Re: [Sursound] Vestibular response, HRTF database, and now with added height...

[Peter Lennox]

Eric, some interesting thoughts there, thanks.
One or two thoughts in reaction:
1) you say " There have been a lot of studies regarding localization in the 
transverse (horizontal) plane" - I know its quite common to conflate these, but 
(as implied in your later thought experiment) - it's worth pointing out that 
"horizontal" is specified as perpendicular to gravity. When a person is 
standing or sitting straight, then if the head is not tilted then the 
conflation is permissible. But. People tilt and move their heads all the time, 
so acuity in hearing in the transverse plane is not the same as acuity in the 
horizontal plane

2) Your question about acuity when the body is not in that 'usual' orientation: 
I've thought the same thing, though the other way around - I put people flat on 
their backs, then played ambisonic material tilted through 90 degrees, to see 
if they got some different experience. So, I was interested in perception in 
the vertical, but using that transverse plane. The experience was different, 
but inconclusive in that it wasn't a controlled experiment, of course. I found 
that identification of source direction was less good than I'd anticipated. BUT 
- actually, (going back to experiences whilst camping - I've lain awake in the 
countryside thinking about these things) - listening (especially for direction) 
with your head so close to the ground is certainly an unfamiliar experience. 
You've messed up a lot of the pinnae effects. Interaural differences may well 
be affected. You've got a peculiar pattern of very early reflections (from the 
ground next to your ears). Most importantly, y
 ou're listening to sources in the sky, with no reflective and occlusive bodies 
around them. There's no 'ground effect' of the sort that a standing or sitting 
person will get - that it, early reflected material that has interacted with 
the ground, including filtering by surface features, clutter (material objects 
and detritus have a tendency to be near the ground due to gravity...) so, 
overall, hearing in that area just won't be the same.
The above might partly account for why, in your experiment, hearing in the 
horizontal might seem better than it ought - there are simply more cues 
available for sources at or near the ground? However, in the camping example, I 
did find increased instances of reversals.

So I had thought there might be an interaction between gravity and spatial 
hearing, but realised that some of it is just down to physics - the sky really 
is different from the ground, we really are sort of "2.5 d" hearers (and 
thinkers?). I'd also wondered whether distance(range) perception might differ 
with direction. It does (items seem nearer), but more to do with the physics of 
the matter - for sources in the sky, sometimes (not always!) there is only a 
direct signal path. So, distance perception as the product of the 
direct/indirect ratio doesn't seem quite the right formulation.

These things need some decent experimentation, it seems to me

Cheers
ppl


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

-Original Message-
From: sursound-boun...@music.vt.edu [mailto:sursound-boun...@music.vt.edu] On 
Behalf Of Eric Carmichel
Sent: 03 November 2012 18:54
To: sursound@music.vt.edu
Subject: [Sursound] Vestibular response, HRTF database, and more

Greetings,
Mostly through serendipity, I have had the pleasure and privilege of great 
teachers. I studied recording arts under Andy Seagle (andyseagle.com) who 
recorded Paul McCartney, Hall & Oats, and numerous others. My doc committee 
included Bill Yost, who is widely known among the spatial hearing folks. And, 
of course, I've learned a lot about Ambisonics from people on this list as well 
as a plethora of technical articles.

I recently sent an email to Bill with the following question/scenario. I 
thought others might wish to give this thought, too, as it gets into HRTFs.

There have been a lot of studies regarding localization in the transverse 
(horizontal) plane. We also know from experiments how well (or poorly) we can 
localize sound in the frontal and sagittal planes. By simply tilting someone 
back 90 degrees, his/her ears shift to another plane. This is different from 
shifting the loudspeaker arrangement to another plane because the semicircular 
canals are now in a different orientation. If a circular speaker array was 
setup in the coronal plane and the person was lying down, then his/her ears 
would be oriented in such a way that the speakers now circle the head in the 
same fashion as they would in the horizontal plane when the person is seated or 
standing. It's a "static" vestibular change, and gravity acting on the 
semicircular canals (and body) lets us know which way is up. But do we have the 
same ability to localize when the body is positioned in different orientations, 
even when the sources "follow" the  orie

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

[Dave Malham]

Hi all,

  Is anyone aware of any research on how the balance/orientation
system and spatial hearing work in zero gravity, preferably both for
real sources and for stereo (blumlein/spaced pair/hybrid) as well as
Ambisonics? If there isn't any, it's time to set up an experiment for
the ISS.

