Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Sampo Syreeni]

On 2022-08-12, Fons Adriaensen wrote:


On Fri, Aug 12, 2022 at 08:57:33AM -0400, Marc Lavallée wrote:


You can't transport a grand piano on a bicycle.

It's possible with an extra wheel:
https://www.rimskipiano.org/rimski-s-bicycle-piano


:-) Would like to see that going downhill...


As I remember, one of the modern classical composers, maybe even Cage, 
once dropped a rock/boulder on a grand piano, as a performance piece. 
Call it the penultimate prepared piano, second only to the explosive 
one.


There's *always* a slope downhill...

Many years ago (1970s) I was at a concert in which an upright piano 
was suspended on a steel cable going from the top of the auditorium 
down to the stage. The (short) performance ended when the instrument 
smashed into the rear wall.


But did it so purposely? Did it kill anyone?

An there was the French street theater group 'Royal de Luxe' who used 
to launch pianos with a ballista. But they cheated, taking out the 
metal frame first.


Right now I'm watching Queen of the South on Netflix. Reportedly it has 
been largely inspired by narcocorrid0.


Forget ballista, forget metal, anything at all. Narcocorrido is the 
worst sort of music you can ever find. It's all polka, with tuba 
baseline, melody from happy men and accordions/harmonicas, all telling 
about real life where men and women are killed, and their children 
raped. Being rid of their eyes, to polka tune.



None of them had anything I'd call artistic about them... :-(


I know the type. Being a libertarian and a well-versed amateur economist 
myself.


Most people who talk economics, do not in fact understand economics. My 
kind included.

--
Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front
+358-40-3751464, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
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Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Sampo Syreeni]

On 2022-08-12, Marc Lavallée wrote:


You can't transport a grand piano on a bicycle.



It's possible with an extra wheel:
https://www.rimskipiano.org/rimski-s-bicycle-piano


More generally, it's called a lever, or leverage. And as we all know, 
there is no theoretical limit to it; it tends towards infinity, as the 
Halligan lenghtens.

--
Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front
+358-40-3751464, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
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Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Junfeng Li]

Dear Lorenzo,

On Fri, Aug 12, 2022 at 6:58 PM Picinali, Lorenzo 
wrote:

> Hello Jungfeng,
>
> this is a good starting reference for human localisation in rooms:
>
>
> https://asa.scitation.org/doi/abs/10.1121/1.390163?casa_token=CFvwSHcyaLAA:bWPPmgMCrq0av1HBq2u_qYarqXatOFggyofiiYVWzguTOLbI3jDLCG65xni64_uMXVKq7setdQ
>
> There are also two further papers by Hartmann on the same topic, which are
> linked at the beginning of the one linked above. In general, early
> reflections can reinforce the sense of localisation of the sound source,
> especially if coming from the same direction (see the conclusions of the
> paper above). Of course familiarity with the room (and/or long-term
> training) will be of help as well.
>

Yeah!
As I know that the reverberation in room contributes a lot to distance
perception or externalization perception for headphone reproduction.
However, I am not sure that reverberation also helps to elevation
perception. therefore, I am wondering whether there is any reference to
point out this idea.



>
> Regarding the training, we actually do have a version of the app for
> iPhones and cardboard HMDs...if that's what you have, send me your github
> username/email address and I'll share the repo with you.
>
>
>
I have no github now. I will create one and let you know as soon as
possible.

Thanks again.

