The speech signal

An introduction to the speech signal with particular emphasis on the recognition of spoken messages is provided. In an attempt to clarify its nature, speech is compared with two other kinds of signal. Some properties of words and phenemes are considered, and unlike many artificial message bearing signals, speech cannot be considered as a simple sequence of independent message units. A speaker adjusts the amount of information in his speech to suit his listener, and the listener carries out an active reconstruction of the message from the information available to him. Turning to recognition by machine, the use of syntactic constraints is first discussed, followed by a look at three kinds of approach to the analysis and representation of speech for recognition purposes. A brief account of speech production is provided in order to explain the motivation for production based representations.