Abstract:
A voice recognition system has a recognition dictionary storing voice information, a primary voice recognition means for performing primary voice recognition in response to input voice information pronounced by a user by the use of the recognition dictionary, and a recognition result judging means for deciding whether the primary voice recognition result is to be accepted or rejected. The voice recognition system includes a transceiver means for sending the input voice information of the user to an additional voice recognition means when the primary voice recognition result is rejected by the recognition result decision means and for receiving a secondary voice recognition result produced as a result of secondary voice recognition of the additional voice recognition means, and a recognition result output means for outputting the primary or secondary voice recognition result to an exterior of the voice recognition system. The voice recognition system also includes a settled result input means for receiving settlement information on the primary or secondary voice recognition result and a dictionary content control means for updating said recognition dictionary based on the settlement information.

Description:
[0001]     This application claims priority to prior Japanese patent application JP 2005-217534, the disclosure of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a voice recognition system and method, and more particularly to a server-client voice recognition system and method. The present invention also relates to a computer-readable storage medium having a program recorded thereon for voice recognition. The present invention is applicable to a voice input interface such as a cellular phone or a personal digital assistant.  
         [0004]     2. Description of the Related Art  
         [0005]      FIG. 1  is a schematic diagram showing an example of a conventional server-client voice recognition system that has a client terminal device and a server device. In the conventional server-client voice recognition system, the client terminal device processes voice recognition of a relatively light load while the server device processes voice recognition of a comparatively heavy load. Specifically, as shown in  FIG. 1 , the conventional server-client voice recognition system has a client terminal device  310  and a server device  320 , which are connected to each other via a communication network  330 .  
         [0006]     The client terminal device  310  includes a voice input unit  311  for inputting a user&#39;s voice, a voice pre-processing unit  312  for performing pre-processing, such as a waveform analysis of an input voice data, and a selector unit  313  for selecting whether subsequent content recognition of pre-processed voice data is to be carried out either in an internal process (in the client terminal device  310 ) or an external process (in the server device  320 ). The client terminal device  310  also includes a primary voice recognition unit  314  and a primary recognition dictionary  315  for the internal content recognition process, a communication unit  316  for communicating with the server device  320 , and a recognition result output unit  317  for sending a result of voice recognition outside the system.  
         [0007]     The server device  320  includes a communication unit  321  for communicating with the client terminal device  310 , a secondary voice recognition unit  322 , and a secondary recognition dictionary  323 . The secondary voice recognition unit  322  and the secondary recognition dictionary  323  are used for the external voice recognition process. For example, this type of a voice recognition system has been disclosed in Japanese Unexamined Patent Publications Nos. 2003-241796 and 2004-133699.  
         [0008]     In such a conventional voice recognition system, the client terminal device  310  and the server device  320  operate as follows.  
         [0009]     Specifically, when voice data is inputted into the voice input unit  311  of the client terminal device  310 , the voice pre-processing unit  312  carries out pre-processing of the voice data, such as a sound waveform analysis of the input voice data and the like. The selector unit  313  operates in response to the result of the sound waveform analysis and selects whether recognition of contents in the input voice data is to be carried out either in the primary voice recognition unit  314  in the client terminal device  310  or the secondary voice recognition unit  322  in the server device  320 .  
         [0010]     If the selector unit  313  selects the primary voice recognition unit  314 , the primary voice recognition unit  314  performs voice recognition of the voice data by the use of the primary recognition dictionary  315  and sends a recognition result to the recognition result output unit  317 . If the selector unit  313  selects the secondary voice recognition unit  322 , the pre-processed voice data is sent from the communication unit  316  in the client terminal device  310  to the server device  320  via the communication network  330 . When the pre-processed voice data is received from the client terminal device  310  by the communication unit  321  in the server device  320 , the secondary voice recognition unit  322  immediately is operated to perform voice recognition of the received voice data by the use of the secondary recognition dictionary  323 . The communication unit  321  returns a voice recognition result to the client terminal device  310  via the communication network  330 . When the communication unit  316  in the client terminal device  310  receives the voice recognition result, the recognition result output unit  317  supplies the result to the user.  
         [0011]     However, in the conventional voice recognition system, the primary recognition dictionary  315  in the client terminal device  310  has a small capacity in order to alleviate an amount of processes required for voice recognition. Accordingly, the client terminal device  310  has a very limited vocabulary for recognition. This often makes recognition of users&#39; voices difficult in dependency upon words in the conventional voice recognition system.  
         [0012]     In such a case, consideration might be made about a way to successively add unrecognized words by each user to the primary recognition dictionary  315  in the client terminal device  310 . However, such a way to add unrecognized words to the primary recognition dictionary  315  imposes a severe burden on the user and results in an increase of an amount of calculation in the client side. This brings about various problems, such as a delay, during the voice recognition process.  