Best regards,
Junfeng




>
>
> --
> Dr Lorenzo Picinali
> Reader in Audio Experience Design<https://www.axdesign.co.uk/>
> Dyson School of Design Engineering
> Imperial College London
> Dyson Building
> Imperial College Road
> South Kensington, SW7 2DB, London
> E: l.picin...@imperial.ac.uk
>
> http://www.imperial.ac.uk/people/l.picinali
> https://www.axdesign.co.uk/
> 
> From: Sursound  on behalf of Junfeng Li <
> junfeng.li.1...@gmail.com>
> Sent: 12 August 2022 11:16
> To: Surround Sound discussion group 
> Subject: Re: [Sursound] On 3D audio rendering for signals with the low
> sampling frequency
>
> Dear Lorenzo,
>
> Thanks a lot for your instructive information.
>
>
>
>
> > addressing the same matter in the Auditory mailing list, David McAlpine
> > suggested to look at perceptual training:
> >
> > https://www.nature.com/articles/nn0998_417
> >
> > While it is true that people with significant hearing loss above 8kHz can
> > still perceive elevation, it is likely that this hearing loss (e.g.
> > age-related sensorineural) appeared gradually, and the person had time to
> > adapt and re-map their spatial hearing cues. As mentioned by others
> > already, these are not just the peaks and notches typical of an HRTF, but
> > also the reflections coming from the surrounding space.
> >
>
> It is really interesting to know that elevation perception is also affected
> by the reflections. Is there any literature to report this conclusion?
> What are the differences of reflections for sound images with different
> elevated angles?
>
>
> >
> > The real issue with hearing training, specifically HRTF accommodation
> > (i.e. learning how to localise sound sources with an HRTF which is not
> your
> > own, which could be extended to learning how to localise sound sources
> > using an altered HRTF, e.g. low-passed at 8kHz), is that it takes some
> > time, it's not really immediate, so if the aim is to just release some
> > spatialised audio online or through other channels for the general
> public,
> > it might be difficult to implement that.
> > But it might be interesting to try! Together with Brian FG Katz in Paris
> > we've done some work looking at short- and long-term HRTF accommodation:
> >
> > https://www.nature.com/articles/s41598-018-37873-0
> >
> > and also at VR-based localisation training
> >
> > https://www.nature.com/articles/s41598-019-54811-w
> >
> > We'll be happy to share with you our Unity (currently used with the
> Oculus
> > Quest 2) spatial hearing training application, so that you can try to
> > low-pass the output at 8kHz, and see whether it could work.
> >
> >
> >
> We have google Cardboard with a mobile phone as the display device. Is it
> suitable to use your Unity for spatial hearing training? If such, could you
> please let us have a try?
>
> Thanks a lot again.
>
> Best regards,
> Junfeng
>
>
>
> >
> >
> >
> >
> >
> > --
> > Dr Lorenzo Picinali
> > Reader in Audio Experience Design<https://www.axdesign.co.uk/>
> > Dyson School of Design Engineering
> > Imperial College London
> > Dyson Building
> &

Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Fons Adriaensen]

On Fri, Aug 12, 2022 at 08:57:33AM -0400, Marc Lavallée wrote:
 
> > You can't transport a grand piano on a bicycle.
> It's possible with an extra wheel:
> https://www.rimskipiano.org/rimski-s-bicycle-piano

:-) Would like to see that going downhill...

Many years ago (1970s) I was at a concert in which an upright piano
was suspended on a steel cable going from the top of the auditorium
down to the stage. The (short) performance ended when the instrument
smashed into the rear wall.

An there was the French street theater group 'Royal de Luxe' who
used to launch pianos with a ballista. But they cheated, taking
out the metal frame first.
 
> > [1] Or not. I've known my share of managers who believe that
> > business logic or ideology can bend the laws of physics or
> > mathematics...
>
> They're probably artists, but with a manager salary.
> Laws of economics (and greed) are easier to bend.

None of them had anything I'd call artistic about them... :-(

Ciao,

-- 
FA

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Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Picinali, Lorenzo]

Hello Jungfeng,

this is a good starting reference for human localisation in rooms:

https://asa.scitation.org/doi/abs/10.1121/1.390163?casa_token=CFvwSHcyaLAA:bWPPmgMCrq0av1HBq2u_qYarqXatOFggyofiiYVWzguTOLbI3jDLCG65xni64_uMXVKq7setdQ

There are also two further papers by Hartmann on the same topic, which are 
linked at the beginning of the one linked above. In general, early reflections 
can reinforce the sense of localisation of the sound source, especially if 
coming from the same direction (see the conclusions of the paper above). Of 
course familiarity with the room (and/or long-term training) will be of help as 
well.

