11. A method of speech synthesis, comprising the steps of: (a) receiving a text input in a text-to-speech system; (b) processing the text input into synthesized speech using a processor of the system; (c) predicting intelligibility of the synthesized speech; (d) determining whether the predicted intelligibility from step (c) is lower than a minimum threshold; (e) outputting the synthesized speech to a user via a loudspeaker if the predicted intelligibility is determined to be not lower than the minimum threshold in step (d); (f) adapting a model used in conjunction with processing the text input if the predicted intelligibility is determined to be lower than the minimum threshold in step (d); (g) reprocessing the text input into subsequent synthesized speech; (h) predicting intelligibility of the subsequent synthesized speech; (i) determining whether the predicted intelligibility from step (h) is lower than the minimum threshold; (j) outputting the subsequent synthesized speech to the user via the loudspeaker if the predicted intelligibility is determined to be not lower than the minimum threshold in step (i); and, otherwise (k) repeating steps (f) through (k).
12. The method of claim 11 , wherein the model in step (f) is a Hidden Markov Model that is adapted using a Maximum Likelihood Linear Regression algorithm.