         [0013]     Furthermore, in the conventional example, when the client terminal device  310  receives a result of voice recognition from the server device  320 , such a result is solely delivered to a user and is not accumulated in the client terminal device  310 . Accordingly, the conventional voice recognition system is inconvenient in that it cannot satisfy user&#39;s needs of getting frequently-used words (vocabulary) or recently-used words.  
       SUMMARY OF THE INVENTION  
       [0014]     The present invention has been made in view of the above drawbacks. It is, therefore, an object of the present invention to provide a voice recognition system, a voice recognition method, and a computer-readable storage medium having a program recorded thereon for voice recognition which can provide a word that meets user&#39;s needs effectively to the user, for example, even if a client terminal device has a small processing capability.  
         [0015]     According to a first aspect of the present invention, there is provided a voice recognition system which can provide a word that meets user&#39;s needs effectively to the user. The voice recognition system has a recognition dictionary storing voice information, a primary voice recognition means for performing a primary voice recognition on input voice information of a user based on the recognition dictionary to produce a primary voice recognition result of the input voice information, and a recognition result decision means for judging a reliability of the primary voice recognition result produced by the primary voice recognition means and for deciding whether to accept or reject the primary voice recognition result. The voice recognition system includes a transceiver means for sending the input voice information of the user to an additional voice recognition means when the primary voice recognition result is rejected by the recognition result decision means and for receiving a secondary voice recognition result produced by a voice recognition function of the additional voice recognition means, and a recognition result output means for outputting the primary voice recognition result outputted from the recognition result decision means or the secondary voice recognition result received by the transceiver means to an exterior of the voice recognition system.  
         [0016]     The voice recognition system also includes a settled result input means for receiving settlement information on the primary voice recognition result or the secondary voice recognition result outputted to the exterior of the voice recognition system, and a dictionary content control means for updating the recognition dictionary based on the settlement information inputted by the settled result input means.  
         [0017]     According to the present invention, even if the primary voice recognition means has a small processing capability, the dictionary content control means continuously updates the recognition dictionary with a settled recognition result. Therefore, the voice recognition system can provide a recognized word that matches the user&#39;s request. Further, even if the user says or pronounces a word that is not registered in the recognition dictionary, a recognition result (secondary voice recognition result) can readily be obtained by the voice recognition function of the additional voice recognition means, in addition to the primary recognition result of the primary voice recognition means. Thus, even if the primary voice recognition means has a small processing capability, a word that is not registered in the recognition dictionary can be recognized by the voice recognition system. Furthermore, a word or a set of words that have been recognized in the server device can automatically be added to the recognition dictionary by the dictionary content control means. Therefore, it is possible to lighten a load imposed on a user when the recognition dictionary is customized for the user.  
         [0018]     According to a second aspect of the present invention, the above decision to accept or reject the primary recognition result depends on an external decision system. Specifically, the recognition result judgment means has a recognition result presentation means for presenting the primary voice recognition result produced by the primary voice recognition means to an external decision system, and a decision result input means for receiving a decision result to accept or reject the primary voice recognition result from the external decision system.  
         [0019]     This arrangement also has equivalent functions to the functions described in the first aspect of the present invention. Additionally, when a decision result (command) is issued by the external decision system (e.g., a user), the decision result is employed as decision information on the primary recognition result. Accordingly, the user can determine whether to update the recognition dictionary. Thus, it is possible to generate a recognition dictionary having a high processing efficiency for voice recognition to ensure enhanced reliability of processing voice information.  
         [0020]     The primary voice recognition means may include a voice pre-processing unit operable to analyze the input voice information so as to extract a feature thereof, and a primary voice recognition unit operable to output the primary voice recognition result based on the feature extracted by the voice pre-processing unit. In this case, the primary voice recognition of the input voice information can promptly be completed by the primary voice recognition means. Further, the secondary voice recognition can also be performed with high accuracy.  
         [0021]     Further, the dictionary content control means may be configured to delete a word based on at least one of order of past settlement information and a frequency of the past settlement information when a size of the words in the recognition dictionary exceeds a processing capability of the voice recognition system. In this case, even if the recognition dictionary has a small capacity and the primary voice recognition means has a small processing capability, the primary recognition result can promptly be outputted for the user&#39;s preference. Further, since a user&#39;s past history of use is used as information for the recognition dictionary, which is used to obtain the primary recognition result, it is possible to obtain information suitable for the user&#39;s preference.  
         [0022]     Furthermore, the dictionary content control means may be configured to send update information to the additional voice recognition means when the recognition dictionary is to be updated. In this case, the additional voice recognition means can have a recognition dictionary including the contents of the recognition dictionary used by the primary voice recognition means. Accordingly, the voice recognition can be performed promptly.  
         [0023]     The additional voice recognition means may be configured by a server device having a voice recognition function. The server device may be communicable with the transceiver means via a communication network.  
