First off, I love this song.
I was listening, and noticed at 1:30 into it, there is a "call and response" type inter-weaving of two vocals. My question is, is it Barbara Mason and a backing vocalist? Or is it two tracks of Barbara's vocals laid down on top of each other? I am trying to listen and see which vocal does not sound like her, but they both do (to my ears).
This led me to re-listen to the whole song. It sounds like there is echo or (some kind of reverb or something?) on her vocals throughout. Maybe they recorded her singing the same thing twice exactly the same and laid them on top of each other? (I know in rock music, they have guitarists play the same thing multiple times and lay all the tracks into the song to make it sound "thicker").
Maybe I am totally crazy here (I have no experience in production/recording). Just curious.