3D surround sound is finally here and it is taking the home theater / media room industry by storm. Having now experienced it as it was intended to be experienced, in a well-designed and engineered environment, the verdict is in. What was once pegged as a mere attempt to sell more speakers is now accepted as a dramatic, exciting, and worthwhile step forward in the surround sound experience.
The first studios and commercial cinema releases incorporating 3D surround formats such as Dolby Atmos and Auro-3D have been around since 2012, but 2014 saw the year of the rise of 3D surround sound formats in the residential market. Much has been learned since the introduction of these formats in 2012. Let’s take a deeper look.
Before we talk about putting these new 3D sound systems into a room, let’s talk about the differences between Dolby Atmos and Auro-3D. They are significant.
Channel-based vs. Object-based sound mixing
In a channel-based sound system (i.e. Auro-3D), a sound designer mixes the many “sound elements” (dialogue, Foley stage effects, music, etc.) by distributing them over several audio tracks and directing them to specific sound channels that correspond to specific speakers or speaker arrays in a surround playback system. The postproduction facility is equipped with these standardized speaker configurations, which must then be matched as closely as possible in the home environment according to these predetermined configurations for accurate 3D surround sound reproduction. An Auro-3D sound mix is comprised mostly of traditional channel-based content, though it also implements a form of object-based sound technology also. Auro-3D believes this hybrid approach has some advantages over purely “object-based” systems, such as a channel-based system’s ability to support live recording of 3D music performances or sound effects. Object-based systems require “live” recordings to be artificially “created” in the mixing environment.
In an object-based sound system (i.e. Dolby Atmos), the sound elements are combined with metadata that describes how and where the sound element should be reproduced in the playback room based on numerous criteria (i.e. position and height level of the object in the sound space). The surround sound processor then “renders” the data with respect to the actual speaker configuration utilized in the room to create the desired 3D surround effect. Dolby Atmos also uses a more traditional channel-based surround “bed” of 7 or 9 speaker channels in combination with the new object elements.
To learn more about Auro-3D and Dolby Atmos, see the videos and website links at the bottom of this article.
Auro-3D calls for 3 layers of loudspeakers that consists of: 1 – Lower Layer – following the same design parameters as a current 5.1 or 7.1 surround configuration 2 – Height Layer – from 4 to 5 discrete channels correlated to the lower layer of speakers (note: Auro-3D does not use a discrete pair of height speakers to correlate to the surround rear channels) 3 -Top Layer – one or more loudspeakers for overhead effects.
Auro-3D has established speaker layouts for up to a 13.1 channel system (based on 7.1 with full complement of height & top layer). Smaller systems start with 9.1 (based on 5.1 with 4 height channels).
The actual number of loudspeakers will vary as room size increases to support multiple rows of seats.
Dolby Atmos approaches this from a different perspective. Supporting up to 128 discrete sound tracks and up to 64 speakers, the commercial version of Dolby Atmos allows for a lot of customization (e.g. a system incorporating a 9.1 Atmos surround channel “bed” allows for 118 discrete surround objects to pan, explode or whiz around via up to 62 speakers and 2 discrete subwoofer channels). Eschewing one size fits all speaker configurations, Dolby enables the home theater designer to design a sound system and speaker placement scheme that fits the unique acoustical properties of the room size and shape. As the sound processing is an “intelligent” system, speaker placement data and positioning metadata in the audio stream will optimize playback for each specific space. The hidden gem here is that a Dolby Atmos surround sound processor “renders” the soundtrack in real time to the specific room/speaker configuration.
The sample speaker layout at the top of this article shows a total of 11 speakers plus a single subwoofer, but depending on the room and desired surround sound performance, you can add quite a few more speakers to this example, and the intelligent Dolby Atmos sound processor will use each additional speaker to steer the sound around the room more accurately. A well-designed speaker configuration will support a virtually unlimited position of sound objects in 3D space, greatly enhancing the audience experience. The difference is immediately noticeable; this is not a gimmick!
OK, So What About My Room?
Both Auro-3D and Dolby Atmos have published specifications for speaker placement configurations for both the commercial cinema and the residential market. You can see some basic examples of residential speaker layout diagrams from the graphics on this page. However, after having spoken to the designers and manufacturers of both systems and designing many theaters to be compatible with both formats, it became very clear that a high-performance private home theater specification should actually fall somewhere between their recommendations for full scale commercial and a scaled residential implementation to achieve the best that each format has to offer. Not only that, but every room will have a unique seating layout, distinct acoustical qualities, and an interior design in which all of the loudspeakers (from 15 to 30 or more!) need to be integrated.
Speaker layout for 3D audio is no small task, especially when you consider that it is just one piece of the holistic engineering puzzle of a high-performance private theater. However, despite the industry confusion and fairly dramatic technical differences in the formats, there are logical speaker placement strategies that can accurately accommodate both Auro-3D and Dolby Atmos formats in a private theater design. The improvement to the overall experience is well worth the effort of integrating such a system.
What If I Want Both Dolby Atmos and Auro-3D?
Good news…you can have both. Right now, the surround sound processors that include both are high-end products…Steinway Lyngdorf‘s new P200 processor and Datasat’s RS20i. Both of these premium level products will make the foundation of an amazing home theater system. Since Dolby Atmos and Auro-3D use slightly different speaker locations for the height channels, the P200 and RS20i have the flexibility of having speakers placed in each format’s “ideal” positions, and they will switch to the corresponding speakers depending on which sound format is decoded. At this time, the more common AVRs (Audio Video Receivers) and Preamplifiers/Processors have either Dolby Atmosor Auro-3D.
Truly, the smart way to approach an investment in any high performance home theater, and specifically with these emerging technologies, is to consult with a professional who has the experience and expertise to yield the most out of every home theater design. Your Tech is that professional.
Dolby Atmos video and website link : https://www.dolby.com/us/en/technologies/dolby-atmos.html
Auro-3D video and website link : https://www.auro-3d.com