bit depths for digital audio. While technically superior than the early digital formats found on CD in the early 80s, these developments did little to provide the consumer with a better experience. Human hearing limits for frequency range and dynamic range had already been met with 48 kHz sampling rates and 24 bit word lengths. Going to higher sampling rates simply filled up the discs with more data and required higher processing power to decode, but provided no audible improvement to the listener.
There have been attempts to push surround sound to more channels, but they were unfortunately not guided by proper acoustical, perceptual, or even logical approaches. 7.1 systems emerged by adding two more surrounds speakers in the location that makes the absolute smallest difference to the listener: directly behind them. Research in psychoacoustics tells us that human listeners are best at localization in the front hemisphere, cued by what we can see. Having more channels behind the listener than in front wastes resources and doesn’t go very far in providing a more immersive and enveloping soundstage.
To make an audible improvement in surround sound requires more Channels in the right locations. That’s what Tom was demonstrating at the Alexis Park during the 2000 CES. But not just any channels. They have to be placed in locations carefully crafted to produce the required cues that give us the impression of a wide, seamless, and enveloping soundstage.
Nine years later we are ready to go beyond 5.1 channels. Our company, Audyssey Labs just announced our latest technology, Audyssey DSX (Dynamic Surround Expansion). Drawing on our research in room acoustics and psychoacoustics we hope to extend an important dimension of sound…space.
May 7th, 2009 at 2:20 pm
This sounds (no play on words) exciting. Curious if you have heard the Symth Realiser head phone system. I just purchased one and I think (if I recall correctly) that you can use the eight channels for height or front sides. Height for sure but not sure about front sides.
May 7th, 2009 at 4:08 pm
We know the Smyth headphone system well. You would have to check with them directly, but I am fairly certain that it can be configured to any combination of 8 channels.
May 10th, 2009 at 7:54 am
Hi Chris,
I had the opportunity to listen to Tom’s 10.2 system when he came to Paris for a demonstartion back in Mar ‘04.
It was simply MAGNIFIQUE.
So if DSX is just half as good, I’ll sign for it!
Hugo
May 11th, 2009 at 5:37 am
10.2 eh? Just how am i supposed to get that one passed the wife!
sounds great, will this mean rolling out calibration packages for studio’s and another rack of outputs for my pro tools rig?
Joe
May 11th, 2009 at 12:43 pm
Hi Joe,
SAF is a factor, but it can be somewhat overcome with smaller speakers and the right room correction. I can help point you to a very good room correction solution if you’d like.
IK Multimedia already sells the ARC plug-in for studio use and Audyssey has a Sound Equalizer pro unit that is used in several studio and post production facilities today.
May 14th, 2009 at 9:14 am
Hi Chris,
Will the new DSX system require a different “Sound Equalizer” for those who have seperate components? What about current users of the Sound EQ - will there be an upgrade option available?
May 14th, 2009 at 10:05 am
Hi Bob,
The Sound Equalizer is purely focused on solving the problem of how sound from each speaker interacts with the room. So, if the system has more than 8 channels then an additional Sound EQ will be required to handle them in a separates system. We expect that there will be new preprocessors with DSX announced by our licensees later this year.
May 17th, 2009 at 3:49 pm
Finally, some actual proof that rear channels are useless. I remember buying into 7.1 when it came out and could never figure out why I was never pleased with it. I look forward to the Audyssey system but since this will cost a ton of money for me to re-vamp my system I’ll just have to wait on it.
May 19th, 2009 at 3:00 pm
Hi Chris:
This is very interesting work. As an acoustical consultant this is not surprising even for home theater applications.
I’m curious about the following statement:
“Auditory Source Width and, increasing it, is a desirable feature. But increasing the spread beyond ±30° for the front speakers was found to cause many imaging problems.”
Under what conditions (room acoustics wise)were the listening tests performed? Were they anechoic conditions or something else?
Thanks
May 23rd, 2009 at 12:13 pm
Hi Doug,
The loudspeaker experiments were performed in an ITU standard room.
