TESSA is an interactive translation system designed to support transactions between a post office clerk and a deaf customer. The system translates the clerk's speech into British Sign Language (BSL), displayed on a screen, using a specially-developed avatar (virtual human). TESSA is a context-constrained exemplification of one of two basic approaches to machine translation, neither of which can currently fulfil all of the demands of successful automatic translation. Drawing on recent research in theoretical psycholinguistics, we show how TESSA is a convincing prototype model of one aspect of real human language processing. Ways are suggested of exploiting this parallel, potentially offering new possibilities for the future design of artificial language systems.

A system designed to allow Post Office counter clerks to communicate with deaf customers by translating speech into sign language is described. The system uses approximately 370 pre-stored phrases which may be signed to the customer using a specially designed avatar. The clerk is unable to memorise this number of phrases and therefore the system attempts to map from their input speech to the semantically equivalent pre-stored phrase. We describe a number of language processing techniques developed to perform the mapping, and give results obtained using alternative formulations of the phrases from a number of speakers. We then give results for recognised speech input and show how misrecognitions effect the mapping system. Best performance is obtained using a mapping system based on an entropy weighted, vector based distance measure between the test phrase and each of the signed phrases.

The design, development, and evaluation of an experimental translation system that aims to aid transactions between a deaf person and a clerk in a post office (PO) is described. The system uses a speech recognizer to recognize speech from a PO clerk and then synthesizes recognized phrases in British Sign language (BSL) using a specially developed avatar. The main objective in developing this prototype system was to determine how useful it would be to a customer whose first language was BSL, and to discover what areas of the system required more research and development to make it more effective. The system was evaluated by 6 prelingually profoundly deaf people and 3 PO clerks. Deaf users and PO clerks were supportive of the system, but the former group required a higher quality of signing from the avatar and the latter a system that was less constrained in the phrases it could recognize; both these areas are being addressed in the next phase of development.

Research at Televirtual (Norwich) and the University of East Anglia, funded predominantly by the Independent Television Commission and more recently by the UK Post Office also, has investigated the feasibility of using virtual signing as a communication medium for presenting information to the deaf. We describe and demonstrate the underlying virtual signer technology, and discuss the language processing techniques and discourse models which have been investigated for information communication in a transaction application in Post Offices, and for presentation of more general textual material in texts such as subtitles accompanying television programmes. (5 pages)