1. A computer implemented method, comprising: displaying a sequence of words on a user interface rendered on a display device; applying, by one or more computers, in response to a user-based selection of a first portion of words in the sequence of words, a first indicium to the user-selected first portion of words in the sequence of words; associating, by the one or more computers, a first character having an associated first voice model to the first portion of words in the sequence of words; and associating, by the one or more computers, a second character having an associated second voice model to a second portion of words in the sequence of words, the second portion of the words in the sequence of words being different from the first portion of words in the sequence of words.