Dave

On 4 November 2012 07:24, Eric Carmichel  wrote:
> Howdy Michael,
> When it comes to death masks, their HRIRs, and localization in the spiritual 
> plane, I won't go there. There's enough in the physical realm to keep me 
> confused. For example, I have a pair of socks with L embroidered on one and R 
> on the other. I have no idea how the sock manufacturer could tell which was 
> which. But so long as I have R and L tattooed on my feet, I can keep things 
> aligned. Shoes, on the other hand, are always trial and error.
> Seriously (kind-of), there seems to be a dearth of info on 
> auditory-vestibular interaction, particularly the dynamic effects. We "know" 
> that a fixed item is stationary when we move our head, and we know that a 
> moving object is in motion when we stand still (or lie down in the case of a 
> good tracing). Lots of studies of vestibular-vision interaction, and there 
> are certainly ways to trick the mind into believing what ain't true is 
> believable.
> Re static anatomical plane inversions: I don't believe that a vestibular cue 
> will turn an azimuth interaural cue into a vertical HRTF cue (or vice a 
> versa).  But if the vestibular interaction is at the level where all cues are 
> used to determine the total 3D location of the source, maybe vestibular input 
> can correct for where the head is situated (?).
> As usual, I ask a lot of naive questions. Perhaps I'm like the prisoners in 
> Plato's Cave Allegory who were only allowed to see (or hear) things from a 
> limited perspective. Release from the cave may be too much for yours truly to 
> comprehend. But as long as I turn toward the shadows (or my feet), everything 
> remains real.
> Best regards,
> E
>
>
>
>
> 
>  From: Michael Chapman 
> To: Eric Carmichel ; Surround Sound discussion group 
> 
> Sent: Saturday, November 3, 2012 9:52 PM
> Subject: Re: [Sursound] Vestibular response, HRTF database, and more
>
>
> 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
> -- next part --
> An HTML attachment was scrubbed...
> URL: 
> 
> ___
> Sursound mailing list
> Sursound@music.vt.edu
> https://mail.music.vt.edu/mailman/listinfo/sursound



-- 
As of 1st October 2012, I have retired from the University, so this
disclaimer is redundant


These are my own views and may or may not be shared by my employer

Dave Malham
Ex-Music Research Centre
Department of Music
The University of York
Heslington
York YO10 5DD
UK

'Ambisonics - Component Imaging for Audio'
___
Sursound mailing list
Sursound@music.vt.edu
https://mail.music.vt.edu/mailman/listinfo/sursound

Re: [Sursound] Vestibular response, HRTF database, and now with added height...

[Dave Malham]

Hi Peter,
Like I just said - needs experiments in zero G. I wonder what the
acoustics in the ISS are like? Might be easier to organise decent
acoustics in a Vomit Comet
(http://en.wikipedia.org/wiki/Reduced_gravity_aircraft) especially as
the padding already there would help. Now, where do we apply for
funding??

Dave

On 5 November 2012 14:18, Peter Lennox  wrote:
> Eric, some interesting thoughts there, thanks.
> One or two thoughts in reaction:
> 1) you say " There have been a lot of studies regarding localization in the 
> transverse (horizontal) plane" - I know its quite common to conflate these, 
> but (as implied in your later thought experiment) - it's worth pointing out 
> that "horizontal" is specified as perpendicular to gravity. When a person is 
> standing or sitting straight, then if the head is not tilted then the 
> conflation is permissible. But. People tilt and move their heads all the 
> time, so acuity in hearing in the transverse plane is not the same as acuity 
> in the horizontal plane
>
> 2) Your question about acuity when the body is not in that 'usual' 
> orientation: I've thought the same thing, though the other way around - I put 
> people flat on their backs, then played ambisonic material tilted through 90 
> degrees, to see if they got some different experience. So, I was interested 
> in perception in the vertical, but using that transverse plane. The 
> experience was different, but inconclusive in that it wasn't a controlled 
> experiment, of course. I found that identification of source direction was 
> less good than I'd anticipated. BUT - actually, (going back to experiences 
> whilst camping - I've lain awake in the countryside thinking about these 
> things) - listening (especially for direction) with your head so close to the 
> ground is certainly an unfamiliar experience. You've messed up a lot of the 
> pinnae effects. Interaural differences may well be affected. You've got a 
> peculiar pattern of very early reflections (from the ground next to your 
> ears). Most importantly,
  y
>  ou're listening to sources in the sky, with no reflective and occlusive 
> bodies around them. There's no 'ground effect' of the sort that a standing or 
> sitting person will get - that it, early reflected material that has 
> interacted with the ground, including filtering by surface features, clutter 
> (material objects and detritus have a tendency to be near the ground due to 
> gravity...) so, overall, hearing in that area just won't be the same.
> The above might partly account for why, in your experiment, hearing in the 
> horizontal might seem better than it ought - there are simply more cues 
> available for sources at or near the ground? However, in the camping example, 
> I did find increased instances of reversals.
>
> So I had thought there might be an interaction between gravity and spatial 
> hearing, but realised that some of it is just down to physics - the sky 
> really is different from the ground, we really are sort of "2.5 d" hearers 
> (and thinkers?). I'd also wondered whether distance(range) perception might 
> differ with direction. It does (items seem nearer), but more to do with the 
> physics of the matter - for sources in the sky, sometimes (not always!) there 
> is only a direct signal path. So, distance perception as the product of the 
> direct/indirect ratio doesn't seem quite the right formulation.
>
> These things need some decent experimentation, it seems to me
>
> Cheers
> ppl
>
>
> 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
>
> -Original Message-
> From: sursound-boun...@music.vt.edu [mailto:sursound-boun...@music.vt.edu] On 
> Behalf Of Eric Carmichel
> Sent: 03 November 2012 18:54
> To: sursound@music.vt.edu
> Subject: [Sursound] Vestibular response, HRTF database, and more
>
> Greetings,
> Mostly through serendipity, I have had the pleasure and privilege of great 
> teachers. I studied recording arts under Andy Seagle (andyseagle.com) who 
> recorded Paul McCartney, Hall & Oats, and numerous others. My doc committee 
> included Bill Yost, who is widely known among the spatial hearing folks. And, 
> of course, I've learned a lot about Ambisonics from people on this list as 
> well as a plethora of technical articles.
>
> I recently sent an email to Bill with the following question/scenario. I 
> thought others might wish to give this thought, too, as it gets into HRTFs.
>
> There have been a lot of studies regarding localization in the transverse 
> (horizontal) plane. We also know from experiments how well (or poorly) we can 
> localize sound in the frontal and sagittal planes. By simply tilting someone 
> back 90 degrees, his/her ears shift to another plane. This is different from 
> shifting the loudspeaker arrangement to another plane because the 
> semicircular canals are now in a different orientation. If a circu

