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Surrounded by sound: how 3D audio hacks your brain | The Verge
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"The technique at the heart of binaural audio can be traced back to Clement Ader, a 19th-century French engineer. In 1881, Ader devised the Theatrophone, a telephonic system of transmission to broadcast a Paris Opera show. Pairs of microphones were systematically spaced in front of the stage, covering the breadth from left to right. Signals from the show were then transmitted via telephone receivers to listeners on the other end. With a pair of receivers, one mounted on each ear, listeners could hear the show from their designated suites at the gallery of Palais de l’Industrie.

In 1933, AT&T Bell Laboratories brought binaural audio to the Chicago World’s Fair. The acoustics research department of the company created a mechanical dummy, which it named Oscar, with microphones placed on its cheeks in front its ears. Oscar sat in a glass room capturing sounds while visitors gathered outside used headphones to hear exactly what the dummy heard. The technique revised the experience introduced by Ader, but both inventions offered poor sound quality.

Through World War II and the decades that followed, progress in binaural faced significant obstacles: primitive techniques failed to achieve accurate, high-fidelity recordings. But in 1973, Neumann, a renowned German microphone company, introduced the breakthrough KU-80, a prototype binaural recording device. Neumann’s iteration consisted of a detached dummy head with microphones placed in the eardrums – the position captured cues with more precision than any of its predecessors. Three generations of dummy heads later, the KU-100, introduced in 1992, featured omnidirectional microphones, expertly preserving the spatial cues and the overall quality of sound. It continues to be the go-to dummy head for binaural recordings.

Now, almost a century after the demise of the Theatrophones, investors are starting to revisit 3D audio technology: the prototype of Sony’s VR headset Project Morpheus includes a custom 3D audio binaural solution in its development kit. "3D audio adds to the feeling of presence that we strive so hard to achieve with the visuals in VR," says Richard Marks, senior director of research and development at Sony Computer Entertainment America. "When sound is perceived to come from the same direction as a visual stimulus, the credibility of the virtual experience is greatly increased. While purely visual VR experiences can be made, adding 3D audio greatly magnifies the impact and depth of a VR experience."

3D audio offers a more expansive experience than its visual counterpart. "Unlike with the visuals, 3D audio is not limited to the field of view of the display and can be rendered to give a 'complete 360-degree' experience," says Marks. "One of the biggest challenges for VR design is that the user can look in any direction, and may not even be looking when something momentous occurs. But using a 3D audio cue, it is possible to steer the user’s attention to look in the direction of the sound, similar to techniques that are used in live theater.""

"Back in Manhattan, Choueiri is considering another problem: since the inception of the technology, binaural audio has been reserved for headphone listening. But Choueiri wants to make the technology accessible over external speaker systems for a wider audience. The challenge is that with speakers, a right ear not only hears its respective cues, but also picks up information meant for the left ear. "It messes up the cues, so instead of hearing 3D sound, the brain just locates the speakers," Choueiri said. "It’s like watching 3D movies without the glasses on."

For decades, this confusing crosstalk between speakers has perplexed the audio community. But Choueiri’s BACCH SP, a filter that enables a pair of speakers to retain the aural cues, creates the illusion of 3D audio for the listeners. Jawbone has employed Princeton University’s algorithm over the last two years to create the LiveAudio filter for its wireless bluetooth speaker, Jambox. Loading the mini-speaker with the digital filter optimizes audio to create a three-dimensional experience. While effective, the experience is limited to a sweet spot — the device needs to be centered in relation to the listener. The illusion instantly collapses when the listener moves from the spot. Choueiri says a version of that software, the BACCH-dSP app, coupled with a head-tracking feature, can sustain the illusion irrespective of the listener’s head movements. That app is scheduled to show up in the store for Mac OS soon, bringing 3D audio experiences to laptops.

Slowly but surely, binaural is becoming a linchpin in virtual reality development. Oculus’ most recent prototype, Crescent Bay, unveiled at CES last month, integrates binaural technology with Rift’s head tracking for complete audio-visual immersion. And while Sony’s Project Morpheus hasn’t announced final specifications of the product yet, their emphasis on 3D audio is evident. As Adam Somers of Jaunt put it, "Binaural audio is critical to an immersive experience within the context of VR. We consider audio to be 50 percent of the immersive experience.""

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ryanmanning  binaural  audio  2015  history  clementader  soundscapes  sound  virtualreality  oculusrift  edg  srg  glvo  video  pointofview  beck  radiohead  binauralrecording  monalalwani  vr 
february 2015 by robertogreco

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