Re: [Sursound] HRTF optimization by using tones/noise?

[Albert Leusink]

Great insights, thank you all, best wishes for the new year!

Brian, I read your article, nice work!. Would you be willing to share which 
were the 7 HRTF's from the LISTEN
database that were considered the optimized subset? I only know them by number 
(1003 etc..), not by letters as
you have them in the article..

Best,

Albert

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Re: [Sursound] HRTF optimization by using tones/noise?

[Stefan Schreiber]

Albert Leusink wrote:


Good evening,

It’s been very informative reading this list and learning from all of you 
experts.

I’m an experienced audio engineer that suddenly discovered Ambisonics due to 
the whole VR 360 explosion.
 

VR needs surround sound, but you could also say that surround sound (at 
least its wide application)  might be "saved" by current VR 
developments. (Surround sound has arguably been ignored by the music 
industry - but also and quite strangely by the audio equipment 
manufacturers, including certain "headphone companies". The IT industry 
didn't help too much either, IMO.)



(Although I have made some recordings with a Calrec MK4 in the mid nineties; we 
would just mix
them down to stereo, not knowing what to do with these “B-format” outputs, 
thinking that they
were used by the “B”BC only…shameful, I now realize…we were young….:-)

As I’m very new in this, so many questions - that even after reading this list thoroughly and other resources - remain unanswered and hopefully some of you can take the time to answer them. 




I’ll try to put them in separate threads so we can tackle the issues one by 
one, unless you prefer otherwise, let me know.

Question 1:

I’m understanding that a big variable re. localization in ambi to binaural 
decoding is picking the right HRTF.
 



True. There has been a lot of research and about three professional 
products, but nothing practical for the music listener.


Now, is there a method whereby we could use test tones or pink/white noise to approximate the subject's HRTF and then use the closest measured HRTF from i.e. the IRCAM or CIPIC database? 


For example let’s say we use 100Hz, 1K, and 10K and the listener has to press a 
button on his device when he hears each tone exactly in the middle or exactly 
at -180 or otherwise. Or using regular and phase reversed tones and subject has 
to
calibrate when they are the loudest or softest?
 



I believe "picking of HRTF data sets"  could/will currently be achieved 
via measurement of (simple) biometric data and/or matching to HRTF data 
bases, as described in these two introductory articles:


I.

http://www.tvtechnology.com/audio/0014/hrtfs-and-binaural-reproduction/276663

(
Interesting:

“Some research labs developed array prototypes that use way more 
capsules,” said Markus Noisternig from Ircam (Institute for Research 
and Coordination in Acoustics/Music, Paris). “At Ircam we are using 64 
high-quality back-electret capsules for musical recordings, and are 
working towards a new prototype using 256 MEMS microphones. The more 
capsules, the higher the spatial resolution, the more precise the 
binaural transcoding.”


But can they overcome certain noise problems? Spatial resolution is not 
all)


II. (2nd part...)

http://www.tvtechnology.com/audio/0014/deriving-hrtfs-and-the-aes692015-file-format/276920


BEM is a very computationally demanding process. “Computations could 
take a half a day on a powerful computer or less on a computer 
cluster,” Noisternig said. “There would be the option to upload the 
mesh-grid to a server that processes the data on a huge cluster and 
sends back the rendering results. Anyway, we are very far from doing 
this on a smartphone.”



There might be ways to reduce computational complexity. (But this is 
also a research topic for Microsoft, Oculus and others.)



Is this a ridiculous idea or does it have some standing? Would it be very CPU 
intensive or just a matter of supplying a spreadsheet with the IRCAM/CIPIC 
measurements and comparing the subject’s answers to that?
 



The only accessible individualization method on mobile devices is to 
find the best match with HRTFs from huge databases,” Noisternig said. 
This method uses a best-fit model that doesn’t involve scanning the 
head, but rather uses some biometric data that can easily be measured, 
like head radius or the distance between the ears. This information is 
sent to HRTF databases, which propose possible HRTF matches to the 
listener, along with a test recording that contains localization 
information. It is expected that there will be some trial and error, 
as the listener selects the best match.



This is a mixed selection process, based on (basic) biometric data and 
refinement.  ("listener selects the best match")
Of course you could go with just one of the two steps. (see method of 
AmbieXplorer version 2, which is "just" the 2nd step.)


In the future, devices like the Kinect (version 2) already allow to 
capture a 3D model of the human head and torso. Pinnae would have to be 
captured with relatively high resolution.


Best,

Stefan

P.S.: I would like to say again that BiLi and AES should lay open their 
AES-69 standard. (Otherwise some de facto standard will be set by 
Oculus, Microsoft or Mozilla Foundation, later and in any case.)



Surely, it’s far from perfect, but what other solutions do we currently have to 
give binaural listeners the best possible outcome apart from 

Re: [Sursound] HRTF optimization by using tones/noise?

[Stefan Schreiber]

Albert Leusink wrote:


Thank you Len,

That does look interesting.

