The Problem with Stereo
On Tuesday, June 28, 2016 at 4:11:20 AM UTC-7, Gary Eickmeier wrote:
Peter -
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Without re-quoting the entire thing, which is available above obviously -=
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another great and interesting post. But let me concentrate on just one=20
aspect of this speaker-room interface problem.
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Most (normal) audiophilles who haven't studied all this will not know the=
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difference between the "spatial" and the "temporal" characteristics that =
you=20
discuss. But we must differentiate the two because the spatial is the muc=
h=20
more important and audible one that has not been studied enough. The spat=
ial=20
means the angles from which the various sound fields arrive at the listen=
er.=20
For example, the direct comes straight from the instruments (or speakers)=
,=20
the early reflected comes from a much wider and deeper set of reflections=
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from the soundstage area but with a significant and important time delay,=
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and the reverberant comes from all around, evenly, with (hopefully) a smo=
oth=20
decay to inaudibility, considered to be 60 dB below the loudest sounds. W=
hen=20
we record we should try to record not just the instruments but also the=
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early reflected sound as part of the whole soundstage, helping to flesh o=
ut=20
the full sound power of the instruments and giving us the timbre of the=
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instruments and the perception of spaciousness that we hear live.
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This perception of spaciousness - very important to stereo and the musica=
l=20
enjoyment, live or reproduced, is caused by the physical placement of tho=
se=20
recorded reflected sounds from angles that are similar to the original. I=
do=20
it by reflection, but you could do it with extra speakers placed near the=
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front and side walls of a smaller room. Anyway, it is the directions from=
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which those sounds arrive that is involved in this perception of=20
spaciousness. This cannot be reproduced by the direct speakers no matter =
how=20
good they are, it must come from the radiation pattern by means of=20
reflection or from those extra speakers.
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OK, so the temporal aspect is also important, but it does not come from t=
he=20
temporal delay of those reflections we were just talking about above. It =
was=20
actually contained in the recording, both the delay of the early reflecti=
ons=20
and the full decay of the reverberant field. You will often see the=20
criticism of a direct and reflecting type of speaker that our home rooms=
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are not as big as the original, so it can't work. But now I hope you (all=
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can see that if we address the spatial part, the temporal will take care =
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itself.
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Moral of the story, we must learn to separate in our thinking the spatial=
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from the temporal characteristics of sound fields.
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Gary Eickmeier
You can't separate them. Spacial perception heavily relies on temporal char=
acter of sound. You can't "hear angles." You can hear temporal differences =
between the right and left ear in sound coming from an angle which your bra=
in will process as sound coming from an angle. Spacial perception relies on=
temporal information.
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