Patent US 4,449,233

This system includes an LPC parameter speech synthesizer which basically needs ten binary bits for each LPC coefficient. However, external sources are allowed reduced storage and frame rate requirements by encoding the set of LPC coefficients in a data frame with bit-allocation, repeat-bit, and variable-length features. A three-memory system provides transformation: a speech word selected by controller 11 is transformed by a ROM (30) into an address to a ROM (12 or 13) which outputs corresponding speech data in reduced encoded format to a ROM (202) which converts the coded frame of coefficients to uncoded ten-bit coefficients as needed by the speech synthesizer.