I have a little understanding of these abilities. Just as I associate certain smells with certain people, I also imagine songs for certain people when I see them. I don't actually hear the songs out loud; I hear them in my head. Sometimes it's not an entire song. It might just be a guitar riff or a few beats of a drum. It happens when I see posts by some DUers, too. I think it might have something to do with watching cartoons and other shows when I was a kid. It's like the little theme songs they play when certain characters appear.
The example of the blind man who uses echo-location is amazing, especially since he's been able to teach five other people how to have it. Just think if we were able to teach it to all blind people! Humanity could reap huge benefits from further study of these people.