Micro Bits, a website dedicated to subway stations around the world, has a great page titled "Voices in the Deep," which compares station announcements in subways in dozens of international cities. According to the list, "in Kyoto, the subway plays beautiful guzheng (sort of an Asian violin) compositions for its door-closing tones," while Lisbon, Portugal, subway riders hear a "buzzing before the doors close." And in Chicago? "A very friendly, pre-recorded male voice is somewhat verbose and talks almost permanently to the passengers." Some city descriptions even include audio files. Check it out.