I've been wanting to ask this question for a while now. Okay, I've heard most people complaining about the Gurgling in an evod, but what I would like to know is, what is it when you get a low pitched fluttering type of a sound. Is this actually the same thing? Very rarely, I will get this sound and I am thinking it is a cousin of the gurgling.
I got the gurgling only once and yes, it was flooded. Could this be that it is actually flooded also (or I was thinking it's trapped air)? To me, it flutters. This is the only way I can explain it. 
