The limits of stereo and the potential of spatial audio

Stereo audio is inching towards its centenary. Its invention is credited to the groundbreaking work of British electronics engineer Alan Blumlein who, in 1931, started developing some of the ideas and patents that are still used in stereo today. But while stereo remains the largest delivery format for sound almost 100 years later, technology has evolved. And where stereo comes up against its limits, spatial audio defies them.

But what is spatial audio exactly, and why is it becoming so popular? What does it mean for live events, and for the events, engineers and musicians who use it? And how are music lovers likely to experience it in the future?

We recently pulled a team of sound and music gurus together to discuss the ins and outs of spatialised sound. We spoke to product and technology marketing engineer at L-Acoustics Jordan Tani, spatial sound engineer Matt Gush, and Berlin-based DJ and producer Jacob Ahrends, known by his stage name O/Y. What follows is the first in a series of articles we’ll be producing on this hot topic.

What is spatial audio?

“Spatial sound is how we experience sound naturally,” says Jordan. “Imagine walking down a street, and hearing people laughing behind you, a bus grumbling past to your left, and a plane flying overhead. If you close your eyes, you can identify where these sounds are coming from, and you can hear them as they grow louder or fade away.”

Spatial audio is often referred to as 3D audio. It’s sound that has been digitally placed in a three dimensional space so that it sounds like it’s coming from different directions — just like it does naturally. There are many different ways of achieving this, and it has been easy to render on headphones for some time (if you’re a gamer, you’ll know all about this). Increasingly, it’s become available on speakers at live events, too. And it’s here that it’s knocking the lights out of stereo.

Reproducing this experience —?in cinema, theatre, music and other art forms — has evolved over the years. In theatre, voices and sound effects came from different areas of the stage or theatre before speakers were ever placed. Blumlein was behind the production of the first stereo film, Trains at Hayes, which was released in 1935. And today, innovations like Dolby Atmos can even be found in home environments. Live events are the latest frontier.?

Why is spatial audio gaining momentum?

“I think the demand for immersive or spatial audio is largely driven by our desire for experiences that we can’t get at home,” Jordan explains. “Events, productions and installations that involve all of the senses have become a source of interest. We want to go to shows that offer something different, that amaze us, and show off the latest innovations —?in terms of what we see, hear and feel. And we want to share them.”

Fortunately, the technical barriers that once limited what these experiences could offer are being dismantled all the time. “I think we’re naturally drawn towards spatial audio,” says O/Y. “But now we’re getting closer and closer to making it a reality in more complex environments, and that’s fuelling global interest in it.”

Is spatial audio complicated for engineers and artists to use?

It was —?but things are changing.

“The tools that I was playing around with during the pandemic seemed like they’d been developed by PhD candidates,” Matt recalls. “I think you almost had to compile the code yourself in order to use it — it was super nerdy, cumbersome stuff. But in the years since then, there have been huge advances, especially in terms of user interface and usability. It’s made the whole process so much easier.”

O/Y agrees. The first time he came to London to prepare for a Polygon performance, he was unsure about what might be involved. “I’d worked on an ambisonic system on a rotating stage before that involved different protocols and complicated routing systems,” he says. “It just wasn’t feasible for everyday use. But when I came to London, I was blown away by how simple the Polygon process was. It took 20 minutes to route everything and I was ready to go. It was so intuitive and playful.”

How does spatial audio play out in live music?

Even if you’re a devoted follower of music, sound, innovation, and where the three intersect, it’s unlikely that you’ve been to a fully immersive soundstage at a concert or festival. While there are pioneers putting them on (Polygon is one), they’re still only just gaining traction.?

“In Berlin, there are more and more immersive concerts happening, but they’re not in the dance music space,” says O/Y. “It’s usually more ambient music. There are sleep concerts where the sound comes from all around you. But in dance music, there still isn’t much.” (And that’s in Berlin!)

The introduction of spatial audio in live music environments, where people can interact with one another, dance and marvel at the music, is nothing short of revolutionary. And it’s such a unique experience that even those who have experienced it time and again find it tough to put into words. “It’s pretty wild to experience a truly immersive audio system,” says Matt. “And it's hard to describe what it's like to stand in a 360-degree audio space without standing in one yourself.”

Suffice to say that being enveloped by a hemispherical stage, where the music moves above, around and through you, is the kind of thing that would likely have reduced Blumlein to tears of joy.?

This conversation is far from over. Stay tuned for our next update on spatial sound.