Multimodal interface systems make it possible to interact with computers using speech and hearing, touch and gesture. The role of vision in human computer interaction could therefore be brought back to its natural place in communication. In many applications, non-visual presentation methods could be used efficiently to provide more natural human-computer interfaces. This evolution is of particular relevance for the visually handicapped. The purpose of this book is to provide a complete understanding of state-of-the-art research in non-visual human-computer interaction. The book is aimed at all researchers and developers interested in improving the accessibility of software applications, especially for people with disabilities.