A binaural audio odyssey

Imagine if you could close your eyes and listen to a guided tour of your own brain, with the sound moving around as if it's inside your head, explaining which mental processes happen where. 

This is the idea behind the Binaural Brain, a 10-minute piece of audio just launched on BBC Taster. Taster is the home of new ideas from the BBC, where novel concepts and technologies are put up for road-testing by the public, usually for three months. Users are invited to explore the content, rate it and answer a few questions about how they found it. So if you fancy having a listen to 'the Brain', all you need is a pair of headphones or earpods, and a quiet environment. Your thoughts are welcome! 

Lorna Walker, a writer and mindfulness teacher – she's one of the voices on the Buddhify app – is the narrator (pictured with me above, right). The script consultant was neuroscientist Lucy Petro at the University of Glasgow.  

Pre-launch, comments from BBC colleagues included, 'it's so relaxing', 'it feels like ASMR' and 'I could fall asleep to that (in a good way!)'. But in the few days since its launch we've had some other really interesting feedback from a more diverse audience. 

A bit of background: Binaural audio is different from stereo, because it's not just left/right, it's 360 degrees (as in real life – sounds can come from all directions). It's widely used in computer games and some radio dramas, but in those cases the sound environment is normally 'out there', whereas what we've attempted to do is bring the sound inside the head. 

There are several ways to create binaural sound, with the 'dummy head' microphone being by far the most photogenic! This is a classic piece of kit  with precisely modelled 'ears' on either side, with microphones inside them. The curves and folds of the human ear, plus the head itself, play a key role in telling our brains where a sound has come from, so these fake ears, head-width apart, allow the microphones to capture audio in a way that accurately encodes its position and direction. It was great  fun to have an afternoon recording with the dummy head, but actually quite challenging to record Lorna's voice so close up – especially asking her to move around while speaking, as it was unforgiving with any noisy breathing, and pesky creaky floorboards in the studio didn't help! The bit that did work well was her moving from one hemisphere to the other. 

 As a listener, you should be able to hear the sound travelling up, down and around, travelling to the different areas of the brain in turn as the narrator talks about them. We're keen to find out from listeners how 'directional' they found the sound – as there are known to be individual differences between people – possibly to do with ear shapes! – and that's been our experience too within the team. We're also interested to know if earpods/headphones makes a difference, and if the binaural effect diminishes completely if you keep your eyes open and watch the video. 

The limitations of the head meant we also did a mono recording and used software to position the sounds in space – as computer games designers do. Recording the script with a traditional microphone and then pulling the sound around using software gave a better effect most of the time. The final audio mix is a combination of both.  We learned a few new things too…  for example, that hearing the movement of the sound travelling from one location to another was more effective than it just 'appearing' in the new location. And that low notes in music seem to suggest something being lower down physically.  

To heighten the sense of it being a personalised experience, i.e. this is your brain we're talking about, there are several interactive moments when the listener is asked to perform simple tasks to activate certain areas of the brain, such as by bringing a particular memory to mind, or making a choice.  

As for me, I've recently left the BBC to go freelance. The Binaural Brain and a few other programmes I've made have linked in with my psychology background, but I've also worked on a whole range of other things, particularly science (knowing what a journal article is, and a bit about statistics has stood me in good stead). I'd love to do more about psychology in the future.