A theory of desirable properties for preprocessors for speech recognizers

The design of preprocessors, or front-ends, for a speech recognition system is considered to be critical to the overall performance of the system. A design methodology, which is inspired by and, in some ways, formulated from the theory of time-frequency analysis, is presented. Examples of specific desirable properties for preprocessors are presented, and preliminary results supporting the need for a frequency transform are summarized. The authors propose eight properties for speech preprocessors. The last property, that of frequency analysis, was experimentally confirmed for single short segments of speaker-independent vowels. It is concluded that frequency transforms are needed for the simple case of speaker-independent vowel recognition