::HIDDEN PLACE::
The opening track of Bjork's album
Vespertine has special frequencies woven into it -- sine-curves of sound, over and under, strengthening the song like Kevlar.
These frequecies drown out ambulance sirens. I know this because, listening to the song on my way to judge a science fair this afternoon, I was nearly run over by an ambulance as I green-means-went at a traffic light.