41. The speech synthesizer of claim 40 wherein said amplitude control means includes means for producing a d.c. signal whose magnitude is determined by the value of said certain input bits, and control means adapted to modulate the amplitude of said first and second control signals in accordance with the magnitude of said d.c. signal.
40. The speech synthesizer of claim 39 wherein said preselected signal characteristic corresponds to the amplitude of said first and second control signals.