Patent Publication Number: US-9886952-B2

Title: Interactive system, display apparatus, and controlling method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority under 35 U.S.C. §119 from Korean Patent Application No. 10-2014-0007910, filed on Jan. 22, 2014, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field 
     Methods and apparatuses consistent with the exemplary embodiments relate to providing an interactive system, a display apparatus, and a controlling method thereof, and more particularly, to providing an interactive system for providing response information corresponding to an uttered voice of a user, a display apparatus, and a controlling method. 
     2. Description of the Related Art 
     If an uttered voice of a user is input to a display apparatus, the display apparatus directly performs a voice recognition process with respect to the uttered voice of the user, or the display apparatus and an external apparatus simultaneously perform a voice recognition process with respect to the uttered voice of the user according to a recognition condition in an interactive system. If the display apparatus and the external apparatus simultaneously perform the voice recognition process, the display apparatus compares the reliability of the voice recognition performed by the display apparatus with the reliability of the voice recognition performed through the external apparatus, selects a highly reliable voice recognition result on the basis of the comparison, and performs an operation based on the selected voice recognition result. 
     However, according to this existing reliability comparing method, the display apparatus and the external apparatus have different candidate groups of execution commands corresponding to the uttered voice. Therefore, reliability of a voice recognition result of the same uttered voice acquired by the display apparatus may be different from reliability of a voice recognition result of the same uttered voice acquired by the external apparatus. 
     For example, the display apparatus may have a candidate group of 100 execution commands corresponding to the uttered voice, and the external apparatus may have a candidate group of 10000 execution commands corresponding to the uttered voice. In this case, although there is a high possibility that the external apparatus will have a similar execution command to a voice recognition result recognized from the uttered voice of the user compared to the display apparatus, the external apparatus may calculate a lower reliability value than the display apparatus. 
     Also, the display apparatus may recognize texts other than the texts related to the 100 execution commands among texts included in the voice recognition result recognized from the uttered voice of the user, as noise to calculate a higher reliability value than that of the voice recognition result acquired by the external apparatus. 
     Although these problems exist, an existing display apparatus simply selects a highly reliable voice recognition result as an execution command of an uttered voice of user. As a result, a voice recognition result different from the uttered voice of the user is selected. 
     SUMMARY 
     Exemplary embodiments address at least the above problems and/or disadvantages and other disadvantages not described above. Also, the exemplary embodiments are not required to overcome the disadvantages described above, and an exemplary embodiment may not overcome any of the problems described above. 
     The exemplary embodiments provide a method for selecting a voice recognition result which is proximate to an intent of a user from among at least two voice recognition results when a display apparatus and an external apparatus simultaneously recognize an uttered voice of a user. 
     The exemplary embodiments provide a method for performing an operation appropriate for an uttered voice of a user or providing response information appropriate for the uttered voice of the user. 
     According to an aspect of the exemplary embodiments, there is provided a display apparatus comprising: an input configured to receive an uttered voice of a user; a communicator configured to transmit a voice signal of the uttered voice to a voice recognition apparatus; a voice recognizer configured to perform a voice recognition process with respect to the uttered voice; and a controller configured to determine a first voice information or a second voice information which has a reliability value greater than or equal to a preset threshold value among a reliability value of the first voice information recognized by the voice recognizer and a reliability value of the second voice information recognized by the voice recognition apparatus, as an execution command of the uttered voice. 
     The first voice information and the second voice information is text information into which the voice signal of the uttered voice is converted. When the reliability values of the first voice information and the second voice information are greater than or equal to the preset threshold value, the controller compares lengths of character strings of the text information of the first voice information and the text information of the second voice information to determine one of the first voice information or the second voice information which has a longer character string to be an execution command. 
     The controller is configured to calculate a similarity value of pronunciation strings from the text information of the first voice information and the text information of the second voice information based on a predefined similarity algorithm when the lengths of the character strings are the same, determine the first voice information as an execution command when the calculated similarity value is greater than or equal to a preset threshold value, and determine the second voice information as an execution command when the calculated similarity value is lower than the threshold value. 
     When the execution command of the uttered voice is determined, the controller is configured to determine a domain based on one of the first voice information and the second voice information determined as the execution command, and determine the one of the first voice information and the second voice information determined as the execution command as a final execution command according to a condition that the determined domain and a domain of a current operation mode of the display apparatus correspond to each other. 
     When the reliability values of the first voice information and the second voice information are lower than the threshold value, the controller is configured to determine domains of the first voice information and the second voice information, apply a weight to the reliability value of one of the first voice information and the second voice information which has a domain corresponding to the domain of the current operation mode of the display apparatus, and determine the one of the first voice information and the second voice information to which the weight is applied as an execution command according to a condition that the reliability value of the one of the first voice information and the second voice information to which the weight is applied is greater than or equal to the threshold value. 
     The display apparatus may further include a storage configured to store control commands corresponding to a plurality of pieces of voice information; and a display configured to display a voice recognition result of response information received from an interactive server. 
