BREAKING GROUND: Unlocking the key to 3D sound

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.