         [0024]     According to a third aspect of the present invention, there is provided a voice recognition method which can provide a word that meets user&#39;s needs effectively to the user. In this method, a voice information of a user is inputted, and a primary voice recognition of the voice information is performed based on a recognition dictionary storing voice information to produce a primary voice recognition result of the input voice information. A reliability of the primary voice recognition result is judged, and it is decided whether to accept or reject the primary voice recognition result. The input voice information of the user is sent to an additional voice recognition means when the primary voice recognition result is rejected. A secondary voice recognition result is produced by a voice recognition function or secondary voice recognition of the additional voice recognition means and received. The primary voice recognition result or the secondary voice recognition result is outputted to an exterior of a voice recognition system. Settlement information on the primary voice recognition result or the secondary voice recognition result outputted to the exterior of the voice recognition system is inputted, and the recognition dictionary is updated based on the inputted settlement information.  
         [0025]     According to the present invention, even if the primary voice recognition means has a small processing capability, the voice recognition system can efficiently and promptly provide a recognized word that suits the user&#39;s preference. Further, a word or a set of words that have been recognized in the server device can automatically be added to the recognition dictionary by the dictionary content control means. Therefore, it is possible to reduce a load on a user which would be caused when the recognition dictionary is customized for the user.  
         [0026]     According to a fourth aspect of the present invention, the above decision to accept or reject the primary recognition result depends on an external decision system. Specifically, instead of the above decision process, the primary voice recognition result is presented to an external decision system, and a decision result to accept or reject the primary voice recognition result is received from the external decision system. This configuration also has equivalent functions to the functions described in the third aspect of the present invention. Additionally, when a decision result (command) is issued by the external decision system (e.g., a user), the decision result is employed as decision information on the primary recognition result. Accordingly, the user can determine whether to update the recognition dictionary. Thus, it is possible to generate a recognition dictionary having a high processing efficiency for voice recognition to ensure enhanced reliability of processing voice information.  
         [0027]     Further, a word may be deleted based on at least one of order of past settlement information and a frequency of the past settlement information when a size of the words in the recognition dictionary exceeds a processing capability of the voice recognition system. Furthermore, when the recognition dictionary is to be updated, update information may be sent to the additional voice recognition means.  
         [0028]     According to a fifth aspect of the present invention, there is provided a computer-readable storage medium having a program recorded thereon for voice recognition which can provide a word that meets user&#39;s needs effectively to the user. The program recorded on the computer-readable storage medium is configured to execute the following procedure. A voice information of a user is inputted, and a primary voice recognition of the voice information is performed based on a recognition dictionary storing voice information of the words to produce a primary voice recognition result of the input voice information. A reliability of the primary voice recognition result is judged, and it is decided whether to accept or reject the primary voice recognition result. The input voice information of the user is sent to an additional voice recognition means when the primary voice recognition result is rejected. A secondary voice recognition result is produced by a voice recognition function of the additional voice recognition means and received. The primary voice recognition result or the secondary voice recognition result is outputted to an exterior of a voice recognition system. Settlement information on the primary voice recognition result or the secondary voice recognition result outputted to the exterior of the voice recognition system is inputted, and the recognition dictionary is updated based on the inputted settlement information.  
         [0029]     According to the present invention, even if the primary voice recognition means has a small processing capability, the recognition dictionary is continuously updated with a settled recognition result. Therefore, it is possible to provide a recognized word that suits the user&#39;s preference. Further, even if the user says a word that is not registered in the recognition dictionary, a recognition result (secondary voice recognition result) can readily be obtained by the voice recognition function of the additional voice recognition means, in addition to the primary recognition result of the primary voice recognition means. Thus, even if the primary voice recognition function has a small processing capability, it is possible to recognize a word that is not registered in the recognition dictionary with ease. Furthermore, a word or a set of words that have been recognized in the server device can automatically be added to the recognition dictionary by the dictionary content control function. Therefore, it is possible to reduce a load on a user which would be caused when the recognition dictionary is customized for the user.  
         [0030]     According to a sixth aspect of the present invention, the above decision to accept or reject the primary recognition result depends on an external decision system. Specifically, instead of the above decision function, the primary voice recognition result is presented to an external decision system, and a decision result to accept or reject the primary voice recognition result is received from the external decision system. This arrangement also has equivalent functions to the functions described in the fifth aspect of the present invention. Additionally, when a decision result (command) is issued by the external decision system (e.g., a user), the decision result is employed as decision information on the primary recognition result. Accordingly, the user can determine whether to update the recognition dictionary. Thus, it is possible to generate a recognition dictionary having a high processing efficiency for voice recognition to ensure enhanced reliability of processing voice information.  
