Mark Lenzi: Picture holding a marble. Then, picture if you had like a six foot in diameter funnel, metal funnel. The sound that marble would make as it goes around and it progressively gets faster as it gets, goes down towards the hole at the end. It’s a sound like I’ve never heard before.

Scott Pelley: Was this subtle? Like, “Did I hear that?”

Mark Lenzi: No. It was, it was actually somewhat loud. I heard it about three or four times. Always in the same spot. Always over my son’s crib and always right before we would go to bed.

Lenzi wears prescribed glasses because sensitivity to light is among his persistent symptoms.

Mark Lenzi: The symptoms were progressively getting worse with me. My headaches were getting worse. The most concerning symptom for me was memory loss, especially short-term memory loss.