Klarinet Archive - Posting 001057.txt from 2000/07

From: Bilwright@-----.net (William Wright)
Subj: [kl] recorded source vs 'in the flesh'
Date: Sun, 30 Jul 2000 13:25:58 -0400

Another item, which sometimes isn't mentioned but is important, is
that slight movements -- such as rotating your head a few degrees --
provides your brain with important acoustic information that cannot be
obtained any other way. This is thanks to the convolutions of the
fleshy parts of our ears. And, of course, this effect is missing with
ear phones, which move in unison with our head. Benade spends several
chapters talking about this.
In fact, ear phones produce an illusion (not always desirable)
because the microphone _does_ pick up reverberations from walls &
furniture and so forth, but then the speaker or ear phone delivers these
multi-directional sounds from a single source.

Photography is a more obvious example of this. Normally the
muscles of our two eyes sense the angle between themselves (the angle
that is required to aim both eyes toward a single object) and thereby we
obtain a 'feeling' of distance. But when we look at a photograph (a
flat surface that lacks its own 3rd dimension), the angle between our
two eyes remains constant while our eyes move from one object to
another. Our brain must cope with a contradiction: "Part of my view of
object-A is blocked by object-B, so obviously object-B is closer (and
isn't as large in reality as it appears in the photograph); but why
doesn't the angle between my eyes change when I look at object-B instead
of at object-A?" This is the cause of optical illusions such as a box
popping in or out, a stairways going either up or down, etc.
Redirecting reverberations from multiple directions through a
single source destroys important information and makes the recording
less attractive. Even with multiple channels piped through different
speakers, some information must disappear. You must use some part of
your intellect to 'look beyond' this deficit, even if you aren't
consciously aware of it.

Cheers,
Bill

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