My guess is for noise canceling. The wind noise is is probably all around, while the voice is very localized and directional, so using a second pick-up out of the talkers direct vocal pattern and subtracting that from the primary should null out lots of LF wind noise.
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Haven't they used noise canceling mics for years in aircraft radio communications?
JR
JR,
The noise cancelling mics used in aircraft/tanks/Grateful Dead/etc. have the mic elements very closely spaced, the sound reaching both elements is closely correlated, reversing the polarity of one element lowers shared noise considerably.
Your guess would require a second mic located some distance off screen.
Having switched polarity of spaced microphones, I have never found the correlation between the two mics to be enough to lower background noise (either band
or wind) by very much, basically just changing the "flavor" of the noise.
That said, using a crossover for the speech band (say 200-4000 Hz) then inverting the polarity of the pass bands above and below the microphone bandpass output, then mixing them back together would effectively reduce out of band noise almost completely. The band pass could be reduced depending on the severity of the background noise and the announcer's voice range and level.
There are probably "anti-noise" plug ins available that do that with only two virtual "knobs".
Art