Sennheiser Powers New Spatial Audio Experience on Netflix

Back in August of 2021, Netflix began supporting Apple’s home-grown Spatial Audio feature via the Netflix app for iOS. If you had a compatible iPhone, iPad, or  Apple TV 4K, you had the opportunity to enjoy Apple’s “spatialized” audio via headphones. The idea was to deliver an immersive audio experience without the need for a big home theater and multiple speakers. But this was a pretty limited offering. Unlike Spatial Audio for Apple Music, which works with any type of headphones, Netflix’s application of the tech relied on head tracking, and so it only worked with Apple’s AirPods (3rd generation), AirPods Pro (1st and 2nd generation), AirPods Max, and Beats Fit Pro. Now, however, Netflix has teamed up with the audio experts at Sennheiser to provide Spatial Audio to all devices. Netflix says that this new Spatial Audio technology “helps to translate the cinematic experience of immersive audio to any (2-channel device), so the work (that) creators do to bring you into the story happens no matter what device you use to watch Netflix.”

Some of the most iconic moments in TV and film are defined by the immersive moments they create through sound.

— Netflix

From standard stereo mixdown (left) to full AMBEO effect (right): re-recording mixers can fully control and fine-tune the spatialization

Audioholics readers know better than most that the subtleties of a surround mix can be just as important as the thunderous explosions. The mood and atmosphere of a scene can be altered, or even completely carried, by the dimensionality of the sound. The creative decisions that go into building that atmosphere have the potential to elicit powerful emotions from the audience, but that only works if the playback equipment can faithfully recreate the sonic brushstrokes of the artists working on the mix. When an immersive Dolby Atmos mix is down-mixed to stereo for playback on a TV or a pair of earbuds, much of the creators’ intent is typically lost. Netflix hopes to remedy (or at least mitigate) this loss through the use of Sennheiser AMBEO technology, which promises to deliver an immersive surround sound experience that is compatible with all 2-channel devices. Sennheiser’s AMBEO 2-Channel Spatial Audio renderer is designed to “translate original immersive mixes into 2-channel audio with a spatial experience that extends beyond stereo,” according to Sennheiser. Netflix is the first streaming platform to use the Sennheiser AMBEO Spatial Audio system, though the tech is available to be licensed by others. Netflix and other industry partners were involved during the development of AMBEO Spatial Audio, helping Sennheiser’s team tweak the system until it met or exceeded expectations.

We feel AMBEO Spatial Audio offers a meaningful improvement for Netflix members. Re-recording mixers often tell me that it better translates their detailed immersive mix work to stereo. Crucially, this process preserves the original sound mix and respects creative intent with a remarkably clean sound.

— Scott Kramer, Manager for Sound Technology at Netflix

How to Get Spatial Audio from your Stereo Device

Netflix expects those users who have surround sound systems to continue enjoying content in its original format. For example, if you have a Roku player or an Apple TV 4K connected via HDMI to an AV receiver, you will continue to hear the 5.1-channel or Dolby Atmos mixes that you’re used to. But if you’re streaming on a 2-channel device, such as a smart TV or a tablet, Spatial Audio will be enabled automatically when you watch a compatible TV show or movie. Netflix is quick to point out that the device must be in stereo mode in order for Spatial Audio to be enabled automatically. Some smart TVs default to “requesting” multichannel audio from a streaming service, just in case the end-user is sending audio out from the TV into a receiver or soundbar via HDMI eARC or an optical Toslink cable. In such cases, Spatial Audio would be disabled, and you’d need to change the audio settings in your TV to “stereo” in order to take advantage of the benefits. (If you see a logo for Dolby Atmos or 5.1-channel audio next to a movie or TV show title, your device is requesting multichannel audio, and Spatial Audio won’t work until you change the audio settings.) So far, only a select few titles are available with Spatial Audio.  For a list of compatible titles, just enter “Spatial Audio” in the Netflix search bar. As of mid-October 2022, 34 titles pop up, including several that are perfect for Halloween: Stranger Things, The Haunting of Bly Manor, the new Resident Evil series, and Day Shift, a vampire horror comedy starring Jamie Fox.

AMBEO 2-Channel Spatial Audio is a two-channel rendering of an immersive mix that is a drop-in replacement for stereo. It provides an improved audio experience wherever stereo is delivered today, be it standard TV sets, stereo systems, headphones, tablets, or laptops. Netflix is the first streaming platform to deliver this significantly improved experience. On select titles, like Season 4 of Stranger Things, Netflix has made AMBEO 2-Channel Spatial Audio the default stream for any two-channel usage. Netflix viewers watching on a stereo (device) will automatically receive an improved and enhanced spatial experience – no user changes required.

— Sennheiser

Dr. Renato Pellegrini of Sennheiser’s AMBEO team says that Sennheiser “firmly believes in the immersive future of audio.” But as one of the world’s top manufacturers of headphones, the company also knows that mobile technology and personal audio are always going to be available to, and used by, a far greater number of people than large, multichannel home theater systems. According to Dr. Pellegrini, the goal of AMBEO 2-Channel Spatial Audio is to make immersive audio accessible to everyone. Dr. Pellegrini stresses that Sennheiser’s system is different from other solutions because “AMBEO rendering respects the original mix, tonal balance, and dialogue integrity, which is exactly what the re-recording mixer is looking for. The processing is in line with Sennheiser’s reputation to deliver tools that are ‘transparent’ and do not interfere with the original sound. In a nutshell: Sennheiser 2-Channel Spatial Audio seeks to translate mixer intent, not to overpower it.” One cool feature is that specific channels can be excluded from rendering while others are modified. For example, the mixer can choose to leave the dialogue untouched, while using the AMBEO technology to make surround and height channels sound more immersive. Also, if the audio contains a piece of 2-channel music that is meant to be heard as ordinary stereo, the music mix can be preserved in the left and right channels, while all other elements of the mix are given an immersive AMBEO rendering.

I’m a huge fan of AMBEO. I experimented with it a lot on the Fear Street movies and was impressed with how the surround channel information was represented. I’m always looking for ways to get that Cinematic sound at home, and on The Adam Project I was able to make the mix sound really immersive on everything from high end soundbars to iPhones, which I believe helps the audience connect more emotionally. It’s been a perfect format on Stranger Things. In the Atmos mix, Vecna’s voice wraps around you, which is an important part of making him scary and larger than life. The fact that AMBEO is able to help recreate that in stereo is very impressive to me.

— Re-Recording Mixer Mark Paterson

If you’re watching Netflix on a laptop or tablet and you’re using the built-in speakers, even a technology like AMBEO will only be able to do so much. The folks at Sennheiser have proven themselves to be very clever, but they aren’t miracle workers. If you’re using headphones, however, I think the sky’s the limit when it comes to potential immersion. Right now, there are multiple companies working on similar, competing technologies — see my recent article about THX Spatial Audio, for example.  But because these technologies can be enjoyed without specialized hardware or software, it might be possible to avoid the dreaded format wars that have sometimes plagued the industry. Will one version of Spatial Audio eventually reign supreme, or will multiple companies continue to work independently toward the common goal of accessible immersive audio?

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