Lydokane - 2011-05-12

My entire collection has been normalized with MP3Gain.  I used Track Gain and set level to 91db.  I now notice that when playing mixed playlists some songs are not as loud as others.  I have been reading a lot but I am still struggling to understand the intricacies of normalized volume vs. volume perceived by the human ear.  Should I have used Album Gain instead of Track Gain?

As I understand it Album Gain bases the volume on the average volume of the album as a whole as opposed to the Track Gain that sets the volume based on the average of the individual track.

How does MP3Gain interpret an album?  Does it look at the individual folder(s) as an album or does it see an album as everything that is currently loaded into the program regardless of the  directory structure?

I apologize if these questions have been asked recently.  A quick search of the forum didn't answer these questions for me.