15. Apparatus as set forth in claim 11, wherein said sample rate control circuit means comprises variable oscillator means operably connected to said voice character conversion controller means and said speech synthesizer means and being responsive to control signals from said voice character conversion controller means for selectively varying the magnitude of each time increment defining said sampling period in a preselected manner such that the time duration of the adjusted sampling period is different from that of the original sampling period, but the total number of time increments defining said adjusted sampling period equals the known number of time increments defining said original sampling period.
11. Apparatus as set forth in claim 10, wherein said digital speech data from the source is subject to speech synthesization using a predetermined sampling period comprising a known number of task-accomplishing time increments; said speech parameter control means including sample rate control circuit means responsive to inputs from said voice character conversion controller means as determined by said voice character selection means thereof for adjusting the sampling period of said digital speech data from the source in a manner altering the digital speech formants contained therein to a preselected degree and providing adjusted sampling period signals as an output; and said speech synthesizer means being coupled to the output of said sample rate control circuit means for receiving said adjusted sampling period signals therefrom as the modified speech data from said speech data reconstructing means is being input thereto.