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Feb. 8, 2012

Vol. 112, No. 7

Campus Notebook

BREAKING GROUND: Unlocking the key to 3D sound

By Jennifer Altmann
Published in the February 8, 2012, issue

Illustration: Phil Scheuer

THE INVENTION Audio technology that allows the listener to experience true three-dimensional sound. Unlike ­surround-sound systems, this invention — called BACCH 3D Sound — enables you to hear with precision where each sound on a recording is coming from. Listen to a recording of a fly ­circling your head, and you can detect exactly where that fly is located. ­Listen to a symphony, and you can hear the viola coming from the left and the bass coming from a spot on the back right. The technology works with any pair of loudspeakers, but not with headphones.

THE SCIENTIST The moment he perfected his invention — at 3 a.m. — Edgar Choueiri (pronounced “Shu-WAY-ri”) *91, professor of mechanical and aerospace engineering, woke up his wife to listen to a recording of Bach’s “Mass in B Minor.” (BACCH 3D Sound stands for Band-Assembled Crosstalk Cancellation Hierarchy and is a tribute to Bach, Choueiri’s favorite composer.) Choueiri created a way of designing a filter that accurately cancels a sound recording’s crosstalk without changing the tonal quality of the sound. Recordings have 3D cues, slight differences in timing and volume between the sound reaching the left ear and the right one. The key to creating accurate 3D sound is canceling the crosstalk, which is the sound meant for the left ear that spills over to the right ear and vice versa, without affecting sound quality.

An engineer who develops plasma rockets for spacecraft propulsion, Choueiri has been an amateur audiophile since childhood, when he lived in his native Lebanon. After dropping in on a conference for audio engineers in 2003, he became captivated by the technical difficulties of 3D audio. His lab was funded by Project X — established by Lynn Shostack in memory of her late husband, David Gardner ’69 — which provides funds to Princeton faculty members in engineering who want to pursue unconventional ideas or those outside of their area of expertise. 

WHERE YOU’LL BE SEEING IT Choueiri’s BACCH 3D Sound is available in a portable wireless speaker called Jambox and will be available in 3D televisions. Sony has given Choueiri $3 million to fund his lab for the next three years and do research on headphones. Choueiri also is exploring how to adapt the technology for use in hearing aids.

Video courtesy of Princeton Engineering, via YouTube

Post Comments
7 Responses to BREAKING GROUND: Unlocking the key to 3D sound

Roger Horn Says:

2012-02-08 21:06:11

Fascinating demo! Fascinating story in current PAW! I went to the Jambox website and found nothing there about BACCH 3D. The PAW story indicated otherwise. Why?

Alan Johnson *08 Says:

2012-02-09 09:40:32

I had the opportunity to see a demonstration of this system, and it is nothing short of incredible. If you think stereo or surround sound is "3D," oh man, you've got another thing coming. The best way I can describe the effect is that most people pick up cues subconsciously that allow them to easily tell whether a sound is actually physically happening in their environment, as opposed to being played back over a speaker. The BACCH system severely diminishes those cues. The only catch is that the effect works best if you are sitting in a fixed position relative to the speaker. Very cool stuff.

Ray Ollwerther '71 Says:

2012-02-16 09:22:25

Professor Edgar Choueri provided the following response to Roger Horn's question: BACCH™ 3D Sound is marketed under the trademark "LiveAudio ™" by Jawbone. LiveAudio is available at this Web page: which contains a link that allows the firmware of any Jambox to be updated to contain a BACCH™ 3D Sound Filter.

Mark Cohen '73 Says:

2013-01-18 10:29:33

Got a Jambox nearly a year ago, and I thought it was good but not great. Then I finally downloaded the LiveAudio software. Oh, my! On some recordings I can hear instruments that clearly seem to be coming from well off to the side of the speaker. When I turn LiveAudio off, all the sound "shrinks down" and is localized to the 6" speaker box. I probably read this article in PAW but didn't make the connection. Hats off to Professor Choueiri!

Dalwinder Singh Sidhu Says:

2013-01-18 10:36:51

I have also made the similar system; I filed patent for it. It does not require lab top. This is stand-alone, uses two independent and identical with monotonous sound suppression with analog processor. I like to see how you do it; maybe we make joint system.

Mark Denison Says:

2013-01-28 09:32:07

WHY does this not work with headphones? The algorithm still requires one sit in the sweet spot of the stereo speakers. I get a great soundstage in the sweetspot of my current high system, with good vinyl source material. I've never heard a headphone that projects a proper soundstage. We only have two ears, so an algorithm should be possible to reproduce the "3D effect" in headphones and eliminate the sweetspot problem. BTW tinny crappy speakers still sound tinny and crappy even with the 3D effect.

Ted Nichols Says:

2013-02-07 16:05:56

I was forwarded this link by a friend. I've recently set up a media center for work that has a palanar ribbon speaker system run by Marantz equipment that is HDMI-switching multiple audio and video sources. If I'm understanding this article correctly, there's no stand-alone appliance that can be used to provide the DSP effects to existing systems? I've seen and sampled some other 3D effects systems and followed some of the progress by SRS and Dolby on this front, so I'd be curious to test this out through an existing 2-channel or multichannel setup. Many thanks for any updates on this.
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Edgar Choueiri *91’s 3D sound