         [0031]     Further, a word may be deleted based on at least one of order of past settlement information and a frequency of the past settlement information when a size of the words in the recognition dictionary exceeds a processing capability of the voice recognition system. Furthermore, when the recognition dictionary is to be updated, update information may be sent to the additional voice recognition means.  
         [0032]     Thus, even if a client terminal device has a small processing capability, it is possible to provide a word that meets the user&#39;s needs.  
         [0033]     As described above, according to the present invention, even if a client terminal device or a voice recognition means has a small processing capability for a primary voice recognition, it is possible to provide a word that suits the user&#39;s preference because a recognition dictionary is continuously updated with a settled recognition result.  
         [0034]     The above and other objects, features, and advantages of the present invention will be apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]      FIG. 1  is a schematic diagram showing an example of a conventional server-client voice recognition system;  
         [0036]      FIG. 2  is a schematic diagram showing an arrangement of a voice recognition system according to a first embodiment of the present invention;  
         [0037]      FIG. 3  is an explanatory diagram showing an example of a primary recognition dictionary in the voice recognition system shown in  FIG. 2 ;  
         [0038]      FIG. 4  is a flow chart showing operation of the voice recognition system shown in  FIG. 2 ;  
         [0039]      FIG. 5  is a schematic diagram showing an arrangement of a voice recognition system according to a second embodiment of the present invention;  
         [0040]      FIG. 6  is an explanatory diagram showing an example of a word history list and a primary recognition dictionary in the voice recognition system shown in  FIG. 5 ;  
         [0041]      FIG. 7  is a flow chart showing operation of the voice recognition system shown in  FIG. 5 ; and  
         [0042]      FIG. 8  is an explanatory diagram showing an example of a word history list in a dictionary content control unit of a voice recognition system according to a third embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0043]     A voice recognition system according to embodiments of the present invention will be described below with reference to  FIGS. 2 through 8 . Similar or corresponding parts are denoted by similar or corresponding reference numerals throughout drawings, and will not be described below repetitively.  
         [0044]      FIG. 2  shows the entirety of a voice recognition system according to a first embodiment of the present invention. As shown in  FIG. 2 , the voice recognition system includes a client terminal device  110  for receiving a user&#39;s voice and a server device (additional voice recognition means)  120  communicable with the client terminal device  110  via a communication network  130 . The illustrated client terminal device  110  performs primary recognition of the user&#39;s voice to produce a primary recognition result of the user&#39;s voice. The server device  120  performs secondary recognition of the user&#39;s voice to produce a secondary recognition result of the user&#39;s voice and outputs the secondary recognition result to the client terminal device  110 .  
         [0045]     The client terminal device  110  includes a voice input unit  111  for receiving an input user&#39;s voice or sound, a primary recognition dictionary  113 , and a primary voice recognition means  112  for performing primary recognition of the input voice by the use of the primary recognition dictionary  113 . Furthermore, a result decision unit (recognition result decision means)  115  is also included in the client terminal device  10  to determine whether a result of the primary recognition is to be accepted or rejected. In addition, a communication unit (transceiver means)  116  is further included to send the voice data to the server device (additional voice recognition means)  120  when the primary recognition result of the voice data is rejected in the client terminal device  110 . In this event, the communication unit  116  requests the server device  120  to perform secondary recognition of the voice data, and receives a result of the secondary recognition. In the client terminal device  110 , a result output unit (recognition result output means)  117  serves to output the result of the recognition outside the system.  
         [0046]     The output recognition result is settled or decided as a decided result of recognition by the user. The client terminal device  110  includes a decision result input unit (decision result input means)  118  for receiving the decided result of recognition. The client terminal device  110  also includes a dictionary content control unit (dictionary content control means)  119  for updating the primary recognition dictionary  113  with reference to the decided result of recognition received by the decision result input unit  118 .  
         [0047]     The illustrated primary voice recognition means  112  performs primary recognition of the voice data. Specifically, the primary voice recognition means  12  includes a voice pre-processing unit  112 A operable to analyze an input voice so as to extract features from the input voice and a primary voice recognition unit  112 B operable to output a primary recognition result of the voice data based on the extracted voice features.  
         [0048]     The client terminal device  110  may have a memory (not shown) storing a program for voice recognition and a central processing unit (CPU) operable to execute the program stored in the memory. In this event, the CPU executes the program to operate the voice pre-processing unit  112 A, the primary voice recognition unit  112 B, the result decision unit  115 , the communication unit  116 , the result output unit  117 , the decision result input unit  118 , and the dictionary content control unit  119  in accordance with the program.  
         [0049]     Next, description will be made about operations of the respective components in the voice recognition system.  
         [0050]     For example, the voice input unit  111  may include a microphone and receives a user&#39;s voice. The voice pre-processing unit (feature output means)  112 A is configured to perform a sound analysis of the input voice and extract a voice feature from the input voice. The primary recognition dictionary  113  has dictionary data including a vocabulary (words) and sounds of the words registered therein as shown in  FIG. 3 .  
