05390278 is referenced by 114 patents and cites 10 patents.

A flexible vocabulary speech recognition system is provided for recognizing speech transmitted via the public switched telephone network. The flexible vocabulary recognition (FVR) system is a phoneme based system. The phonemes are modelled as hidden Markov models. The vocabulary is represented as concatenated phoneme models. The phoneme models are trained using Viterbi training enhanced by: substituting the covariance matrix of given phonemes by others, applying energy level thresholds and voiced, unvoiced, silence labelling constraints during Viterbi training. Specific vocabulary members, such as digits, are represented by allophone models. A* searching of the lexical network is facilitated by providing a reduced network which provides estimate scores used to evaluate the recognition path through the lexical network. Joint recognition and rejection of out-of-vocabulary words are provided by using both cepstrum and LSP parameter vectors.

Title
Phoneme based speech recognition
Application Number
7/772903
Publication Number
5390278
Application Date
October 8, 1991
Publication Date
February 14, 1995
Inventor
Christopher K Toulson
Dollard des Ormeaux
CA
Patrick J Kenny
Montreal
CA
Matthew Lennig
Montreal
CA
Vishwa N Gupta
Brossard
CA
Agent
Dallas F Smith
Assignee
Bell Canada
CA
IPC
G10L 5/04
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