At any given moment, hundreds of people are listening to Leonard Cohen’s Hallelujah. A participatory humming experience reveals an invisible vibration uniting people around the world currently listening to the song. Online listener data is transformed into a virtual choir of humming voices. The number of voices corresponds to the current listener count, visible on a numerical display. By humming along into the microphones, participants generate low-frequency vibrations, closing the circuit of collective resonance with their bodies.