Ron DiCesare
Issue: October 1, 2009


Surround sound is a very broad term that covers many different audio configurations. The number of channels and the placement of the speakers vary with each format. 5.1 is the most common, but other types include many more channels and can even reproduce the experience of height. The future will very likely bring new formats and applications of the surround experience, such as the highly versatile format of 10.2.


In 1987, Tomlinson Holman, chief scientist at Audyssey Laboratories ( and professor at USC in Los Angeles, coined the term 5.1. Holman is a true audio pioneer whose forward thinking includes developing THX, and more recently, the 10.2 surround sound format. Holman’s vision of 10.2 goes beyond the limitations of 5.1. “The original documents say that 5.1 is a system for the minimum amount of channels needed to accompany a picture,” he says. “It was known to have limitations because it had to be put on a film digitally, so there was a cap on things with 5.1.
“All through the period from 1987 to 1997, I was working on what the next logical step was from 5.1,” he continues. “We know that everyone can hear the difference between mono and stereo. The same is true between stereo and 5.1 in the home theater market. So for me, the next obvious step was from five to ten. There are three basic reasons: physical acoustics, psychoacoustics and desires of filmmakers, composers and producers.”
10.2 uses five front speakers positioned left wide, left, center, right and right wide. There are three rear surround speakers positioned center, left surround and right surround. Interestingly, there is a choice of either left and right surround diffuse, or left and right surround direct, depending on the program’s content. There are two height speakers positioned in the front left and right above the listener. Lastly, there are two LFE channels positioned left and right. 10.2 has a total of 14 electrical channels, but uses 12 speakers for playback. “Now, 10.2 is a bit of a fudge, because we have found that if you could sit perfectly in the center, you still could tell where the speakers are placed if you turned your head around,” explains Holman. “So, I added two more channels so that we have two types of rear surrounds to choose from. The producers and content creators can choose between localized [direct] surround channels for specific events, or general [diffuse] surround channels for things like ambiences or reverberations.”
He says there are two reasons to have two low frequency channels at 120Hz. “The first reason is with the combined 10 channels, the power level requirement for a single LFE would quadruple its size! So, it’s a lot easier to have two subwoofers since they hardly cost anything regarding the bandwidth size. The second reason is that it allows you to make a left or right difference in the low frequencies. True, some people may disagree that you can detect left or right with the low frequencies, but it is there for those who want it. Ultimately, 10.2 is 14 electrical channels but I call it 10.2 speaker locations.”
One of the most exciting aspects of the 10.2 format is the ability to reproduce height. “Height relates to psychoacoustics,” says Holman. “As you raise stereo speakers in front of you, the imaging holds up very well. Because 10.2 can reproduce height, the sequence I would most like to see done in 10.2 would be the attack on Pearl Harbor.”
Though 10.2 is not commonplace yet, it is starting to take hold. Holman understands the difficulties of introducing a new audio format. “We do envision this format everywhere, but it’s a bit of a chicken and the egg problem. We know that it is not going to sell until there is more software for it. There is progress being made; it is embedded in Apple’s QuickTime and called TMH 10.2. And, there is space allotted for 12 channels in the digital cinema format. So, right now we have about 25 items of program material. We keep adding more content so that we can become embedded in people’s consciousness.”
10.2 very well may be the future of surround sound. One of the most logical steps toward the wide spread use of 10.2 might be IMAX, especially due to the stereo height channels. Holman would welcome the standardized use of 10.2 for IMAX, but he envisions 10.2 being used for any type of media and having a much wider audience. “It would be a set of computer files that have 12 channels which could be set with metadata,” he explains. “The metadata would tell the audio how to be reproduced and play in a 10.2 large room, or in a 10.2 small room, or a regular 5.1 room. It could even include how to play it in 4 channels in the car, or the best possible mix for an iPod, and so forth. It would be all one big data file with all these side streams saying what to do with the audio based on what your situation is. It would be tailored to fit every possible media. Different mixes could be made and the mix data would be recorded and sent to DSP in the home. This was the vision 28 years ago when they got started. Now today, it’s not crazy at all.
“That’s where I see surround sound going,” continues Holman. “It will be really hard to convince the music industry and others to follow through, but, the metadata is the answer. 10.2 can be done in a scalable fashion to be down-mixed to fit your choice of number of speakers. It is this concept of scale-ability that makes 10.2 suitable for everyone.”


