Digital Speech Technology

Speech generating devices (SGDs) – both dedicated devices as well as general purpose computers with suitable hardware and software – are important to children and adults who might otherwise not be able to communicate adequately through speech. These devices generate speech in one of two ways: they play back speech that was recorded previously (digitized speech) or synthesize speech from text (text-to-speech or TTS synthesis). This chapter places digitized and synthesized speech within the broader domain of digital speech technology. The technical requirements for digitized and synthesized speech are discussed along with recent advances in improving the accuracy, intelligibility, and naturalness of synthesized speech. The factors to consider in selecting digitized and synthesized speech for augmenting expressive communication abilities in people with disabilities are also discussed. Finally, the research needs in synthesized speech are identified.