A Digital Speech Synthesizer

A method for constructing a speech synthesizer using microprocessors (AMD 2900) is described. A set of time‐varying digital filters which produces speech signals was realized by a program written using only microinstructions. After each interval of a few ms, if the filter coefficients are given, the activated filter can produce output speech signals. The synthesizer consists of a 16‐bit ALU with a cycle time of 270 ns, a 16‐bit parallel multiplier with a calculating speed of 500 ns, and an interface controller. As for the filter configuration of the synthesizer, a new lattice form is proposed based on the production process of speech. In the synthesis of consonants, the location of the noise source can be simulated easily by the filter. The filter coefficients can be transferred from a CPU through the selector channel. The channel interface uses a microcontroller which executes the microroutine in ROM. As rewriting of the microprogram can be implemented easily, the system is flexible.