Dolby Atmos: What You Hear
Among practitioners and scholars, there is a common quip that a technological change in film sound amounts to a “quiet revolution” for filmgoers. Last year’s roll-out of Dolby Atmos perhaps only further corroborates this observation. Of the several films mixed and released in the new format — films that include Brave (2012), The Hobbit (2012), and A Good Day to Die Hard (2013) — few mention Atmos in their promotional material. Additionally, filmgoers may be unable to distinguish an Atmos mix from a typical 5.1 or 7.1 soundtrack. Given that films like G.I. Joe: Retaliation (2013) were not initially conceived with Atmos in mind, to the untrained ear there may not always be a discernible difference between Dolby’s new format and previous technologies. Nonetheless, Atmos offers a filmgoing experience worth discussing, for if it or a similar system were to become the industry standard, then questions arise as to how its potential aesthetic might shape the way films sound and look. This blog post therefore provides just a few preliminary observations regarding the significance of Dolby Atmos’s technological and stylistic features.
With respect to its mixing capabilities, the Atmos system can send discreet sounds to up to 61 individual speakers and 3 low-frequency subwoofers. This updates Dolby’s recent 7.1 configuration (color-coded below), which consists of three full-range speakers behind the screen, a channel for each side wall, and a left and right channel for the rear wall. Additionally, 7.1 can feed low-frequency effects to an LFE or “.1” channel located behind the screen.
Atmos essentially keeps this 7.1 configuration but adds two more speakers behind the screen, two channels for ceiling speakers, and two additional LFE channels for the theater’s rear corners, creating ostensibly an 11.3 foundation. Generally, this foundation might contain the film’s music, ambient and background sounds, and — in the front speakers — the onscreen dialog and sound effects.
Most importantly, Atmos can send up to 128 sound effect “objects” to any single speaker in the auditorium. Whereas an offscreen bird might emanate from the entire left wall of speakers in 7.1, filmmakers can now mix the soundtrack so the bird emanates first from only the far speaker on the left, then from a front ceiling speaker, then from an adjacent speaker, and so forth if the filmmakers wish to recreate a bird’s circuitous flight through an auditorium. Further, because not every theater wired for Atmos will have the exact same number of speakers, the system can modify where it mixes its sound objects in order for that bird to journey identically through a 37- and 61-channel space.
This new means of mixing sound effects is known as a “pan through array,” and—as Dolby argues—the capability is an extensive improvement over the panning limitations of previous formats. Take for instance this early fly-over effect from the 5.1 mix of Broken Arrow (1996). As the airplane travels through the image from the background to the foreground, the sound pans from the front channels into the rear channels (circled in red below), creating the illusion that the plane is also traveling through the theater.
In Atmos these effects still exist, but the added channels on the sides and ceiling allow filmmakers more control over a pan’s speed and intensity. For example, as we crane toward the tornado in Disney’s Oz: The Great and Powerful (2013; pictured below), the storm’s howls slowly engulf one row of speakers at a time in order to create a more foreboding atmosphere and pace.
However, we should not assume that these chill-inducing aesthetics are how practitioners will continue to mix in Atmos once this introductory period is over. To offer some historical context, when Hollywood first introduced digital surround sound to audiences in the early 1990s, films utilizing these new technologies were also sporting aggressive sound designs. For instance, during the final gun battle from Carlito’s Way (1993) we hear screams, gunfire, and other sound effects, yet when we listen to just the two rear surround channels we hear only guns and bullets. The inclusion of only these sounds in the surround speakers would seem to create the illusion that bullets are actually whizzing by the heads of filmgoers.
(Here is an excerpt from the battle with every channel activated…
… and here is the excerpt again with only the rear surround channels activated.)
While Carlito’s Way typifies how 5.1 systems sounded during their first few years, such aggressive and kitschy mixes seemed to become passé by the end of the decade, with these more sensory experiences mainly quarantined for science-fiction or war films, and with most panning effects reserved for interplay between only the front speakers. I suspect a similar stylistic trajectory might also happen with Dolby Atmos.
So in lieu of treating aggressive sound mixing as essential to the Atmos aesthetic, we might conceive of the technology’s long-term appeal in two other ways. First, Atmos replaces each theater’s surrounds with higher-quality speakers that are capable of carrying wider frequency ranges. As opposed to previous soundtracks that were stored on 35mm, the increase in data space afforded to Atmos on DCP hard drives can then allow for more audio information and greater textural detail to emanate from these newer speakers. Second, and perhaps more interestingly, there are the ceiling channels. DreamWorks’s The Croods (2013) noticeably utilizes these new locations through its fabrication of reverberation and echo. During the film’s opening egg chase, the filmmakers mix Alan Silvestri’s A-TEAM-esque score so that it “bounces” off the ceiling like it would in a concert hall or indoor stadium. In addition, both The Croods (pictured below) and Rise of the Guardians (2012) feature fireworks and other elevated actions that take advantage of the ceiling’s speakers.
Ceiling channels and more detailed sonic textures are pleasurable additions, but they may pale in comparison to some of the more chill-inducing moments currently offered by filmmakers. If you are curious about experiencing these aggressive sound mixes firsthand then you may want to plan a trip to your closest Atmos theater before this type of aesthetic once again becomes passé.