     When the first voice information is recognized by the voice recognizer and being determined as the execution command, the controller is configured to perform a control operation according to a control command corresponding to the first voice information among the control commands stored in the storage and, when the second voice information is received from the voice recognition apparatus and being determined as the execution command, transmit the second voice information to the interactive server through the communicator, and receive response information related to the second voice information from the interactive server. 
     According to another aspect of the exemplary embodiments, there is provided a method of controlling a display apparatus. The method comprising receiving an uttered voice of a user; performing a voice recognition process with respect to the uttered voice to calculate a reliability value of first voice information; transmitting a voice signal of the uttered voice to a voice recognition apparatus; when a voice recognition result of the uttered voice is received from the voice recognition apparatus, comparing the reliability value of the first voice information and a reliability value of second voice information included in the voice recognition result with a preset threshold value; and when the reliability value of the first voice information or the second voice information is greater than or equal to the threshold value, determine the first voice information or the second voice information which has the reliability value greater than or equal to the threshold value as an execution command of the uttered voice. 
     The first voice information and the second voice information is text information into which a voice signal of the uttered voice is converted. When the reliability value of the first voice information and the reliability value of the second voice information is greater than or equal to the threshold value, lengths of character strings of the text information of the first voice information and the text information of the second voice information are compared to determine the first or second voice information which has a longer character string to be an execution command. 
     When the lengths of the character strings are the same, a similarity value of pronunciation strings of the text information of the first voice information and the text information of the second voice information are calculated based on a pre-stored similarity algorithm, when the calculated reliability value is greater than or equal to a preset threshold value, the first voice information is determined as an execution command, and when the calculated similarity value is lower than the threshold value, the second voice information is determined as the execution command. 
     The method may further comprise, when the execution command of the uttered voice is determined, determining a domain based on the one of the first voice and the second voice information determined as the execution command; and determining the one of the first voice information and the second voice information determined as the execution command as a final execution command according to a condition that the determined domain corresponds to a domain of a current operation mode of the display apparatus. 
     The method may further comprise when the reliability value of the first voice information and the reliability value of the second voice information is lower than the threshold value, determining domains of the first voice information and domains of the second voice information; and applying a weight to one of the reliability value of the first voice information and the reliability value of the second voice information which has a domain corresponding to the domain of the current operation mode of the display apparatus. The first voice information or the second voice information to which the weight is applied may be determined as an execution command according to whether the reliability value of the first voice information or the reliability value of the second voice information to which the weight is applied is greater than or equal to the threshold value. 
     The method may further comprise, when the first voice information is determined to be the execution command, performing a control operation according to a control command corresponding to the first voice information among a plurality of pre-stored control commands, and when the second voice information is determined to be the execution command, receiving response information corresponding to the second voice information from an interactive server and displaying a voice recognition result related to the received response information. 
     According to another aspect of the exemplary embodiments, there is provided an interactive system including a display apparatus configured to, when an uttered voice of a user is input, perform a voice recognition process based on a voice signal of the uttered voice, and transmit the voice signal to a voice recognition apparatus; and the voice recognition apparatus is configured to perform a voice recognition process based on the voice signal received from the display apparatus, and transmit a voice recognition result of the voice recognition process to the display apparatus. When the voice recognition result is received from the voice recognition apparatus, the display apparatus determines one of first voice information and second voice information which has a reliability value greater than or equal to a preset threshold value among a reliability value of the first voice information recognized in the display apparatus and a reliability value of the second voice information included in the voice recognition result, as an execution command of the uttered voice. 
     The first voice information and the second voice information may be text information into which a voice signal of the uttered voice is converted. When the reliability values of the first voice information and the reliability values of the second voice information are greater than or equal to the threshold value, the display apparatus may compare lengths of character strings of the text information of the first voice information and the text information of the second voice information to determine the first voice command or the second voice information which has a longer character string as an execution command. 
     The display apparatus may calculate a similarity value of pronunciation strings of the text information of the first voice information and the text information of the second voice information based on a predefined similarity algorithm when the lengths of the character strings are the same, determine the first voice information as an execution command when the calculated similarity value is greater than or equal to a preset threshold value, and determine the second voice information as an execution command when the calculated similarity value is lower than the threshold value. 
     The display apparatus may determine a domain based on one of the first voice information and the second voice information determined as the execution command when the execution command of the uttered voice is determined and determine the first voice information or the second voice information determined as the execution command as a final execution command according to whether the determined domain corresponds to a domain of a current operation mode of the display apparatus. 
     When the reliability values of the first voice information and the reliability values of the second voice information are lower than the threshold value, the display apparatus determines domains of the first voice information and the second voice information, applies a weight to the reliability value of one of the first voice information and the second voice information which has a domain corresponding to the domain of the current operation mode of the display apparatus, and determines the first voice information and the second voice information to which the weight is applied as an execution command according to a condition that the reliability value of the first voice information and the second voice information to which the weight is applied is greater than or equal to the threshold value. 
