Immersive sound takes the traditional multi-channel surround experience to a whole new level by using height or presence channels (speakers mounted high on walls or a ceiling) to create a dome of sound.
Your Guide To Immersive Sound: Atmos, Auro-3D, And DTS:X
Todd Anderson | Aperion Audio
Immersive sound has taken the home theater world by storm, easily matching the emergence of 4K Ultra High Definition and High Dynamic Range video as the industry’s hottest topics. Equipment manufacturers have universally embraced the technology and are actively releasing gear to make some form of immersive sound a reality in the home environment. While this is great news for hardcore enthusiasts, it means new terminology, products, and system implementation hurdles exist for average non-technical buyers. If you find yourself in the latter camp – don’t fret – we have you covered. Today, we’ll take a look at the history of immersive sound, review the status of three current immersive sound solutions, and get you up to speed on what kind of equipment you’ll need to bring immersive sound into your theater room.
Immersive Sound: What is it?
Most everyone is familiar with the concept of traditional surround sound. It’s used to wrap audio around a listener using either 5.1 (five speakers, one subwoofer) or 7.1 speaker configurations.
Surround sound is strictly a channel-based technology, which means audio content is encoded to playback through specific speakers in a pre-defined arrangement. Immersive sound takes the traditional multi-channel surround experience to a whole new level by using height or presence channels (speakers mounted high on walls or a ceiling) to create a dome of sound. The resulting “3D” audio effect is absolutely stunning and ushers the listener that much closer to experiencing artificial sound that mirrors real-world auditory experiences. While traditional channel-based audio can be used to create immersive sound, a new type of audio encoding called “object-based audio” is proving to be highly effective. Object-based audio allows Hollywood moviemakers to program an audio mix that pinpoints sounds to specific areas of space within a room. Properly equipped AV Receivers (AVRs) can decode a film’s object-based encode and use available speakers to best replicate sound placement as intended by the filmmaker.
There are three different immersive sound formats on the market:
- Dolby Atmos
Auro-3D is the oldest, first hitting commercial theaters with the release of George Lucas’ 2011 film Red Tails. It has remained a viable format on the commercial side of the equation, but has yet to gain serious traction in the United States home market.
Dolby Atmos arrived (commercially) about a year after Auro-3D and has made strong inroads into the home market. Hundreds of theatrical releases have been encoded with Atmos and the format has seen dozens of titles hit store shelves on Blu-ray disc.
DTS:X was first announced to the public in early 2015 and – until recently – has remained in development. We expect to see DTS:X firmware updates released by equipment manufacturers throughout 2016.
The existence of three competing immersive sound technologies gives home theater owners plenty of options and this year’s class of moderately priced AVRs appears to be future proof when considering new 4K video requirements. That means upgrading to immersive sound now is a viable possibility. The bad news is that each immersive sound codec requires its own specific hardware and (in the case of Auro-3D) speaker layout. Choosing a format to pursue requires an understanding of what each one offers and where they stand in the current market.
Dolby Atmos is the current king of immersive sound. Roughly 1,000 commercial theaters have deployed Atmos speaker systems and nearly every major AVR manufacturer features some iteration of the technology embedded in its gear. Media is prevalent too, with nearly 40 movie titles available on Blu-ray disc (and many more on the way). Atmos is an object-based codec that operates using speaker configurations ranging from 5.1.2 (five surround channels, one subwoofer, two ceiling presence channels) to 7.1.4 or 9.1.2 in the home. Current top-end AVRs aren’t capable of supporting configurations larger than eleven channels, yet.
Atmos ready AVRs (otherwise known as Atmos enabled) first appeared in late 2014 along with the first Atmos encoded Blu-ray title: Transformers: Age of Extinction. Early adopters of first generation Atmos AVRs were limited to 5.1.4 or 7.1.2 speaker configurations. Current 2016 models typically offer 5.1.2 and 5.1.4 compatibility on less expensive models and full 7.1.4 compatibility on top-of-the-line models. It’s important to note that AVRs offering 7.1.4 sound only have nine internal amplifier sections (able to run 7.1.2 speakers as a standalone unit); an external two-channel amplifier is needed to run a full 7.1.4 speaker array.
Too good to be true?
One of the detractions to Atmos is the necessity for presence channels in the ceiling. That means that users need to install in-ceiling speakers or speakers mounted on the ceiling. An alternative solution is to install Atmos-enabled speaker modules that can be placed on top of existing front channel and surround sound speakers. These modules are designed to bounce sound off a ceiling to create the illusion of in-ceiling speakers. This solution is easier to implement but isn’t as effective as true in-ceiling speakers. Modules do a decent job of tricking ears when it comes to high frequency sounds, but low frequency sound waves are much more difficult to direct and bounce in a controlled fashion.
Building your Atmos system
You can build an Atmos speaker system using an existing surround sound set-up as a base. Dolby says that an optimal set-up features a minimum of five surround channels (three front, two side, and/or two rear) deployed at the same height (using front channels as a reference point) and presence channels mounted slightly in front of seating, over seating, or behind seating. According to THX laboratory testers, the best Atmos layout employs two presence channels mounted over seating and two mounted in front of seating; rear mounted presence channels are less optimal. THX testers have also suggested that an Atmos system is sonically handicapped without the use of rear surround channels. That means a 5.1.2 or 5.1.4 Atmos system is okay, but a 7.1.2 or 7.1.4 system will have audible benefits.
Most Blu-ray players that support Dolby TrueHD will work with Atmos encoded discs. However, some older players might have onboard hardware that’s incapable of handling a Blu-ray disc feature used by Atmos called “seamless branching.” Seamless branching is a method of disc authoring that stacks movie scenes out of sequential order on a disc. If a player is ill equipped, then audio dropouts will be heard. This is something to keep in mind (and potentially budgeted for) when investing in an Atmos system.
