SYNTHESIZING PHONEME STRING OF PREDETERMINED DURATION BY ADJUSTING INITIAL PHONEME DURATION VALUES FROM MULTIPLE REGRESSION BY ADDING VALUES BASED ON THEIR STANDARD DEVIATIONS

Statistical data including an average value, a standard deviation, and a minimum value of a phoneme duration of each phoneme is stored in a memory. When speech production time is determined for a phoneme string in a predetermined expiratory paragraph, the total phoneme duration of the phoneme string is set so as to become equal to the speech production time. Based on the set phoneme duration, phonemes are connected and a speech waveform is generated. To set a phoneme duration for each phoneme, a phoneme duration initial value is first set based on an average value, obtained by equally dividing the speech production time by phonemes of the phoneme string, and a phoneme duration range, phoneme. Then, set based on statistical data of each the phoneme duration initial value is adjusted based on the statistical data and the speech production time.