No vibrations, only sound. Early this morning, I had an opportunity to try getting past them again. This time, as I fell asleep, the loud noise was the ringing in my ears, but when I momentarily relaxed, the sound was suddenly amplified, and it became normal again once my heart rate increased a half-second later. I did this 4 times in the span of 10 seconds in a conscious effort to keep my heart rate down when the noises amplified, but it's hard. The noises don't gradually increase, they become really loud within a fraction of a second. I'm hoping to eventually succeed in my efforts, as I did succeed in slightly lowering my heart rate during the noise spike.
Never underestimate the power of the ponies.