     The display apparatus performs a control operation according to a control command corresponding to the first voice information when the first voice information is determined to be an execution command, and transmits the second voice information to an interactive server to receive response information corresponding to the second voice information and displays a voice recognition result corresponding to the received response information when the second voice information is determined to be the execution command. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and/or other aspects will be more apparent by describing certain exemplary embodiments with reference to the accompanying drawings, in which: 
         FIG. 1  is a view illustrating an interactive system for providing response information appropriate for an uttered voice of a user, according to an exemplary embodiment; 
         FIG. 2  is a view illustrating an interactive system for providing response information appropriate for an uttered voice of a user, according to another exemplary embodiment; 
         FIG. 3  is a block diagram of a display apparatus according to an exemplary embodiment; 
         FIG. 4  is a block diagram illustrating a detailed structure of a controller, according to an exemplary embodiment; 
         FIG. 5  is a view illustrating a comparison between lengths of character string of text information of first voice information and text information of second voice information, according to an exemplary embodiment; 
         FIG. 6  is a view illustrating a comparison between similarity information of a pronunciation string of text information of first voice information and similarity information of a pronunciation string of text information of second voice information, according to an exemplary embodiment; 
         FIG. 7  is a block diagram of an interactive server according to an exemplary embodiment; 
         FIG. 8  is a flowchart of a method of controlling a display apparatus, according to an exemplary embodiment; and 
         FIG. 9  is a flowchart of a method of determining first or second voice information as an execution command of an uttered voice of a user if reliability values of the first voice information and the second voice information are greater than or equal to or lower than a preset first threshold value in a display apparatus, according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Exemplary embodiments are described in greater detail with reference to the accompanying drawings. 
     In the following description, the same drawing reference numerals are used for the same elements even in different drawings. The matters defined in the description, such as detailed construction and elements, are provided to assist in a comprehensive understanding of the exemplary embodiments. Thus, it is apparent that the exemplary embodiments can be carried out without those specifically defined matters. Also, well-known functions or constructions are not described in detail since they would obscure the exemplary embodiments with unnecessary detail. 
       FIG. 1  is a view illustrating an interactive system for providing response information appropriate for an uttered voice of a user, according to an exemplary embodiment.  FIG. 2  is a view illustrating an interactive system for providing response information appropriate for an uttered voice of a user, according to another exemplary embodiment. 
     Referring to  FIG. 1 , the interactive system includes a display apparatus  100 , a voice recognition apparatus  200 , and an interactive server  300 . 
     The display apparatus  100  may be an apparatus that may access the Internet and may be realized as various types of electronic devices such as a smart television (TV), a portable phone such as a smartphone, a desktop personal computer (PC), a notebook PC, a navigation system, etc. If an uttered voice of a user is input, the display apparatus  100  performs an operation corresponding to the input uttered voice of the user. In detail, the display apparatus  100  may perform a function or output a voice recognition result related to the uttered voice of the user according to a control command corresponding to the uttered voice of the user. 
     The voice recognition apparatus  200  generates text type voice information based on a voice signal of the uttered voice of the user and calculates a reliability value of the text type voice information based on the text type voice information and pattern information of each of a plurality of pre-stored uttered voices. The voice recognition apparatus  200  transmits a voice recognition result, including the text type voice information generated from the voice signal of the uttered voice of the user and the reliability value of the text type voice information, to the display apparatus  100 . 
     The interactive server  300  parses the text type voice information received from the display apparatus  100  to extract utterance factors, generates response information for performing the operation corresponding to the uttered voice of the user based on the extracted utterance factors, and transmits the response information to the display apparatus  100 . Therefore, the display apparatus  100  may display the voice recognition result related to the uttered voice of the user on a screen based on the response information received from the interactive server  300 . 
     In detail, if the uttered voice of the user is input, the display apparatus  100  converts the input uttered voice into a voice signal, that is, a digital signal, and performs a voice recognition based on the voice signal to generate voice information (hereinafter referred to as first voice information) of the uttered voice of the user. If the first voice information is generated, the display apparatus  100  may calculate a reliability value of the first voice information based on the pattern information of each of the pre-stored plurality of uttered voices. 
     If the uttered voice of the user is input, the display apparatus  100  transmits the voice signal of the input uttered voice to the voice recognition apparatus  200 . If the voice signal is received, the voice recognition apparatus  200  performs a voice recognition with respect to the received voice signal to generate voice information (hereinafter referred to as second voice information) of the uttered voice of the user. If the second voice information is generated, the voice recognition apparatus  200  may calculate a reliability value of the second voice information based on the pattern information of each of the plurality of pre-stored uttered voices. If the reliability value of the second voice information is calculated, the voice recognition apparatus  200  transmits a voice recognition result, including the second voice information and the reliability value of the second voice information, to the display apparatus  100 . 
     The first voice information and the second voice information may be text type information into which the voice signal of the uttered voice of the user is converted. According to exemplary embodiments, the display apparatus  100  and the voice recognition apparatus  200  may generate the uttered voice of the user as text type voice information by using a speech-to-text (STT) algorithm. 