May 26th, 2009 at 11:05 am
Did you have a certain low frequency extension for the additional fronts in mind when designing DSX? For instance, 80Hz?
June 10th, 2009 at 2:05 pm
The content going to the additional wide and height speakers is full range, but the speakers can be any size because bass management will redirect the bass to the subwoofer. You can read more about bass management here: http://www.audyssey.com/blog/category/blog/2009/05/small-vs-large/
July 25th, 2009 at 9:02 am
Very excellent advanced technology!
I am in the final stages of custom installing a new basement theater. I want to do an 11.4 audio system with Denon’s AVR-4310CI as the pre-amp connected to Denon’s POA-A1HDCI Ultra-Reference 10 Channel Power Amplifier, with the required sub-woofer amps and 1×4 sub processor/equalizer and another power amp if needed for the additional channels.
Can this system support the additional 4 front channels, specifically, the new L/R highs and L/R wide, in addition to the traditional 7.1 (in my case a 7.4)?
-Robert
August 18th, 2009 at 11:11 am
in your blog, I read,
“Human hearing limits for frequency range and dynamic range had already been met with 48 kHz sampling rates and 24 bit word lengths. Going to higher sampling rates simply filled up the discs with more data and required higher processing power to decode, but provided no audible improvement to the listener.”
Does that SACD and other high bit formats are of no use? I am not trying to start any argument as I have never heard any of these types of media, but the thought did pop into my head when I read this.
My guess would be that blind testing would show this to be the case and that the real benefit of SACD would be limited to the sound stage created by the additional channels of discs that are encoded with that content.
August 18th, 2009 at 2:12 pm
The greatest contribution of SACD was its ability to deliver more than two channels. So, I wouldn’t call it useless and your guess is correct.
August 18th, 2009 at 11:42 pm
what ever happen to two center chennal speaker. the thing was to have two center chennal and two front speaker.
August 19th, 2009 at 12:02 pm
Two center channels was never a consideration in any of our work. There are very bad comb filtering artifacts that happen when you do that so it is not a good idea.
August 28th, 2009 at 4:10 am
In a 9.1 DSX Surround A Setup, would a direct radiating, bipole or dipole be the speaker of choice for the LS/RS position? Also, what type of speaker would you recommend for the remaining positions? Your graphs for the various surround modes are very detailed as far as angle and elevation, but they fail to illustrate a recommended distance for the RH/LH speaker position in relation to the central listening area. I’m guessing the distance for the RH/LH isn’t too important as any time delays will be taken care of with a proper calibration anyway. Thanks.
August 28th, 2009 at 4:54 am
In my last question, I meant to ask what “size” (tower or bookshelf) instead of what “type” for the front surround positions LW/RW and LH/RH. I’m sure matching the LW/RW with the L/C/R is the only way to go for a seamless surround stage. Whereas with the LH/RH, directly matching the other front speakers only in terms of voice-matching only would be more than adequate considering the generally restricted placement for the height channels. Correct? Thanks.
August 31st, 2009 at 1:12 pm
Chris,
I work for a custom a/v dealer and recently installed a Denon AVR 4310CI in my home. Thought you might like to see excerpts from the writeup I gave the owner.
This is the 5th AVR from 2 different manufacturers I have installed in my now 4 year old home. My room setup is far from ideal: 12 ft ceilings, hardwood floor (with a large rug and some cloth furniture), very open floor plan. The room containing the system is 18 wide x 26 deep but has a foyer and dining room separated by arches.
I have 7 ceiling mounted speakers and a floor sub. LCR are Sonance and the remainder are Klipsch. Until now I have connected them in the standard 7.1 arrangement: LCR, surround LR, and surround back LR. With the 4310 I used connected the surround back LR as surround A – LR. I connected the surround LR to the amp assign jacks and assigned them as “front wide”. I ran the Audyssey setup and allowed it to measure 8 positions, following the suggestions in the Audyssey site. I also enabled DSX through the amp.