Regarding the training, we actually do have a version of the app for iPhones 
and cardboard HMDs...if that's what you have, send me your github 
username/email address and I'll share the repo with you.

Best
Lorenzo


--
Dr Lorenzo Picinali
Reader in Audio Experience Design<https://www.axdesign.co.uk/>
Dyson School of Design Engineering
Imperial College London
Dyson Building
Imperial College Road
South Kensington, SW7 2DB, London
E: l.picin...@imperial.ac.uk

http://www.imperial.ac.uk/people/l.picinali
https://www.axdesign.co.uk/

From: Sursound  on behalf of Junfeng Li 

Sent: 12 August 2022 11:16
To: Surround Sound discussion group 
Subject: Re: [Sursound] On 3D audio rendering for signals with the low sampling 
frequency

Dear Lorenzo,

Thanks a lot for your instructive information.




> addressing the same matter in the Auditory mailing list, David McAlpine
> suggested to look at perceptual training:
>
> https://www.nature.com/articles/nn0998_417
>
> While it is true that people with significant hearing loss above 8kHz can
> still perceive elevation, it is likely that this hearing loss (e.g.
> age-related sensorineural) appeared gradually, and the person had time to
> adapt and re-map their spatial hearing cues. As mentioned by others
> already, these are not just the peaks and notches typical of an HRTF, but
> also the reflections coming from the surrounding space.
>

It is really interesting to know that elevation perception is also affected
by the reflections. Is there any literature to report this conclusion?
What are the differences of reflections for sound images with different
elevated angles?


>
> The real issue with hearing training, specifically HRTF accommodation
> (i.e. learning how to localise sound sources with an HRTF which is not your
> own, which could be extended to learning how to localise sound sources
> using an altered HRTF, e.g. low-passed at 8kHz), is that it takes some
> time, it's not really immediate, so if the aim is to just release some
> spatialised audio online or through other channels for the general public,
> it might be difficult to implement that.
> But it might be interesting to try! Together with Brian FG Katz in Paris
> we've done some work looking at short- and long-term HRTF accommodation:
>
> https://www.nature.com/articles/s41598-018-37873-0
>
> and also at VR-based localisation training
>
> https://www.nature.com/articles/s41598-019-54811-w
>
> We'll be happy to share with you our Unity (currently used with the Oculus
> Quest 2) spatial hearing training application, so that you can try to
> low-pass the output at 8kHz, and see whether it could work.
>
>
>
We have google Cardboard with a mobile phone as the display device. Is it
suitable to use your Unity for spatial hearing training? If such, could you
please let us have a try?

Thanks a lot again.

Best regards,
Junfeng



>
>
>
>
>
> --
> Dr Lorenzo Picinali
> Reader in Audio Experience Design<https://www.axdesign.co.uk/>
> Dyson School of Design Engineering
> Imperial College London
> Dyson Building
> Imperial College Road
> South Kensington, SW7 2DB, London
> E: l.picin...@imperial.ac.uk
>
> http://www.imperial.ac.uk/people/l.picinali
> https://www.axdesign.co.uk/
> ________________
> From: Sursound  on behalf of Fons
> Adriaensen 
> Sent: 12 August 2022 08:48
> To: sursound@music.vt.edu 
> Subject: Re: [Sursound] On 3D audio rendering for signals with the low
> sampling frequency
>
>
> ***
> This email originates from outside Imperial. Do not click on links and
> attachments unless you recognise the sender.
> If you trust the sender, add them to your safe senders list
> https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping
> for this address.
> ***
> On Thu, Aug 11, 2022 at 06:40:28PM +0800, Junfeng Li wrote:
>
> > Do the early reflections contribute to elevation perception ?
>
> Well, something which is probably not related to HRTF does.
> Older people often have hearing limited to 8 kHz or even less,
> but may still

Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Junfeng Li]

Dear Lorenzo,

Thanks a lot for your instructive information.