     If the voice recognition result of the uttered voice of the user is received from the voice recognition apparatus  200 , the display apparatus  100  compares the reliability value of the first voice information and the reliability value of the second voice information included in the received voice recognition result with a preset threshold value (hereinafter referred to as a first threshold value). In other words, the display apparatus  100  compares the reliability value of the first voice information with the preset first threshold value, and compares the reliability value of the second voice information with the first threshold value. If the reliability value of one of the first voice information and the second voice information is greater than or equal to the first threshold value according to the comparison result, the display apparatus  100  determines the one of the first voice information and the second voice information which has the reliability value which is greater than or equal to the first threshold value as the voice information which is an execution command. 
     According to the exemplary embodiments, if the reliability value of the first voice information is greater than or equal to the first threshold value, the display apparatus  100  determines the first voice information as an execution command. The display apparatus  100  may perform a control operation according to a control command corresponding to the first voice information among control commands corresponding to a plurality of pieces of pre-stored voice information. 
     If the reliability value of the second voice information is greater than or equal to the first threshold value, the display apparatus  100  determines the second voice information as an execution command and transmits the second voice information determined as the execution command to the interactive server  300 . The interactive server  300  generates response information related to the uttered voice of the user based on the second voice information received from the display apparatus  100  and transmits the response information to the display apparatus  100 . Therefore, the display apparatus  100  may display the voice recognition result related to the uttered voice of the user on the screen based on the response information received from the interactive server  300 . 
     If the first voice information and the second voice information respectively have the reliability values greater than or equal to the first threshold value, the display apparatus  100  may compare lengths of character strings of text information of the first voice information and the second voice information and determine the first voice information or the second voice information which has a longer character string as an execution command. 
     According to the exemplary embodiments, the text information of the second voice information may have a longer character string than the text information of the first voice information. In this case, the display apparatus  100  determines the second voice information as an execution command and transmits the second voice information determined as the execution command to the interactive server  300 . The interactive server  300  generates response information related to the uttered voice of the user based on the second voice information received from the display apparatus  100  and transmits the response information to the display apparatus  100 . Therefore, the display apparatus  100  may display a voice recognition result related to the uttered voice of the user on the screen based on the response information received from the interactive server  300 . 
     If the character strings of the text information of the first voice information and the second voice information are the same, the display apparatus  100  extracts pronunciation strings from the text information of the first voice information and the text information of the second voice information. The display apparatus  100  calculates a similarity value from the extracted pronunciation strings of the first voice information and the second voice information and compares the calculated similarity value with a preset threshold value (referred to as a second threshold value). If the calculated similarity value is greater than or equal to the second threshold value according to the comparison result, the display apparatus  100  may determine the first voice information as an execution command and perform a control operation according to a control command corresponding to the first voice information determined as the execution command among pre-stored control commands. 
     The present exemplary embodiment is not limited thereto, and if the first or second voice information that will be determined as an execution command is not determined based on the similarity values of the first voice information and the second voice information, the display apparatus  100  may compare the lengths of the character strings of the text information of the first voice information and the second voice information to determine the first voice information or the second voice information which has a longer character string to be an execution command. 
     According to another exemplary embodiment, the display apparatus  100  may determine the first voice information or the second voice information determined as the execution command, as a final execution command according to whether a domain of the first or second voice information determined as the execution command corresponds to a domain of a current operation mode of the display apparatus  100 . 
     According to the exemplary embodiments, if the current operation mode of the display apparatus  100  is a broadcast program execution mode, the display apparatus  100  may set the domain of the current operation mode to a control-related domain. If the current operation mode of the display apparatus  100  is an application execution mode, the display apparatus  100  may set the domain of the current operation mode to a content recommendation-related domain. For example, if the current operation mode of the display apparatus  100  is the application execution mode, and the first voice information or the second voice information determined as the execution command corresponds to the control-related domain, the display apparatus  100  may determine that the control-related domain and the content recommendation-related domain do not correspond to each other and determine the first voice information or the second voice information, which is not determined as an execution command, as a final execution command. 
     If the current operation mode of the display apparatus  100  is the application execution mode, and the first voice information or the second voice information determined as the execution command corresponds to the content recommendation-related domain, the display apparatus  100  may determine that the control-related domain and the content recommendation-related domain correspond to each other and determine the first or second voice information determined as the execution command as a final execution command. 
     Therefore, as described above, the display apparatus  100  may perform a control operation related to the uttered voice of the user based on the first or second voice information determined as the final execution command or may display a voice recognition result related to the uttered voice of the user based on the response information received from the interactive server  300 . 
     If the reliability values of the first voice information and the second voice information are lower than the first threshold value, the display apparatus  100  may determine domains of the first voice information and the second voice information and apply a weight to a reliability value of the first or second voice information having the determined domain corresponding to the domain of the current operation mode of the display apparatus  100 . 
     If the reliability value of the first or second voice information to which the weight is applied is greater than or equal to the first threshold value, the display apparatus  100  may determine the first or second voice information, to which the weight is applied, as an execution command and perform a control operation related to the uttered voice of the user based on the first or second voice information corresponding to the determined execution command or display a voice recognition result related to the uttered voice of the user based on the response information received from the interactive server  300  as described above. 
