Re: [Sursound] A Thanks... And Another Post

[diatonis]

> Message: 1
> Date: Sun, 24 Feb 2013 06:14:12 +0100
> From: J?rn Nettingsmeier 
> Subject: Re: [Sursound] A Thanks... And Another Post
> To: Eric Carmichel , Surround Sound discussion
> group 



Recommendations For Surround Sound Production
http://www.grammy.org/files/pages/SurroundRecommendations.pdf

Found on this page:
http://www.grammy.org/recording-academy/producers-and-engineers/guidelines



> On 02/22/2013 03:25 AM, Eric Carmichel wrote:
>
>> Regarding localization, home theatre sound and the 80-Hz xover
>> point:
>>
>> I?ll confess ignorance when it comes to knowledge of a separate or
>> unique physiological mechanism used to localize (or omni-ize)
>> ultra-low frequencies.
>
> same here. if there is indeed a special mechanism at work, i'd like to
> learn what it might be.
>
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Re: [Sursound] A Thanks... And Another Post

[Eric Benjamin]

On 02/22/2013 03:25 AM, Eric Carmichel wrote:

>> I’ll confess ignorance when it comes to knowledge of a separate or
>> unique physiological mechanism used to localize (or omni-ize)
>> ultra-low frequencies.


Jörn Nettingsmeier  wrote:
> same here. if there is indeed a special mechanism at work, i'd like to learn 
>what it might be.
AND
> yeah, the "inability to localise bass sounds" is a very persistant urban 
> myth. 
>"in rooms", ok, but anybody who has been near an open-air rocknroll stage 
>during 
>subwoofer calibration will have no trouble localising the sound :)

Indeed, the same time-based mechanism for localization appears to operate down 
to the lowest audible frequencies.  There is very little published about this 
because it would appear that psychoacousticians consider 125 Hz to be a 'very 
low frequency'.  The best reference of which I know is Klumpp and Eady, "Some 
Measurements of Interaural Time Difference Thresholds", JASA Vol 28, No.5. 
 Their data shows that the threshold of detection increases monotonically from 
1 
kHz down to 90 Hz, and post hoc analysis shows that the threshold is 
proportional to 1/f.  My own measurements show good localization performance 
down to 50 Hz or so.

If any of you have better references on low-frequency localization, I'd like to 
read them.  

So far as the in-room localization is concerned, I experience strong 
localization down to the lowest frequencies for sinusoids.  The trouble is that 
the localization is almost always wrong.  Standing waves cause there to be 
large 
Interaural Level Differences which wouldn't occur out-of-doors, resulting in 
near and in-head localization.

I can see no reason why the low-frequency localization mechanisms 
would suddenly fail at low frequencies.  They get less sensitive but just keep 
working.

Eric Benjamin
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[Sursound] Saga of the Subs

[Eric Carmichel]

. The 
original reason for considering three vertically-aligned hexagonal arrays is: 
1) providing “unobtrusive” space for video (the logistics of the video and the 
visual stimuli are still in the making); 2) not able to fly heavy or large 
loudspeakers from ceiling; 3) making smaller speakers symmetrical (above and 
below) subs as well as listening position. RE number 3: I believed that time 
alignment for complex sounds whose constituent frequencies will emanate from 
both subs and satellites would be more phase cohesive in this arrangement than 
simply putting an array of subs on an arbitrarily-chosen plane located towards 
the floor. I'll be the first to admit that my notions are often wrong or (less 
significant) totally overkill. I have no problem with either overkill or being 
proven wrong.

[from Jörn] “...but it's quite easy to render, say, a passing car, together 
with its characteristic floor reflection in case that’s relevant for cars, in 
higher order... getting a complete ambient recording in HOA is hard and 
involves something like the eigenmike, but ‘artificial’ stimuli can just be 
panned, exploiting the improved focus of HOA.

