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3D audio: reinventing the wheel - PSNEurope

3D audio: reinventing the wheel

In this week's feature Professor Rumsey looks at the sudden rise in popularity of the weird and wonderful world of 3D audio and how binaural recording might finally have come of age.
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It's quite remarkable how “new technology” can be promoted as if the current proponent is the first person ever to have thought about it. Unless I’m much mistaken there’s quite a lot of this going on at the moment with 3D audio, in particular that flavour of 3D audio that uses binaural recording or processing. All of a sudden it’s becoming cool. We can only assume that people are finally waking up to the fact that a very large amount of audio is consumed via headphones – the ideal medium for delivering binaural signals. If not this, it must be the publicity arising from 3D movies and television that has finally led consumers and producers to recognise the importance of fully three-dimensional spatial sound. My eldest daughter sent me a few links to recent sound-related things she’d found (“cos it’s your bag…”). Entirely unprompted by me she mentioned a podcast about the work of Edgar Choueiri, a professor from Princeton, saying “I don't see how this is anything new from those sounds you played me on headphones about 15 years ago. Unless it's because you can listen to this on speakers...” She also mentioned a 3D song, Propeller Seeds, recently released by Imogen Heap, created in collaboration with sound designer Nick Ryan. When you listen to it on headphones it seems to involve quite a lot of binaural spatialisation, which Ryan has also used in some other projects such as a spot for Nike CTR360 football boots and “the world’s first 3D audio enhanced publication”, Ken Follett’s Fall of Giants.

Finally, there is a new iOS game, Papa Sangre, which relies almost entirely on 3D audio delivered over headphones. The developers have implemented the first ever real-time binaural processing engine that runs on a handheld device, enabling you to chase down monsters in the land of the dead purely on the basis of audio cues. This, they say, was “bloody hard”. Back in the early 1980s I heard the “Holophonic” recordings of Hugo Zuccarelli for the first time, including various effects of hair cutting and matchbox shaking fairly close to the head, which were impressive on headphones. Then there were experimental BBC radio plays made using binaural recording, which you had to listen to on headphones. Their remarkable spatial realism made me wonder why it wasn’t used more, but then there’s always been a challenge to bridge the gap between headphone and loudspeaker reproduction. I’ve sat in numerous demos of crosstalk-cancelled binaural reproduction on loudspeakers, but I’ve never been entirely convinced that it sounds natural and the sweet spot is typically quite small.

It can work quite well when a user is fixed, say in front of a computer monitor, but not if they want to move around. Choueiri, though, is trying to improve the quality of crosstalk-cancelled reproduction by applying analytical tools from his plasma physics research. The results seem better than some others I’ve heard (see http://www.princeton.edu/3D3A/). So, while none of this seems as revolutionary as the hype would suggest, and these are only a few examples, it’s the move into mainstream popular culture that suggests binaural recording has finally come of age. It just goes to show how long it can take before the right combination of ideas, technology and market circumstances comes about for an old concept to “make it”. 

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