     In the present exemplary embodiment, the voice recognition apparatus  200  and the interactive server  300  have been separately described in the interactive system. However, the exemplary embodiment is not limited thereto, and the interactive system may include the display apparatus  100  and the interactive server  300  as shown in  FIG. 2 . In this case, like the voice recognition apparatus  200  described above, the interactive server  300  may perform a voice recognition process with respect to a voice signal of an uttered voice of a user to generate voice information and transmit a voice recognition result, including the generated voice information and a reliability value of the voice information, to the display apparatus  100 . 
     A control operation related to an uttered voice of a user or an operation of providing a voice recognition result in the interactive system including the display apparatus  100 , the voice recognition apparatus  200 , and the interactive server  200  has been described in brief. 
     Elements of the display apparatus  100  will now be described in detail. 
       FIG. 3  is a block diagram of the display apparatus  100 , according to an exemplary embodiment. 
     Referring to  FIG. 3 , the display apparatus  100  includes an input  110 , a communicator  120 , a voice recognizer  130 , a controller  140 , a storage  150 , and a display  160 . 
     The input  110  receives an uttered voice of a user. In detail, if an analog uttered voice of the user is input, the input  110  samples the inputted analog uttered voice of the user to convert the inputted analog uttered voice of the user into a digital signal. If the inputted uttered voice of the user includes noise (for example, an air conditioner sound, a vacuum clear sound, etc.), the input  110  may remove the noise from the uttered voice of the user and convert the uttered voice of the user, from which the noise is removed, into a digital signal. The input  110  may also receive various types of user controls and transmit the various types of user controls to the controller  140 . In this case, the input  110  may receive a user control command through a touch pad, a key pad including various types of function keys, numerical keys, special keys, character keys, etc. or a touch screen. 
     The communicator  120  transmits a voice signal of the uttered voice of the user input through the input  110  to the voice recognition apparatus  200  and receives a voice recognition result of the voice signal from the voice recognition apparatus  200 . The communicator  120  may also transmit voice information determined as an execution command to the interactive server  300  according to a control command of the controller  140  and receive response information generated in relation to the voice information from the interactive server  300 . 
     The communicator  120  may include various types of communication modules such as a short-range communication module (not shown), a wireless communication module (not shown), etc. The short-range wireless communication module is a communication module that performs a wireless communication with the interactive server  300  that is positioned in a short range, and an external server (not shown) that provides a content, may be, for example, Bluetooth, Zigbee, or the like. The wireless communication module is a module that is connected to an external network to perform a communication according to a wireless communication protocol such as WiFi, IEEE, or the like. The wireless communication module may further include a mobile communication module that accesses a mobile communication network to perform a communication according to various mobile communication standards such as 3 rd  Generation (3G), 3 rd  Generation Partnership Project (3GPP), Long Term Evolution (LTE), etc. 
     The voice recognizer  130  performs a voice recognition process with respect to the uttered voice of the user input through the input  110  to generate first voice information. Here, the first voice information may be text information into which the voice signal of the uttered voice of the user is converted. According to exemplary embodiments, the voice recognizer  130  may convert the uttered voice of the user into a text by using an STT algorithm. 
     For example, if an uttered voice “Turn up the volume!” is inputted, the input  110  converts the uttered voice “Turn up the volume!” into a digital voice signal. In this case, the voice recognizer  130  may generate text type of first voice information from the voice signal of the uttered voice “Turn up the volume!” Here, the voice recognizer  130  may generate first voice information related to the uttered voice of the user based on a candidate group of a plurality of pieces of voice information that are stored in the storage  150  and calculate a reliability value of the generated first voice information. 
     The controller  140  controls overall operations of the elements of the display apparatus  100 . In particular, if the uttered voice of the user is converted into the digital voice signal through the input  110 , the controller  140  controls the voice recognizer  130  to perform a voice recognition process based on the voice signal. Also, if the uttered voice of the user is converted into the digital voice signal through the input  110 , the controller  140  controls the communicator  120  to transmit the voice signal to the voice recognition apparatus  200 . Therefore, the voice recognizer  130  may perform the voice recognition with respect to the uttered voice of the user through an operation as described above, and the communicator  120  may transmit the voice signal of the uttered voice of the user to the voice recognition apparatus  200 . 
     The controller  140  determines the first or second voice information which has a reliability value equal to a preset threshold value (hereinafter referred to as a first threshold value) among the reliability value of the first voice information recognized by the voice recognizer  130  and a reliability value of second voice information included in the voice recognition result received from the voice recognition apparatus  200 , as an execution command of the uttered voice of the user. 
     For example, the user may utter a voice “Show me MBC!”. If this uttered voice is input, the input  110  may convert the inputted uttered voice into a digital voice signal, and the voice recognizer  130  may generate first voice information related to the uttered voice of the user based on a candidate group of a plurality of pieces of voice information stored in the storage  150  and calculate a reliability value of the generated first voice information as described above. 
