In the page's words:

What exactly is the "Heartphones - Hamburg's headphone party"?

Heartphones is a headphone party at which every visitor receives a pair of wireless headphones, allowing them to adjust the volume themselves and choose between several channels of music. At this party, lots of people dance to different music. The headphones show who is listening to which channel.

We offer three music channels. These are usually: K1: Indie / Alternative / Rock / Emo, K2: Everything from 2000 onwards; Pop, Charts, German Rap, Party, and K3: 80s/90s/Trash. But that can vary from time to time and we always adapt a little to the audience anyway. A little bit. ;)