Generating Segment Durations in a Text-To-Speech System: A Hybrid   Rule-Based/Neural Network Approach
  A combination of a neural network with rule firing information from a rule-based system is used to generate segment durations for a text-to-speech system. The system shows a slight improvement in performance over a neural network system without the rule firing information. Synthesized speech using segment durations was accepted by listeners as having about the same quality as speech generated using segment durations extracted from natural speech. 
Gerald Corrigan, Noel Massey and Orhan Karaali