Mutes the audio ads on play.spotify.com, while they are still being played, so *everyone* is happy. I have tried to make it as tiny and straightforward as possible, with less than 22 lines of well commented code. Kudos to la_poigne for providing me a relatively good kick-start.
Supporting the Spotify revenue model is important for the welfare of the music industry in the digital age. This script does not remove advertising from the web player, just mutes the audio commercials.
If you want to get rid of the in-page ads use something like uBlock or AdBlock Plus with a nice set of filter lists like Fanboy's.
This one gets rid of the in-header ads: