Abstract:
A method and system for use with a computer speech recognition system to efficiently identify valid system commands to users. The method involves a series of steps including: receiving data representative of a speech recognition system user input; comparing the data to a grammar defined for the speech recognition system to determine whether the data is representative of a user input which is a valid system command; and notifying the user as to whether the data is representative of a valid system command. The process can also involve the additional steps of determining a functional expression for the data; and comparing the functional expression to a set of all functional expressions permitted in the grammar to identify any alternate user inputs for producing the functional expression.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not Applicable  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable  
         BACKGROUND OF THE INVENTION  
         [0003]    1. Technical Field  
           [0004]    This invention relates to the field of computer speech recognition and more particularly to a method and system for informing a system user of available and alternative speech commands.  
           [0005]    2. Description of the Related Art  
           [0006]    Speech recognition is the process by which an acoustic signal received by microphone is converted to a set of text words by a computer. These recognized words may then be used in a variety of computer software applications for purposes such as document preparation, data entry and command and control. Speech recognition is generally a difficult problem due to the wide variety pronunciations, individual accents and speech characteristics of individual speakers.  
           [0007]    One of the difficult aspects of speech recognition systems relates to a user&#39;s ability to navigate through the speech-enabled application using various commands and controls. In the simplest possible command and control grammar, each function that the system can perform has no more than one speech phrase associated with it. At the other extreme is a command and control system based on natural language understanding (NLU). In an NLU system, the user can express commands using natural language, thereby providing total linguistic flexibility in command expression. Current command and control systems are moving beyond the simple one function—one speech phrase grammar, but will not achieve NLU in the foreseeable future.  
           [0008]    For systems that approach but do not achieve the flexibility of NLU, it is possible that a user may wish to gain a better understanding of the speech commands which are available. For example, it is possible that a given user may want to know whether a particular speech command will be recognized. Alternatively, a user who knows one way of issuing a speech command might want to know the other ways that he or she could issue speech commands to achieve the same system function or operation. This desire might come from simple curiosity, or might arise from a desire to determine a more efficient speech command or a desire to try out speech commands that have a better recognition accuracy for that user than the speech command that he or she has been using.  
           [0009]    Conventional speech recognition systems offer various means to present the user with a list of all valid speech commands, typically filtered in some way to facilitate a search for a particular command. This approach works reasonably well given fairly simple command and control grammars. However, as command and control grammars begin to approach NLU, the number of available ways to state commands increases to the point of making such approaches cumbersome. Thus, there has arisen a need to provide more effective systems and methods for informing a system user of available and alternative speech commands.  
         SUMMARY OF THE INVENTION  
         [0010]    The invention concerns a method and system for efficiently identifying valid system command in a speech recognition system. The method of the invention involves a plurality of steps including: receiving data representative of a speech recognition system user input; comparing the data to a grammar defined for the speech recognition system to determine whether the data is representative of a user input which is a valid system command; and notifying the user as to whether the data is representative of a valid system command. Further, the method can include the additional steps of: determining a functional expression for the data; and comparing the functional expression to a set of all functional expressions permitted in the grammar to identify any alternate user inputs for producing the functional expression.  
           [0011]    According to one aspect of the invention, the process can include notifying the user of the alternate user inputs for producing the functional expression and listing the alternate user inputs in sequence based upon a criteria. For example, the criteria can be the order in which the alternate user inputs were identified in the search, alphabetical order, length, recognition accuracy, and a user preference. In the case where there are not other alternative user inputs, the method can include the step of notifying the user that there exist no alternate user inputs for producing the functional expression. Although the method can employ any suitable programming for searching out alternative user inputs to achieve the same functional result, one advantageous method for accomplishing this result is by searching a set of translation rules to identify the functional expression and the alternate user inputs.  
           [0012]    According to a second aspect, the invention can be a computer speech recognition system for efficiently identifying valid system commands to users. In that case, the system includes interface programming for receiving data representative of a speech recognition system user input; processor programming for comparing the data to a grammar defined for the speech recognition system to determine whether the data is representative of a user input which is a valid system command; and display programming for notifying the user as to whether the data is representative of a valid system command. The system also preferably includes function determining programming for determining a functional expression for the data; and function comparison programming for comparing the functional expression to a set of all functional expressions permitted in the grammar to identify any alternate user inputs for producing the functional expression. The function determining programming can preferably include programming for searching a set of translation rules to identify the functional expression and the alternate user inputs.  
