Methods and apparatus for performing speaker independent recognition of commands in parallel with speaker dependent recognition of names, words or phrases

Abstract

Methods and apparatus for activating telephone services in response to speech are described. A directory including names is maintained for each customer. A speaker dependent speech template and a telephone number for each name, is maintained as part of each customer's directory. Speaker independent speech templates are used for recognizing commands. The present invention has the advantage of permitting a customer to place a call by speaking a person's name which serves as a destination identifier without having to speak an additional command or steering word to place the call. This is achieved by treating the receipt of a spoken name in the absence of a command as an implicit command to place a call. Explicit speaker independent commands are used to invoke features or services other than call placement. Speaker independent and speaker dependent speech recognition are performed on a customer's speech in parallel. An arbiter is used to decide which function or service should be performed when an apparent conflict arises as a result of both the speaker dependent and speaker independent speech recognition step outputs. Stochastic grammars, word spotting and/or out-of-vocabulary rejection are used as part of the speech recognition process to provide a user friendly interface which permits the use of spontaneous speech. Voice verification is performed on a selective basis where security is of concern.

What is claimed is:  
     
       1. A method of providing a service in response to speech, comprising the steps of: 
       identifying the speaker;  
       performing in parallel,  
       i. a speaker independent speech recognition operation to identify a spoken command;  
       ii. a speaker dependent speech recognition operation in an attempt to identify a word; and performming an operation in response to the spoken command identified by performing the speaker independent speech recognition operation.  
     
     
       2. The method of  claim 1 , 
       wherein the spoken command is a command to dial a telephone number; and  
       wherein the step of performing an operation includes the step of:  
       dialing a telephone number associated with a word detected by performing the speaker dependent speech recognition operation.  
     
     
       3. The method of  claim 2 , wherein the word is a name, the method further comprising the steps of: 
       retrieving from a database, a plurality of speaker dependent speech templates associated with the identified speaker to be used when performing the speaker dependent speech recognition operation; and  
       retrieving from a data base, a telephone number associated with the name identified by performing the speaker dependent speech recognition operation.  
     
     
       4. The method of  claim 2 , further comprising the step of: 
       retrieving from a database, a plurality of speaker dependent speech templates associated with the identified speaker, to be used when performing the speaker dependent speech recognition operation.  
     
     
       5. The method of  claim 2 , further comprising the step of: 
       performing an arbitration operation to determine whether the output of the speaker independent speech recognition operation or the output of the speaker dependent speech recognition operation should be used when there is a conflict between the output of the two speech recognition operations.  
     
     
       6. A method of providing a telephone service in response to a caller's speech, the method comprising the steps of: 
       identifying the caller;  
       performing, in parallel,  
       i. a speech recognition operation on the speech to identify an explicit command in the speech;  
       ii. a speaker dependent speech recognition operation on the speech to identify a word, other than an explicit command, in the speech; and  
       performing an action as a function of the outcome of the speech recognition operations performed in parallel.  
     
     
       7. The method of  claim 6 , 
       wherein the word is a name; and  
       wherein the step of performing an action includes the step of:  
       dialing a telephone number associated with the name.  
     
     
       8. The method of  claim 6 , further comprising the steps of: 
       detecting a first speech time interval to which an identified explicit command corresponds:  
       detecting a second speech time interval to which an identified word corresponds; and  
       if there is a substantial overlap between the first and second time intervals, performing an arbitration operation to determine whether to respond to the detected command or to take some other action.  
     
     
       9. The method of  claim 8 , wherein a substantial overlap between the first and second time intervals exists when the first and second time intervals overlap by 50% or more. 
     
     
       10. A device for responding to speech, comprising: 
       means for performing speaker independent speech recognition on the speech to detect the presence of a spoken command in the speech;  
       means for performing speaker dependent speech recognition on the speech to detect a non-command word in the speech, the speaker independent and speaker dependent speech recognition means operating in parallel; and  
       a device for performing an action in response to the detection of a command by the speaker independent speech recognition means.  
     
     
       11. The device of  claim 10 , further comprising: 
       an arbiter coupled to the speaker independent and speaker dependent speech recognition means, the arbiter for determining the action to be taken in response to the detection of a spoken command by the speaker independent speech recognition means and a non-command word by the speaker dependent speech recognition means.  
     
     
       12. The device of  claim 11 , further comprising a voice verification circuit coupled to the arbiter for selectively performing voice verification on the speech. 
     
     
       13. The device of  claim 12 , further comprising: 
       a database coupled to the speaker dependent speech recognition means, the database including a plurality of speaker dependent speech recognition templates and telephone numbers, a telephone number being associated with each speaker dependent speech recognition template.  
     
     
       14. The device of  claim 13 , further comprising: 
       a telephone for receiving the speech from a caller;  
       a switch for coupling the telephone to the speaker independent and speaker dependent speech recognition means.  
     
     
       15. A method of providing a telephone service in response to speech of a caller, the method comprising the steps of: 
       
         performing a first speech recognition operation on the speech in an attempt to identify a name;  
       
       
         performing a second speech recognition operation on the speech in an attempt to identify an explicit command; and  
       
       
         upon detecting a name in said speech but failing to detect a command, dialing a telephone number associated with the detected name. 
       
     
     
       16. The method of  claim 15 , further comprising the steps of: 
       
         identifying the caller; and  
       
       
         accessing a database associated with the caller, the database including a plurality of names and telephone numbers, at least one telephone number being associated with each name. 
       
     
     
       17. The method of  claim 16 , wherein the second speech recognition operation is a speaker independent speech recognition operation. 
     
     
       18. The method of  claim 17 , wherein the first speech recognition operation is a speaker dependent speech recognition operation. 
     
     
       19. The method of  claim 18 , wherein the first and second speech recognition operations are performed in parallel. 
     
     
       20. The method of  claim 19 , further comprising the step of: 
       
         upon detecting the presence of a name and the presence of an explicit command, performing an arbitration step to determine whether to respond to the detected command or to dial a telephone number corresponding to the name whose presence was detected. 
       
     
     
       21. The method of  claim 19 , 
       
         wherein the database further includes a plurality of speech recognition templates for a plurality of names; and  
       
       
         wherein the step of performing the first speech recognition operation includes the step of using the plurality of speech recognitions templates to perform the first speech recognition operation. 
       
     
     
       22. A voice dialing system which is responsive to the speech of a system user, the system comprising: 
       
         means for performing a first speech recognition operation on the speech in an attempt to identify a name;  
       
       
         means for performing a second speech recognition operation on the speech in an attempt to identify an explicit command;  
       
       
         means for dialing a telephone number associated with a detected name, when a name is detected by said first speech recognition operation and a command is not detected by said second speech recognition operation. 
       
     
     
       23. The voice dialing system of  claim 22 , further comprising: 
       
         a database including a plurality of names and telephone numbers, at least one telephone number being associated with each name. 
       
     
     
       24. The voice dialing system of  claim 23 , wherein means for performing a first speech recognition operation and means for performing a second speech recognition operation are arranged in parallel with one another. 
     
     
       25. The voice dialing system of  claim 24 , wherein the means for performing a second speech recognition operation is a speaker independent speech recognizer. 
     
     
       26. The voice dialing system of  claim 25 , wherein the means for performing a first speech recognition operation is a speaker dependent speech recognizer.