> addressing the same matter in the Auditory mailing list, David McAlpine
> suggested to look at perceptual training:
>
> https://www.nature.com/articles/nn0998_417
>
> While it is true that people with significant hearing loss above 8kHz can
> still perceive elevation, it is likely that this hearing loss (e.g.
> age-related sensorineural) appeared gradually, and the person had time to
> adapt and re-map their spatial hearing cues. As mentioned by others
> already, these are not just the peaks and notches typical of an HRTF, but
> also the reflections coming from the surrounding space.
>

It is really interesting to know that elevation perception is also affected
by the reflections. Is there any literature to report this conclusion?
What are the differences of reflections for sound images with different
elevated angles?


>
> The real issue with hearing training, specifically HRTF accommodation
> (i.e. learning how to localise sound sources with an HRTF which is not your
> own, which could be extended to learning how to localise sound sources
> using an altered HRTF, e.g. low-passed at 8kHz), is that it takes some
> time, it's not really immediate, so if the aim is to just release some
> spatialised audio online or through other channels for the general public,
> it might be difficult to implement that.
> But it might be interesting to try! Together with Brian FG Katz in Paris
> we've done some work looking at short- and long-term HRTF accommodation:
>
> https://www.nature.com/articles/s41598-018-37873-0
>
> and also at VR-based localisation training
>
> https://www.nature.com/articles/s41598-019-54811-w
>
> We'll be happy to share with you our Unity (currently used with the Oculus
> Quest 2) spatial hearing training application, so that you can try to
> low-pass the output at 8kHz, and see whether it could work.
>
>
>
We have google Cardboard with a mobile phone as the display device. Is it
suitable to use your Unity for spatial hearing training? If such, could you
please let us have a try?

Thanks a lot again.

Best regards,
Junfeng



>
>
>
>
>
> --
> Dr Lorenzo Picinali
> Reader in Audio Experience Design<https://www.axdesign.co.uk/>
> Dyson School of Design Engineering
> Imperial College London
> Dyson Building
> Imperial College Road
> South Kensington, SW7 2DB, London
> E: l.picin...@imperial.ac.uk
>
> http://www.imperial.ac.uk/people/l.picinali
> https://www.axdesign.co.uk/
> ________________
> From: Sursound  on behalf of Fons
> Adriaensen 
> Sent: 12 August 2022 08:48
> To: sursound@music.vt.edu 
> Subject: Re: [Sursound] On 3D audio rendering for signals with the low
> sampling frequency
>
>
> ***
> This email originates from outside Imperial. Do not click on links and
> attachments unless you recognise the sender.
> If you trust the sender, add them to your safe senders list
> https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping
> for this address.
> ***
> On Thu, Aug 11, 2022 at 06:40:28PM +0800, Junfeng Li wrote:
>
> > Do the early reflections contribute to elevation perception ?
>
> Well, something which is probably not related to HRTF does.
> Older people often have hearing limited to 8 kHz or even less,
> but may still be able to perceive elevation in some way.
>
> Early reflections (in a acoustically familiar environment) may
> play a role. Also of course expectations - remember that human
> perception is not objective, it is mostly based on a mental
> reconstruction of a scene. We expect certain sounds to come
> from above. Even cultural elements may play a role in how
> certain sounds are perceived.
>
> This is very well known in visual perception - for example people
> who have never lived in a world in which straight lines and right
> angles are everywhere are not sensitive to some visual illusions
> based on perspective.
>
> But what really puzzles me [1] is why a system that for whatever
> reason is limited to an 8 kHz bandwidth is expected to provide
> full 3D audio. It's just not realistic. You can't do a rock
> concert with a one Watt amplifier. You can't transport a grand
> piano on a bicycle.
>
> [1] Or not. I've known my share of managers who believe that
> business logic or ideology can bend the laws of physics or
> mathematics...
>
> Ciao,
>
> --
> FA
>
> ___
> Sursound mailing list
> Sursound@music.vt.edu
> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here,
> edit account or options, view archives and so on.
> ---

Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Picinali, Lorenzo]

Hello to everyone,

addressing the same matter in the Auditory mailing list, David McAlpine 
suggested to look at perceptual training:

https://www.nature.com/articles/nn0998_417

While it is true that people with significant hearing loss above 8kHz can still 
perceive elevation, it is likely that this hearing loss (e.g. age-related 
sensorineural) appeared gradually, and the person had time to adapt and re-map 
their spatial hearing cues. As mentioned by others already, these are not just 
the peaks and notches typical of an HRTF, but also the reflections coming from 
the surrounding space.

