Text independent speaker recognition for transparent command ambiguity resolution and continuous access control

• US 20020002465A1
• Filed: 04/12/2000
• Published: 01/03/2002
• Est. Priority Date: 02/02/1996
• Status: Active Grant

• Current Assignee: Nuance Communications, Inc. (Microsoft Corporation)
• Original Assignee: Stephane Herman Maes
• Inventors: Maes, Stephane Herman
• Granted Patent: US 6,477,500 B2
• Time in Patent Office: Days
• US Class Current: 704/275
• CPC Class Codes: G10L 15/065 Adaptation
• CPC Class Codes: G10L 17/04 Training, enrolment or model building
• CPC Class Codes: G10L 17/14 Use of phonemic categorisation or speech recognition prior to speaker recognition or verification

Abstract

Feature vectors representing each of a plurality of overlapping frames of an arbitrary, text independent speech signal are computed and compared to vector parameters and variances stored as codewords in one or more codebooks corresponding to each of one or more enrolled users to provide speaker dependent information for speech recognition and/or ambiguity resolution. Other information such as aliases and preferences of each enrolled user may also be enrolled and stored, for example, in a database. Correspondence of the feature vectors may be ranked by closeness of correspondence to a codeword entry and the number of frames corresponding to each codebook are accumulated or counted to identify a potential enrolled speaker. The differences between the parameters of the feature vectors and codewords in the codebooks can be used to identify a new speaker and an enrollment procedure can be initiated. Continuous authorization and access control can be carried out based on any utterance either by verification of the authorization of a speaker of a recognized command or comparison with authorized commands for the recognized speaker. Text independence also permits coherence checks to be carried out for commands to validate the recognition process.

Claims

1. A method of text independent speaker recognition comprising the steps of

sampling overlapping frames of a speech signal,

computing a feature vector for each said frame of said speech signal,

comparing each said feature vector with vector parameters and variances stored in a codebook corresponding to an enrolled speaker,

accumulating the number of frames for which the corresponding feature vector corresponds to vector parameters and variances in a codebook, and

identifying an enrolled speaker or detecting a new speaker in response to results of said accumulating step or said comparing step, respectively.

2. A method as recited in claim 1, including the further step of

initiating an enrollment procedure when a new speaker is detected.

3. A method as recited in claim 2, wherein said enrollment procedure includes the step of

presenting an enrollment menu.

4. A method as recited in claim 1, including the further steps of

recognizing a command or a plurality of commands, retrieving enrolled information corresponding to said speaker identified by said identifying step, and

interpreting said command in accordance with said enrolled information retrieved by said retrieving step.

5. A method as recited in claim 4 wherein a command of said plurality of commands is selected in accordance with said enrolled information retrieved by said retrieving step.

6. A method as recited in claim 4, wherein said command is carried out by a procedure which differs between enrolled speakers, said method including the further step of

selecting a procedure to carry out said command in accordance with said enrolled information retrieved by said retrieving step.

7. A method as recited in claim 4, wherein said enrolled information includes an alias.

8. A method as recited in claim 4, wherein said enrolled information includes a preference of said speaker identified by said identifying step.

9. A method as recited in claim 4, including the further step of providing feedback of a result of said interpreting step to said speaker.

10. A method as recited in claim 1, including the further step of verifying a speaker by:

performing consistency checks;

building a cohort of similar speakers; and

comparing the speaker counts to the cohort counts during the identification.

11. A method as recited in claim 4, including the further step of

verifying the speaker of said command recognized by said step of recognizing a command.

12. A method as recited in claim 4, including the further steps of

retrieving a command which is authorized for a speaker identified by said identifying step, and

comparing said command which is authorized for said speaker with said command recognized by said recognizing step.

13. A method as recited in claim 11, wherein said step of retrieving a command includes the step of accessing a look-up table in accordance with said speaker identified by said identifying step.

14. A method as recited in claim 1, including the further step of

checking coherence of said command recognized by said recognizing step.

16. Apparatus as recited in claim 14, further comprising

means for recognizing a command or a plurality of commands,

means for retrieving enrolled information corresponding to said speaker identified by said identifying step, and

means for interpreting said command in response to said means for retrieving said enrolled information.

17. Apparatus as recited in claim 14, further including

means for recognizing a command or a plurality of commands,

means for retrieving enrolled information corresponding to said speaker identified by said means for identifying a speaker, and

means for interpreting said command responsive to said enrolled information retrieved by said means for retrieving enrolled information.

18. Apparatus as recited in claim 16, wherein a command of said plurality of commands is selected in accordance with said enrolled information.

19. Apparatus as recited in claim 16, wherein said command is carried out by a procedure which differs between enrolled speakers, said apparatus further including

means for selecting a procedure to carry out said command in accordance with said enrolled information.

20. Apparatus as recited in claim 16, further including

means for verifying the speaker of said command.

21. Apparatus as recited in claim 16, further including

means for performing checking coherence of said command.

15. Apparatus including a speech recognition system and a text independent speaker recognition system, said text independent speaker recognition system comprising

means for sampling overlapping frames of a speech signal,

means for computing a feature vector for each said frame of said speech signal,

means for comparing each said feature vector with vector parameters and variances stored in a codebook corresponding to an enrolled speaker, and

means for accumulating the number of frames for which the corresponding feature vector corresponds to vector parameters and variances in a codebook corresponding to an enrolled speaker.