The Beginner’s Guide to Spatial Audio

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Ed Gillett

Guest Writer

Sonos Era 300 is our first all-in-one speaker to support spatial audio with Dolby Atmos, making it easier than ever to experience immersive, enveloping sound you can feel all around you. But what exactly is spatial audio? Read on to find out.

If you’ve seen the term spatial audio recently but wondered what this concept means, you’re not alone. Sitting at the cutting edge of audio technology and sound design, there’s still plenty of confusion about what ‘spatial’ audio is and what it sounds like.

In this post, we’re breaking down how spatial audio can bring new levels of depth and immersion to your favourite music and films, and how to listen on your Sonos system.

What is spatial audio?

Put simply, spatial audio is an immersive, three-dimensional listening experience. Using multiple channels projecting outwards from each speaker, it can place individual sounds (or 'objects') with greater precision and variety than traditional stereo sound.

Most music we currently listen to is mixed in either mono (with sound coming from a single channel) or stereo (where sound is separated into two channels: the left and the right).

With mono, all the different elements of a song – the guitar, the drums, and the vocals – are combined to play through a single ‘stream’ of audio, all appearing to come from the same place. Stereo, on the other hand, separates and assigns sound elements to one channel or the other, adding more space and directionality to your music. It’s how you can hear a guitar solo on the left and backing vocals on the right, similar to listening to a live concert. This is what is known as the ‘soundstage’.

When listening in mono and stereo, your speakers are placed at the same level, delivering a sound experience in two dimensions. But with spatial audio, you add another dimension to the equation: height.

Working with spatial audio techniques, engineers and artists can now place sound within a three-dimensional canvas rather than being limited to two channels, opening up countless new creative possibilities. So not only are you hearing sound from the left and right but also forward and above, creating a multi-dimensional soundstage.

“Spatial audio is the next generation of listening”, says Sarah Ryan, Senior Manager of Product Marketing at Sonos, and one of the people who worked closely on Era 300’s development.

“Artists and creators have so many more options”, she explains.

“You can have the slide guitar sound as though it's flying overhead in the chorus of Elton John's ‘Rocket Man’, or you can place specific sound elements in precise locations for a certain period of time, almost like you’re in the room with the artist or band”.

The next generation of cinematic sound

While spatial audio can expand the horizons of your favourite music, it can also bring your home cinema to new heights.

To achieve multi-channel surround sound, you normally need four or more rear speakers in your setup: two placed to the left and right of your couch, and two or more placed overhead. You can experience that same multi-dimensional sound using just Era 300 as your two rear speakers in a home cinema setup, as the lateral and overhead channels in each create an all-encompassing soundstage you can feel all around the room.

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How does it work?

Spatial audio on Sonos Era 300 is powered by Dolby Atmos, the leading audio technology for object-based sound. Dolby Atmos dynamically maps audio objects in 3D space, then places these objects around the room consistent with the speaker’s position.

To produce sound that feels like it’s coming from above, upward-firing drivers in the speaker bounce sound off the ceiling. That reflected audio — combined with the sound coming directly from the speaker — makes it feel like sound is coming from spaces all around you.

“One of the ways I describe Era 300 is as a sound projector”, says Doug Button, lead Audio Systems Engineer at Sonos, who put his 38 years of experience designing speakers into ensuring that Era 300 sets a new benchmark for spatial audio.

Sonos uses what’s called beam-forming technology and waveguides in the design of Era 300, each of which help to focus sound in a specific location rather than dispersing it across a horizontal plane.

“Because you don’t want all the sound to go directly to the listener, sound is projected onto the walls and ceiling to create this sonic panorama that has both height and width”, Button explains. “We realised that just pointing the driver in the right direction wasn’t enough, you really need the processing and waveguide design to help achieve that”.

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Doug Button, Lead Audio Systems Engineer at Sonos
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A first-of-its kind design

With Sonos Era 300, creating an immersive listening experience has been the result of countless innovations and collaborative iterations between Sonos’ teams of audio engineers and industrial designers.

“One of the cornerstones of every Sonos product is that we want dialogue and vocal clarity to be exceptional”, says Button. “But our first prototypes just didn’t have that same presence. We had two woofers on the front and a little waveguide, and it just didn’t really work very well.”

In a moment of inspiration, Principal Industrial Designer Philippe Vossel sketched a different vision for Era 300, with the two woofers moved to the sides. This opened the door for more engineering possibilities for Button, and more design possibilities for Vossel — proving the value of teamwork.

“Moving the woofers opened up the whole front for me to make an absolutely perfect waveguide for vocal clarity”, Button recalls. “It also created a natural space for [Philippe] to design the user interface”.

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However, perfectly placing the waveguides and woofers was only the first challenge. Next came the upward-firing drivers: a critical component for delivering a true spatial audio experience.

“I could still hear sound coming directly from the speaker rather than reflecting off the ceiling”, Button details. “It didn’t feel like it was floating up in the air”.

Thanks to another cross-collaborative effort, Director of Audio Platform Engineering, Paul Peace uncovered how to cancel out any unwanted, forward-facing sound. It was at this moment Button said, “everything just clicked”.

“The real magical point came when we began listening tests”, Button explained. “People started asking us: Are you sure all this sound is coming from that one little speaker”?
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A note on placement

Because of the way three-dimensional audio works, the placement of Sonos Era 300 is important. For the speaker to most effectively project sound, you should leave space above and to the side of the speaker rather than fitting it into a bookshelf where the sound beams might get blocked. You can learn more about placement tips here.

Why should I listen with spatial audio?

Just as stereo sound was once a groundbreaking experience compared to mono, spatial audio is creating new relationships between artists and listeners.

Spatial audio gives your favourite music more clarity, depth, and detail than ever before. It can feel like you’re in the room with the artist, experiencing the music exactly as it sounded in the studio, or even listening from within the song itself. For films, spatial audio offers unprecedented realism and immersion, placing you firmly in the centre of the action.

Hear the difference yourself

Because of the way sound reflects off walls and floors, traditional stereo setups often have a ‘sweet spot’ within a room: an ideal place to sit where you’ll get the best listening experience. Unlike stereo, spatial audio doesn’t require a sweet spot. Instead, the whole room becomes the sweet spot with sound sent in all directions, allowing you to experience rich detail no matter where you’re seated.

The Sonos Sound Experience team hand-picked a selection of tracks that will allow you to experience spatial audio to its fullest. You can listen to the curated playlist on Amazon Music Unlimited here.

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How can I listen to spatial audio on Sonos?

To experience your music with spatial audio, you’ll need one or more Era 300 speakers and a Dolby Atmos-supported streaming service.

For the ultimate cinematic experience at home, add two Era 300 speakers as rears to a powerful soundbar like Arc or Beam (Gen 2). For more information on setting up surround sound, see our Ultimate Guide To Sonos Home Cinema.

No matter how you choose to listen, Era 300 offers a new generation of sonic possibilities.

“With spatial audio, people can bring their music and films to life in a way that is authentic to the creators”, explains Sarah Ryan. “The listening experience truly is amazing”.

As your options for listening continue to evolve, so will we. We are constantly evaluating the state of audio and looking for new ways for listeners to experience all the content they love with ease on Sonos. We’ll continue to update this post with new information, including when we introduce new spatial audio offerings from other streaming partners. And we want to hear from you. What else do you want to know about listening to spatial audio on Sonos? Just tag @sonos or send us a DM.

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