Three Dimensional Sound

Edgar Choueiri
Professor, MAE and Director, Electric Propulsion & Plasma Dynamics Lab, Princeton University

2296th Meeting Abstract
Friday, February 3, 2012 8:15 PM

Edgar Choueiri


This lecture will discuss a process known as "3D Audio." 3D Audio is sound reproduction that allows a listener to (1) hear sounds in a three-dimensional manner, as if the listener is in the original recorded sound field, and (2) precisely locate sound sources in that 3D space. For example, assume during a recording session that an insect flies in a circle around the recording microphones. A listener of the recording, played back through the loudspeakers of the 3D Audio system, would hear the same insect as if it were circling his or her own head.

3D Audio over loudspeakers has obvious applications for 3D cinema, 3D TV, pro audio, computer gaming, teleconferencing, medical aid for hearing-impaired patients, military training, virtual reality systems, and the multi-billion-dollar home entertainment industry.

The lecturer will present the pros and cons of the three most promising methods for 3D sound reproduction: (1) Wavefield Synthesis, (2) Ambisonics, and (3) Binaural audio through loudspeakers. He will then discuss several recent advances covering the third "binaural method," which have led to the development of the BACCH 3D sound technology at Princeton University.

The lecturer will also discuss how the "binaural method" is capable of delivering the necessary cues for 3-D Audio to the ear-brain system using only two transducers (if the "crosstalk" between the left (right) transducer and the right (left) ear is canceled). However, one problem is that this crosstalk cancellation (XTC) inherently imposes a strong spectral coloration on the sound that is intolerable by audio engineering standards. But the team at Princeton has had a recent breakthrough which makes it possible to produce optimized XTC filters (called BACCH filters) that impose no spectral coloration to the sound. The design of these BACCH filters and their uses in various 3D Audio applications will be discussed.

The talk will conclude with a demonstration of a BACCH 3D sound system.

About the Author:

Edgar Choueiri is a professor of applied physics at the Mechanical and Aerospace Engineering Department of Princeton University and Associated Faculty at the Department of Astrophysical Sciences, Program in Plasma Physics. He is also Director of Princeton University's Engineering Physics Program and Chief Scientist at the university's Electric Propulsion and Plasma Dynamics Lab, a recognized center of excellence in research in the field of advanced spacecraft propulsion. He is also the director of Princeton's 3D Audio and Applied Acoustics (3D3A) Lab.

Professor Choueiri is a world-renown leader in the field of plasma physics and plasma propulsion for spacecraft. He is the author of more than 145 scientific publications, and encyclopedia articles on plasma rockets, plasma physics, instabilities and turbulence in collisional plasmas, plasma accelerator modeling, space physics and applied mathematics. An avid audiophile, acoustician and classical music recordist, his decades-long passion for perfecting the realism of music reproduction has led him to work on the difficult fundamental problem of designing advanced digital filters that allow the natural 3D audio to be extracted from stereo sound played through two loudspeakers, without adding any spectral coloration to the sound (i.e. without changing its tonal character). He was able to solve this problem mathematically by applying the analytical and mathematical tools he uses in his plasma physics research.

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