ELC: Yes, sound design for a few vehicles moving simultaneously can be done 
without much trouble. For a general audience, L-R panning works well, 
particularly when a large part of their concentration is on the video. Adding 
lot of moving objects is more difficult because they will have overlapping 
interaction--the degrees of freedom grows exponentially. I have to be careful 
that I don't substitute physical wave propagation accuracy for perceptual 
realism. Although we can only give attention to two or three moving sources at 
a time [any references as to an actual number, I don’t think it’s large], a 
highly complex scene may better be left to an Ambisonic recording mic that can 
pick up every nuance in one fell swoop. A HOA mic would be wonderful, but can't 
afford one at this time.

[Jörn, re 400/700 Hz crossover frequency] “...not if you wish to employ 
conventional woofers.”

ELC: Agreed, but rare is the day I do everything in a conventional manner. I 
suppose “thinking outside of the box” has dual meaning when it comes to 
loudspeakers :)

Again, many thanks for the ideas, help, and encouragement.

Eric C. (a.k.a. ELC)
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Re: [Sursound] A Thanks... And Another Post

[Jörn Nettingsmeier]

On 02/24/2013 07:25 PM, diatonis wrote:

Message: 1
Date: Sun, 24 Feb 2013 06:14:12 +0100
From: J?rn Nettingsmeier 
Subject: Re: [Sursound] A Thanks... And Another Post
To: Eric Carmichel , Surround Sound discussion
 group 




Recommendations For Surround Sound Production
http://www.grammy.org/files/pages/SurroundRecommendations.pdf


many thanks for this link, very very useful indeed. it should be noted, 
though, that this text describes a theoretical, best practises guideline 
for the audio industry. many very widely distributed music surround 
productions do not adhere to it, and cinema is a wholly different beast 
altogether.
but yeah, if everybody adhered to these recommendations, the world would 
be a better place :)


the only gripe i have with this after a casual first glance is the 
monitor level recommendation. a range of omg six(!) db is no 
recommendation at all.
and pity those engineers who monitored for years at 85dB SPL for 0dB. 
for most practical reference levels before the advent of EBU R128, that 
kind of power constitutes grievous bodily harm.




--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT

http://stackingdwarves.net

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Re: [Sursound] A Thanks... And Another Post

[Fons Adriaensen]

On Sun, Feb 24, 2013 at 10:42:21PM +0100, Jörn Nettingsmeier wrote:
 
> many thanks for this link, very very useful indeed. it should be
> noted, though, that this text describes a theoretical, best
> practises guideline for the audio industry. many very widely
> distributed music surround productions do not adhere to it, and
> cinema is a wholly different beast altogether.
> but yeah, if everybody adhered to these recommendations, the world
> would be a better place :)

It's a quite well done document, even if it is stating the
obvious many times (but apparently there is a need for that).
My only gripe with it so far is the statement that 'integer
resamping ratios are likely to produce less artefacts'. 
Could be true if some defective resampling algorithm is used,
but in general this is nonsense.

Ciao,

-- 
FA

A world of exhaustive, reliable metadata would be an utopia.
It's also a pipe-dream, founded on self-delusion, nerd hubris
and hysterically inflated market opportunities. (Cory Doctorow)

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Re: [Sursound] Saga of the Subs

[etienne deleflie]

>
> ELC: Visual cues may play part in this ability, too, but I fully agree
> with you: The sound-source direction is unambiguous in certain situations.
> This is why I wish to include multiple subs in my forthcoming experiments.
> Another common myth is how much the Doppler Effect plays in our perception
> of an object moving towards or away from us. A car moving towards us will
> have a constant, albeit upwardly shifted, frequency. There is no frequency
> change until the moment the car passes. Note that I selectively use the
> word frequency, not pitch. Perceived pitch DOES change, but is a function
> of increasing intensity, not a constantly-changing frequency.


do you mean increasing intensity of the whole frequency spectrum, or just
the increasing intensity of the higher frequencies? Higher frequencies are
more perceivable, but that will be a function of a change in frequency
spectrum, more than an increase in intensity. Would it not?

