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Binaural Sound: BBC Research & Development

August 9, 2019

Curious but struggling to understand the difference between stereo and binaural? Today's blog guest pointed me in the direction of a great online example by the folks at Enhancing Audio Description. Grab your headphones and listen to these two tracks below..

The first is in stereo, and the second is an enhanced version with added sound effects using binaural audio.

Cool, init?

 

This blog post goes into the nitty gritty of binaural tech, plus offers an insight into how the BBC R&D team are working with creative in-house teams to really make their content sing - either online, on TV, on radio or in podcasting. But we've also got a ton of stuff for you to listen to if you're intrigued by what all this VR, AR, 360, binaural stuff is about.

 

For example, did you know - whilst wearing headphones sat in your pants on your sofa - you can take actually a walk along the Congo River, you can hear what it's like to sleep on the streets rough or even go for a haircut in a virtual barbers?

 

From ASMR, accessibility tech, head tracking and spatial gaming experiences to something called 8D audio where the music spins around your head like a washing machine... There really is far more happening in the audio world than just the usual stereo or surround sound mixes we've all accepted as the norm!

 

So grab a notepad, keep your headphones nearby and make yourself a cup of tea. Enjoy having a listen through some of the trailers in the YouTube videos below, and meet Tom Parnell - a technical producer in the BBC Research and Development team based at MediaCityUK.

Clare Q - Binaural sound has been and gone a few times over the last 140 years, now everyone is back wearing headphones (45% podcast listeners) - is it back in fashion?

 

Tom A - I wouldn’t say it’s fashionable, but certainly it has a following; aficionados have been DIY recording their own binaural using in-ear mics ever since the 70s. And I’m in contact with a few audiophiles who have loved my Proms mixes!

In other genres, it’s difficult to know how it’s being received. A third of our radio audience listen using headphones, so we certainly think it’s worth providing special/exclusive/companion material in an enhanced format for headphone/in-ear listeners.

Some programmes/podcasts are produced only in binaural, others have two mixes produced (stereo and binaural), other programmes might publish extra clips in binaural, for listening to again later.

I did an experiment for Radio 1 Essential Mix, using binaural for their idents, so that they ‘stood-out’ in a different way to using lots of compression – with sounds appearing outside the head and in extreme positions, like right up behind one ear!

 

Q - Has the rise in VR video helped interest and tech around binaural sound develop?

 

A – I think so. It’s certainly a ‘sexier’ way to market binaural sound, and raise awareness of it among commissioners.

And more and more VR and video games are adopting binaural sound seriously, and the sense of immersion is certainly amplified with ‘tracked’ spatial soundtracks, where the sound changes depending on the viewer’s position and orientation in the game, or the direction they’re looking at a 360 video.

While a lot of VR doesn’t have spatial sound, it’s becoming better known and adopted because stereo or even mono soundtracks don’t match the immersive video.

 

Q - Tech wise, where we even start?!

 

A – In the past, binaural could only be produced using a dummy head microphone (pictured left).

 

We still use them, and in-ears mics, but now we can take a standard mono or stereo recording, and apply a binaural filter (head-related transfer function/HRTF), which outputs a left and right channel, and contains all the audio cues (delay and level differences between left and right, and equalisation differences) that trick the listener’s brain in to thinking the source is coming from a particular direction.

 

If you want to move a source around the 3D sound field, a series of HRTFs can be applied in real-time in order to produce the perception of a source moving around the head. Automate this process for several sources and you can quickly produce a convincing spatial effect which can sound quite realistic.

 

Unlike stereo, which can sound very close and in your head, binaural can often sound out of the head, which is quite a unique attribute.

 

For this, we use:

  • Nuendo with IOSONO’s Spatial Audio Workstation (cost of high-end DAW and programme plug-in), with the BBC’s bespoke binaural renderer

  • Sennheiser AMBEO Orbit VST plug-in, which is free and really convincing 

  • Noisemakers interactive audio software plugins (€89)

  • Blue Ripple Sound: position sources into the Ambisonics format 

  • There are other VST plugins for 360 video audio and SDKs for the Unity and Unreal game engines, which are helpfully free at the moment but they don’t sound as good as the above

  • Facebook 360

  • Google Resonance

 

It’s also important to capture soundscapes in three dimensions rather than just on one or two mics.

 

We use ‘3D’ mics like the Sennheiser AMBEO VR mic (pictured right), old Soundfield mics which sound recordist Chris Watson uses) and spatial mic arrays, like the Schoeps ORTF-3D.

 

Q - Should we be spending a fortune on proper headphones to really enjoy listening to all of this binaural stuff?

 

Headphones vary in quality as much as stereo loudspeakers, so you’ll have a better binaural effect using high-quality open headphones in a quiet environment (I use Sennheiser HD600).

Closed headphones (Sennheiser HD25) are great for noisy environments, and even noise-cancelling headphones don’t mess with the binaural cues. In-ears work well, and even the cheapest will provide some spatial effect.

