The Ultimate Guide to Dolby Atmos, Part 1: What is Atmos and How Does It Work?

Dolby Atmos is revolutionary surround sound technology, bringing a thrilling new height element to three-dimensional audio and producing sound that is spacious, immersive, and real.

Dolby Atmos is an “object-based” audio format that lets creators precisely place and move individual sounds virtually anywhere in a three-dimensional space—including overhead—to present a fully enveloping listening experience.

It used to be that Dolby Atmos could only be experienced in theaters. But today, you’re spoiled for choice of Atmos-enabled TVs, sound bars, receivers, streaming services, and even mobile devices, with a vast amount of movies, TV broadcasts, videogames, and music available in Atmos surround.

Now that Atmos is everywhere, you might be asking yourself, is this the right time to upgrade to an Atmos sound system? Is system setup complicated? How much does it cost to get started? We’re digging into these questions and more in our four-part series exploring this groundbreaking immersive sound format. In this first installment, we’ll look back at the difference between Dolby Atmos and traditional surround sound, and we’ll let you know what you need to enjoy immersive Atmos sound at home.

A Little History

Dolby has been trailblazing surround sound technologies for film for nearly 50 years, beginning with the debut of the Dolby Stereo matrixed optical four-channel format in 1976. More cinema-sound breakthroughs followed with Dolby SR, Dolby Digital Surround, Dolby Digital Surround EX, and Dolby Digital Plus formats. But when Dolby Atmos sound debuted in 2012 at the premiere of the Disney/Pixar animated film Brave, it ushered in a new, truly multidimensional surround-sound experience. In the ensuing decade Dolby Atmos has become the leading surround-sound platform for film, television, and games.

Meanwhile, Dolby Atmos Music, which debuted in 2019, is gaining momentum, at home, in mobile experiences including cars and headphones, and even at live events. For more than 80 years, with the exception of a few esoteric surround formats, most recorded music has been heard in stereo. Dolby Atmos Music is changing that, applying the same immersive technology used to create Atmos soundtracks to the music production process.

With Atmos, movie, game, broadcast, and music producers have unprecedented freedom to create expressive, dynamic mixes with more depth and realism than ever before.

The effect is transportive: You’re no longer sitting on your couch, you’re riding that horse, zooming through the galaxy in a spaceship, ducking on the battlefield as mines explode around you and helicopters swoop overhead in hair-raising realism. For music fans, it’s like falling in love with your favorite songs all over again, as you’re enveloped in newly immersive, lifelike sound.

Thanks to the vast catalog of content and the simplicity and affordability of home systems, Dolby Atmos is gaining traction everywhere. Let’s dig into how it works.

Object-Oriented Versus Channel-based Surround

It’s important to understand that Dolby Atmos is not a gimmick or special effect; it’s a different way to design and present sound on a new plane and with more precision, for an incredibly lifelike sound field. This realism comes from Atmos’ object-oriented approach to sound.

Traditional sound mixes are channel-based, meaning recorded sounds are assigned to channels, which are assigned to speakers. In a stereo recording, sounds meant to be heard on the left are reproduced by the left speaker and sounds meant to be heard on the right are reproduced by the right speaker, with an optional subwoofer handling deep bass.

Traditional surround-sound formats expand on stereo, assigning sound to a center channel and additional surround speakers around the room. This type of surround sound is typically available for five- or seven-channel sound systems; these configurations are referred to as 5.1 and 7.1, respectively. (The first number represents the full-range speakers and the “point one” represents the subwoofer.) Though these setups sound much more immersive than mono or stereo sound, they’re still limited to a defined number of channels, and limited to a horizontal plane.

Dolby Atmos, on the other hand, gives content creators the flexibility to manipulate individual sounds as objects that can be placed with pinpoint accuracy anywhere within a 3D space—including overhead—without being directly assigned to specific speakers.