Etienne



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Re: [Sursound] Saga of the Subs

[Robert Greene]

This is wrong about the Doppler effect and perception of distance.
It would be correct if the object moving and emitting sound
as it moved were coming straight towards you and going through
you and then moving away. But a police car with a siren say
is not aiming straight at you(or at least you better hope not!)
It is going by on a straight line that has a closest point to you
but that closest point is not you! So the amount of pitch shift
in fact changes continuously, being a max shift up when the
car is far away, diminishing gradually until the car is as close
to you as it will get(at which point the car is not changing distance
from you at all  in the instantaneous sense) and then gradually
as the object moves away with increasing speed relative to you!
the pitch falls to a minimum.
This is not dependent on mel shifting with level--it is
literally the case on the frequency level. (The mel shift
would be the same whether the car were approaching or departing--
just reversed in time. This as I recall is not what is observed--
the situation does not have time reversal symmetry)
Robert

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Re: [Sursound] Saga of the Subs

[Robert Greene]

Dont pay any attention to this about intensity and the
Doppler shift for moving objects,  would be my 
suggestion. It is almost all 
wrong. ELC is mistaken here. 
See my public post please.

Robert

On Mon, 25 Feb 2013, etienne deleflie wrote:



ELC: Visual cues may play part in this ability, too, but I fully agree
with you: The sound-source direction is unambiguous in certain situations.
This is why I wish to include multiple subs in my forthcoming experiments.
Another common myth is how much the Doppler Effect plays in our perception
of an object moving towards or away from us. A car moving towards us will
have a constant, albeit upwardly shifted, frequency. There is no frequency
change until the moment the car passes. Note that I selectively use the
word frequency, not pitch. Perceived pitch DOES change, but is a function
of increasing intensity, not a constantly-changing frequency.



do you mean increasing intensity of the whole frequency spectrum, or just
the increasing intensity of the higher frequencies? Higher frequencies are
more perceivable, but that will be a function of a change in frequency
spectrum, more than an increase in intensity. Would it not?

Etienne



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Re: [Sursound] Saga of the Subs

[Eric Carmichel]

Hello Robert,

Perception of distance is a complex interaction, 
and psychoacoustical experiments generally limit the number of variables
 (out of necessity) studied in static or laboratory settings.
Not 
that I disagree with you, but there's more to the "Doppler Illusion" (as
 it has been called) than meets the eye... er, the ear.
For two related papers, please refer to the following links:

http://www.public.asu.edu/~mmcbeath/mcbeath.research/Doppler/Doppler.html

http://psychology.clas.asu.edu/files/1996_JEP-HPP%28DopplerIllusion%29.pdf

I
 did something similar while an undergrad, but did have enough 
confidence in my own measurements to submit the findings for 
publication. Most of what I realized is that a measurable change in 
pitch seemed too small for anyone but a trained musician to perceive it,
 yet everyone could judge the object as approaching and then receding. 
The spectral nature of the moving vehicle changed, but mostly due to 
relative proximity of buildings and obstacles and diffraction. But the 
fundamental pitch of, say, a siren, when isolated, didn't provide the 
dominant cue. I guess it's akin to the duplex theory of localization: We
 use the cues that are available; there's not an instant switch between 
one mode to the next, particularly when complex sounds interact with the
 head and pinnae, and head movements also help resolve ambiguities. 
Vision and experience naturally add to our perception of distance and 
motion.

Thanks for corrections, but please also consider viewing the above two links--I 
need to re-read them myself.
Best,
Eric



 From: Robert Greene 
To: Eric Carmichel ; Surround Sound discussion group 
 
Sent: Sunday, February 24, 2013 5:46 PM
Subject: Re: [Sursound] Saga of the Subs
 

This is wrong about the Doppler effect and perception of distance.
It would be correct if the object moving and emitting sound
as it moved were coming straight towards you and going through
you and then moving away. But a police car with a siren say
is not aiming straight at you(or at least you better hope not!)
It is going by on a straight line that has a closest point to you
but that closest point is not you! So the amount of pitch shift
in fact changes continuously, being a max shift up when the
car is far away, diminishing gradually until the car is as close
to you as it will get(at which point the car is not changing distance
from you at all  in the instantaneous sense) and then gradually
as the object moves away with increasing speed relative to you!
the pitch falls to a minimum.
This is not dependent on mel shifting with level--it is
literally the case on the frequency level. (The mel shift
would be the same whether the car were approaching or departing--
just reversed in time. This as I recall is not what is observed--
the situation does not have time reversal symmetry)
Robert
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