We all know that loud noise can damage your hearing - but it seems not enough noise can also impair it. Consequently, people in cities have better hearing than those in quiet villages.

Researchers at the Universtity of Giessen in Germany spent over a decade testing the hearing of some 10,000 people. As expected, people exposed to very loud noises as part of their jobs, such as construction workers, had poor hearing. But those living in quiet rural areas had hearing not much better. And people, including airline pilots or orchestral musicians, who encoutner constant noise at work, could hear very well. Firefighters, whose lives can depened on sounds, had exceptional hearing.

The team concluded that continual exposure actually "trains" the ear to tolerate it; it is sudden, extreme noise that does the damage. Which would explain why Asian villagers, whose quiet lives are punctuated by occasional firework celebrations, have the worst hearing of all.