Thank you David,
>From your comments below, it looks to me that what I'm trying to describe m=
ight not be phasing.
I'm stumped, and probably way out on a limb by now.
Curt
Avocet wrote:
>> 1) Could these phase differences possibly occur on such a minute scale a=
nd at such a rapid rate that the resulting "flanging" or "wavy" effect is a=
lmost imperceptible to most people?
>
> Curt,
>
> Our ears cannot hear phase differences on continuing sounds between left =
and right, only transients with different timings. But, and a big but, if y=
ou mix left and right with a time or phase difference you will generate fla=
nging. This mixing can take place at any stage but if it is in playback lou=
dpeakers, you could then hear the effect which might not be audible on head=
phones.
>
>> 2) Would your explanation accommodate the observable fact that introduci=
ng boundaries/baffles into the picture almost always stabilizes the image, =
eliminating the effect?
>
> Boundaries, baffles, reflectors, all tend to boost sounds arriving at rig=
ht angles, but this can quickly become too conplex to analyse. The fallback=
from difficult theory is what you hear with your ears.
>
>> 3) Any thoughts on how this anomaly occurs in M-S arrays?
>
> Yes. From the front, M-S arrays give a very good stereo image for sound o=
bjects up to the angle where the rising S signal becomes lower than the (us=
ually) falling M signal. Beyond that angle, including vertical pickups, the=
derived left and right signals get out of phase. You can widen the "sweet"=
pickup area by decreasing the S signal, but at some point, and at the rear=
of the rig, left and right will go out of phase.
>
> I said above that we can't hear phase on continuing sounds, but in this c=
ase we can hear out of phase transients clearly, especially in headphones. =
Try it. If you reverse the phase of left or right, the back of the M-S pair=
becomes the sweet spot.
>
> David
>
> David Brinicombe
> North Devon, UK
> Cogito cogito ergo cogito sum - Ambrose Bierce
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