Prior to installing the amp I had watched and recorded via DVR the HBO HD broadcast of Max Payne. Sounded great on the 3808. I watched several scenes on the 4310 and was amazed at the difference. As the DSX site mentions, now ALL of my speakers were engaged in the movie. The soundstage was indeed wider. Voices were more clear. I heard pieces of paper blowing across the screen I had not heard before. There is a scene during which Max runs through a building firing and being fired upon…..WOW. You could hear the shots and the hits with proper direction and depth. I’m not certain how to explain it except to say it was enveloping without being painful or distracting.
Last night we rented Watchmen on DVD (I loved comic books as a kid and love most of the movies now…Ironman, etc.) I will say this movie is the exception. BUT, the audio was awesome. I’m playing this on old technology – a Panasonic DMR-E80H. I don’t have a BluRay so I let the amp upscale to 1080i. It did a good job and I did not notice any artifacts. This movie is a little like Sin City…..graphic with a lot of bone crunching and head splitting. It has an aircraft in a lot of scenes. Again the sound was absolutely stunning. There is a thunderstorm in one scene, not at the forefront but as background noise. The thunder moved realistically between the various speakers including the very back ones (set up as surround A). Oddly, a real thunderstorm was approaching a little later and we could NOT tell the difference until we started to see the lightning.
October 4th, 2009 at 6:38 pm
Hi Chris,
I’m new to the site and was looking for your response to Wes’ entries on August 28th. I have the same questions and am trying to decide on how to prepare for both front heights and wides using the new Onkyo TX-NR1007 I just ordered. My current configuration includes Definitive Tech’s Mythos twos for front L and R with a Mythos thee center. For the rear surround L and R I’m using Speakercraft AIM8ONEs.
Thanks,
Skip
October 5th, 2009 at 1:51 pm
Hi Skip,
The recommendation for the DSX Wide and Height speakers is very broad. You can use any type of speaker that is practical in your room. As with standard 5.1 systems, you will get better results if the speakers are from the same family as your three main fronts because of the match in timbre.
October 7th, 2009 at 10:34 am
Hi Chris
I’m very interested in DSX partially for the improvement I’m sure it will bring to sound quality but also because I hope it will allow for non acoustically transparent, high gain / high contrast screens to be used.
If I place the LCR’s below the screen and use a pair of front height channels, will this make the sounds appear from half way up the screen height?
October 22nd, 2009 at 2:49 pm
Hi Rob,
DSX Height Channels are not intended to raise the front sound image. The Height (and Wide) channels are there to reproduce the additional acoustical and perceptual cues needed to produce an expanded and more enveloping sound stage. They don’t perform any vertical or horizontal panning of dialog.
November 4th, 2009 at 4:22 pm
Hi.
I eagerly await the right 9.1 or 9.2 DSX system.
I have prepared my spouse for the inevitable.
I have been a fan of the ‘wide’ speaker configuration for some time–I’ll explain. I am a fan of old Fosgate surround processors; I sometimes still use them for listening to music. However, for some outdoor applications it was not practical to arrange the speakers in a typical L/R front plus L/R rear configuration. As an alternative, I would position the two rear channel speakers as L/R ‘wide’ speakers. Using the Fosgate Model Four “Popular” surround setting, I always found the alternative ‘wide’ speaker configuration to offer a compelling soundstage that did not lead to fatigue.
p.s., the Fosgate “Rock” setting, on the other hand, did not work well with the alternative speaker configuration (too many ambient effects steered to the ‘rear’ channel speakers that caused fatigue when positioned as ‘wide’ speakers).
November 23rd, 2009 at 12:13 pm
“The Height (and Wide) channels are there to reproduce the additional acoustical and perceptual cues needed to produce an expanded and more enveloping sound stage. They don’t perform any vertical or horizontal panning of dialog.”
Chris,
Does this mean that sound effects are not panned through the Heights/Wides either?
JSS
November 23rd, 2009 at 2:20 pm
Hi John,
If the effects were meant to be panned they will be picked up by the algorithm and panned. I was referring to dialog in that quote because someone wanted to raise the dialog higher up using the Height channels. That’s not a good idea and Audyssey DSX will not do that.