My home listening room is 20ft x 20ft sqr (6.6m x 6.6m).
Originally I was fooled into thinking directionality was not significant
at low/sub-bass frequencies ... until I tried it.
I now use four subs one at the approximate mid-point of each wall
(somewhat adjusted to accommodate the domestic guidance counselor...).
Anyone who claims low bass is not perceived with direction has NEVER
tried it for real. It is VERY apparent.
- Neil
On 6/9/2011 12:25 PM, Fons Adriaensen wrote:
On Thu, Jun 09, 2011 at 11:03:56AM -0400, jim moses wrote:
But the unanswered question is, can we really detect the originating
direction of low frequency sound if you do not
have assistance of the over 80-120Hz overtones ?
conventional thought says no. This matches my experience. This description
from wikipedia
http://en.wikipedia.org/wiki/Sound_localization#Evaluation_for_low_frequenciesseems
pretty good to me.
"For frequencies below 800 Hz, the dimensions of the head (ear distance
21.5 cm, corresponding to an interaural time delay of 625 µs), are smaller
than the half wavelength of the sound waves. So the auditory system can
determine phase delays between both ears without confusion. Interaural level
differences are very low in this frequency range, especially below about
200 Hz, so a precise evaluation of the input direction is nearly impossible
on the basis of level differences alone. As the frequency drops below 80 Hz
it becomes difficult or impossible to use either time difference or level
difference to determine a sound's lateral source, because the phase
difference between the ears becomes too small for a directional evaluation.
"
Two more (Euro)cents:
Just performed a little experiment.
Sine wave of 50 Hz, linear rise to full amplitude in 150 ms, hold 250 ms,
linear fade out of 150 ms. The spectrum of such a signal is more than 60
dB down at 100 Hz re. its peak at 50 Hz.
Panned to random directions in 3rd order Ambisonics and reproduced on
the horizontal octagon at the LABEL studio (Quested SR8).
I can *easily* tell from which direction it comes. There is some
front/back ambiguity if (and only if) I keep my head fixed, but
that is to be expected.
Ciao,
_______________________________________________
Sursound mailing list
Sursound@music.vt.edu
https://mail.music.vt.edu/mailman/listinfo/sursound
