"P Stamler" wrote in message


Right you are, Bill and Arny. Sorry -- forgot to take a square root
while I was calculating. In reality, if signal #2 is 5.868dB or so
below signal #1, it will add 1dB to the cumulative noise. So anything
less than that, all things being equal, is not worth bothering with
or worrying about.

I agree that this is a good rule of thumb. Somehow I hadn't thought of the
problem exactly that way.

Of course one has to remember the underlying presumptions, one of which is
that both noises have the same spectral balance. In real life this is not
the case much of the time. If you mix two noises with significantly
different spectral balance (i.e., pink and white) the contribution of the
source with lower amplitude may be more or less audible.