The work reported in this thesis is a feasibility study of the possibilities and practical
problems of applying speech control and natural language understanding techniques to
the use of a computer by a physically disabled person. Solutions are proposed for the
overcoming of some of the difficulties and limitations of the available equipment, and
guidance given for the application of such systems to real tasks.
The use of voice control with a low cost industrial robot is described. The limitations
introduced by the speech control hardware, such as restricted vocabulary size and
artificial manner of speaking are partially overcome by software extensions to the
operating system and the application of natural language understanding techniques.
The application of voice control and audio response to common application packages
and a programming environment are explored.
Tools are developed to aid the construction of natural language understanding systems.
These include an extension to the use of an existing context-free parser generator to
enable it to handle context-sensitive grammars, and an efficient parallel parser which is
able to find all possible parses of a sentence simultaneously.
Machine readable dictionary construction is investigated, incorporating the analysis of
complex words in terms of their root forms using affix transformations, and the incorporation of semantic information using a variety of techniques, such as semantic
fields, the previously mentioned affix transforms, and object-oriented semantic trees.
The software developed for the system is written in Borland Pascal on an IBM
compatible P C , and is produced in the form of library modules and a toolkit to facilitate
its application to any desired task.