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Re: "upside down" mic?
Author: Martin Schneider/Neumann
Date: 03/07/2013
Yes, it's clear what you ask for. But there is no such documentation available, not from any manufacturer I know of. Of course such measurements have been made by us, but it's not that one can put the results in a few words. There was a Canadian AES paper, something like 80 pages, in 1989, if I remember correctly; just measurements, no auditory evaluation. And, in the frontal range, we're talking about single dBs; furthermore angle and dimension dependant and only in the high-mid to high frequency ranges.

One example, regarding your specific application, general acoustics, as explained in the textbooks, gives a theoretical background:

Reflections from the floor: use the -6dB per double distance law for spherical waves. [Assuming the mouth is next to a point source, which it really only is at low frequencies] Measure the distance from mouth to mic. Measure the distance from mouth to floor to mic. Calculate how many dBs the floor reflection will be lower, compared to the direct sound. If you're very correct, add a few dBs of attenuation, due to the directivity of the capsule. [Taken from the published polar patterns] If you're over-correct add another few dBs for the mouth directivity [One has to look that up in acoustics papers]. Don' forget the floor absorption, if there's a carpet or the like. Then judge carefully if there is any chance that a reversed positioning will have an audible effect.
Then... realize that there is also a ceiling in the studio, and that the inverse effect will take place with the ceiling reflection....
Part 2: make a double-blind test with the setup in reality, to confirm (or not) the theoretical findings, and if you hear any difference.

Summing up, if there were a good comprehensive written text, I'd give you the link. But... I don't know of any. One has to gather together all the aspects that one knows of acoustics.

I hope that explains my difficulties to give a satisfying answer.

Best regards,
Martin Schneider / Neumann Mic. Development  
 
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