>So we'll get useful cancellation of noise frequencies from around 275
>Hz and below... which is pretty low, but if the room noise you're
>fighting contains traffic rumble and drone, this could be useful.
>Obviously, the closer the two mics are, the higher the frequency at
>which useful cancellation will become available.
>
>>
> > >Of course this has has the most effect at cancelling lower
>> >frequencies, where the distance between mics is just a small fraction
>> >of a wavelength.
>>
>> Precisely. A high-pass filter would do the same thing more cleanly.
>
>Sure, but a high pass will cut EVERYTHING, possibly including
>frequencies of interest.
A high pass filter will cut exactly what you set it for.
>Anyway, I was just putting the idea out there. I have tried this
>technique (with some success) for voice pickup in noisy environments,
>where the speaker talks closely into one mic and the other is about 6"
>away from his mouth.
Many years ago the Grateful Dead experimented with out-of-phase omni
mic pairs spaced about 1" apart. The singer would sing very close
into one mic. The separation from the environment was eerie.
-Dan Dugan
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