I absolutely loved this so I'm surprised to see so many negative reviews. The ambiguity about if the group are genuinely hearing a shared noise and what the noise is vs are they a group of lost souls who've been seduced into a cult - like group is perfect. It is up to us the viewer to make of it what we will. As someone who has been through a spiritual awakening, I can clearly see what the writer was getting at as a main theme - who are really the mad ones here, the group or how "normal" society functions. It touches on so many profound issues.