           [0013]    Similar to the previously described method, the system display programming further comprises programming for notifying the user of the alternate user inputs for producing the functional expression and programming for listing the alternate user inputs in sequence based upon criteria selected from the group consisting of: the order in which they were identified in the search, alphabetical order, length, recognition accuracy, and a user preference. Finally, the system display programming can further include programming for notifying the user that there exist no alternate user inputs for producing the functional expression.  
           [0014]    According to a third aspect, the invention may comprise a machine readable storage, having stored thereon a computer program having a plurality of code sections executable by a machine for causing the machine to perform a series of steps. These steps can include: receiving data representative of a speech recognition system user input; comparing the data to a grammar defined for the speech recognition system to determine whether the data is representative of a user input which is a valid system command; and notifying the user as to whether the data is representative of a valid system command. The machine readable storage may cause the machine to perform additional steps such as determining a functional expression for the data; and comparing the functional expression to a set of all functional expressions permitted in the grammar to identify any alternate user inputs for producing the functional expression. The machine readable storage can also be programmed for causing the machine to perform the further step of notifying the user of the alternate user inputs for producing the functional expression. As previously described relative to the method and system of the invention, the machine readable storage can similarly be arranged for causing the machine to perform the further step of listing alternate user inputs in sequence based upon specified criteria.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    There are presently shown in the drawings embodiments which are presently preferred, it being understood, however, that the invention is not so limited to the precise arrangements and instrumentalities shown, wherein:  
         [0016]    [0016]FIG. 1 shows a computer system for speech recognition on which the system of the invention can be used.  
         [0017]    [0017]FIG. 2 is a block diagram showing a typical high level architecture for the computer system in FIG. 1.  
         [0018]    [0018]FIG. 3 is a block diagram showing a typical architecture for a speech recognition engine.  
         [0019]    [0019]FIG. 4 is a flow chart illustrating a process for informing a speech recognition system user of available and alternative speech commands.  
         [0020]    [0020]FIGS. 5A and B show a dialog box for informing a speech recognition system user whether a speech command is available.  
         [0021]    [0021]FIG. 6 shows a dialog box for informing a speech recognition system user of alternative command phrases which are available.  
         [0022]    [0022]FIG. 7 is an example of a set of translation rules.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    [0023]FIG. 1 shows a typical computer system  20  for use in conjunction with the present invention. The system is preferably comprised of a computer  34  including a central processing unit (CPU), one or more memory devices and associated circuitry. The system also includes a microphone  30  operatively connected to the computer system through suitable interface circuitry or a “sound board” (not shown), and at least one user interface display unit  32  such as a video data terminal (VDT) operatively connected thereto. The CPU can be comprised of any suitable microprocessor or other electronic processing unit, as is well known to those skilled in the art. An example of such a CPU would include the Pentium or Pentium II brand microprocessor available from Intel Corporation or any similar microprocessor. Speakers  23 , as well as an interface device, such as mouse  21 , can also be provided with the system, but are not necessary for operation of the invention as described herein.  
         [0024]    The various hardware requirements for the computer system as described herein can generally be satisfied by any one of many commercially available high speed multimedia personal computers offered by manufacturers such as International Business Machines Corporation (IBM), Compaq, Hewlett Packard, or Apple Computers.  
         [0025]    [0025]FIG. 2 illustrates a typical architecture for a speech recognition system in computer  20 . As shown in FIG. 2, the system typically includes an operating system  24  and a speech recognition engine application  26 . In the example shown, a speech text processor application  28  and a voice navigator application  22  are also provided. However the invention is not limited in this regard and the speech recognition engine application  26  can be used with any other application program which is to be voice enabled. In FIG. 2, the speech recognition engine  26 , speech text processor  28  and the voice navigator  22  are shown as separate application programs. It should be noted however that the invention is not limited in this regard, and these various application programs could be implemented as a single, more complex applications program. For example the speech recognition application  26  could be combined with the speech text processor application or with any other application to be used in conjunction with the speech recognition application. Also, if no other speech controlled application programs are to be operated in conjunction with the speech text processor application and speech recognition engine, then the system can be modified to operate without the voice navigator application. The voice navigator primarily helps coordinate the operation of the speech recognition engine application.  
