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Introduction to 3D Audio with Professor Choueiri


(A Video with Animations and Demos)

Produced by Princeton University. Filmmaker: Mike Wood


More About Professor Choueiri, The Inventor. The Scientist. The Brain and the Soul of BACCH©

Professor 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 a 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 150 scientific publications, and encyclopedia articles on plasma rockets, plasma physics, instabilities and turbulence in collisional mathematics. He has been the Principal Investigator in more than 30 competitively selected research projects (including two space experiments), funded by NASA, the US Air Force the National Science Foundation, and other governmental and private institutions. He is Fellow of the American Institute of Aeronautics and Astronautics and the recipient of many awards and honors including a knighthood. 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 analytical and mathematical tools he uses in his plasma physics research.


Crosstalk Canceller (XTC) Basics





Image Courtesy of Princeton University


The BACCH-SP is a crosstalk canceller (XTC)

Normally, sound from two speakers reaches both ears. This crosstalk cues the listener that the position of the sound source is the speakers. XTC removes the crosstalk.

With the left ear only hearing the left speaker (and vice versa), the listener can hear the cues in the music that position the sound sources where the artists intended.


What makes BAACH the Best XTC?



For each band, we finds the optimal amount of XTC that is the right balance between cancellation, available power and room reflections. 

The result is the optimal XTC, the best possible XTC given the room, the speakers and the performance of human anatomy. 




Home Tech Software Showcase


You only have two ears, so you should only need two speakers to reproduce every sound in the world.  Bit Cauldron’s AudioCauldron 3D Sound Software incorporates BACCH 3D Sound technology from Princeton University.  3D Sound restores the true immersive nature of stereo by removing the corruption of stereo cues due to crosstalk. 



The BACCH Innovation


BACCH Headphone Technology

Approaching 100% Externalization

BACCH Headphone 3D Sound grabs the sound of headphones and pulls it outside your head.

With the HRTF libraries that were state-of-the-art before BACCH technology, only 30-70% of listeners will believed that a sound is externalized, or outside their head.

BACCH Headphones bring Externalization to almost 100%


BACCH Speaker Technology

>20 dB Crosstalk Cancellation (XTC) with flat response and no dynamic range loss

BACCH Speaker 3D Sound makes the speakers melt away and leaves the sound coming from anywhere in the room.

The XTC technologies before BACCH were a trade-off between sweet spot size, steerability, spectrally uncolored sound, and no dynamic range loss.

BACCH Speakers can have it all at the same time. 


Because 3D Sound can place sound sources anywhere, it can place any number of virtual surround sound speakers in any configuration. 



Achieving High-Spatial fidelity binaural rendering over headphones for every individual listener  without generating individualized measurements has been the cauldron at the end of the 3D Audio rainbow for years. 

Media Coverage of BACCH 3D Sound technology





Band Assembled Crosstalk Cancelled Hierarch


BACCH-SP is for Speakers

BACCH-HP for Headphones



For each band, we finds the optimal amount of XTC that is the right balance between cancellation, available power and room reflections.  The result is the optimal XTC, the best possible XTC given the room, the speakers and the performance of human anatomy. 




A complete technical explanation is available in the paper Optimal Crosstalk Cancellation for Binaural Audio with Two Loudspeakers.


Quotes about the BACCH-SP Reference System



“I heard a spatial presentation that was indistinguishable from real life”

Robert Harley, Editor, The Absolute Sound 


“The reverberation on the recordings was now a stable, solid halo around the performers, just as it is in reality”

John Atkinson, Editor, Stereophile


“The 3D-ness of the presentation was absolutely startling...  literally dissolved both the speakers and room... “

Michael Lavorgna, AudioStream 


“Better sounding than stereo, better than 5.1, better than 10.2!”

Bob Katz, Grammy-award winning audio mastering engineer and author 


“The sound spread to the full width of the room, and projected sound forward… [the] 3D claim is no hype; … sounds amazing”

Steve Guttenberg, CNET audio reviewer


More Quotes about the BACCH-SP Reference System


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