| 摘要 |
In speech recognition words to be recognized may be represented by finite state machines and recognition is based on analyzing transitions through the machines as an utterance occurs. One value which is then required for each state of each machine in a timescale which is compatible with continuous speech recognition is minimum cumulative distance; that is the smallest of values dependent on reaching one of the states from a starting position, considering all possible paths. In the present invention a specially constructed Viterbi engine is provided for calculating cumulative distances at high speed. Latch circuits holding pointers allow a RAM to be read to provide, for a current machine state, both stored cumulative distances of states with transitions to that state and stored penalties corresponding to the transitions. A logic circuit comprising an ALU finds the cumulative distance for each path as far as the current state, selectes the minimum and adds another penalty dependent on the current state. Thus a minimum cumulative distance is provided for storage and for a speech recognition decision making circuit. The process is repeatedly carried out for each state of each machine. The total number of iterations of the engine in reaching each minimum cumulative distance is also held in the RAM and updated by the logic circuit. |
