Re: [LAD] what does "full range" mean with regard to ambisonics and speakers? - Linux-audio-dev

1 Aug 2010

"Bearcat M. ?andor"  &lt;hometheater(a)feline-soul.com&gt; wrote:

...
  Thank you.  I think i understand all that, but let me
take this apart to
 make sure.  What you're [J?rn Nettingsmeier is] saying is that having full range
speakers only
 effects the playback quality of the music not the ambisonics and
 that ambisonics itself does not *need* full range speakers, but that
 having full range speakers is better than not. Is that correct? 
There are (at least) two things to reproduce:
the frequency range and the localisation.
Ambisonics satisfies localisation cues up to
about 5 kHz, and down to very low.  (There is
evidence that humans can localise
frequencies below 20 Hz using things like
chest cavities.  Ambisonics can reproduce
such localisation cues if these frequencies are
in the source.)  So, for localisation, the
speakers can top out at 5 kHz.  However,
music played though such speakers is unlikely
to sound very good.  At the low end, lower is
better.  However, it is a law of diminishing
returns, limited by the standing waves in your
listening room which will interfere with the
localisation of subwoofers.

...
  I think part of my confusion is that i'm still
thinking of it as having
 6 or 8 or more *channels* when that is not the case.  The speakers are
 not steered, they are driven. So you are not going to have a situation
 where the speakers behind you are only reproducing high to midrange
 information as was the case with Dolby pro-logic or something. Right? 
Right.  With Ambisonics, all the speakers
cooperate to localise a sound.  While the
speakers on the left push, those on the right
pull.  (This is less pronounced with
frequencies above 400 Hz and less important
with higher-order Ambisonics, but ignore this.)

Regards,
Martin
-- 
Martin J Leese
E-mail: martin.leese  stanfordalumni.org
Web: http://members.tripod.com/martin_leese/