Gongs get loud. Not painful, but louder than you might expect, and you feel the vibration through the floor as much as you hear it. The bowls and drums are much gentler, and the volume builds and fades over the hour rather than staying up the whole time.
You're lying under blankets for about an hour. If the volume is ever too much, you can move your mat farther from the gong - just tell me, or set up farther away from the start.
People notice different things during a session. Some drift in and out of sleep. Some see colours or images. Some just lie there making shopping lists. I won't tell you what your experience means, and you don't have to share it with anyone.