An audio response unit for telephone needs

An audio response unit has been built that synthetizes messages composed of a fixed sentence and any number from 0-999 999. The method used is synthesis by concatenation of words, and automatic corrections on pitch and rhythm are used to improve naturalness and intelligibility. The synthesizer is a part of a channel vocoder. This audio response unit is to be used in a telephone exchange to answer cost inquiries from the subscribers. Larger applications using touch-tone telephone as data input device are under consideration.