The real issue with hearing training, specifically HRTF accommodation (i.e. 
learning how to localise sound sources with an HRTF which is not your own, 
which could be extended to learning how to localise sound sources using an 
altered HRTF, e.g. low-passed at 8kHz), is that it takes some time, it's not 
really immediate, so if the aim is to just release some spatialised audio 
online or through other channels for the general public, it might be difficult 
to implement that.
But it might be interesting to try! Together with Brian FG Katz in Paris we've 
done some work looking at short- and long-term HRTF accommodation:

https://www.nature.com/articles/s41598-018-37873-0

and also at VR-based localisation training

https://www.nature.com/articles/s41598-019-54811-w

We'll be happy to share with you our Unity (currently used with the Oculus 
Quest 2) spatial hearing training application, so that you can try to low-pass 
the output at 8kHz, and see whether it could work.

Best
Lorenzo





--
Dr Lorenzo Picinali
Reader in Audio Experience Design<https://www.axdesign.co.uk/>
Dyson School of Design Engineering
Imperial College London
Dyson Building
Imperial College Road
South Kensington, SW7 2DB, London
E: l.picin...@imperial.ac.uk

http://www.imperial.ac.uk/people/l.picinali
https://www.axdesign.co.uk/

From: Sursound  on behalf of Fons Adriaensen 

Sent: 12 August 2022 08:48
To: sursound@music.vt.edu 
Subject: Re: [Sursound] On 3D audio rendering for signals with the low sampling 
frequency


***
This email originates from outside Imperial. Do not click on links and 
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If you trust the sender, add them to your safe senders list 
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***
On Thu, Aug 11, 2022 at 06:40:28PM +0800, Junfeng Li wrote:

> Do the early reflections contribute to elevation perception ?

Well, something which is probably not related to HRTF does.
Older people often have hearing limited to 8 kHz or even less,
but may still be able to perceive elevation in some way.

Early reflections (in a acoustically familiar environment) may
play a role. Also of course expectations - remember that human
perception is not objective, it is mostly based on a mental
reconstruction of a scene. We expect certain sounds to come
from above. Even cultural elements may play a role in how
certain sounds are perceived.

This is very well known in visual perception - for example people
who have never lived in a world in which straight lines and right
angles are everywhere are not sensitive to some visual illusions
based on perspective.

But what really puzzles me [1] is why a system that for whatever
reason is limited to an 8 kHz bandwidth is expected to provide
full 3D audio. It's just not realistic. You can't do a rock
concert with a one Watt amplifier. You can't transport a grand
piano on a bicycle.

[1] Or not. I've known my share of managers who believe that
business logic or ideology can bend the laws of physics or
mathematics...

Ciao,

--
FA

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Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Fons Adriaensen]

On Thu, Aug 11, 2022 at 06:40:28PM +0800, Junfeng Li wrote:

> Do the early reflections contribute to elevation perception ?

Well, something which is probably not related to HRTF does.
Older people often have hearing limited to 8 kHz or even less,
but may still be able to perceive elevation in some way.

Early reflections (in a acoustically familiar environment) may
play a role. Also of course expectations - remember that human 
perception is not objective, it is mostly based on a mental
reconstruction of a scene. We expect certain sounds to come
from above. Even cultural elements may play a role in how
certain sounds are perceived.

This is very well known in visual perception - for example people
who have never lived in a world in which straight lines and right
angles are everywhere are not sensitive to some visual illusions
based on perspective.

