VR Audio Reimagined

Virtual Reality has taken centre stage in 2016 – it’s a technology that has been discussed since the 1950s, but like many fads has quickly faded into the unknown. 2016 has been different though. In 2016 the quality of VR reached such a point that consumers took note; headsets such as the Oculus Rift and HTC Vive are now in the hands of users around the world.

So why has VR suddenly caught on? Well, that’s because the quality of the visuals and interactivity that these headsets offer now gives people a reason to use them. Using VR, people can quite simply immerse themselves in a fantasy world (not to mention forget the horrors that 2016 brought).

While the visual and interactive elements of these headsets have been iterated and improved, the audio has been somewhat of a stumbling block. Sure 3D audio formats such as Dolby Atmos, DTS:X and Auro-3D can give the illusion that you’re actually standing in a 3D space – but it’s not enough to trick the brain that you’re actually there.

That’s where Dirac comes along. At CES 2017, this Swedish audio research company might just change the way people experience VR. Instead of just listening to the audio in a 3D environment, users may finally get the chance to immerse themselves in the fantasy – whether it be through visuals, interactivity or audio.

The VR Audio Game Changer

Dirac Research has thus far concentrated on optimising acoustics in home cinema systems, mobile phones and cars, but its presence at CES 2017 will signal a new frontier for the company – virtual reality and augmented reality.

After several years of research, Dirac is now ready to show off what it calls ‘Dynamic 3D Audio,’ which is an AR/VR platform featuring patent-pending dynamic HRTFs (head-related transfer functions) that consider the isolated movements of the head in relation to the human torso.

Reproducing a 3D environment through stereo headphones is a complicated process and one in which Dirac has been dedicated to researching. The reason it’s so complicated is because of the way sound acts in a 3D space: there are subtle interferences that cause people to experience sound differently to others.

Sound travels through the air as distinct waves and depending on distance, it will take varying amounts of time to reach a person. Those further away will hear a sound a fraction of a second after those who are closer. This distinction is also what helps the human brain identify where a sound is coming from – if you’re standing in a room and a pin drops to the left of you, your left ear will hear that sound sooner than your right ear. The volume will also be louder in your left ear than it will be in your right. The brain will then process that information and inform you that it’s coming from the left.

Humans don’t hear in a two-dimensional space though, so left and right is just one part of the equation. If your brain solely relied on volume and the time it took to reach your ear, then it would often receive the same result even if the sound is happening directly beside you, in front of you or behind of you. In order to get the full picture, the body relies on head-related transfer functions.

The head-related transfer functions are the changes a sound wave makes on its approach to your ear. Sound will reflect off your head and shoulders, as well as the curved surfaces of the human ear. Each of these reflections will make subtle changes to the sound wave and in turn, interfere with one another. This causes parts of the wave to get bigger or smaller, changing the sound’s volume or quality.

It’s because of the different reflections and the impact on the shape of the sound wave that your brain can pinpoint exactly where a sound is coming from.

Using HRTFs, audio companies have been emulating surround sound on stereo headphones for years. This is also how Dolby Atmos for headphones works. They all come with one significant flaw however. Current industry-standard HRTFs incorrectly assume that the body and head must always move in tandem, and that’s simply not the case in VR.

Through its development of Dynamic 3D Audio, Dirac’s technology for the first time takes into account the position of a user’s head by using accurate head tracking information to monitor and measure the isolated head movements with high resolution and minimum latency.

Dirac’s research led to the company creating what it calls ‘dynamic HRTFs’. CE Pro Europe caught up with Dirac co-founder and CEO, Dr. Mathias Johansson, to discuss its approach.

“Basically, simply measuring a HRTF with a dummy head and adding some reverberation would not cut it,” notes Mathias. “We had to rework the entire process of HRTF measurements to come up with error-free and completely accurate high-resolution HRTFs; we had to modify and improve our technologies that are used to simulate real acoustic venues in various acoustic settings and we had to use all our insights and knowledge gained over the last 20 years in room acoustics and psychoacoustics to come up with a solution in line with our ambitions.

