Patent US 4,433,210

A phoneme-based speech synthesizer that is particularly adapted for implementation on a single integrated circuit chip. The vocal tract is comprised of a fixed resonant filter and a plurality of tunable resonant filters whose resonant frequencies are controlled in accordance with the values of certain control parameters. The vocal tract is implemented utilizing a capacitive switching technique which eliminates the need for large valued components to achieve the relatively low frequencies of human speech. In addition, a novel digital transition circuit is included which gradually transitions the values of the vocal tract control parameters as they change from phoneme to phoneme. A unique glottal source generator is also disclosed which is adapted to digitally generate a glottal pulse signal in a manner which readily permits the glottal pulse to be spectrally shaped in any desired configuration.