1. A method of computerized training using an interactive computerized training system, comprising: providing over a network by an application server for display a terminal of a content designer an avatar user interface configured to enable the content designer to at least: select an avatar from a library of avatars; assign a role in a presentation to a selected avatar; assign a voice to a selected avatar; receiving at the application server over the network from the content designer terminal at least a selection of first avatar from the library of avatars, and role assignment, a first voice assignment for a first presentation, and a second voice assignment for a second presentation; presenting via a user terminal to a user the first presentation of the first avatar speaking using the received first voice assignment, in the assigned role, using a first script, wherein the first avatar is animated and lips of the first avatar are synchronized with vocalization, using the first assigned voice, of the first script; presenting via the user terminal to the user the second presentation of the first avatar speaking using the received second voice assignment, in the assigned role, using the first script, wherein the first avatar is animated and lips of the first avatar are synchronized with vocalization, using the second assigned voice, of the first script so that the user can evaluate the effect of voice on a listener.