Pandora is really in a groove this morning. One of its channels is playing song after song that I like. Usually, I have to thumbs down about every fourth song. But all that training has paid off. Pandora seems to know my tastes. At least this morning.

I’ve been told (but haven’t checked) that Pandora works because it hires people to tag the gazillions of songs in its library with lots and lots of metadata: The style, tempo, key, gender of the singers … on and on. That enables it to find other songs you might like by looking at the attributes of the ones you do like. It works.

And yet, what do I really like about a particular track? That the singer is female or the chorus brings in backup singers? Nah. Within the range of songs I like — I have one channel crystallized around Duke Ellington and another around the Stones and the Beatles — I like this song because the singer’s voice cracks and that one because the bass thumps really loudly in the bridge. I like this one because of the absurdity of the lyrics and that one because the melody is broken across several instruments. And then there’s that other one that I like because I used to listen to it with my high school friends.

Except for that last characteristic,with a large enough sample and sufficiently fine-grained analytic tools, could a site figure out what I like about this song and that? Or is this a case where the difference between signal and noise is just too much in the ears of the beholder?