But what really puzzles me [1] is why a system that for whatever
reason is limited to an 8 kHz bandwidth is expected to provide 
full 3D audio. It's just not realistic. You can't do a rock
concert with a one Watt amplifier. You can't transport a grand
piano on a bicycle.

[1] Or not. I've known my share of managers who believe that
business logic or ideology can bend the laws of physics or
mathematics...

Ciao,

-- 
FA

___
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Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Steven Boardman]

Ah ok, so you are stumped if the playback system can only play back at a
16khz sampling rate, as it will always remove HF.
I didn't realise the restriction was there, i thought you meant just the
original file..

Good luck

Best

Steven

On Fri, 12 Aug 2022, 07:28 Junfeng Li,  wrote:

> Dear Steven,
>
> In my opinion, the main problem is the limitation of the playback system to
> 16/8kHz.
> No matter what we process before output, we have to downsample to 16/8kHz
> when playback. Therefore, the useful information in high frequencies is
> lost, which hampers the localization performance.
>
> Best regards,
> Junfeng
>
>
>
>
> On Thu, Aug 11, 2022 at 9:59 PM Steven Boardman  >
> wrote:
>
> > Hi Fons
> >
> > It wasn't the up sampling i was hoping would produce a better result, it
> > was the down sampling of the hrtf i thought would be worse. At least then
> > it is less truncated ..
> > Of course i should of mentioned it was only a guess.
> > As far as spectral recovery, i was thinking more along the lines of
> > T-Design sampling the b-format (hopefully after a little upmixing to a
> HOA)
> > and applying the recovery to the T-Format directions, before converting
> > back to B-format, and then convolving..
> > Of course all another guess, and pointless if the OP is limited to a
> > sampling frequency of 16khz throughout, and hasn't even mentioned what
> > format the original is in. ;)
> >
> > Cheers
> >
> >
> > On Thu, 11 Aug 2022, 11:22 Fons Adriaensen,  wrote:
> >
> > > On Thu, Aug 11, 2022 at 10:29:12AM +0100, Steven Boardman wrote:
> > >
> > > > You may get a slightly better performance by up sampling the 8khz to
> > > > 44.1/48 before convolution with the hrtf.
> > >
> > > If the upsampling is any good it will not produce any signal above
> > > the original limit of 8 kHz. So this won't make any difference.
> > >
> > > > In the post production world we sometimes use 'spectral recovery'
> > > > algorithms like in Izotope RX, to regain high frequency content lost
> > from
> > > > remote recording sessions, with the likes of 'zoom'. This may get
> you a
> > > > little closer still.
> > >
> > > Unlikely. The 'recovered' HF content will not contain the original
> > > elevation cues. The only way this could help is in case the bandlimited
> > > signal appears elevated, adding some artificial HF may bring it back
> > > to horizontal where it probably should be. But the original info is
> > > lost anyway.
> > >
> > > One way to recognise a signal as coming from an elevated source
> > > could be to analyse the distribution of early reflections. But
> > > I doubt very much if this would be a practical solution.
> > >
> > > --
> > > FA
> > >
> > > ___
> > > Sursound mailing list
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Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Junfeng Li]

Dear Steven,

In my opinion, the main problem is the limitation of the playback system to
16/8kHz.
No matter what we process before output, we have to downsample to 16/8kHz
when playback. Therefore, the useful information in high frequencies is
lost, which hampers the localization performance.

Best regards,
Junfeng




On Thu, Aug 11, 2022 at 9:59 PM Steven Boardman 
wrote:

