I didn't see the part of your post where you mentioned your age at first, I just downloaded the file and opened it up. Without that information, my first instinctive guess was "early 30s". It certainly is feminine; one thing I'd like to add though is that phone tends to distort people's voices quite a bit. Can't really say how exactly, but I know I've had trouble recognizing close friends' voices for the first 1-2 times we talked on the phone before because they sounded so different there than IRL. So don't despair too much about it.