The Town Tune is the small melody that plays whenever the player talks to a character, when you walk into a door, and also the small melody that plays whenever the Clock Tower bell rings on the hour. A town tune can range anywhere from 1 to 15 notes, as well as the ability to choose one that will play a random note. In the original Animal Crossing, you could change your town tune by facing the billboard next to the Post Office. In Animal Crossing: Wild World and Animal Crossing: City Folk, you can change the town tune by going to the civic center in the Town Hall, talking to Pelly or Phyllis. In Animal Crossing: New Leaf, the town tune can be changed by talking to Isabelle.
Town tunes can also be played on instruments that can be bought in Tom Nook's. If music is playing at the same time, the instrument plays at the same speed.
Every game before New Leaf have their own town tune while the N64 and GameCube versions have the same (except Dōbutsu no Mori e+, which have the different tune). However in New Leaf, there are 4 different default town tunes that chosen randomly each time you start the new town.
Sometimes, when town tunes are played while talking to a character, it can relate to the villager's personality.
Cranky villagers may make the tune sound somewhat strange, peppy villagers will make the tune sound bouncy and normal villagers will take your tune and make it perky.