     For example, the storage  150  may store voice information corresponding to 100 candidate groups of uttered voices such as MBC, KBS, SBS, EBS, turn up the channel, turn down the channel, turn up the volume, turn down the volume, etc. In this case, if text type of voice information “Show me MBC!” is generated from the voice signal of the uttered voice of the user, the voice recognizer  130  may recognize voice information “MBC” of voice information “Show me MBC!” as first voice information of the uttered voice of the user based on the voice information corresponding to 100 candidate groups stored in the storage  150  and recognize the other voice information, i.e., “Show me”, as noise. The voice recognizer  130  may calculate a reliability value of the first voice information based on voice information corresponding to candidate groups stored in the storage  150 . As in the above-described example, the storage  150  may store voice information “MBC” among voice information corresponding to 100 candidates, and the first voice information recognized from the uttered voice of the user may be “MBC.” In this case, since voice information matching the first voice information is stored in the storage  150 , the voice recognizer  130  may calculate a reliability value as 100. 
     Similarly to this, if the voice signal of the uttered voice of the user is received from the display apparatus  100 , the voice recognition apparatus  200  may recognize the uttered voice of the user from the received voice signal to calculate second voice information and a reliability value of the second voice information. 
     According to the exemplary embodiments, the voice recognition apparatus  200  may convert the uttered voice of the user into a text by using an STT algorithm. As in the above-described example, if the voice signal of the uttered voice “Show me MBC!” is received, the voice recognition apparatus  200  may generate text type of second voice information “Show me MBC!” by using an STT algorithm. The voice recognition apparatus  200  may calculate a reliability value of the text type of second voice information “Show me MBC!” based on the candidate group of the plurality of pieces of voice information that are stored in the voice recognition apparatus. The reliability value of the second voice information may be lower than or equal to the reliability value of the first voice information calculated through the voice recognizer  130  of the display apparatus  100 . The calculation of the reliability value based on the first or second voice information recognized from the voice signal is a well-known technology, and thus a detailed description thereof is omitted herein. 
     The voice recognition apparatus  200  is an apparatus that performs the voice recognition with respect to the uttered voice of the user and may store many more pieces of voice information of the uttered voice than the display apparatus  100 . In other words, the number of objects of a candidate group corresponding to voice information related to an uttered voice stored in the voice recognition apparatus  200  may be larger than the number of objects of a candidate group corresponding to voice information related to an uttered voice stored in the display apparatus  100 . Since a larger number of objects of the candidate group corresponding to the voice information exist than in the display apparatus  100  as described above, there is a high possibility that voice information similar to the second voice information recognized by the voice recognition apparatus  200  will exist. Therefore, although there is a high possibility that the second voice information recognized by the voice recognition apparatus  200  will be more similar to the uttered voice of the user than the first voice information recognized by the voice recognizer  130  of the display apparatus  100 , there is a high possibility that the reliability value of the second voice information calculated through the voice recognition apparatus  200  will be lower than or equal to the reliability value of the first voice information calculated through the voice recognizer  130 . 
     If the reliability value of the second voice information is calculated, the voice recognition apparatus  200  transmits a voice recognition result, including the second voice information and the reliability value of the second voice information, to the display apparatus  100 . 
     If the voice recognition result is received, the controller  140  may determine the first or second voice information which has a reliability value greater than or equal to a preset first threshold value among the reliability value of the second voice information included in the received recognition result and the reliability value of the first voice information calculated through the voice recognizer  130 , as an execution command. For example, the reliability value of the second voice information may be 85, and the reliability value of the first voice information may be 100 as in the above-described example. Also, if the preset first threshold value is set to 90, the controller  140  may determine the first voice information among the first voice information and the second voice information which has a reliability value greater than the first threshold value to be an execution command. 
     Therefore, the controller  140  acquires a control command related to the first voice information among control commands corresponding to the plurality of pieces of voice information stored in the storage  150 , and performs a control operation based on the acquired control command. In other words, the controller  140  may change a currently selected channel into channel MBC according to a control command related to the first voice information generated in relation to the uttered voice “Show me MBC!”. 
     If the reliability values of the first voice information and the second voice information are greater than or equal to the preset first threshold value, the controller  140  may determine the first or second voice information as an execution command according to similarity between the text information of the first voice information and the second voice information. For this, the controller  140  may have a structure as shown in  FIG. 4 . 
       FIG. 4  is a block diagram illustrating a detailed structure of the controller  140 , according to an exemplary embodiment. 
     Referring to  FIG. 4 , the controller  140  includes a similarity processor  145  and an execution command determiner  143 . 
     In detail, if reliability values of first voice information and second voice information are greater than or equal to a first threshold, the similarity processor  145  compares lengths of character strings generated from text information of the first voice information and the second voice information to determine whether there is voice information which has a longer character string among the first voice information and the second voice information. If it is determined that one of the first voice information and the second voice information has a longer character string than the other, the execution command determiner  143  determines the first or second voice information which has the longer character string to be an execution command. 
     An operation of comparing lengths of character strings of text information of first voice information and second voice information to determine an execution command of an uttered voice of a user if reliability values of the first voice information and the second voice information are greater than or equal to a first threshold value, will now be described in detail. 
       FIG. 5  is a view illustrating a comparison between lengths of character strings of text information of first voice information and second voice information, according to an exemplary embodiment. 