The sound produced by a full 7.1.4 Atmos speaker array is a revolutionary advancement in audio. The resulting dome of audio immersion can place special effects all around a room, but also adds noticeable height to audio featured in a system’s front three channels (such as a film’s score). There have been quite a few spectacular Atmos Blu-ray releases, highlighted by Gravity: Diamond Luxe Edition, John Wick, and San Andreas. Hollywood is still learning how to use Atmos to its advantage and the future for the audio codec is incredibly bright. Atmos encoded movies are backwards compatible making them playable in standard Dolby TrueHD on legacy equipment.
Auro-3D currently occupies the role of the “Little Engine That Could” in the U.S. home market but the company is bullish about its prospects. According Filip De Pessmier (Segment Director, Auro Tech), Auro-3D is big in Europe, even bigger in Asia, and is actively working with high-end AV manufacturers in the United States. Recently, Auro Tech unveiled two new brands of audio products: StormAudio and GalaxisAudio. These brands offer customers access to amplifiers and processors that are Auro-3D, Dolby Atmos, and DTS:X enabled.
Similarities to Atmos
Auro-3D is dissimilar to Dolby Atmos in that it relies on channel-based audio mixing. Speaker arrangements consisting of (up to) thirteen speakers create immersion using layers of sound produced by ear level and wall-bound height channels located in the front, back, and sides of a room. Home systems can also utilize one center mounted ceiling channel (Voice of God) in rooms with higher ceilings. This obviously makes mixing and matching optimally deployed Auro-3D and Atmos speaker systems difficult. There might be ways of placing speakers in unique “happy medium” arrangements to take advantage of both codecs, but we lack real world testing to know if this is worth pursuing.
Auro-3D systems have been deployed in over 550 commercial theaters worldwide and more than 35 postproduction facilities have installed the Auro-3D Studio System to create content for home theaters. Blu-ray discs featuring the codec are limited to a handful of movie titles (Pixels being the most recognizable) and albums. Equipment is also relatively limited in quantity and price. Auro-3D has primarily found its way to higher-end AVR models (in North America) and the company’s new StormAudio and GalaxisAudio products aren’t exactly inexpensive. Denon is one of the few manufacturers producing moderately priced Auro-3D enabled AVRs, however activating Auro-3D on these models incurs a separate fee.
Auro-3D is certainly hampered by equipment costs, speaker requirements dissimilar to Atmos, and an overall lack of media in the North American market. That’s highly unfortunate because Auro-3D’s audio impact is breathtaking. The codecs use of layered sound around a listening space is beyond immersive and decidedly different than the object-oriented effect generated by Atmos. Auro’s marketing team says its system creates a “sound based hemisphere” of immersion, a notion that is hard to dismiss. It truly ushers a sense of “being there” and hearing sound as if it were in a seamlessly expansive real world environment.
DTS:X was first announced at the Consumer Electronics Show in January 2015 and has remained vaporware until several weeks ago. Similar to Auro-3D and Atmos, DTS:X can only functionally operate on equipment endowed with special hardware. Luckily, most manufacturers spent the majority of 2015 shipping AVRs with that hardware onboard. Last month Denon and Marantz began to deliver downloadable DTS:X firmware updates to make this hardware usable and we expect Yamaha to release something similar in March. DTS says that other manufacturers will announce their firmware rollout schedules soon.
A key feature of this object-oriented codec is speaker flexibility. DTS’s marketing team says it doesn’t require any specific speaker layout to work; anything goes. This means that DTS:X has the potential to play nicely with both Atmos and Auro-3D speaker arrangements. That being said, recent media materials from DTS clearly depict recommended speaker layouts (5.1.2 through 7.1.4) that look nearly identical to Dolby Atmos arrangements. They emphasize ear level surround channels and four ceiling presence channels.
DTS:X began appearing in commercial theaters last August with blockbusters hits such as Sicario and The Hunger Games: Mockingjay – Part 2. Blu-ray releases have been notably sparse with only four titles to date (American Ultra, Crimson Peak, Ex Machina, and The Last Witch Hunter). Much like Atmos, DTS:X is a backwards compatible codec that can be played on equipment compatible with its legacy Blu-ray codec, DTS-HD Master Audio.
DTS:X demo material was publicly revealed at CEDIA 2015 in Dallas, TX and reports indicate that it aptly demonstrated the codecs ability to achieve excellent levels of auditory immersion. DTS-HD Master Audio has been a preferred audio codec for years, and there’s every reason to believe DTS:X will follow suit. Look for DTS:X encoded Blu-ray titles to flood the home market during the coming year.
Immersive sound marks a revolutionary step forward in audio and we’re only beginning to hear its potential. This begs the question: is it the right time to dive-in and buy new equipment to support an immersive sound experience? Absolutely, it is. If you decide to set-up an Atmos/DTS:X system, you’ll likely find it to remain functionally viable for years to come. While Auro-3D has less traction in the North American market, its ability to produce an absolutely convincing natural effect makes it something true enthusiasts should consider.
Your own overall immersive experience will directly mirror your ability to properly set-up the largest multi-channel speaker arrangement possible. You should consider a 5.1.2 channel system using Atmos enabled speaker modules to be the least desirable solution and a full 7.1.4 system with in-ceiling speakers to be ultimately optimal. There are plenty of set-up guides available through Dolby, DTS, and Auro Tech. Read them and follow the guidelines for your chosen immersive audio solution. If you do, you’ll inject a new level of audio performance into your theater room that’s sure to please.
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