[Scott Dorsey]

In article ,
mcp6453 wrote:
It's been a long time since I heard the explanation, but there is a ratio below which a foreground vocal will mask a
second microphone's pickup of that same vocal in the mix. The ratio of the amplitude is 1:3, as I recall. Can anyone
tell me what that effect (or law of physics or phenomenon) is called?

I think you're talking about the 1:3 rule, which is a sort of mixture of
physics and psychoacoustics and possibly unwarranted assumptions.

IF you have two microphones and IF they are cardioids, and IF the distance
between the microphones is more than three times the distance between the
microphones and the sources, then you're apt to hear audible comb filtering
when the mikes are mixed at identical levels.

Now, there are a whole lot of assumptions involved in that. It's assuming
the microphone is getting a certain amount of off-axis leakage, and it's
assuming that you're not noticing comb filtering below a certain point, and
it's assuming everything is more or less at the same level in the mix.

But it's still a reasonable rule to follow that is mostly accurate. For
recording in the digital world we can use time delay to line mikes up so
that the comb filtering either disappears or becomes so great that it's
no longer an issue. In the PA world you don't really get much ability to
do that, nor can you do it in the analogue mixing world.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."