     As shown in  FIG. 5 , the voice recognizer  130  of the display apparatus  100  may generate first voice information  520  “recommended” in relation to an uttered voice  510  “recommended channel”, and the voice recognition apparatus  200  may generate second voice information  530  “recommended channel” in relation to the uttered voice  510  “recommended channel”. If reliability values of the first voice information  520  and the second voice information  530  are greater than or equal to a preset first threshold value, the similarity processor  145  generates character strings from text information of the first voice information  520  and the second voice information  530 . As shown in  FIG. 5 , a character string  521  “[#c{u.c{On#]” may be generated from the text information of the first voice information  520 , and a character string  531  “[#c{u.c{On.c{En.O1#]” may be generated from the text information of the second voice information  530 . 
     If the character strings  521  and  531  of the respective first voice information  520  and the second voice information  530  are generated, the similarity processor  145  calculates a similarity value  540  based on the character strings  521  and  531  of the respective first voice information  520  and the second voice information  530 . As shown in  FIG. 5 , since a length of the character string  531  of the second voice information  530  is longer than a length of the character string  521  of the first voice information  520 , the similarity value  540  which is lower than a preset threshold value may be calculated. 
     If the similarity value  540  which is lower than the preset threshold value is calculated, the execution command determiner  143  may determine the second voice information  530  among the first voice information  520  and the second voice information  530  as a voice recognition result similar to an uttered voice of a user and determine the second voice information  530  as an execution command of the uttered voice of the user. 
     If lengths of character strings of the text information of the first voice information and the second voice information are the same, the similarity processor  145  calculates a similarity value of pronunciation strings generated from the text information of the first voice information and the second voice information by using a predefined similarity algorithm. Here, the predefined similarity algorithm may be confusion matrix. However, the present exemplary embodiment is not limited thereto, and the similarity processor  145  may compare the pronunciation strings generated from the text information of the first voice information and the second voice information to calculate the similarity value based on how many of the same pronunciation characters the pronunciation strings include. 
     If the similarity value of the pronunciation strings generated from the text information of the first voice information and the second voice information is calculated as described above, the execution command determiner  143  may compare the calculated similarity value with a preset threshold value (hereinafter referred to as a second threshold value). If the calculated similarity value is greater than or equal to the second threshold value, the execution command determiner  143  may determine the first voice information as an execution command of the uttered voice of the user. If the calculated similarity value is lower than the second threshold value, the execution command determiner  143  may determine the second voice information as an execution command of the uttered voice of the user. 
     An operation of determining an execution command of an uttered voice of a user according to similarity between pronunciation strings generated from text information of first voice information and second voice information if lengths of character strings generated from the text information of the first voice information and the second voice information are the same, or a similarity value of the lengths of the character strings is greater than or equal to a preset threshold value, will now be described in detail. 
       FIG. 6  is a view illustrating similarity information of pronunciation strings of text information of first voice information and second voice information, according to an exemplary embodiment exemplary embodiment. 
     As shown in  FIG. 6 , the voice recognizer  130  of the display apparatus  100  may generate first voice information  620  “fitness” in relation to an uttered voice  610  “fitness”, and the voice recognition apparatus  200  may generate second voice information  630  “business” in relation to the uttered voice  610  “fitness”. Reliability values of the first voice information  620  and the second voice information  630  may be greater than or equal to a preset first threshold value, and lengths of character strings generated from text information of the first voice information  620  and the second voice information  630  may be the same. In this case, the similarity processor  145  generates pronunciation strings from the text information of the first voice information  620  and the second voice information  630 . As shown in  FIG. 6 , a pronunciation string  621  “[#p{i.t{u-.ni.su#]” may be generated from the text information of the first voice information  620 , and a pronunciation string  631  “[#pi.j-u-.ni.s&#39;u-#]” may be generated from the text information of the second voice information  630 . 
     If the pronunciation strings  621  and  631  of the first voice information  620  and the second voice information  630  are generated, the similarity processor  145  calculates a similarity value  640  according to a similarity between the pronunciation strings  621  and  631  of the respective first voice information  620  and the second voice information  630 . In detail, the similarity processor  145  may compare pronunciation characters belonging to the pronunciation strings  621  and  631  of the respective first voice information  620  and the second voice information  630  to calculate the similarity value  640  based on how many of the same pronunciation characters the pronunciation strings  621  and  631  include. 
     If the similarity value  640  is calculated, the execution command determiner  143  compares the similarity value  640  with a preset second threshold value. If the similarity value  640  is greater than or equal to the second threshold value according to the comparison result, the execution command determiner  143  may determine the first voice information  620 , among the first voice information  620  and the second voice information  630 , to be a voice recognition result which is similar to an uttered voice of a user, and determine the first voice information  620  to be an execution command of the uttered voice of the user. 
     If the similarity value  640  is lower than the preset second threshold value, the execution command determiner  143  may determine the second voice information  630 , among the first voice information  620  and the second voice information  630 , to be a voice recognition result similar to the uttered voice of the user, and determine the second voice information  630  to be an execution command of the uttered voice of the user. 
