Gary, yes, no, maybe. In the case of the leaking air. that sound supersedes all other sounds and becomes dominate. The other sounds are heard (so in that sense you are correct) but they mesh together into one secondary sound. You hear it but as one sound not 10-20 individual sounds. So for the listener to hear each line of the music distinctively you need to introduce it individually.

Now, as I said, I don't remember the exact place or person that introduced this concept to me, but I believe it might have been presented in a arranging, composition class I took at Norfolk State College when I was at the Naval School f Music.

I also don't think that what was meant, that you didn't hear more than two sounds at once but that you couldn't properly comprehend more than two sounds (lines of music) at once. I need to be more careful as to how I explain things!

So, yes, no, maybe.