Finding More Space: Sennheiser On Its Journey with Netflix to Expand Two Channel Audio to Bring In an Immersive Feel

Finding more space: Sennheiser on its journey with Netflix to expand two channel audio to bring in an immersive feel By Kevin Emmott

Monday, June 12, 2023 - 12:50

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At NAB 2023 Sennheiser introduced its Ambeo 2-Channel Spatial Audio renderer for live broadcasting. Already established in the market as a file-based solution for over the top (OTT) streaming, the company is looking for sports broadcast partners to help bring more immersive space to live sports.

Head of Sennheiser pro labs, Renato Pellegrini, tells us about its development with Netflix, why it is so important to partner directly with sports broadcasters, and how he hopes it will encourage every broadcaster to make immersive audio its default output format.

We talk a lot about immersive audio for live sports. We talk about how sound designers are creating experiences to build an emotional connection, and how broadcasters are experimenting with different formats and techniques to manage the sound. We talk about how efficient metadata is at keeping us organised, and how artificial intelligence (AI) is helping to automate processes to reduce the workload on the overworked mix engineer.

We have even discussed what immersive actually means on a philosophical level. As an industry we're all over it.

Find out what the experts are saying on immersive audio with SVG Europe Audio's Look Back at Qatar here

But outside the industry, that's not necessarily the case. Despite the popularity of 3D soundbars and the built-in accessibility of Dolby Atmos in Sky Glass, not everyone is reaping the benefit. Most people don't have a home cinema system, and even if they do, half the time they might be watching the game on their phone, or their laptop, or on a tablet. In real life, most people are still listening to programme output on two channels.

But what if there was a way to provide a more immersive experience from every single 3D audio mix, irrespective of the device you are using? Over the last few years Sennheiser's Pro Labs have been looking for ways to do exactly this, to extract more value from immersive mixes and deliver them to a wider range of users.

Netflix steps up

Sennheiser's Ambeo 2-Channel Spatial Audio renderer was launched in June 2022, when Netflix was the first OTT provider to go live with it in the cloud.

The renderer creates an enhanced two-channel mix from an immersive signal that works across headphones, TVs, and other stereo environments. Netflix now provides more than 700 titles which use the technology; Premium Plan subscribers can hear them by searching for, spatial audio .

The development attracted attention from sports broadcasters looking to enhance their offering, and following feedback at IBC 2022, Sennheiser was quick to develop a stream-based version. The Ambeo 2-Channel Spatial Audio renderer for live production was launched at NAB 2023.

Pellegrini says: It is more expensive to produce an immersive mix and if we can only validate the additional cost by the number of immersive listeners it is a more difficult business case. While many high-profile sporting events are already produced in immersive formats, a spatialised renderer like AMBEO can encourage broadcasters to invest in immersive mixes at other events because it also improves the listening experience for the majority of viewers listening in stereo.

If we can help justify that cost by adding value for the entire audience it becomes an easier argument; we think that technologies like the Ambeo 2-Channel Spatial Audio ups the game for all viewers.

Not like other renderers

Of course, there are a number of spatialised renderers on the market, buoyed by the widespread adoption of binauralised audio from big brands like Apple. And nor is it a new technology; binaural audio has been around as an immersive two-channel format since 1881.

But according to Pellegrini, that is not what this is. Firstly, unlike many other renderers, Ambeo works in real time, which Pellegrini admits was quite a challenge: In fact, it was our biggest challenge. The software needs to create and QA two independent mixes to be on air within a couple of picture frames; in Europe the allowed total end-to-end latency from microphone input to mix output must be below 80ms. Such short time frames can in practice only be met using automation so we set out to design a tool which enables mixers to concentrate solely on the immersive mix and trust the system to create the spatialised stereo mix automatically.

Secondly, the way it spatialises the mix is different to other renderers. It is not stereo and it is not binaural. It is something else, he says. Sennheiser is well known for headphones, so in the early development stages we asked Netflix if they wanted something that would sound great on headphones, says Pellegrini. They replied that because most of their end users listen to content on a TV, they would be more interested if we could make the TV sound output more immersive. But that they also wanted improvements to the headphone output as well!

It impacted on development in a positive way. We already knew how to approach a binaural headphone mix so our goal became how to develop something which sounded better on all stereo devices. We worked directly alongside Netflix for 18 months, as well as with producers and end users to make sure the benefits were there for everyone.

Using a combination of transaural, binaural and some other (confidential) technologies, Sennheiser says the renderer provides a more immersive experience whatever you are listening on.

Automating the system

We had extensive discussions with production companies to ensure their recording engineers were happy with the output and we learned that different production companies worked with very similar settings to each other, and independent of genre. A doc

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