US Patent 7765103 Rule based speech synthesis method and apparatus

A rule based speech synthesis apparatus by which concatenation distortion may be less than a preset value without dependency on utterance, wherein a parameter correction unit reads out a target parameter for a vowel from a target parameter storage, responsive to the phoneme at a leading end and at a trailing end of a speech element and acoustic feature parameters output from a speech element selector, and accordingly corrects the acoustic feature parameters of the speech element. The parameter correction unit corrects the parameters, so that the parameters ahead and behind the speech element are equal to the target parameter for the vowel of the corresponding phoneme, and outputs the corrected parameters.