1. A method comprising: receiving a stress pattern for both a language and an accent in the language; detecting, based on the stress pattern, incorrect stress patterns in selected acoustic units representing speech to be synthesized, wherein the selected acoustic units were selected by a separate unit-selection speech synthesizer; performing an analysis of the incorrect stress patterns, wherein the analysis comprises a word level analysis, a phrase level analysis, and a sentence level analysis on the incorrect stress patterns; and modifying, via a processor and prior to waveform synthesis, the incorrect stress patterns in the selected acoustic units based on the analysis, to yield corrected stress patterns, wherein the corrected stress patterns conform to the stress pattern for the language.