Sony’s 7.1 surround sound format is called Sony Dynamic Digital Sound, or SDDS for short. At Sony Pictures Post Production, (www. supervising sound mixer Greg P. Russell has recently mixed films such as Transformers: Revenge of the Fallen, Angels & Demons and Cloudy With a Chance of Meatballs. Russell has extensive experience with Sony’s SDDS 7.1 surround format. Though it is not widely used in theaters, 7.1 offers some interesting benefits over 5.1 surround sound. “SDDS is a Sony format, but anyone can mix in 7.1 in any other studio,” explains Russell. “At Sony, we have been the pioneers of 5 channels across the front, which is left wide, left, center, right and right wide, and of course the left and right surrounds, along with the LFE, give you the 8 channels in total.
“In the mid to late ‘90s, I really played around with 7.1 on such films as The Mask of Zorro and Godzilla,” he continues. “That’s where I really started to create and work with these 5 channels across the front. I was a big fan of it right from the start because when you have that kind of energy coming off the screen, you can separate the elements. I like to use the far left and right channels as an outer stereo pair and the interior left and right channels, closest to the center channel, as an inner stereo pair. For example, if I have some really thumpy low-end elements for an explosion, I can separate them from the hard left and right and put them into the interior left and right. That creates better audio imagery with a little more definition. Having 5 speakers handling the full load rather than 3 speakers gives you more separation and clarity.”
Dialogue, no matter what the surround sound format, can sometimes benefit from slight panning to match the action on the screen. “Moving dialogue across the screen with the 5 speakers of SDDS can be tricky,” explains Russell. “We do it, but we never want it to be distracting. The robot voices in Transformers were moved slightly left and right to accommodate two different voices speaking, though it wasn’t a 7.1 mix. Very soft panning can be effective — a little of that can go a long way because we never want to be distracting. It can work great for off-camera lines, too, but the norm is to keep it center.”
Making a theatrical release in SDDS 7.1 compatible with the typical 5.1 home theater market means Russell must account for the differences between the size of the room and the amount of speakers in the home. “It usually is another day on the dub stage to make the 5.1 home theater mix,” he says. “As much as I love having 5 speakers across the front with 7.1, the 5.1 version is what most people are going to hear in most theaters and especially their homes.”
Transformers: Revenge of the Fallen, and Cloudy With a Chance of Meatballs was mixed at the Cary Grant Theater at Sony located in Culver City, CA. The impressive 332-seat re-recording motion picture theater features the Harrison MPC2 digital mixing console with 320 channels running Digidesign’s Pro Tools|HD. “We have great rooms and we very are fortunate,” he says. “They are upgrading the console with the latest version of the Harrison. The Cary Grant is the largest room in our facility.”


By far, 5.1 is the most common format of surround sound used in TV and film mixing.
“Most theaters are only capable of playing back 6 tracks. So, a 6-track is the norm, and that’s what a 5.1 mix is,” says Jim Bolt, re-recording mixer at LA’s Fox Studios (www. “Therefore we mix according to what most theaters can present and what the commercial output is going to be.”
Bolt creates a surround mix for both the 5.1 theatrical version and the 5.1 home theater market. “On feature films such as Star Trek (2009) and Aliens in the Attic, when we are done with the theatrical mix, we do what is called a near-field mix, which is for the home release format. The biggest difference between 5.1 mixing for a theater and mixing for the home is the dynamic range. In a feature film, you have a little more room to be dynamic with louder louds and softer softs. Mixing for the home 5.1 system requires a smaller range of the dynamics, it’s not as much as a feature film.
“When we do a near-field mix, we set up near-field speakers in a dub stage to match a home theater environment,” continues Bolt. “The speakers are about six to 10 feet from where you are sitting. The left and right speaker positions are not as wide in the home, and the surrounds are very close to you compared to a theater. We also have a device that simulates the Dolby AC3 encode/decode to listen to how it will be played at home when we are working.”
Bolt says making a home theater mix from the theatrical mix isn’t done with a singular device or technique. “It’s finesse, and there is no formula for it. Each show is an individual and needs to be handled differently each time. Now, we try to present the same dynamic range for the theater in the home. But we are limited with the levels and we have to compensate for that. There are technical things that we must do to achieve this. The quiet levels really have to come up to play as low level in the home. What was low level in the theater would get lost in the home theater market so you have to make up for that. And the loud stuff is sometimes a little overbearing in the home. We don’t want people using their remote control like a mixer, where they are turning the sound up when they can’t hear the dialogue and turning it down when it’s too loud.”
There are many physical differences between a home theater and a movie theater, with size of the room just one of them. One interesting difference pertains to the location of the surround speakers. The surround speakers are located along the side walls of the theater in addition to the back wall. “The speakers along the left side wall combined with the left speakers on the back wall are all considered to be the left surround,” says Bolt. “And the speakers along the right side wall combined with the right speakers on the back wall are all considered to be the right surround. So, depending where you sit in a theater, it’s possible to have the surrounds in front of you. That’s because the front rows need to have surrounds, too. The only way that is possible is by having speakers along the sides within the range of the audience in the front row.”
To compensate for this difference, the audio timing for the surround speakers is taken into account. “In the theaters, the surround speakers are timed on a delay to match what is coming out of the front speakers,” he says. “Otherwise, the surround sound would get to you first because those speakers are closer to you. And the farther back you go in the theater, the larger the time delay is for the surrounds simply because it takes longer for the sound of the front speakers to reach you.”
Star Trek was mixed at Fox Studios using all three dubbing theaters, the Howard Hawks, the John Ford and the Robert Wise. Each theater is equipped with the AMS Neve Digital Film Console and Pro Tools. “The compressors on the DFC are great, very gentle, soft and not abusive,” reports Bolt, who also uses the Cedar DNS3000 noise reduction system and mixes on a 5.1 Genelec monitoring system.
A variation of 5.1 for the home and the theater is called Dolby EX. The main difference is that it includes a center surround channel for a total of seven channels, or what is called 6.1. This format has limited support in the field. “It’s a total of 7 channels,” says Bolt,“so, you have to specifically prepare a surround mix for 6.1 when you are working. It can affect the levels and imaging of the surrounds if you are not technically prepared for it.”


