[Sursound] Vestibular response, HRTF database, and more

[Eric Carmichel]

 
with EAR foam plugs and audiometric insert phones. 
VVMic and live recordings via Ambisonics is a solution to creating 
"electric" listening in the real world. Again, I'm referring solely to CI 
simulations. With the advent of electric-acoustic stimulation (EAS), 
more than one mic is used per ear: One for the CI and a second for the 
HA. Combinations of polar patterns can be created. Respective frequency 
responses and processing can be sent to one or two ears (diotic and 
dichotic situations). One caveat for using vocoding to mimic CIs is that the 
acoustic simulation (and therefore stimulation) still necessitates a traveling 
wave along the normal-hearing listener's basilar membrane. The time it takes to 
establish a wave peak is not instantaneous (though compressional waves in the 
the inner ear are virtually instantaneous), and I believe a time-domain 
component to inner ear (mechanical) action can't easily be excluded when using 
"acoustic" simulation of CIs. I suppose I could look at data from BAERs and the 
Greenwood approximation to account for the time-frequency interaction. Just 
some thinking... and ideas to share with others interested in hearing 
impairments. 


By the way, Teemko, if you're reading this, just wanted to let you know that 
Bill Yost said he'd read your thesis over the weekend. I notice that Bill and 
Larry Revit are in your references list. Larry isn't a fan of Ambisonics--said 
to me in a phone communication that it sounds "tinny". I suppose it does if one 
were to listen through laptop speakers or from poor source material. Not sure 
what his source was.
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Re: [Sursound] Patent application: Data structure for HOA

[Stefan Schreiber]

Peter Lennox wrote:

Basically, stereo intrinsically features cross-talk; listening over headphones removes this. 
So putting it back in, via some kind of Blumlein shuffling, fixes that. if you want externalisation, you need some room effect (artificially generated or whatever). So you can have 'stereo-via-headphones', it's just a case of subtlety.

Dr Peter Lennox

School of Technology,
Faculty of Arts, Design and Technology
University of Derby, UK
e: p.len...@derby.ac.uk
t: 01332 593155
 



Problems of listening to stereo via headphones is not just related to 
crosstalk. (Which might not be some "natural thing" in the first place.)


Binaural representation suffers because of HRTF questions, head 
movements, "maybe" other factors.


In fact, aren't most problems are already discussed/solved, but awaiting 
commercialization?


Hint:

http://smyth-research.com/


We had this discussion before, at least I have some strange déjà vu 
feeling here... :-)


Best,

Stefan Schreiber




To: Surround Sound discussion group
Subject: Re: [Sursound] Patent application: Data structure for HOA

On 1 Nov 2012, at 23:07, Stefan Schreiber  wrote:

 


The next and valid question is if stereo via headphones actually works so well at all... 
(Many people have problems, such as in-head effects, lack of perceived "real 
space", etc.)

If you would fix these problems, then you could probably also reproduce 
convincing binaural surround via headphones.
   



Of course stereo doesn't work through headphones! That's why there's a 
difference between stereo and binaural, because stereo assumes speakers being 
IN FRONT of the listener, not perpendicularly left and right of the listener. 
That's why there are head phone processors which in essence transcode regular 
stereo into binaural stereo.

Sennheiser sold such a processor for a while, I still have it somewhere. It worked rather 
well, except that the electronics were of inferior quality using cheap, low-power 
components. So then I had the choice of listening to super-clean audio from my Metric 
Halo headphone output, but have "in head" stereo, or to listen to grungy, muddy 
sound, with the proper sound stage.

That's also EXACTLY why UHJ needs to be decoded to binaural, because being 
stereo compatible, without decoding it works just as well or just as badly as 
regular stereo works on headphones.

A mobile device music player app can solve these issues for both UHJ and 
regular stereo by doing the proper binaural decoding/transcoding, and since 
it's an app and not a hardwired appliance, it's easy to let users select 
different HRTF in the app's preferences, or even let advanced users load 
personalized HRTFs.

Ronald

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Re: [Sursound] Vestibular response, HRTF database, and more

[Michael Chapman]

Eric,

A bit wide of your topic ... if not indeed off topic.

If you lie a young healthy person (i.e. 'normal' skin elasticity)
on their back and take a copy of their face (a mask).

If you place this on your desk (paperweight-like) it may draw
comments, but not about it being unnatural.

Now hang it on the all. It won't look right and people are
likely to say so. Those who have seen 'death masks' in
museums might even ask if it is one.

(You can extend this ... with strange results ... to parts
of the body that are 'normally' clothed ... but that is
another matter.)

So a trivial example of an audience's automatic (and
unconscious) compensation for orientation.

Think you now have to do the experiments you've
outlined ;-)>

Michael

or orientation



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