Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

The Advantages of Floor Coupled Up-Firing Speakers
The Advantages of Floor Coupled Up-Firing Speakers
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 6th March 2013, 07:47 PM   #1951
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Suomi
The classical precedence effect / law of the first wavefront / Haas effect is based on interaural signals. So it operates in horisontal spatial domain.

We also know that HRTF is responsible for vertical spatial hearing. However the frequencies that allow vertical directional hearing is much above 1kHz.

Thus it could be safely assumed below 1kHz there is negligible available contributions to allow height perception. And we also know that a direct sound and its floor reflection are having same incidence angle relative to median plane i.e. interaural difference is the same for both sounds (this follows the Blauertian cone of confusion).

Based on all of this, I conclude there is no vertical precedence effect below 1kHz. Thus the floor reflection at 1.3ms below 1kHz cannot be perceived, other than changes in timbre perhaps but to what extend is unknown.


- Elias
__________________
Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
  Reply With Quote
Old 6th March 2013, 08:55 PM   #1952
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
Quote:
Originally Posted by Elias View Post
conclude there is no vertical precedence effect below 1kHz. Thus the floor reflection at 1.3ms below 1kHz cannot be perceived, other than changes in timbre perhaps but to what extend is unknown.
- Elias
surely I can be wrong but isn't it just the other way round?

there IS a precedence effect -> reflection CANNOT be perceived as separate sound event (like in the case of horizontal lateral reflections covered by the Haas effect)

consequently:

there IS NOT a precedence effect -> a reflection CAN be perceived as separate sound event
__________________
"high phooey and hystereo" - Yascha Heifetz

Last edited by graaf; 6th March 2013 at 08:58 PM.
  Reply With Quote
Old 7th March 2013, 08:17 AM   #1953
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Suomi
Quote:
Originally Posted by graaf View Post
surely I can be wrong but isn't it just the other way round?

there IS a precedence effect -> reflection CANNOT be perceived as separate sound event (like in the case of horizontal lateral reflections covered by the Haas effect)

consequently:

there IS NOT a precedence effect -> a reflection CAN be perceived as separate sound event

Well, the precedence is related in spatial direction. But below 1kHz it is not possible to detect the elevation, because as said the ITD will remain the same and HRTF does not give clues. So since it is not possible to determine the perceived direction for such sounds, there cannot be a precedence of any of the reflections. The sound direction remains ambiguous regardles of the order of the reflected sounds.


- Elias
__________________
Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
  Reply With Quote
Old 7th March 2013, 08:36 AM   #1954
markus76 is offline markus76  Germany
Banned
 
Join Date: May 2008
Location: Switzerland
"Research into
localization in the median plane, [1] [2] [10] [11],
concluded that three requisites were necessary for an
auditory stimulus to be accurately placed in a vertical
space: (a) the sound must be complex, (b) the complex
sound must include frequencies above 7000 Hz, and (c)
the pinna must be present."

"5 Conclusions
Our ability to localize sound sources on the median
plane relies primarily on pinna effects. According to
Blauert [1][2] and others, the curves within the pinna
reflect different frequencies depending on the source
elevation. It was clear from the experiments conducted
that localization on the median plane is poor for
phantom images generated by loudspeakers at any of the
three angles tested, with inaccurate median locations
and significant localization blur. Further, for sources
behind the subject on the median plane the results were
particularly poor. This suggests that a single
loudspeaker placed on the median plane and used for
height enhancement would be of little benefit for
vertical localization."

ELEVATION PERCEPTION: PHANTOM IMAGES IN THE VERTICAL HEMI-SPHERE , JAMES L. BARBOUR, AES 24th International Conference on Multichannel Audio

[1] Blauert, J. 1997, Spatial Hearing, MIT Press,
ISBN 0-262-02413-6
[2] Blauert, J. 1969-70, Sound Localization in the
Median Plane, Acustica, Volume 22, pp. 205-
213
[10] Roffler, S. and Butler, R. 1968 Factors that
Influence the Localization of Sound in the
Vertical Plane, Journal of the Acoustical
Society of America, Volume 43, No. 6, pp.
1255-1259
[11] Roffler, S. and Butler, R. 1968 Localization of
Tonal Stimuli in the Vertical Plane, Journal of
the Acoustical Society of America, Volume 43,
No. 6, pp. 1260-1266
  Reply With Quote
Old 7th March 2013, 08:43 AM   #1955
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
Quote:
Originally Posted by Elias View Post
Well, the precedence is related in spatial direction. But below 1kHz it is not possible to detect the elevation, because as said the ITD will remain the same and HRTF does not give clues. So since it is not possible to determine the perceived direction for such sounds, there cannot be a precedence of any of the reflections. The sound direction remains ambiguous regardles of the order of the reflected sounds.


- Elias
I am not sure if I understand You well.

But what I said before can be explained by the fact that lateral localization relies completely on binaural triangulation of a sound source, exactly therefore a lateral reflection carries no useful information about localization and it can only be a distraction from that perspective - hence the effect of suppression of perception.

on the contrary, in case of the vertical localization we have no "built-in" triangulation mechanism so why would our auditory system suppress a ground reflection?