         [0051]     The primary voice recognition unit (voice recognition means)  112 B is configured to retrieve a word corresponding to the user&#39;s voice from the primary recognition dictionary  113  based on the voice feature extracted by the voice pre-processing unit  112 A. For example, when the user says “e-mail address,” the primary voice recognition unit  112 B retrieves words corresponding to the user&#39;s voice from the primary recognition dictionary  113 . Specifically, the primary voice recognition unit  112 B reads both words “e-mail” and “address” from the primary recognition dictionary  113  on the basis of features inputted from the voice pre-processing unit  112 A. Then, the primary voice recognition unit  112 B attaches the word “e-mail” to the word “address” and produces or generates a set of words “e-mail address.” Thereafter, the primary voice recognition unit  112 B supplies the set of words “e-mail address” to the result decision unit  115 . If the primary voice recognition unit  112 B fails to read the corresponding word, then the primary voice recognition unit  112 B notifies the result decision unit  115  of the failure.  
         [0052]     For example, when a word is inputted from the primary voice recognition unit  112 B into the result decision unit (recognition result decision means)  115 , the result decision unit  115  calculates a likelihood or similarity of the input word. If the likelihood of the input word is high, the result decision unit  115  judges that the input word is one required by the user and accepts the input word. If the likelihood of the inputted word is low, the result decision unit  115  judges that the input word is different from the one required by the user and rejects the input word.  
         [0053]     For example, when input words are “e-mail address,” which are registered in the primary recognition dictionary  113 , the result decision unit  115  judges a likelihood of the inputted words to be high and accepts the input words. Let another word “registration” be not registered in the primary recognition dictionary  113 . If the word “registration” is wrongly recognized, for example, as “change” by the primary voice recognition unit  112 B and is inputted to the result decision unit  115 , then the result decision unit  115  judges a likelihood of the inputted word to be low and rejects the inputted word.  
         [0054]     If a word outputted from the primary voice recognition unit  112 B is rejected by the result decision unit  115 , the communication unit (transceiver means)  116  sends the voice features extracted by the voice pre-processing unit  112 A to the server device  120  via the communication network  130 . Then, the communication unit  116  receives a voice recognition result from the server device  120  via the communication network  130 . The result output unit (recognition result output means)  117  is configured to output a voice recognition result (primary or secondary recognition result) of the user&#39;s voice, which is produced in the client terminal device  110  or the server device  120 , to the outside of the system.  
         [0055]     When the user inputs a request to settle or decide an outputted recognition result, the settled or decided result input unit (settled result input means)  118  outputs the request to the dictionary content control unit (dictionary content control means)  119 . The dictionary content control unit (dictionary content control means)  119  registers new dictionary data in the primary recognition dictionary  113  according to the received request. Further, the dictionary content control unit  119  deletes oldest words from the primary recognition dictionary  113  if the number of registered words exceeds the processing capability of the client terminal device  110  (execution of a word deletion function).  
         [0056]     As shown in  FIG. 2 , the server device  120 , which serves as an additional voice recognition means, includes a communication unit  121 , a secondary recognition dictionary  122 , and a secondary voice recognition unit  123 . The communication unit  121  is configured to receive a feature from the client terminal device  110  via the communication network  130  and send a secondary voice recognition result to the client terminal device  110  via the communication network  130 .  
         [0057]     The secondary recognition dictionary  122  registers dictionary data including words corresponding to voices that could not be recognized by the client terminal device  110 , together with reading of the words registered therein. Further, the secondary voice recognition unit  123  has a function of retrieving a word corresponding to the user&#39;s voice from the secondary recognition dictionary  122  based on a voice feature received from the client terminal device  110 . In addition, the secondary voice recognition unit  123  performs secondary voice recognition of the user&#39;s voice, and returns a secondary recognition result to the client terminal device  110 .  
         [0058]     Next, operation of the voice recognition system in the first embodiment will be described with reference to a flow chart shown in  FIG. 4 .  
         [0059]     As shown in  FIG. 4 , a user&#39;s voice is inputted into the voice input unit  111  in the client terminal device  110  (Step  151 ). The input voice is subjected to a sound analysis in the voice pre-processing unit  112 A to extract a feature of the voice (Step  152 ). Then, the primary voice recognition unit  112 B retrieves the primary recognition dictionary  113  and performs primary voice recognition on the basis of the features extracted by the voice pre-processing unit  112 A (Step  153 : voice recognition process).  
         [0060]     For example, when the user says or pronounces “e-mail address,” the primary voice recognition unit  112 B retrieves words from the primary recognition dictionary  113 , reads words “e-mail” and “address” from the primary recognition dictionary  113  based on the features of both the words, and outputs the words “e-mail address” to the result decision unit  115 . If the primary voice recognition unit  112 B fails to read any corresponding word from the primary recognition dictionary  113 , the primary voice recognition unit  112 B might output a false word to the result decision unit  115 .  FIG. 3  shows an example of words stored in the primary recognition dictionary  113 .  
