For that matter, how much do artists get paid each time I listen to a track on a CD?
Hmmm, let's see: Artists get about 10% of retail
A CD costs $10, and say there are ten tracks on the CD.
Thus, each track costs $1, and the artists earns ten cents per track.
Most of my CDs were purchased at least ten years ago. I have no doubt I have listened to many of those tracks at least 100 times (those that were purchased more recently obviously don't have the same number of "listens", but - barring sudden death or deafness - I expect they will in time).
So the artist gets about $0.001 (1/10th of a cent) every time I listen to a track.
That's slightly less than Pandora pays and 6 times less than Spotify. Even assuming they get slightly better rates and I listen to the tracks far less frequently, the artists are still earning about as much money each time I listen to a track on CD (well, okay, ripped to MP3 but you know what I mean).
You could argue that the percent the artist is earning is far too low - that the middlemen are siphoning off too much into their own pockets - but that's a different issue. As it stands, it seems to me that online streaming services are paying them about the same (if not more) than they might get from more traditional sales, at least if you calculate based on the number of times a song is heard.
Maybe measuring "per listen" (stream) isn't the optimal way of calculating revenue.