         [0026]    In a preferred embodiment which shall be discussed herein, operating system  24  is one of the Windows family of operating systems, such as Windows NT, Windows 95 or Windows 98 which are available from Microsoft Corporation of Redmond, Wash. However, the system is not limited in this regard, and the invention can also be used with any other type of computer operating system. The system as disclosed herein can be implemented by a programmer, using commercially available development tools for the operating systems described above. As shown in FIG. 2, computer system  20  includes a computer memory device  27 , which is preferably comprised of an electronic random access memory and a bulk data storage medium, such as a magnetic disk drive.  
         [0027]    Audio signals representative of sound received in microphone  30  are processed within computer  20  using conventional computer audio circuitry so as to be made available to the operating system  24  in digitized form. The audio signals received by the computer are conventionally provided to the speech recognition engine application  26  via the computer operating system  24  in order to perform speech recognition functions. As in conventional speech recognition systems, the audio signals are processed by the speech recognition engine  26  to identify words spoken by a user into microphone  30 .  
         [0028]    [0028]FIG. 3 is a block diagram showing typical components which comprise speech recognition application  26 . As shown in FIG. 3 the speech recognition engine  26  receives a digitized speech signal from the operating system. The signal is subsequently transformed in representation block  34  into a useful set of data by sampling the signal at some fixed rate, typically every 10-20 msec. The representation block produces a new representation of the audio signal which can then be used in subsequent stages of the voice recognition process to determine the probability that the portion of waveform just analyzed corresponds to a particular phonetic event. This process is intended to emphasize perceptually important speaker independent features of the speech signals received from the operating system. In modeling/classification block  36 , algorithms process the speech signals further to adapt speaker-independent acoustic models to those of the current speaker. Finally, in search block  38 , search algorithms are used to guide the search engine to the most likely words corresponding to the speech signal. The search process in search block  38  occurs with the help of acoustic models  40 , lexical models  42  and language models  44 .  
         [0029]    [0029]FIG. 4 is a flow chart illustrating a method for permitting a user to discover available and alternative speech commands. As shown in FIG. 4A, the speech recognition engine application  26  monitors user inputs in step  48 . These user inputs can include navigator commands, commands or dictation inputs directed to an associated speech enabled application program, and command directed to the speech recognition application engine application  26 . The user inputs are preferably speech commands, but can also be in the form of control signals received via the operating system  24  from a pointing device such as a mouse or a keyboard. In step  50 , the system determines whether it has received a user input inquiring as to whether a particular command is valid. In step  50 , the command for this purpose is shown as “Can I say this?” However, the invention is not limited in this regard and it will be understood by those skilled in the art that any other appropriate command utterance can be used for this purpose. Similarly, the “Can I say this?” command can also be made available to the user by an on-screen icon or menu command which has the same effect as the speech command.  
         [0030]    If the speech recognition system receives the proper command in step  50 , it proceeds to step  52  to display the “Can I say this?” dialog box. An example of such a dialog box  86  is illustrated in FIGS. 5A and 5B. As shown therein, the dialog box  86  preferably consists of a set of instructions  81 , a data entry field  88  in which phrases that are spoken or typed by a user can be entered when the dialog box  86  is open, and a status area  83  showing whether the given phrase is or is not in the active command grammar.  
         [0031]    As shown in FIG. 4B, the system monitors user inputs in step  62 . These inputs, which can be in the form of keyboard entries or words spoken by a user, are inserted in step  64  into the data entry field  88 . These words or phrases are then compared in step  66  to valid command phrases and/or formats stored in memory. In step  68 , a determination is made as to whether the phrase or text in the data entry field  88  is valid system command. If so, then the user is notified in step  70  that the command is in the current command grammar. As shown in FIGS.  5 A, the status area  83  is preferably used for this purpose by displaying the word “Yes”. If the phrase or text is found not to be a valid system command, then the user is notified in step  72  that the command is not in the current command grammar, preferably by displaying the word “No” in the status area  83 . In this way, a user can determine whether a phrase they plan to say, or have been saying with unsuccessful results, is in or out of the current command grammar.  
         [0032]    The foregoing process is useful in a speech recognition system in which the number of active command phrases causes search through a conventional list of possible commands to be impractical and inconvenient. The system is also useful for helping a user to determine if the failure of the speech system to recognize a particular phrase is due to the phrase not being in the active grammar or must be due to some other cause.  
