Method for adding phonetic descriptions to a speech recognition lexicon

1. A method for adding an acoustic description of a word to a speech recognition lexicon, the method comprising:

converting the text of the word into at least one orthographically derived acoustic description of the word;

generating a score for an orthographically derived acoustic description based in part on a comparison between the orthographically derived acoustic description and a speech signal representing a user's pronunciation of the word;

identifying a speech-based acoustic description of the word and a score for the speech-based acoustic description from the speech signal representing the user's pronunciation of the word, wherein the speech-based acoustic description is not associated with the text of the word; and

selecting one of the orthographically derived acoustic description and the speech-based acoustic description as the acoustic description of the word based on the score for the orthographically derived acoustic description and the score for the speech-based acoustic description.

2. The method of claim 1 wherein generating a score for an orthographically derived acoustic description comprises generating an acoustic model score.

3. The method of claim 2 wherein identifying a score for the speech-based acoustic description comprises generating an acoustic model score for at least one speech-based acoustic description and using the score as at least part of the score for the speech-based acoustic description.

4. The method of claim 3 wherein generating an acoustic model score for the orthographically derived acoustic description and generating an acoustic model score for at least one speech-based acoustic description comprises using the same acoustic model to generate both acoustic model scores.

5. The method of claim 3 wherein identifying a score for the speech-based acoustic description further comprises generating a language model score for the at least one speech-based acoustic description and using the language model score as part of the score for the at least one speech-based acoustic description.

6. The method of claim 5 wherein generating an acoustic model score and generating a language model score for at least one speech-based acoustic description comprises generating an acoustic model score and a language model score for a sequence of syllable-like units and wherein the speech-based acoustic description is derived from the sequence of syllable-like units.

7. The method of claim 6 wherein deriving the speech-based acoustic description from the sequence of syllable-like units comprises dividing the sequence of syllable-like units into a sequence of phonemes.

8. The method of claim 6 wherein generating a language model score comprises generating a language model score based on a trigram language model for syllable-like units.

9. The method of claim 6 wherein generating an acoustic model score for a sequence of syllable-like units comprises generating acoustic model scores for each of a sequence of phonemes that form the sequence of syllable-like units.

10. The method of claim 1 further comprising displaying a user interface comprising an edit box in which a user may enter the text of the word and a list box that displays words for which an acoustic description has been previously added to the speech recognition lexicon.

11. The method of claim 10 further comprising:

receiving an indication that a user has selected a word in the list box;

retrieving the added acoustic description of the word from the speech recognition lexicon; and

converting the retrieved acoustic description into an audible signal.

12. A computer-readable medium having computer-executable instructions for performing steps comprising:

receiving text of a word for which a phonetic description is to be added to a speech recognition lexicon;

receiving a representation of a speech signal produced by a person pronouncing the word;

converting the text of the word into a text-based phonetic description of the word;

generating a speech-based phonetic description of the word from the representation of the speech signal without using the text of the word; and

selecting a phonetic description of the word to add to the speech recognition lexicon by selecting between the text-based phonetic description and the speech-based phonetic description based in part on the correspondence between each phonetic description and the representation of the speech signal.

13. The computer-readable medium of claim 12 wherein generating a speech-based phonetic description comprises:

generating a plurality of possible phonetic descriptions;

using at least one model to score each possible phonetic description; and

selecting the possible phonetic description with the highest score as the speech-based phonetic description.

14. The computer-readable medium of claim 13 wherein using at least one model comprises using an acoustic model and a language model.

15. The computer-readable medium of claim 14 wherein using a language model comprises using a language model that is based on syllable-like units.

16. The computer-readable medium of claim 15 wherein each syllable-like unit comprises a sequence of phonemes and wherein using an acoustic model to score a possible phonetic description comprises generating acoustic model scores for each of the phonemes in a syllable-like unit and summing the acoustic model scores of the phonemes to generate an acoustic model score for the syllable-like unit.

17. The computer-readable medium of claim 12 wherein:

converting the text of the word into a text-based phonetic description further comprises generating a score for the text-based phonetic description based on the correspondence between the text-based phonetic description and the representation of the speech signal;

generating a speech-based phonetic description further comprises generating a score for the speech-based phonetic description based on the correspondence between the speech-based phonetic description and the representation of the speech signal; and

selecting between the text-based phonetic description and the speech-based phonetic description comprises selecting the phonetic description with the highest score.

18. The computer-readable medium of claim 12 wherein the steps further comprise:

receiving an instruction to generate an audible pronunciation of a phonetic description previously added to the speech recognition lexicon;

retrieving the added phonetic description from the speech recognition lexicon; and

causing an audible pronunciation to be generated based on the retrieved phonetic description.