On 03/03/2012 00:40, 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
Even ignoring the maths, experience has shown that the naive formulae given above (which have been
quoted in quite a few places - even I've used them in the past) just don't produce sensible, usable
results in practise. Further, of the two figures that have been expressly given by Aaron of at
least four speakers for the 2-D and six for the 3-D case (for first-order playback) the 3-D six
speaker case performs relatively poorly in real rooms, 8 speakers giving a noticeably better result
in terms of image stability, especially with listener movement. As a rule of thumb, with no explicit
mathematical backing, I would say that 2*(M + 1)^2 for 3D and 2(M + 1) for low order systems are
more realistic minima - note I can only comment on up to 3rd order horizontal and 2nd order
with-height, others will have to comment on higher orders.
As Fons was saying, there are real reasons why large numbers of speakers can be counter-productive,
especially in "good" (meaning dry, with few early reflections). On the other hand, in difficult
acoustic situations, the point at which the number of speakers becomes a problem rather than a help
may be higher.
Now back to conference organising - hope I'll be seeing many of you in just
under three weeks (gulp)
Dave
--
These are my own views and may or may not be shared by my employer
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