IMAX has become more and more common over the years, but there is a very important distinction to make. Todd-AO’s ( premiere IMAX mixer, Ken Teaney, explains how not every film is fully produced in the IMAX format from beginning to end. “I have done more IMAX mixing than any other person, with 35 or 36 films on my credit list, including my most recent one called Grand Canyon Adventure: River At Risk. All of these films, right from the start, were shot in IMAX and cut the way IMAX is cut. For example, compared to a normal film, IMAX shots tend to be a little longer. The concept is to give the audience the time to look around. The frame is so large that it takes time to take it all in. Generally speaking, most of the action happens on the bottom part of the screen. That’s where people’s heads and line of site normally rest.
“Another important distinction is that during shooting, the film loads are very, very short,” he continues. “A smaller, lighter, specially-designed IMAX camera, like the one used on location on Everest, may only have one minute of film in each load. So, for a standard feature film, this would not be practical. When it comes to a true IMAX film, done from the ground up, directors like Greg MacGillivray truly know how to use the immensity of the shot in their framing and panning. Pans tend to be slower paced because people need a chance to look at everything. Panning too quickly can make people who are prone to motion sickness get sick. Now more and more IMAX is done in 3D, so it is all shot differently and paced differently. Almost always, a true IMAX film is like an educational documentary short film, usually under 40 minutes long. Sure, there are more IMAX theaters popping up and Hollywood has been trying to get on board, but until we get over the obstacles of filming in IMAX, I don’t think you will see a traditional Hollywood-type film shot in IMAX, fully. That will most likely change when we get to an all-digital version of it.”
The IMAX audio format is different from the standard 5.1 layout. “The current IMAX format is 6 channels laid out as left, center, right, left surround, right surround and overhead,” says Teaney. “The single overhead speaker is located at the top of the IMAX screen directly above the center speaker. There is a seventh speaker that is a subwoofer, but it is not a seventh channel. This is somewhat of an enigma because it is not a discreet LFE channel. Like any subwoofer, it derives its information from all the channels. All the channels are feeding the subwoofer at a certain frequency range, at 120Hz and below. Those of us who work this format have asked for an LFE channel because it would nice to mix specifically for the sub.”
Now, with the surround speakers, it’s a level playing field, he says. “It is sonically pure, because you don’t have a limited frequency range like you have with a standard film. Here, the surrounds are the same size as the front speakers behind the screen. Full range surround speakers make for some pretty interesting stuff that can happen behind your head. Now, combine that with the fact that IMAX theaters are almost always wider than they are longer, the result is that the surrounds feel like they are a lot closer to you. It’s like the sound is right by your head.”
The IMAX surround sound format offers the experience of height with a single overhead channel. “The overhead is an interesting speaker because we use it sparingly,” he says. “I mixed a film called Dolphins, which is a great example of how most of the action is at the bottom third of the screen. So when the dolphin goes up to the surface to breath and breaks the surface, you hear that at the top of the screen. It’s a magical moment in the film because of the overhead channel. Another good example is with the mix I did for Everest, which is the highest grossing IMAX film to date. We started the avalanche at the top of the screen in the overhead speaker. As the avalanche came down the screen, so did the sound. It comes down from the overhead, into the center, then spreads into the mains, and buries the camera and sweeps behind you into the surrounds. The cool thing is that the sound never changes with its full range of frequency and intensity. It’s such an amazing physical force when it comes off the mains and into the surrounds. You really feel it.”
Grand Canyon Adventure: River at Risk was mixed at Burbank’s Todd-AO on Stage 2 using the AMS Neve Digital Film Console. The Lexicon 480L was used for reverbs and the iZotope RX plug-in was used to help remove the excessive noise created by the IMAX camera on the dialogue tracks and production sound. “We always do a quick knock-off print master and run over to the California Science Center to listen to it in an actual IMAX theater,” says Teaney. “We take our notes there and then make changes based on what we heard there.
“The IMAX format is an amazing sonic experience,” says Teaney. “It’s designed to allow the audio to be as large as the picture. We can do full pans from back to front and not have to compensate for any limitations because the surrounds are the same size as the mains and can reproduce anything the mains can. What makes it such an immersive experience is that the surrounds can put the audience in the middle of what they are seeing. It’s so much fun to work in, it’s a sonic playground!”