“In very simplified language, ours is a high-end alternative to existing positional audio technologies for headphones. It’s for transparent sound reproduction and for the highest accuracy in localising sound. For example, if in a VR environment a helicopter is hovering 10 yards in front of me, regardless of which way I turn my head, that helicopter needs to and will stay perfectly fixed.”

Familiar Ground

Dirac has been in the business of immersive audio for a while. While it may not get the credit like Dolby Atmos, Auro-3D or DTS:X, the technology the company possesses has the ability to transport listeners to any location in the world. One example of the company’s immersive technologies in use is in the Volvo XC90’s Bowers & Wilkins audio system. Here users can simulate real acoustic venues simply by pressing a button. The Gothenburg Concert Hall reproduction was what nabbed it the Car Tech Award for best sound system.

The difference between Dirac’s approach and that of its competitors is in high-quality audio. To truly fool people that they’re in the moment, then high-end sound quality is required. In VR that is incredibly important.

“In VR, sound quality requirements and the importance of it are actually greater than in many other applications, as the goal of VR is to fully immerse the user, convincing him or her that they are in a different world,” notes Mathias. “If any detail of the sound playback is flawed, it immediately dissolves the illusion of true reality.”

While dynamic HRTFs were an important part of the equation for Dirac’s new Dynamic 3D Audio AR/VR platform, the company had to lean on all of its existing knowledge to make it work.

“Our approach to VR was one of great attention to detail. Not just a single detail, such as the dynamic HRTF (head-related transfer function) approach that we developed and pioneered, and is fundamental to the quest of true immersion, but every detail that would impact the sound reproduction,” adds Mathias.

“Given our 15 years of experience in acoustics optimisation in rooms of every size, in addition to optimisation of speakers and earphones of all types, we knew from the outset that to get this right we had to dive a lot deeper than anyone had done thus far.”

The end-result from that attention to detail is a product that is capable of processing sound from any format – whether it be object based or channel based – and fully immerse users in a 3D space.

Coming To An Array Of Devices Near You

Dirac’s technology will be made available to VR headset makers, mobile phone makers and headphone makers. Some of those prospective customers have already come forward with an interest in the new technology – although the company won’t confirm who. Of course it hopes that with a CES 2017 demo it will receive even more attention from prospective customers.

Despite discussions with different potential licensees, the company also says it is too soon to say when its Dynamic 3D Audio AR/VR platform will be available to general consumers.

So what benefit does Dirac want to communicate with potential customers? CE Pro Eu asked Mathias, who notes: “For high-end headphone makers, specifically, this is an opportunity to actually offer a home cinema or stereo reproduction on par with the best sound systems on the market, at a fraction of the cost.”

Dirac’s technology helped the Volvo XC90 nab the best sound system award at the Car Tech Awards

That wasn’t the only benefit however: “In virtual reality, we can design the acoustic properties of a virtual room anyway we want with full control over both the time domain and the frequency domain.”

CES 2017 will mark Dirac’s debut in the VR/AR space, but it wasn’t a decision taken lightly.

Mathias concludes: “Firstly, as audio enthusiasts we see a real opportunity in that virtual reality can and will create a new and higher degree of high fidelity, overcoming all problems caused by room acoustics and loudspeakers that even the best acoustic treatment and room correction solutions can’t match. That’s is an extremely exciting prospect.

“Secondly, as tech enthusiasts we’re really excited about the opportunities that AR, in particular, offers. We see a multitude of exciting advanced sound technology applications being applied to augment reality, and to augment human abilities.

“Frankly, we’ve always felt most at home – and most comfortable – when confronted with the combination of an exciting potential end-user application and a difficult technical audio problem. AR/ VR offers us just that – the end-user applications are almost endless and the challenge is very real. It’s under these conditions that Dirac thrives, and will continue to thrive. Our demo at CES is both proof of this and a taste of what’s to come.