Adventures in 3D Sound!

Edgar Choueiri knows how things work; he’s a rocket scientist – officially, the Director of Princeton University’s Electric Propulsion and Plasma Dynamics Laboratory. If NASA ever sends a person to Mars, Choueiri’s research probably will have played a role. But Kurt Andersen visited his lab recently to get a taste of the future right now. Choueiri’s hobby is acoustics. He has developed a way to render sound in three dimensions, and given Studio 360 listeners an exclusive first listen of his 3D audio technology.  
Unlike surround sound and other elaborate hardwiring, his breakthrough consists of a software algorithm applied to sound files that allows stereo playback to sound much more real and lifelike. Imagine swatting at a fly buzzing 360 degrees around your head; or instinctually standing back as a roaring train pulls into a crowded station; or closing your eyes and being able to pick out the soloists in a choral performance of a Bach Mass  (see how Bach’s Mass in B Minor inspired Choueiri’s 3D work).
The 3D audio in the show segment above is calibrated for stereo speakers only so it won’t work on headphones. To hear the effect, sit in front of your computer speakers, with your ears about equidistant from the left and right speakers. (It can’t hurt to close your eyes.)
Try out the clips below, in which Choueiri demonstrates the sound of water in 3D.
  
3D Audio Demonstration for Speakers

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3D Audio Demonstration for Headphones

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[Note: If you are using a recent Apple MacBook you may not be able to hear the full effect of the 3D due to a known problem in the MacBook design (related to the location of the internal “subwoofer”) that creates a strong Left-Right imbalance in the audio, which could not be compensated for while creating this 3D audio.]
So how does it work? Conventional stereo recordings already incorporate rich location information, but our ears do not capture it during playback because of what engineers call “crosstalk”: the fact that your left ear hears sound from the left speaker but also the right speaker (and vice versa). This explains why stereo recordings don’t recreate dimensionality as accurately as your ears and your brain hear sound in space. The trick is to cancel the crosstalk without altering the sound quality–something no one has ever quite pulled off until now.  
Drawing on some of the math in plasma physics, Choueiri devised a digital algorithm that cancels crosstalk transparently without changing the tonal quality of the sound. The brain naturally does the rest, allowing listeners to pinpoint the original placement of sound in space more like it would if we were hearing the “real thing.”   Among efforts to develop 3D sound, Choueiri’s approach is unique in that it does not require specialized playback equipment.   The digital filter is designed to work on any stereo recording played through any pair of speakers.
Video: The Science Behind 3D Sound

Much like hi-fi stereo changed the game in the late 50s, Choueiri’s advances are being closely watched by the music and entertainment industry. Hollywood – already smitten with 3D film – is interested, as are videogame producers. Choueiri also hopes to apply his 3D technology to hearing aids.
Choueiri’s dual interests trace back to his childhood in Lebanon in the ’60s. He was obsessed with space travel and his father’s recording equipment. In a tape that his sister uncovered just three years ago, young Edgar borrowed the reel-to-reel and left a message for his middle-aged self:

I am 11 years old now and you must be well above 30 years old. Although you exist in a different time, I am talking to you through this machine I have in my hands. I am not sure if this tape will survive. I hope that you have realized my dreams and have become somebody in the world of machines, electronics, and sound. I would love it if you are working in aerospace and electronics and playing with instruments.

Mission accomplished.
  
What music or sound do you want to hear in 3D? Leave a comment and let us know.