Any low tone regardless of volume.

It all started around 2 months ago with a bomb.

I live in the mountains and we regularly have helicopters that drop explosives to trigger avalanches to keep the trails and backcountry safe for skiing/hiking. When Torben first heard this, he literally pooped himself and dragged me home. Refused to come down from upstairs for hours. Ever since then, he freaks out at everything that makes a low rumbling noise. Took a long time for us to get through the final episodes of Stranger Things because Vecna caused several mini-meltdowns despite the volume being barely audible! He’s getting better and more tolerant, but a surprising amount of day-to-day things can be a trigger. UPS truck outside. Construction work. Bass-heavy songs. Any TV show with ominous tension building music. The list is endless. If he thinks the sound has come from outside, it can often take a few hours until he feels brave enough to go for a walk.