Some sources indeed suggest that floor reflection may carry useful information about a sound source localisation, about its elevation, apparently also providing a sort of vertical triangulation:

Quote:
preliminary observations suggest that (1) the upward bias in elevation seen for anechoic sounds is reduced when a floor reflection is added
see: Human Systems Integration Division @ NASA Ames - Projects

It seems that vertical localisation is not just HRTF but more complicated mechanism and floor reflection may be important.

It may also be a useful cue in the distance perception:

Quote:
The dominant factors in determining distance perception are to some extent dependent on the reverberation time of the room. For two similar sounds close to and far away from the listener the one further away will have the following differences: (...) Less difference between time of direct sound and first floor reflection
see: http://www2.ph.ed.ac.uk/teaching/cou...alisation1.pdf
__________________
"high phooey and hystereo" - Yascha Heifetz
  Reply With Quote
Old 7th March 2013, 09:15 AM   #1956
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Suomi
Quote:
Originally Posted by markus76 View Post
ELEVATION PERCEPTION: PHANTOM IMAGES IN THE VERTICAL HEMI-SPHERE , JAMES L. BARBOUR, AES 24th International Conference on Multichannel Audio

We can place the bass-midrange speaker at any height and the perception does not change due to the elevation, IF the frequency band if below 1kHz.

However there might be perceptual changes on speakers at different heights because of room induced complex reflection patterns which are height dependent. This can change the low frequency ITD which results in perceived difference on speaker height. But the reason is not the elevation perception perse but the room.


- Elias
__________________
Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
  Reply With Quote
Old 7th March 2013, 09:22 AM   #1957
markus76 is offline markus76  Germany
Banned
 
Join Date: May 2008
Location: Switzerland
ITD changes height perception? Doesn't compute.
  Reply With Quote
Old 7th March 2013, 09:44 AM   #1958
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
Quote:
Originally Posted by markus76 View Post
"5 Conclusions
Our ability to localize sound sources on the median
plane relies primarily on pinna effects. According to
Blauert [1][2] and others, the curves within the pinna
reflect different frequencies depending on the source
elevation. It was clear from the experiments conducted
that localization on the median plane is poor for
phantom images generated by loudspeakers at any of the
three angles tested, with inaccurate median locations
and significant localization blur. Further, for sources
behind the subject on the median plane the results were
particularly poor. This suggests that a single
loudspeaker placed on the median plane and used for
height enhancement would be of little benefit for
vertical localization."
the operating term above is primarily

interestingly Markus usually talks rather about " summing localization in the median plane":

page 100 of this thread

and also about "breakdown of precedence" in the median plane:

page 172 of this thread

apparently He believes that this is possible in the median plane but only in case of the ceiling reflection, not in case of the floor reflection, interesting, isn't it?
__________________
"high phooey and hystereo" - Yascha Heifetz
  Reply With Quote
Old 7th March 2013, 09:48 AM   #1959
graaf is offline graaf  Poland
diyAudio Member
 
graaf's Avatar
 
Join Date: Jun 2007
Quote:
Originally Posted by Elias View Post
the perception does not change due to the elevation, IF the frequency band if below 1kHz.
it follows from Your personal experience or from any scientific study?

because generally it appears to be a consensus in literature that frequency range critical for localisation perception is >0.5 kHz

I suggested above (and with some good reasons I believe) that the important range extends roughly 0.4<4.0 kHz

perhaps Allison would concur and exactly therefore the floor coupled woofers in His designs are low-passed at 350 Hz?

and perhaps this was main cause of Snell Type 1 problematic soundstaging - not the floor position of the tweeter but floor position of the midwoofer crossed to high (at 2 kHz)?
__________________
"high phooey and hystereo" - Yascha Heifetz

Last edited by graaf; 7th March 2013 at 10:00 AM.
  Reply With Quote
Old 7th March 2013, 09:59 AM   #1960
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Suomi
Quote:
Originally Posted by markus76 View Post
ITD changes height perception? Doesn't compute.
No I mean speaker height can change ITD due to different room reflection pattern which can cause lateral shifts.
__________________
Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
  Reply With Quote

Reply


The Advantages of Floor Coupled Up-Firing SpeakersHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Using a diffuser cone for up-firing speakers tspringer99 Multi-Way 19 23rd July 2014 02:04 AM
Floor Standing Speakers. gurpreetsingh Full Range 11 12th June 2012 06:42 AM
side/ rear firing speakers Good/Bad? mcmahon48 Multi-Way 1 6th February 2009 12:28 PM
How far can the driver of a down-firing sub be from the floor? The Paulinator Subwoofers 11 16th May 2007 08:10 PM
Woofer: side firing pair vs front firing? tcpip Multi-Way 13 9th September 2005 02:13 PM


New To Site? Need Help?

All times are GMT. The time now is 01:58 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki