1. A computer implemented method comprising: providing a plurality of characters having different associated voice models; receiving a user selection of one of the characters from the plurality of characters to associate with one or more portions of a sequence of words rendered on a user display device; associating by one or more computers the selected character from the plurality of characters with the selected one or more portions of a sequence of words; and modifying by the one or more computers a voice model associated with the selected character based on data received from the user through the user interface, the voice model characterized by a set of attributes.