[ProAudio] stereo perception through headphones

[Edward Gosfield III]

Hello All
For those who are intrigued, inspired by David, I looked into E. 
Choueiri at Princeton.  He spends  much of his academic time working on 
plasma physics and propulsion.

https://mae.princeton.edu/people/faculty/choueiri

But he also designed a stereo processing system which he intends to 
"remove crosstalk" through a set of methods including a 'universal 
filter', but culminating in individualized in-ear-canal measurements and 
a software package.  Apparently, though, this is mainly intended to 
improve reproduction through stereo speakers, (although reviewers found 
it effective on stereo speaker playback of binaural material)

Lots of links to academic papers on ambisonics and virtual soundfields.

He also has material related to binaural recording and playback, 
including links to a couple of vocal tracks to illustrate the 3D effect 
of his processing of stereo.  Unfortunately it's not music,  and is 
specified for particular speakers. (Jambox). If other speakers are used 
"the 3D effect will be compromised" . On my bookshelf SPICAs  it does 
create the illusion of a speaker behind the listener (left rear for me), 
which 'stereo width enhancers' don't do.  It's a bit reminiscent of some 
of the 'spatializers' for audio-for-video playback, but more specific in 
source placement.  Very interesting. I'd love to hear the real deal, on 
music that I know well or recorded myself.

Main audio website for Choueiri:
http://www.princeton.edu/3D3A/

news piece:
https://www.cnet.com/news/rocket-scientist-converts-stereo-into-3d-sound/

Apparently I should have said "Head-Related-Transfer-Functions" not 
'headphone related' .  One is HRTF, the other is HpTF ;-)

Here is an happy 'audiophile' reporting at length his subjective 
experience:
[system obtainable for $5K-7K for the basic stereo speaker processing 
system, in 2017
Including RME interface, binaural mikes for calibration, and proprietary 
software...
Other versions  for $6k-$7k include adnl headphone equalization and 
processing features.
MAC only.]

https://www.audiostream.com/content/bacch4mac-3d-audio-playback-system

and a 2015 report from the Mother Church of Audiophilia:

https://www.stereophile.com/content/bacch-sp-3d-sound-experience
says:

"The price (including infrared tracking cameras, microphones, and a 
dedicated iPad controller) is $54,000" (circa 2015)

I'll wait for the mass market version.  It should take the video game 
industry by storm if they can manage to make it fit standard domestic 
computer capabilities.


EG

On 1/30/2020 2:38 PM, David Josephson via ProAudio wrote:
> As Scott mentioned, most stereo recordings intended for speaker 
> playback translate poorly to headphone playback. There are some fixes 
> for that, most of which involve feeding some of one channel's signal 
> to the other channel with phase shift or delay. You end up with a 
> different mix for the headphone listener. See the research of Edgar 
> Choueri at Princeton for some recent work in this area.
>