System and method for spelling recognition using speech and non-speech input

1. A system for recognizing a combination of speech and alternate input, the method comprising:

a processor;

a first module configured to control the processor to generate an unweighted grammar permitting all letter sequences that map to a received non-speech input;

a second module configured to control the processor to select a database of words;

a third module configured to control the processor to generate a weighted grammar using the unweighted grammar and a statistical letter model trained on the database of words;

a fourth module configured to control the processor to receive speech from a user associated with the non-speech input after receiving the non-speech input and after generating the weighted grammar; and

a fifth module configured to control the processor to process the received speech and non-speech input using the weighted grammar.

2. The system of claim 1 , wherein the database of words is a domain of words related to the non-speech input.

3. The system of claim 1 , further comprising a sixth module configured to control the processor to perform speech recognition based on the received speech and non-speech input using the weighted grammar.

4. The system of claim 1 , wherein the statistical letter model is an N-gram letter model.

5. The system of claim 4 , wherein the N-gram letter model is unsmoothed.

6. The system of claim 1 , further comprising a sixth module configured to control the processor to generate a final letter string based on a database lookup.

7. The system of claim 1 , wherein the non-speech input comprises a portion of a word.

8. A method of recognizing input from a user, the method comprising:

receiving a first input from a user;

performing spelling recognition via an automatic speech recognition system on the first input, the speech recognition being performed using a statistical letter model trained on a database of words;

generating a letter lattice based on the first input; and

performing, with each second input received from the user after the first input, until a letter string is correctly recognized:

constraining the letter lattice based on the each sound input to yield a constrained letter lattice; and

generating a new letter string of possible word spellings based on the constrained letter lattice.

9. The method of claim 8 , wherein constraining the letter lattice further comprises locating the most probably path through the lattice.

10. The method of claim 8 , wherein the first input comprises input from one of a speech input device and a non-speech input device.

11. The method of claim 8 , wherein the statistical letter model is an N-gram letter model.

12. The method of claim 11 , wherein the statistical letter model is unsmoothed.

13. The method of claim 8 , further comprising generating a final letter string based on a database lookup.

14. The method of claim 13 , wherein generating the final letter string based on a database lookup further comprises using a finite state network that accepts only valid letter strings.

15. The method of claim 13 , wherein receiving input comprises receiving a portion of a word.

16. The method of claim 8 , further comprising, if an automated speech recognition confidence is below a predetermined level, prompting the user to enter the first three or less letters of the input by using a keypad.

17. A computer-readable storage medium storing instructions for controlling a computing device having a processor to recognize input from a user, the instructions comprising controlling the processor to perform steps comprising:

generating an unweighted grammar permitting all letter sequences that map to a received non-speech input;

selecting a database of words;

generating a weighted grammar using the unweighted grammar and a statistical letter model trained on the database of words;

receiving speech from a user associated with the non-speech input after receiving the non-speech input and after generating the weighted grammar;

performing recognition via automatic speech recognition (ASR) on the received speech and non-speech input using the weighted grammar; and

if an automated speech recognition confidence is below a predetermined level:

disambiguating possible spellings by generating a letter lattice based on a user input modality; and

constraining the letter lattice and generating a new letter string of possible word spellings, with each portion of the speech received from the user, until a letter string is correctly recognized.

18. The computer-readable storage medium of claim 17 , wherein the user input modality comprises speech input devices and non-speech input devices.

19. The computer-readable storage medium of claim 17 , wherein the statistical letter model is an N-gram letter model.

20. The computer-readable storage medium of claim 19 , wherein the statistical letter model is unsmoothed.