The Musical sound is any tone with characteristics such as controlled pitch and timbre. From the tinkle of a bell to the slam of a door, any sound is a potential ingredient for the kinds of sound organization called music. Music arises from human behaviour, and the study of human behaviour is part of biology. Some believe that folk music originated as art music that was changed and probably debased by oral transmission, while reflecting the character of the society that produced it. In many societies, especially preliterate ones, the cultural transmission of folk music requires learning by ear, although notation has evolved in some cultures. Different cultures may have different notions concerning a division between "folk" music on the one hand and of "art" and "court" music on the other.