         [0033]    In addition to the need to help users determine whether a particular phrase is a valid command, recent developments have also demonstrated the need for a system which also helps users identify alternative commands given a known valid command. In particular, speech systems are developing such that they are approaching but do not quite have natural language understanding. This means that a wide variety of commands might be acceptable for achieving a particular result. However, certain commands may be more or less efficient than others. Also, a particular user&#39;s pronunciations for certain commands may be more readily understood by the speech recognition system than others. Accordingly, step  54  in FIG. 4A preferably monitors system inputs for a spoken command or its equivalent mouse or keyboard input to determine if the system has received a command associated with the “How else can I say this?” dialog box. If such a command is received, the system proceeds in step  56  to open the “How can I say this?” dialog box  90  which is shown in FIG. 6.  
         [0034]    The “How else can I say this?” dialog box preferably includes a set of instructions  92 , a data entry field  94  in which phrases that are spoken or typed by a user can be entered when the dialog box  90  is open, and an alternate command list area  96 . Of course, the invention is not limited in this regard and any equivalent arrangement of information will also be acceptable.  
         [0035]    After opening the “How else can I say this?” dialog box in step  56 , the system proceeds in step  74  to monitor user inputs from the keyboard or speech. In. step  76 , any such user inputs are inserted into the data entry field  94 . In a preferred embodiment, the cue to the system to begin the search for alternates would be a 300 to 500 millisecond pause in the dictation or typing of the input phrase. The resumption of typing or dictation would trigger another search after a similar pause. An alternate way to achieve this would be to have a search button included in the dialog box. However, searching on pause requires less effort from the user.  
         [0036]    In step  77 , the system makes an initial determination as to whether the input phrase exists in the active grammar. If not then it preferably notifies the user of this fact by displaying a suitable message in the alternate list area  96  such as “ 21  Not in grammar&gt;.” If the phrase does exist in the active command grammar, then the system proceeds to step  79  as shown.  
         [0037]    In step  79 , the system compares the text in the data entry field  94  to the command phrases and/or functions stored in memory to identify any equivalent alternate commands. It will be appreciated by those skilled in the art that the precise mechanism for identifying the alternate phrases can vary from system to system. One approach involves the use of translation or rewrite rules such as the set given by way of example in FIG. 7. With the code shown in FIG. 7, if a user said “Move to the top of the next section”, the translation rule would be move(nextsection, top). If a user said “Jump to the beginning of the next section, the translation rule produced would also be move(nextsection, top). If a user said something with a different meaning, however, then the translation rule produced would be different. For example, “Move to the bottom of the last page” would produce move(lastpage, bottom). FIG. 7 is one example of a set of translation rules and it will be recognized by those skilled in the art that many different translation rules are possible for use with different commands and formats, all such rules being within the scope of the invention.  
         [0038]    The translation rules provide a way to unambiguously identify phrases that have the same functional consequences—they identify the alternate ways to say something in a given grammar. All that is required to find the alternates is to search through the translation rules produced by the grammar, then present the alternates to the user as previously described.  
         [0039]    For systems that do not support translation rules, different methods of producing the function expressed in the natural commands phrase would be required. For example, a parsing program can be used for this purpose. It will be readily appreciated by those skilled in the art that any method suitable procedure can be used to accomplish the foregoing result provided that it is capable of taking a given phrase, determining its functional expression or result and searching the set of all functional expressions permitted in the grammar to identify the alternate speech phrases that could produce that functional expression.  
         [0040]    In step  80  the system makes a determination as to whether any alternate commands are identified. If so, these alternate commands are presented to the user in step  84 . In a preferred embodiment, the alternate commands are displayed in the alternates list  96  shown in FIG. 6. If no alternate commands exist in the active command grammar, then the system notifies the user in step  82  that there are no alternate commands. This can be accomplished by any suitable means such as by displaying the message “&lt;no alternates for this phrase&gt;”.  
         [0041]    While the foregoing specification illustrates and describes the preferred embodiments of this invention, it is to be understood that the invention is not limited to the precise construction herein disclosed. The invention can be embodied in other specific forms without departing from the spirit or essential attributes. Accordingly, reference should be made to the following claims, rather than to the foregoing specification, as indicating the scope of the invention.