From: Rob Danielson <>
>
> At 10:31 PM -0800 2/21/05, Ken Durling wrote:
>
>>>At 08:44 PM 2/21/2005, you wrote:
>>>
>>><snip>
>>>
>>
>>>>>Here's one example. I made a stereo recording with 21" spaced omnis
>>>>>of a large flock of seagulls circling above me about 10-75' feet for
>>>>>about 3 minutes. Listening at home, I noticed that my ability to
>>>>>track the bird motions in stereo was limited to 2, at most 3 birds at
>>>>>a time even though 10 or more were calling in flight at any given
>>>>>moment. My attention seemed geared to pick out only the closer moving
>>>>>birds with the rest of the birds becoming a stationary background
>>>>>plane in my mind. I would guess that the further away the birds, the
>>>>>more difficult it would be to articulate their motion.
>>
>>>
>>>Interesting - might it not have been more discernible with directional
>>>mics? I haven't done much with this, but accurate imaging requires care=
ful
>>>phase control too, as I understand it.
>
>
> As per your interest in portraying many birds in motion, its possible
> there are limits as to how many objects one can perceive as being in
> motion at once within a stereo or guad field.
This is a fairly well known characteristic of our hearing. We tend to
filter out or merge most sound into the background and focus on a
limited number of sounds at a time. We may shift from sound to sound
doing this, or follow a single set of sounds. Our ability to filter
sounds far exceeds what we can do with computers.
I'll point out the book "Ecological Psychoacoustics" as being a good one
on current thinking on the subject. There is a merging of lab
psychoacoustics with the more outdoor studies of hearing going on. The
lab predictions often fail when confronted with real life hearing
situations.
You are probably fighting a uphill battle trying to get your listener's
to lock into the whole. Locking into some birds while having a swirling
background of more birds is more likely.
Walt
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