> Hi Fons
>
> It wasn't the up sampling i was hoping would produce a better result, it
> was the down sampling of the hrtf i thought would be worse. At least then
> it is less truncated ..
> Of course i should of mentioned it was only a guess.
> As far as spectral recovery, i was thinking more along the lines of
> T-Design sampling the b-format (hopefully after a little upmixing to a HOA)
> and applying the recovery to the T-Format directions, before converting
> back to B-format, and then convolving..
> Of course all another guess, and pointless if the OP is limited to a
> sampling frequency of 16khz throughout, and hasn't even mentioned what
> format the original is in. ;)
>
> Cheers
>
>
> On Thu, 11 Aug 2022, 11:22 Fons Adriaensen,  wrote:
>
> > On Thu, Aug 11, 2022 at 10:29:12AM +0100, Steven Boardman wrote:
> >
> > > You may get a slightly better performance by up sampling the 8khz to
> > > 44.1/48 before convolution with the hrtf.
> >
> > If the upsampling is any good it will not produce any signal above
> > the original limit of 8 kHz. So this won't make any difference.
> >
> > > In the post production world we sometimes use 'spectral recovery'
> > > algorithms like in Izotope RX, to regain high frequency content lost
> from
> > > remote recording sessions, with the likes of 'zoom'. This may get you a
> > > little closer still.
> >
> > Unlikely. The 'recovered' HF content will not contain the original
> > elevation cues. The only way this could help is in case the bandlimited
> > signal appears elevated, adding some artificial HF may bring it back
> > to horizontal where it probably should be. But the original info is
> > lost anyway.
> >
> > One way to recognise a signal as coming from an elevated source
> > could be to analyse the distribution of early reflections. But
> > I doubt very much if this would be a practical solution.
> >
> > --
> > FA
> >
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Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Steven Boardman]

Hi Fons

It wasn't the up sampling i was hoping would produce a better result, it
was the down sampling of the hrtf i thought would be worse. At least then
it is less truncated ..
Of course i should of mentioned it was only a guess.
As far as spectral recovery, i was thinking more along the lines of
T-Design sampling the b-format (hopefully after a little upmixing to a HOA)
and applying the recovery to the T-Format directions, before converting
back to B-format, and then convolving..
Of course all another guess, and pointless if the OP is limited to a
sampling frequency of 16khz throughout, and hasn't even mentioned what
format the original is in. ;)

Cheers


On Thu, 11 Aug 2022, 11:22 Fons Adriaensen,  wrote:

> On Thu, Aug 11, 2022 at 10:29:12AM +0100, Steven Boardman wrote:
>
> > You may get a slightly better performance by up sampling the 8khz to
> > 44.1/48 before convolution with the hrtf.
>
> If the upsampling is any good it will not produce any signal above
> the original limit of 8 kHz. So this won't make any difference.
>
> > In the post production world we sometimes use 'spectral recovery'
> > algorithms like in Izotope RX, to regain high frequency content lost from
> > remote recording sessions, with the likes of 'zoom'. This may get you a
> > little closer still.
>
> Unlikely. The 'recovered' HF content will not contain the original
> elevation cues. The only way this could help is in case the bandlimited
> signal appears elevated, adding some artificial HF may bring it back
> to horizontal where it probably should be. But the original info is
> lost anyway.
>
> One way to recognise a signal as coming from an elevated source
> could be to analyse the distribution of early reflections. But
> I doubt very much if this would be a practical solution.
>
> --
> FA
>
> ___
> Sursound mailing list
> Sursound@music.vt.edu
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Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Junfeng Li]

Dear Steven and Fons,



On Thu, Aug 11, 2022 at 6:22 PM Fons Adriaensen  wrote:

> On Thu, Aug 11, 2022 at 10:29:12AM +0100, Steven Boardman wrote:
>
> > You may get a slightly better performance by up sampling the 8khz to
> > 44.1/48 before convolution with the hrtf.
>
> If the upsampling is any good it will not produce any signal above
> the original limit of 8 kHz. So this won't make any difference.
>
>
Since the rendering system only can produce 8kHz or 16kHz sound signal at
its output, therefore, if we upsample the input signal to 44.1 or 48kHz, we
have to downsample the 3D-processed signal to 8/16kHz. In this sense,
elevation cues are still missing.


> > In the post production world we sometimes use 'spectral recovery'
> > algorithms like in Izotope RX, to regain high frequency content lost from
> > remote recording sessions, with the likes of 'zoom'. This may get you a
> > little closer still.
>
> Unlikely. The 'recovered' HF content will not contain the original
> elevation cues. The only way this could help is in case the bandlimited
> signal appears elevated, adding some artificial HF may bring it back
> to horizontal where it probably should be. But the original info is
> lost anyway.
>
>
Yeah. It seems difficult to playback the elevation cues due to the lack of
the high frequencies.


