In the March 2011 edition of The Atlantic, Hal Espen interviews Princeton professor Edgar Choueiri about his pure stereo filter (http://www.theatlantic.com/magazine/archive/2011/03/what-perfection-sounds-like/8377/). He promises “truly 3-D reproduction of a recorded soundfield.” Espen’s description of the demo in an anechoic room evokes an acoustic experience that surpasses all previous technologies for presence... both for natural sound and music.
The problem that Prof. Choueiri identified and claims to have solved is a filter which removes cross talk between stereo channels without audible spectral coloration. His approach was documented in a 24 page paper described by Mr. Espen as “fiendishly abstruse.” Since then, Prof. Choueiri obtained Project X funding at Princeton to code his filter and test it in his 3-D audio lab (not his primary work at Princeton... he teaches applied physics and develops plasma rocket engines for spacecraft propulsion.)
Human hearing, including the audio processing in the human brain, is sensitive and sophisticated. When we hear a conventional stereo recording, with channel cross talk, we have to “work” to process and interpret the signal. This “work” creates a barrier between the listener and the audio experience the technology was trying to reproduce. Prof. Choueiri: “The most tiring part of stereo is the fact that the image spatially doesn’t correspond to anything that you ordinarily hear.” “That’s what drove me to create this thing. Your brain is getting the right cues, and you relax. Your brain stops trying to recreate reality.”
I love this story because spatial sound reproduction is considered by most technologists to be a solved problem. Most development since the introduction of the CD has been development of multi-speaker technologies that use brute force to add sound to action-adventure cinema experiences. There has been some work on digital audio signal processing to allow customization of a stereo audio signal to reproduce different concert spaces or to correct artifacts from earlier recording technologies, but Prof. Choueiri’s work goes back to the fundamental problem of stereo fidelity, the focus of audio engineering before 1980.
I’m neither an audio engineer, nor an audiophile, however, I have a strong preference for live music over reproduced music because of the quality of the experience. I’ve assumed that the problem with reproduced music has been the cost of creating a good audio environment in my home, not the fundamental technology. This work causes me to reexamine that assumption.
What’s your perspective on Prof. Choueiri’s invention? Is a great leap forward or just an over-hyped incremental improvement?
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