Patent ID: 7624015

Claim:
A system, comprising: a speech recognition processor that receives unconstrained input speech and outputs a string of words, the speech recognition processor being based on a numeric language that represents a subset of a vocabulary, the subset including a set of words identified as being relevant for interpreting and understanding number strings; a numeric understanding processor containing classes of rules for converting the string of words into a sequence of digits; an acoustic model database utilized by the speech recognition processor, the acoustic model database organized with two sets of subword units, a first set of hidden Markov models that characterize acoustic features of numeric words and a second set that characterizes acoustic features of remaining vocabulary words in the acoustic model database, and when each word in the first set is modeled by three segments comprising a head, a body and a tail, and wherein each word has one body and a plurality of heads and tails, and wherein the three segment structure only applies to single digit words; a validation database that stores a set of valid sequences of digits; and a string validation processor that outputs validity information based on a comparison of a sequence of digits output by the numeric understanding processor with valid sequences of digits in the validation database.