[Sursound] Which order (but not extactly high order)?

[Eric Carmichel]

Greetings,
I would like to model microphone pickup patterns in conjunction with HRTFs and 
Ambisonic recordings that I've made. To give a specific example, I would like 
model a miniature supercardiod mic, pointed forward, that is located proximal 
(or superior) to the pinna. This would be akin to a directional mic on a 
hearing aid or CI processor. The HRTF can be approximate, as the mic is likely 
to be placed slightly above the pinna and close to the head, not right at the 
opening of the ear canal. Some mics, however, are located in the concha, so the 
IRs from the Listen Project would approximate the mic placement, but not the 
mic's polar pattern.
I have recordings of cafeterias and public spaces that I made using a TetraMic. 
VVMic allows me to create first-order mic patterns that can be rotated in 
space. This alone is useful, but does not include the acoustic shadow that 
would be created by a hearing aid wearer's head. I have the Harpex VST, too. 
Harpex includes the HRIRs from the Listen Project (Svein, please correct me if 
I'm wrong on this), thus making binaural simulations a snap. But to get an HRTF 
that includes a specific mic pick-up pattern is a little trickier.
I had initially used VVMic to create the mic pattern I wanted, and then aimed 
it to the direction I wanted. Input was B-formatted wav files. The resulting 
output is a single channel, or N identical channels if I want to create N 
tracks. I created 4 tracks and used these as pseudo B-formatted material in 
Harpex.
The other "order" would be to create a stereo (binaural) output via Harpex from 
the original (authentic) B-formatted material. Then one of the two channels, L 
or R, could be made into four identical tracks that can be fed to VVMic to get 
the intended polar response. The four tracks, of course, are not B-format.
A bit of head scratching tells me neither method outlined above is correct. At 
least the binaural output from Harpex should be equivalent to an 
omnidirectional mic placed at an ear's concha (ITE hearing aids), and that 
could be used for simulations of electric listening. But I'd really like to 
model hybrid devices that combine both electric (cochlear implant) and acoustic 
(hearing aid) stimulation. It seems that using Ambisonic recordings without the 
need for loudspeakers would be an elegant way to simulate CI listening in 3-D 
environments, but using normal-hearing listeners.

Regarding my recent post (vestibular-auditory interactions and HRTFs): Thanks 
to Peter L. for making my clumsy wording clearer and to Dave M. for making the 
idea more direct and to the point. I have to be careful when referencing the 
anatomical horizontal plane versus the horizontal plane that lies perpendicular 
to gravity. Although a bit off topic of Ambisonics, the post did directly 
relate to spatial hearing. Because it's easy to do virtual mic rotations with 
Ambisonic material, Ambisonics could be a useful tool for studying 
vestibular-auditory interactions.
Thanks to everyone,
Eric
-- next part --
An HTML attachment was scrubbed...
URL: 
<https://mail.music.vt.edu/mailman/private/sursound/attachments/20121105/7ac6a6d2/attachment.html>
___
Sursound mailing list
Sursound@music.vt.edu
https://mail.music.vt.edu/mailman/listinfo/sursound