         [0061]     Next, the result decision unit  115  calculates a likelihood of the inputted word or words and decides whether each of the words is accepted or rejected (Step  154 : recognition result decision process). If the result decision unit  115  calculates a likelihood of the inputted word to be high and decides to accept the inputted word (Step  154 : accept), then the result decision unit  115  outputs the word of the recognition result, which is given from the primary voice recognition unit  112 B, to the result output unit  117  (Step  155 ). Then, the process returns to Step  152  described above. On the other hand, if the result decision unit  115  calculates a likelihood of the inputted word to be low and decides to reject the inputted word (Step  154 : reject), then the result decision unit  115  obtains a voice features from the voice pre-processing unit  112 A and outputs the voice features to the communication unit  116 . The communication unit  116  sends the input voice features to the communication unit  121  in the server device  120 , which serves as an additional voice recognition means, via the communication network  130  (Step  156 ).  
         [0062]     In the server device (additional voice recognition means)  120 , when the communication unit  121  receives the voice features from the client terminal device  110  (Step  157 ), the communication unit  121  outputs the received voice features to the secondary voice recognition unit  123 . Then, the secondary voice recognition unit  123  retrieves a word corresponding to the user&#39;s voice from the secondary recognition dictionary  122  based on the received voice features so as to perform a secondary voice recognition (Step  158 ). Thereafter, the secondary voice recognition unit  123  outputs a secondary recognition result obtained by the secondary voice recognition to the communication unit  121 . The communication unit  121  sends the secondary recognition result to the communication unit  116  in the client terminal device  110  via the communication network  130  (Step  159 ).  
         [0063]     When the communication unit  116  of the client terminal device  110  receives the secondary recognition result from the server device  120  as an additional voice recognition means (Step  160 : secondary recognition result acquisition process), then the communication unit  116  outputs the secondary recognition result to the result output unit  117 . The result output unit  117  outputs the voice recognition result in a manner such that the user can recognize the result (Step  161 : recognition result output process). Then, when a request to settle the outputted recognition result is inputted into the settled result input unit  118 , then the settled result input unit  118  outputs the inputted request to the dictionary content control unit  119  (Step  162 : settled result input process). The dictionary content control unit  119  registers new dictionary data in the primary recognition dictionary  113  according to the received request. Further, the dictionary content control unit  119  deletes oldest words from the primary recognition dictionary  113  to update the primary recognition dictionary  113  if the number of registered words exceeds the processing capability of the client terminal device  110  (Step  163 : dictionary update control process). Then, the process is terminated.  
         [0064]     According to the voice recognition system in the first embodiment, even if the user says a word that is not registered in the primary recognition dictionary  113  of the client terminal device  110 , the word can be subjected to voice processing in the server device  120  and provided to the user. Therefore, the voice recognition system can provide a word that matches a user&#39;s request even if the client terminal device  110  is small in processing ability.  
         [0065]     Further, according to the voice recognition system in the first embodiment, even if a word cannot be recognized by the client terminal device  110 , there is a strong possibility that the word can be recognized by the server device  120  (additional voice recognition means) with the secondary recognition dictionary  122  having a large number of registered words. Therefore, even if the user says a word that is not registered in the primary recognition dictionary  113  of the client terminal device  110 , such a word can be recognized by the voice recognition system.  
         [0066]     Furthermore, according to the voice recognition system in the first embodiment, a word or a set of words that have been recognized in the server device  120  can automatically be added to the primary recognition dictionary  113  in the client terminal device  110 . Therefore, it is possible to lighten a load imposed on a user when the primary recognition dictionary  113  is customized for the user.  
         [0067]      FIG. 5  shows an entire arrangement of a voice recognition system according to a second embodiment of the present invention. As shown in  FIG. 5 , the voice recognition system includes a client terminal device  200  and a server device  120  as an additional voice recognition means communicable with the client terminal device  200  via a communication network  130 . This configuration is similar to the voice recognition system in the first embodiment.  
         [0068]     The client terminal device  200  in the second embodiment includes a result presentation unit (recognition result presentation means)  205  for presenting a primary recognition result to an external decision system and a decision input unit (decision input means)  206  for fetching a decision result as decision information from the external decision system. The result presentation unit  205  and the decision input unit  206  are arranged between the primary voice recognition means  112  and the result decision unit (recognition result decision means)  115  both of which have been already described in the first embodiment.  
