At 4:44 AM -0700 9/29/10, James Shatto wrote:
> > --- On Tue, 9/28/10, Rob Danielson
><<type%40uwm.edu>> wrote:
>
> > I'm not sure whether it applies to others, but
>> I've stopped using headphones for stereo imaging
> > evaluation...
James Responded
>I stopped using headphones because of other issues. If there's any
>phase cancellation issues between L and R outputs, you don't hear
>that on headphones....enough to cancel most of the low end in most
>of the recorded content. ....
>
>- James
>
Hi James--
Very true-- if one has carefully installed speakers so the room and
nearby surfaces are creating new phase problems. ;-) The catch-22 is
many people don't have the luxuries of dedicated listening
environments and must resort to good headphones.
As theory predicts and the tests I've done have confirmed,
phase-related problems arising from stereo mics separated no more
than a couple of feet would be _above 500 Hz_ because wavelengths
under 500Hz wrap around the largest baffles we use and sum on both
channels. Low Hz cancellation happens a lot when recording in larger
interior spaces, but its much less common outside, in the field. It
does happen when one is recording in more enclosed settings like
hollows, river bottoms making it tricker to find sweet spots where
the waves are less conflicting.
A lot of the spatial imaging cues reside in the octave from 500 Hz to
1K where phase cancellation can occur in outdoor settings from
conditions like reflective surfaces on the order of 12-24" away.
Most of us have learned this by trial and error but its instructive
to see it confirmed another way. Rob D.
--
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