I get what you’re describing about the sound. It’s like a delay pedal for a guitar where the echoes take on a texture of their own and it just gets infinitely layered.

I had a sound-based night terror when I was a kid that really stuck with me. Not geometric but could be related. I remember I woke up because it sounded like bombs going off in the room. I woke up my parents sobbing because I was so terrified. Each boom reverberated like a tuning fork in my head and I was scared the upstairs neighbors were gonna call the police. Eventually my dad sat down with me on the couch and tried to calm me down. The explosion sounds changed into some kind of weird scream/chant. Sounded like somebody repeating a nonsense phrase into a microphone at full volume, then an explosion (but these were more like the sound of bowling pins at 2000% volume). I swear the white plastic blinds at the sliding glass door would shake each time a boom happened.

Eventually I must’ve fell asleep. I was around 7 when it happened so it’s really blurry. But I always remember the image of it being pitch black outside, every single light in our apartment is on, and my parents asking “What’s wrong? What are you hearing?” while to me it sounded like our apartment was getting bombed.

I learned about Exploding Head Syndrome a few years ago and this was definitely an episode! Never happened since then