Position-dependent phonetic models for reliable pronunciation identification

1. A method comprising:

receiving a representation of a speech signal;

a processor decoding the representation of the speech signal into a sequence of words using a word language model and an acoustic model;

a processor converting each word in the sequence of words into a sequence of position-dependent phonetic tokens using a phonetic token lexicon, which provides a position-dependent phonetic token description of each word in a lexicon, wherein each position-dependent phonetic token comprises a phone and a position indicator that indicates the position of the phone within a syllable; and

a processor determining probabilities for sub-sequences in the sequences of position-dependent phonetic tokens by applying sub-sequences of position-dependent phonetic tokens converted from the sequence of words to a position-dependent phonetic language model that describes probabilities of sequences of position-dependent phonetic tokens comprising a conditional probability of a position-dependent phonetic token given at least two preceding position-dependent phonetic tokens and probabilities of individual position-dependent phonetic tokens.

2. The method of claim 1 further comprising utilizing the at least one probability as a confidence measure.

3. The method of claim 1 wherein at least one position indicator indicates one of a group of syllable positions consisting of onset consonant, and coda consonant.

4. A hardware computer storage medium encoded with a computer program, causing the computer to execute steps comprising:

decoding a representation of a speech signal using a position-dependent phonetic language model that provides probabilities of sequences of position-dependent phonetic tokens wherein each position-dependent phonetic token comprises a phone and a position identifier that identifies a position within a syllable, wherein decoding produces at least one sequence of position-dependent phonetic tokens;

receiving a symbol represented by a portion of the speech signal, wherein the symbol is not part of the language of a lexicon; and

annotating a lexicon by storing a sequence of position-dependent phonetic tokens as a pronunciation for the symbol that is not part of the language of the lexicon, wherein annotating the lexicon further comprises identifying syllable boundaries from the position-dependent phonetic tokens and placing syllable boundaries in the lexicon.

5. The hardware computer storage medium of claim 4 wherein a position identifier is one of a group of position identifiers consisting of onset consonant and coda consonant.