I had a job where I had to work in a cubicle for several months, in a sea of other cubicles. The person next to me had a radio going, which didn't bother me because the volume was kept very low. Through the course of the day, though, background noise changes, and what you might not hear at all at midday you'll hear little bits of when things are quieter. It was late 1997, and to this day I can hear any single note of Green Day's "Time of Your Life" or Celine Dion's Titanic song and identify it immediately.