1. A computer-implemented method of dynamically modifying automated machine playback of messages in an interactive voice response system in a manner that approximates actual human dialog by varying key variables associated with an application domain, comprising the steps of: creating a table or database with synonyms of the key variables and predetermined rules for selecting a synonym for a key variable based on a context of a message to be generated; receiving a user request for information; retrieving data based on the information requested; generating a message responsive to the user request for conveying the information to the user, the message being generated using syntactic rules; dynamically modifying the message by altering intonation and selecting an appropriate synonym for each key variable of the message from the table or database, wherein the altering and the selecting are both based on a context of the information to be presented, wherein the context is related to the application domain and defines situations where different key variables can be selected based on certain determination criteria; and playing back the modified message to the user; wherein the intonation includes at least one of a volume, a speed, and a pitch, wherein the key variables include at least one of key verbs and adverbs, and wherein the key variables are selected among a finite set of synonyms in the table or database based on the context of the information to be presented to the user.