         [0069]     With this structure, an external judgment system judges whether the primary recognition result presented by the result presentation unit  205  is to be accepted or rejected and inputs the decision result to the decision input unit  206 . In other words, judgment of the client terminal device  200  depends on the decision of the external decision system that may be a user. In this case, a user may serve as the external decision system. As shown in  FIG. 5 , other arrangements of the voice recognition system are the same as those of the voice recognition system in the first embodiment (see  FIG. 2 ).  
         [0070]     The voice recognition system in the second embodiment has equivalent functions to those in the first embodiment. Additionally, the voice recognition system in the second embodiment has the following functions. Specifically, when a decision result (command) issued by the external decision system (e.g., a user) is inputted into the voice recognition system, the decision result is employed as decision information on the primary recognition result. Accordingly, the user can determine whether the primary recognition dictionary is updated or not. Thus, it is possible to generate a recognition dictionary having a high processing efficiency for voice recognition to ensure enhanced reliability of processing voice information.  
         [0071]     The client terminal device  200  may have a memory (not shown) storing a program for voice recognition and a central processing unit (CPU) operable to execute the program stored in the memory so as to operate the voice recognition means  112  (a voice pre-processing unit  112 A and a primary voice recognition unit  112 B), the result presentation unit  205 , the decision input unit  206 , the result decision unit  115 , the communication unit  116 , the result output unit  117 , the settled result input unit  118 , and the dictionary content control unit  119 .  
         [0072]     The result presentation unit (recognition result presentation means)  205  is configured to present a primary recognition result, which is outputted from the primary voice recognition unit  112 B, to the user (external decision system) in a manner such that the user can recognize the primary recognition result. Then, the user (external decision system) inputs a decision result of accepting or rejecting the presented primary recognition result of a word into the decision input unit (decision input means)  206 . The decision input unit  206  serves to fetch the decision result from the user (external decision system). At any rate, the result presentation unit  205  and the decision input unit  206  may be collectively called a result judgment unit or means, together with the result decision unit or means  115  because they serve to decide whether the primary voice recognition result is accepted or rejected.  
         [0073]     Here, the dictionary content control unit  119  acts to control and update the primary recognition dictionary  113 . The dictionary content control unit  119  has a word history list  113   a  as shown in  FIG. 6 . The word history list  113   a  includes word history data composed of words, phonetic signs or pronunciations of the words, order of use, and frequencies of use. A largest value in order of use means that the word is most recently used. The dictionary content control unit  119  may delete a word having a smallest value in order of use listed in the word history list  113   a  (e.g., a word “number” in  FIG. 6 ) from the primary recognition dictionary  113  when the primary recognition dictionary  113  has been full of registered words. Alternatively, the dictionary content control unit  119  may delete a word having a lowest frequency of use (e.g., a word “change” in  FIG. 6 ).  
         [0074]     When the dictionary content control unit  119  registers a new word in the primary recognition dictionary  113 , a largest value in order of use among the registered words in the word history data or a frequency of use “00001” is stored in the word history list  113   a  for the new word. Here, a word that has been deleted from the primary recognition dictionary  113  may not be deleted from the word history list  113   a  by the dictionary content control unit  119 . Thus, the number of words registered in the word history list  113   a  is equal to or more than the number of words registered in the primary recognition dictionary  113 .  
         [0075]     Next, operation of the voice recognition system in the second embodiment will be described with reference to a flow chart shown in  FIG. 7 .  
         [0076]     In this embodiment, when a user&#39;s voice is inputted into the voice input unit  111  in the client terminal device  200 , the voice input unit  111  outputs the voice to the voice pre-processing unit  112 A (Step  251 ). The voice pre-processing unit  112 A extracts voice features of the input voice by a sound analysis (Step  252 ). Then, the primary voice recognition unit  112 B performs a primary voice recognition through retrieval in the primary recognition dictionary  113  based on the features extracted by the voice pre-processing unit  112 A (Step  253 ).  
         [0077]     For example, when the user says “e-mail address,” the primary voice recognition unit  112 B retrieves words from the primary recognition dictionary  113 , reads words “e-mail” and “address” from the primary recognition dictionary  113  based on the voice features, and outputs the words “e-mail address” to the result presentation unit  205 . If the primary voice recognition unit  112 B fails to read any corresponding word from the primary recognition dictionary  113 , the primary voice recognition unit  112 B outputs a false word to the result presentation unit  205 .  
         [0078]     Next, the result presentation unit  205  presents the inputted word to the external decision system, e.g., the user (Step  254 : recognition result presentation process). Then, the decision input unit  206  receives a decision result of the presented word from the external decision system (decision result input process) and outputs the decision result to the result decision unit  115 . The result decision unit  115  decides whether the presented recognition result according to the inputted decision result (Step  255 ) is to be accepted or rejected. If the result decision unit  115  decides to accept the recognition result (Step  256 : accept), then the result decision unit  115  outputs the word of the recognition result, which is inputted from the primary voice recognition unit  112 B, to the result output unit  117 . Then, the process returns to Step  253  described above.  