I wonder how they are trying to accomplish their supposed instant calibration. 
Couldn't find any details on their site.
 


No. Maybe this is just a startup promise?!

They instantly calibrate to your unique head size and ear shape, 
bringing you a listening experience that is customized to the way 
you hear the world everyday. 


Sounds quite good, at least to my ears.;-)

Now the hard part: How?

The patented technology within OSSIC headphones can turn 7.1 surround 
sound into an even more immersive sound experience.


Didn't they mean "5.1"? Otherwise, how many 7.1 surround recordings do 
you have?


By rendering sound in all directions - up, down, near, far, in-front 
and even behind you, 3D Audio immerses you in the content.



The < direction > is "far", then "even behind you".

Whether for listening to music, watching movies, or playing your 
favorite video game, you'll instantly hear a difference in quality and 
immersion.



Sounds like marketing language. The key word is "instantly", see 
above.:-D



Best regards,


Stefan


But in the case that one does not have access to their products,
 




We're launching soon! Help us spread the word:



means: Not available, "believe us", "coming soon"



 


On Dec 29, 2015, at 1:18 PM, len moskowitz  wrote:

Albert Leusink wrote:


   


... but what other solutions do we currently have to give binaural listeners 
the best possible outcome apart from getting themselves measured or them going 
through a whole list of HRTF?s ?
 


These folks may have the right idea:


   http://www.ossic.com/3d-audio




Len Moskowitz (mosko...@core-sound.com)
Core Sound LLC
www.core-sound.com
Home of TetraMic



   


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Re: [Sursound] HRTF optimization by using tones/noise?

[Albert Leusink]

Thank you Len,

That does look interesting.

 I wonder how they are trying to accomplish their supposed instant calibration. 
Couldn't find any details on their site.

But in the case that one does not have access to their products,
It'd still be interested in hearing opinions about the workability of my
tones and noise idea...

Regards,

Albert. 

> On Dec 29, 2015, at 1:18 PM, len moskowitz  wrote:
> 
> Albert Leusink wrote:
> 
> 
>> ... but what other solutions do we currently have to give binaural listeners 
>> the best possible outcome apart from getting themselves measured or them 
>> going through a whole list of HRTF?s ?
> 
> 
> These folks may have the right idea:
> 
> 
> http://www.ossic.com/3d-audio
> 
> 
> 
> 
> Len Moskowitz (mosko...@core-sound.com)
> Core Sound LLC
> www.core-sound.com
> Home of TetraMic
> 
> 
> 
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Re: [Sursound] HRTF optimization by using tones/noise?

[len moskowitz]

Albert Leusink wrote:


... but what other solutions do we currently have to give binaural 
listeners the best possible outcome apart from getting themselves 
measured or them going through a whole list of HRTF?s ?



These folks may have the right idea:


    http://www.ossic.com/3d-audio




Len Moskowitz (mosko...@core-sound.com)
Core Sound LLC
www.core-sound.com
Home of TetraMic



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Re: [Sursound] HRTF optimization by using tones/noise?

[Bo-Erik Sandholm]

To get yorur feet wet, try
ambiexplorer app on a Phone or tablet with some downloaded ambisonic files.

As I understand it you can choose from The included hrtfs with variation
based on head width between The ears.

According to ericsson media lab staff this is one of The most important
parameters.

Br Bo-Erik
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[Sursound] HRTF optimization by using tones/noise?

[Albert Leusink]

Good evening,

It’s been very informative reading this list and learning from all of you 
experts.

I’m an experienced audio engineer that suddenly discovered Ambisonics due to 
the whole VR 360 explosion.

(Although I have made some recordings with a Calrec MK4 in the mid nineties; we 
would just mix
them down to stereo, not knowing what to do with these “B-format” outputs, 
thinking that they
were used by the “B”BC only…shameful, I now realize…we were young….:-)

As I’m very new in this, so many questions - that even after reading this list 
thoroughly and other resources - remain unanswered and hopefully some of you 
can take the time to answer them. I’ll try to put them in separate threads so 
we can tackle the issues one by one, unless you prefer otherwise, let me know.

Question 1:

I’m understanding that a big variable re. localization in ambi to binaural 
decoding is picking the right HRTF.

Now, is there a method whereby we could use test tones or pink/white noise to 
approximate the subject's HRTF and then use the closest measured HRTF from i.e. 
the IRCAM or CIPIC database? 

For example let’s say we use 100Hz, 1K, and 10K and the listener has to press a 
button on his device when he hears each tone exactly in the middle or exactly 
at -180 or otherwise. Or using regular and phase reversed tones and subject has 
to
calibrate when they are the loudest or softest?

Is this a ridiculous idea or does it have some standing? Would it be very CPU 
intensive or just a matter of supplying a spreadsheet with the IRCAM/CIPIC 
measurements and comparing the subject’s answers to that?

Surely, it’s far from perfect, but what other solutions do we currently have to 
give binaural listeners the best possible outcome apart from getting themselves 
measured or them going through a whole list of HRTF’s ?

Thanks !

Albert






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