 

Q - How can audio producers make better use of binaural sound in their own podcasts? 

 

A – It should be relevant and used when needed. Lots of spatial content can be fatiguing.

The best mixes I’ve heard use binaural naturally to portray a realistic environment or to create a particular response - intimacy, busyness, calm.

The contrast between in-head sounds (standard panning) and external sound (binauralised) can be really effective.

And for ease of production, speech is often recorded and reproduced in standard stereo and atmospheres/ambiences in binaural.

Get started recording with in-ear mics for example Sennheiser AMBEO headset, Roland CS10EM or experiment with the Sennheiser Orbit plugin.

 

Q - Any recommendations of 360 podcast/binaural projects you've heard or are working on? 

 

A - Here are some recent BBC binaural podcasts/programmes that are really worth listening to, and still available. They’ve all been made by radio producers who have received R&D/BBC Academy training on spatial audio production.

 

Hearing Homelessness, a BBC Radio 4 project capturing life on street, and what the sounds mean to those rough sleeping.

 

Forest 404 is an eco thriller with music by Bonobo.

 

Congo: A River Journey is a sound rich immersive journey along the Congo River in the democratic republic of Congo by BBC World Service.

 

BBC Radio 4 series, In My Head is a step inside the minds of characters with extraordinary jobs.

 

Proms 2019 mixes - listen to immersive headphone mixes from the BBC Proms (below is Nothing To Be Written).

Sound recordist Chris Watson is great and records quite a bit of binaural on location. I’m going to remix a Prom into binaural that uses his spatial (and stereo) wildlife recordings. Hopefully it’ll be a feature-like, montage-y, slow-radio thing.

(Note from ed: By the way blog readers, we interviewed Chris about this particular project 'The Lost Words' earlier in the week - read/watch/listen to it here.)

 

Q - Aside from podcasts and radio, who else/where else is using binaural sound technology?

 

A - It's more popular than you think - ASMR, VR, gaming and technology for visually-impaired users are all embracing binaural options.

 

First, up is the classic demo of the Virtual Barber Shop... this YouTube video is now 12 years old with over 31 million views. It really is a video to showcase in how binaural sound can be used!

ASMR (autonomous sensory meridian response is an experience characterized by a static-like or tingling sensation on the skin that typically begins on the scalp and moves down the back of the neck and upper spine) is mega popular on YouTube. 

(Note from ed: here's a nice video of a crackling fire just because...)

‘8D Audio’ seems to be an algorithm for taking a stereo music track, spinning it round your head using binaural tech, and washing the whole thing in lots of reverb. Apparently, it’s very popular...

(Note from ed: Here's one we picked by the Goo Goo Dolls!)

VR (Virtual Reality):

I did the binaural for these BBC pieces...

Nothing to be Written is a 7-minute contemporary response to the stories behind First World War ‘field postcards’.

The Turning Forest is a virtual reality fairytale (watch the trailer below).

Other interesting BBC projects:

Damming the Nile (below) is a BBC News Virtual Reality documentary series where you're taken on a journey from the sacred source of the Blue Nile, down waterfalls and through canyons to see this giant dam being built. You even travel on East Africa’s first metro train and go for a traditional Ethiopian lunch!

Planet Earth II in VR and 360, this one (below) is with David Attenborough narrating in the Costa Rican jungle.

Non-BBC experiences I like:

Notes on Blindness by ARTE Experience is a VR journey into a world beyond sight. In 1983, after decades of steady deterioration, John Hull became totally blind. To help him make sense of the upheaval in his life, he began documenting his experiences on audio cassette. Original diary recordings form the basis of this project, an interactive nonfiction using new forms of storytelling to explore his cognitive and emotional experience of blindness.

 

6x9 (above by The Guardian) takes you to a virtual cell, telling a story of the psychological damage of extreme isolation. Right now, more than 80,000 people are in solitary confinement in the US. They spend 22-­24 hours a day in their cells, with little to no human contact for days or even decades.

 

Gaming:

I hear these games have excellent binaural sound...

Resident Evil 2

Hellblade: Senua’s Sacrifice

Hunt: Showdown

AR (Augmented Reality):

Bose shades - yes they're actually sunglasses! (pictured above) - have little speakers in each arm which use binaural tech to add ‘produced’ sound to the sound that the wearer is hearing acoustically. It’s tracked too, so as the wearer moves around, the sound re-renders appropriately.

 

Accessibility: 

Microsoft Soundscape uses binaural tech to help visually-impaired users by enhancing their environment. It uses 3D audio cues to help people, particularly those with blindness or low vision, build up a clearer picture of their surroundings so they can become more confident and empowered to get around on their own.

Is your tiny mind blown from all the possibilities too? Who knew audio could be such fun and so creative, eh?

Thanks to Tom Parnell for sending us a wealth of insight into what the BBC is up to on binaural projects, and for all the links too! If you're curious and want more, then there’s general information on BBC R&D’s work on binaural here: https://www.bbc.co.uk/rd/projects/binaural-broadcasting

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