> One way to recognise a signal as coming from an elevated source
> could be to analyse the distribution of early reflections. But
> I doubt very much if this would be a practical solution.
>
>
Do the early reflections contribute to elevation perception ?

Thanks again.
Junfeng




>
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Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Fons Adriaensen]

On Thu, Aug 11, 2022 at 10:29:12AM +0100, Steven Boardman wrote:

> You may get a slightly better performance by up sampling the 8khz to
> 44.1/48 before convolution with the hrtf.

If the upsampling is any good it will not produce any signal above
the original limit of 8 kHz. So this won't make any difference.

> In the post production world we sometimes use 'spectral recovery'
> algorithms like in Izotope RX, to regain high frequency content lost from
> remote recording sessions, with the likes of 'zoom'. This may get you a
> little closer still.

Unlikely. The 'recovered' HF content will not contain the original
elevation cues. The only way this could help is in case the bandlimited
signal appears elevated, adding some artificial HF may bring it back
to horizontal where it probably should be. But the original info is
lost anyway.

One way to recognise a signal as coming from an elevated source 
could be to analyse the distribution of early reflections. But
I doubt very much if this would be a practical solution. 

-- 
FA

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Re: [Sursound] On 3D audio rendering for signals with the low sampling frequency

[Steven Boardman]

Hi Junfeng

Elevation is mainly determined by high frequency, so removing this will
severely impede the performance.
You may get a slightly better performance by up sampling the 8khz to
44.1/48 before convolution with the hrtf.
In the post production world we sometimes use 'spectral recovery'
algorithms like in Izotope RX, to regain high frequency content lost from
remote recording sessions, with the likes of 'zoom'. This may get you a
little closer still.
Hope this helps.

Best

Steve


On Thu, 11 Aug 2022, 03:26 Junfeng Li,  wrote:

> Dear all,
>
> We are working on 3D audio rendering for signals with low sampling
> frequency.
> As you may know, the HRTFs  are normally measured at the high sampling
> frequency, e.g., 48kHz or 44.1kHz. However, the sampling frequency of sound
> signals in our application is restricted to 16 kHz. Therefore, to render
> this low-frequency (≤8kHz) signal, one straight way is to first downsample
> the HRTFs from 48kHz/44.1kHz to 16kHz and then convolve with sound signals.
> However, the sound localization performance of the signal rendered with
> this approach is greatly decreased, especially elevation perception. To
> improve the sound localization performance, I am now wondering whether
> there is a certain good method to solve or mitigate this problem in this
> scenario.
>
> Any discussion is welcome.
>
> Thanks a lot again.
>
> Best regards,
> Junfeng
>
> -
> Junfeng Li, Ph.D.
> Institute of Acoustics
> Chinese Academy of Sciences
> URL: www.jaist.ac.jp/~junfeng
> -
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[Sursound] On 3D audio rendering for signals with the low sampling frequency

[Junfeng Li]

Dear all,

We are working on 3D audio rendering for signals with low sampling
frequency.
As you may know, the HRTFs  are normally measured at the high sampling
frequency, e.g., 48kHz or 44.1kHz. However, the sampling frequency of sound
signals in our application is restricted to 16 kHz. Therefore, to render
this low-frequency (≤8kHz) signal, one straight way is to first downsample
the HRTFs from 48kHz/44.1kHz to 16kHz and then convolve with sound signals.
However, the sound localization performance of the signal rendered with
this approach is greatly decreased, especially elevation perception. To
improve the sound localization performance, I am now wondering whether
there is a certain good method to solve or mitigate this problem in this
scenario.

Any discussion is welcome.

Thanks a lot again.

Best regards,
Junfeng

-
Junfeng Li, Ph.D.
Institute of Acoustics
Chinese Academy of Sciences
URL: www.jaist.ac.jp/~junfeng
-
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