1. A method allowing computer-generated speech to be rendered with a multi-voice font that is different than source voice fonts used to generate the multi-voice font, the method comprising the acts of: loading the source voice fonts; assigning weights to characteristics of each source voice font; obtaining text to be rendered as the computer-generated speech; predicting characteristic values for the text for each source voice font using at least one characteristic prediction model associated with each source voice font; merging the predicted characteristic values with the corresponding weights to produce interpolated characteristic values; and rendering the text as computer-generated speech having the interpolated characteristic values.