Hello Jörn,
Thanks for your views on all this!!
Will look for the Zotter et al. paper.
My best,
Jo
On 2 Mar 2012, at 4:40 pm, Jörn Nettingsmeier wrote:
hi joseph,
On 03/02/2012 08:02 PM, [email protected] wrote:
Hi All,
A few naive HOA Qs I'm hoping to gain some insight on...
1) Order (M) is related to minimum number of loudspeakers by:
(M + 1)^2 for 3D
2M + 1 for 2D
Is there a similar relationship for order and loudspeaker array
radius?
not really. only in the sense that you need higher orders for larger
listening areas, in the general case.
there is a similar formula mentioned in one of franz zotter et al.'s
papers which tells you for any given order for how many zero crossings
of a wave the reconstruction will be correct (obviously
frequency-dependant). sorry i don't have the paper around right now...
The practical question comes down to, does my room (or installation)
size end up limiting the order I can successfully synthesise?
no. but you might find there is little benefit in going much higher
than third order if your desired listening area is only for a few
people.
no matter how small your room or listening area, source sharpness and
stability will improve with higher orders. only you might find
yourself way up the diminishing returns curve pretty quickly.
but if you have to play back lower order material as well (such as a
native soundfield recording), i found it is advisable to have a
separate low-order decoder which uses fewer speakers, for better
clarity and less phasing.
aaron heller disputes this, he claims to have observed no detrimental
effects in vastly over-specified systems, and if you look at
simulations where N->oo, he should be right, but in practice i have
found systems with many more speakers than strictly necessary to be
significantly worse in terms of phasiness... maybe others can comment
and clarify.
As an
example, if I'd like to try 5th order, do I need to make sure my room
is
at least minimum size? (Yeah, there are problems regarding loudspeaker
positioning, etc., but let's disregard that for now.)
2) And a related question.... For HOA do I prefer a narrow dispersion
loudspeaker over a wide dispersion loudspeaker?
you must make sure that all speakers cover your desired listening area
completely, without significant loss of HF.
other than that, the directivity of the speaker governs how much
diffuse sound in relation to direct sound will be generated. so as a
very rough guide, for a very live room and large speaker distance,
more directive speakers might be beneficial. vice versa, in a small
and quite dead room, widely dispersing speakers might be more pleasant
to listen to, since they will excite more diffuse sound, which helps
gloss over phasing problems.
a matter of taste, and your mileage may vary.
best,
jörn
--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487
Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT
http://stackingdwarves.net
_______________________________________________
Sursound mailing list
[email protected]
https://mail.music.vt.edu/mailman/listinfo/sursound
_______________________________________________
Sursound mailing list
[email protected]
https://mail.music.vt.edu/mailman/listinfo/sursound
