Listen Party: How We Built the Co-listening Feature
The idea for Listen Party came about almost by accident: we wanted to listen to a new album together with friends from different cities — at the same time, in the same rhythm, with reactions in real time. By morning the first prototype was ready.
Technically it is built on SignalR: a persistent connection between the participants of a room, through which playback events fly — start, pause, seek. One participant becomes the "host", and their player sets the pace for everyone else.
Synchronization turned out to be the hardest part. Everyone's network is different, latencies fluctuate, and the naive "just send the track position" approach led to a couple of seconds of drift — enough to ruin the experience. The solution was constant correction: clients gently catch up to the host's position without jolting playback.
Listen Party reminded us why we make SoundSphere at all. Music is about shared experience. And when the technology disappears, leaving only the feeling that you are listening together — that is when you know it worked.
