FIG. 12.  Block diagram of the Klattalk synthesizer in which a new voicing algorithm (top) has been added to the synthesizer (bottom) that was described in Klatt (1980). Nineteen variable control parameters are identified, including the new voicing source parameters OQ (open quotient) and TL (spectral tilt). Other synthesizer constants that are not shown, such as the frequencies of the fixed fourth and fifth formant resonators, can be reset by the user by modifying a set of speaker-defining constants.