What is Dolby Atmos? How are consumers engaging with mixes produced in Dolby Atmos? Is Dolby Atmos the way of the future?
Dolby Atmos is the latest and greatest step in the world of surround sound. In addition to the typical '5.1' setup, Dolby Atmos introduces height to the surround sound world, by utilizing overhead speakers. Each sound can be placed in a 3d space, controlling where the sound is coming from. This is called 'object-based' audio format. In the production world, most mixing and mastering engineers will utilize 11 speakers in their monitoring setup to be able to hear accurately where the sounds they are placing will be perceived when played back in other Dolby Atmos environments.
Historically, we haven't seen a lot of music produced in surround. If you wanted to mix a rock band in surround, it would be difficult to get to crazy with sound placements without confusing the listener. "Why does the snare sound like its coming from behind me, and the guitars above me?" Most of the time, if you were going to be mixing a rock band in surround, you would likely be using the surrounding speakers more for spatial effect than anything else, to more accurately replicate the sound of a band playing in a great sounding concert hall, or something like that. Perhaps you might include some synth lines or sound effects to fill some of the rear space or above space, but the band would more or less be placed in front of you. Some more ambient, textural, or electronic music may be more suited to surround environments, as adding textural elements tends to be more commonplace in those genres.
But wait, who even listens to music in surround? If it takes so many speakers to mix, is it cost effective? Do we not expect that most music listening takes place on Bluetooth speakers, in cars, and headphones? Or some other various stereo and mono environments? Why does this matter?
Here is where I think Dolby has done a beautiful job with marketing. A number of consumer devices, are coming 'Dolby Atmos certified', and Apple Music supports Dolby Atmos playback. Apple AirPods are Dolby Atmos certified. A number of soundbar companies are creating 'Dolby Atmos' soundbars.
Now lets take a brief pause to look specifically at AirPods, in terms specifically of how they would perform as a 'surround sound' playback system in general terms. Each individual AirPod each contain a single 11mm driver. Regardless of how you look at it, AirPods can only operate as a stereo playback system, as there is only one speaker coming from your left, and one from your right. What is going on here?
In a traditional stereo recording, we talk about spatial elements of a mix all the time. 'The mix sounds huge' does not just mean width, which comes from different sound coming from one ear from the other (in broad terms). However, sometimes mixes sound deeper. Sometimes they sound taller. Have you ever turned around while wearing headphones, thinking you heard something behind you, realizing it was just something in the song? The human ear is very clever in how it perceives sound, and if we are clever as engineers, we can convince the listener that they are hearing sounds from behind them, when in fact they are only hearing sound from directly to the left, and directly to the right of them.
Without getting too technical, the biggest effect that impacts the human perception of where a sound source originates is comb filtering. Comb filtering occurs when a sound reaches your ear in two or more instances, at slightly different times. If someone speaks to you from across a table, You will hear their voice directly through the air, and again having bounced off the desk. The time difference is not typically perceptible (if it was it would be perceived as an echo), but you will hear them differently than if the table was not there. You will 'hear' the table. Select frequencies of the voice will actually cancel themselves out in your ear, in a 'comb' pattern. I won't include a picture of what occurs, as it is easily Google-able.
The big takeaway is that we can reproduce spatial characteristics by carefully applying this effect in a digital way. What can then be done, and I believe is what is done by Dolby, is to have a specific algorithm that applies predetermined comb filtering, reverb, and other processing to each channel of audio entering the AirPods– the channels for 'above sound', 'rear sound' etc,– and then sums the result to stereo for playback. From the listeners perspective, they are given an immersive 'surround' experience, however they are really just hearing a series of psychoacoustic algorithms designed to simulate a sound 'coming from' a different direction.
What I think is particularly interesting about this, is that you technically do not need the Dolby Atmos algorithms to achieve this effect. These algorithms could hypothetically be reverse engineered, and you could design a mix template that sums to stereo a very 3d, object-based feel. The resulting output file would just be a stereo mix, which would be more compatible on more playback systems, but could sound virtually the same as a mix created in Dolby Atmos played on a 'stereo' playback system like AirPods. The nice part about Dolby Atmos is that Dolby takes care of the hard parts of setting things up for you, they give you a much easier to use interface, and when played back on a true surround system using 5+ speakers, you will get a more natural feeling playback.
Essentially, Dolby has bottled the process and made it very user-friendly, provided you have an appropriate monitoring setup. But will Dolby Atmos have practical application in music production? This type of question is more interesting than I think it was with previous iterations of surround sound, given the prevalence of 'Dolby Atmos Certification' among some popular consumer products. If Apple Music is pushing it, there is a possibility that some number of artists choose to produce their music in surround.
The unfortunate stopper goes back I think to my earlier example of the rock band, as well as limitations of many studios. A lot of music would not be taken particularly well. While innovation is of course important in mixing, it is also important to keep in mind the listener expectations, and ensure the focus of the mix stays clear. If Dolby Atmos catches on, I think there could be a lot of room for creative use of the additional channels and space. While some genres will remain relatively untouched, and most music will continue to be produced in stereo, Dolby Atmos may prove to be very exciting and encourage listeners to engage more deeply with their listening experience.
It is possible also that Dolby Atmos does not catch on. Many top level studios will not feel the incentive to incur the additional monitoring costs and room setup costs to become certified to produce in the Atmos environment. Smaller project studios, further to that, won't even be able to consider such a hefty investment for what would practically allow no additional benefit for most of their clients. The market will only be able to support a small number of Dolby Atmos studios, at least for the immediate future.
While promising with its marketing and implementation in consumer products, I don't believe that Atmos will be able to take much more stake in the music market than previous iterations of surround sound. The cost/benefit to producing music in Atmos weights heavily against buying into producing in Atmos, as most consumers will continue to engage with music in ways that Atmos does not meaningfully impact. That being said, I do believe that there will be larger inroads to surround mixed music with Atmos. I think some artists will pursue Atmos as more than just a gimmick, and make some very awesome surround records.