         [0079]     On the other hand, if the result decision unit  115  decides to reject the recognition result (Step  255 : reject), then the result decision unit  115  outputs the voice feature, which has been obtained from the voice pre-processing unit  112 A, to the server device (additional voice recognition means)  120  via the communication unit  116 . The communication unit  116  sends the voice feature, which has been inputted from the voice pre-processing unit  112 A, to the communication unit  121  in the server device  120  via the communication network  130  (Step  257 ).  
         [0080]     When the communication unit  121  in the server device  120  receives the voice features from the client terminal device  200  (Step  258 ), the communication unit  121  outputs the voice features to the secondary voice recognition unit  123 . Then, the secondary voice recognition unit  123  retrieves a word corresponding to the user&#39;s voice from the secondary recognition dictionary  122  based on the input voice features so as to perform secondary voice recognition (Step  259 ). Thereafter, the secondary voice recognition unit  123  outputs a secondary recognition result obtained by the secondary voice recognition to the communication unit  121 . The communication unit  121  sends the secondary recognition result to the communication unit  116  in the client terminal device  200  via the communication network  130  (Step  260 ).  
         [0081]     When the communication unit  116  of the client terminal device  200  receives the secondary recognition result from the server device  120  (Step  261 ), then the communication unit  116  outputs the secondary recognition result to the result output unit  117 . The result output unit  117  outputs the secondary recognition result in a manner such that the user can recognize the result (Step  262 ). Then, when a request to settle or decide the outputted recognition result is inputted into the settled result input unit  118 , then the settled result input unit  118  outputs the inputted request to the dictionary content control unit  119  (Step  263 ). The dictionary content control unit  119  refers to the word history list  113   a  and registers new dictionary data in the primary recognition dictionary  113  if needed by the received request. If the number of registered words in the primary recognition dictionary  113  exceeds the processing capability of the client terminal device  200 , then the dictionary content control unit  119  deletes oldest words from the primary recognition dictionary  113  to update the primary recognition dictionary  113  (Step  264 ). Then, the process is terminated.  
         [0082]     The voice recognition system in the second embodiment has similar effects to those of the voice recognition system in the first embodiment. Further, since a user&#39;s past history of use is used in the word history list  113   a  of the dictionary content control unit  119  as information for the primary recognition dictionary  113  of the client terminal device  200 , it is possible to obtain information suitable for the user&#39;s preference.  
         [0083]     According to the voice recognition system in the first and second embodiments, voice features outputted from the voice pre-processing unit  112 A are outputted as voice data to be sent from the client terminal device to the server device. However, a sound wave data may be sent directly to the server device.  
         [0084]     Further, the voice recognition system in the first embodiment may employ the dictionary content control unit  119  and the primary recognition dictionary  113  described in the second embodiment.  
         [0085]     Furthermore, the voice recognition system in the second embodiment employs order of use and frequencies of use as historical operation data. However, historical operation data are not limited to those examples. Further, order of use and frequencies of use may be employed solely or in combination. The upper limit of the number of words in the primary recognition dictionary  113  may be set according to the processing capability of the system. The upper limit may be dynamically changed if a load varies depending on environments.  
         [0086]      FIG. 8  is an explanatory diagram showing an example of a word history list  213   a  in a dictionary content control unit of a voice recognition system according to a third embodiment of the present invention. In the third embodiment, the word history list  213   a  as shown in  FIG. 8  is provided in addition to the dictionary content control unit  119  of the voice recognition system in the first or second embodiment. The dictionary content control unit  119  is configured to control words in the primary recognition dictionary  113  based on the word history list  213   a.  In this case, information on the word history list  213   a  is sent from the communication unit  116  of the client terminal device to the server device  120 . The server device  120  thus receives the information on the word history list  213   a.  Accordingly, the server device  120  can obtain user&#39;s input histories without requiring user&#39;s presence or separately monitoring user&#39;s using conditions.  
         [0087]     The example shown in  FIG. 8  is designed for a market search engine for cellular phones. From the word history list  213   a  shown in  FIG. 8 , it is possible to surmise that the user is interested in purchasing a television. Accordingly, a company that manages the server device can send information on new products to the user. Thus, it is possible to utilize the voice recognition system for sales promotion of the company. Further, in the conventional method, a voice recognition result should be analyzed to obtain customer information. However, according to the voice recognition system in the third embodiment, use of the work history list  213   a  eliminates the need of analyzing a voice recognition result.  
         [0088]     In the third embodiment, the voice recognition system sends the work history list  213   a  from the communication unit  116  of the client terminal device  200  to the server device. However, the user may set the word history list  213   a  not to be sent to the server device. Further, the user may set the work history list  213   a  to be sent to the server device each time the client terminal device communicates with the server device  120  for voice recognition.  
         [0089]     Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.