DECtalk software: text-to-speech technology and implementation

DECtalk is a mature text-to-speech synthesis technology that Digital has sold as a series of hardware products for more than ten years. Originally developed by Digital's Assistive Technology Group (ATG) as an alternative to a character-cell terminal and for telephony applications, today DECtalk also provides visually handicapped people access to information. DECtalk uses a digital formant synthesizer to simulate the human vocal tract. Before the advent of the Alpha processor, the computational demands of this synthesizer placed an extreme load on a workstation. DECtalk Software has an application programming interface (API) that is supported on multiple platforms and multiple operating systems. This paper describes the various text-to-speech technologies, the DECtalk Software architecture, and the API. The paper also reports our experience in porting the DECtalk code base from the previous hardware platform.