     As shown in  FIG. 4 , the controller  140  may further include an apparatus status manager  141 . The execution command determiner  143  may determine whether preset voice information determined as an execution command will be determined as a final execution command based on an execution result of the apparatus status manager  141 . 
     In detail, the apparatus status manager  141  periodically monitors a current operation mode of the display apparatus  100  and transmits the monitoring result to the execution command determiner  143 . Therefore, if first or second voice information is determined as an execution command of the uttered voice of the user, the execution command determiner  143  may determine the first or second voice information determined as the execution command as a final execution command according to whether a domain of the current operation mode of the display apparatus  100  corresponds to a domain of the first or second voice information determined as the execution domain. In other words, if the domain of the current operation mode of the display apparatus  100  corresponds to the domain of the first or second voice information determined as the execution command, the execution command determiner  143  determines the first or second voice information determined as the execution command as a final execution command. If the domain of the current operation mode of the display apparatus  100  does not correspond to the domain of the first or second voice information determined as the execution command, the execution command determiner  143  may determine the first or second voice information, which is not determined as an execution command, as a final execution command. 
     According to the exemplary embodiments, if first voice information among the first voice information and the second voice information is determined as an execution command, the execution command determiner  143  may determine a domain based on the first voice information. For example, first voice information that is determined as an execution command in relation to an uttered voice “Search for action movie!” may include text information “action”. In this case, the execution command determiner  143  may determine a domain of the first voice information as an apparatus control-related domain for changing a channel based on a control command related to the first voice information “action”. 
     If the display apparatus  100  operates in an application execution mode based on status information about the current operation mode of the display apparatus  100  monitored through the apparatus status manager  141 , the execution command determiner  143  may determine a domain of the current operation mode of the display apparatus  100  as a content recommendation-related domain. 
     If the domain of the first voice information determined as the execution command and the domain of the current operation mode of the display apparatus  100  are determined as described above, the execution command determiner  143  determines whether the two domains correspond to each other. If it is determined that the two domains do not correspond to each other, the execution command determiner  143  may determine second voice information, which is not determined as an execution command, as a final execution command. 
     If the first voice information determined as the execution command is a control-related execution command for controlling an operation of an apparatus, and the display apparatus  100  operates in the application execution mode, the controller  140  may not control an operation of the display apparatus  100  based on the first voice information determined as the execution command. Therefore, if the two domains do not correspond to each other, the execution command determiner  143  may determine the second voice information, which is not determined as the execution command, as a final execution command, and the controller  140  may transmit the second voice information determined as the final execution command to the interactive server  300  through the communicator  120  to receive response information related to the uttered voice of the user. 
     If reliability values of the first voice information and the second voice information are lower than a first threshold value, the controller  140  determines domains of the first voice information and the second voice information and applies a weight to a reliability value of the first or second voice information which has the determined domain corresponding to the current operation mode of the display apparatus  100 . The controller  140  may determine the first or second voice information, to which the weight is applied, as an execution command according to whether the reliability value of the first or second voice information is greater than or equal to a first threshold value. 
     In detail, if the reliability values of the first voice information and the second voice information are lower than the first threshold value, the controller  140  may determine the first or second voice information as an execution command based on the apparatus status manager  141  and the execution command determiner  143  described above with reference to  FIG. 4 . 
     In more detail, if the reliability values of the first voice information and the second voice information are lower than the first threshold value, the execution command determiner  143  determines domains of the first voice information and the second voice information. For example, the current operation mode of the display apparatus  100  may be the application execution mode. In this case, the execution command determiner  143  may determine the domain of the current operation mode of the display apparatus  100  as a content recommendation-related domain. Also, the execution command determiner  143  may determine the domain of the first voice information as a control-related domain for controlling an apparatus operation and determine the domain of the second voice information as a content recommendation-related domain. 
     If the domains of the first voice information and the second voice information and the domain of the current operation mode of the display apparatus  100  are determined as described above, the execution command determiner  143  may acquire first or second voice information which have a domain corresponding to the domain determined in relation to the current operation mode of the display apparatus  100 . As in the above-described example, the domain of the second voice information may correspond to the domain determined in relation to the current operation mode of the display apparatus  100 . In this case, the execution command determiner  143  applies a weight to the reliability value of the second voice information. The execution command determiner  143  determines whether the reliability of the second voice information to which the weight is applied is greater than or equal to the first threshold value. 
     If it is determined that the reliability value of the second voice information to which the weight is applied is lower than the first threshold value, the execution command determiner  143  ends the determining of the execution command of the uttered voice of the user in relation to the first voice information and the second voice information. If the determining of the execution command is ended, the controller  140  generates a notification message for requesting re-uttering of the user&#39;s voice, and controls the display  160  to display the generated notification message on a screen. 
     If it is determined that the reliability value of the second voice information to which the weight is applied is greater than or equal to the first threshold value, the execution command determiner  143  determines the second voice information as an execution command of the uttered voice of the user. If an execution command of the first or second voice information is determined, the controller  140  may perform a control operation or transmit the corresponding first or second voice information to the interactive server  300  based on the first or second voice information determined as the execution information. 
     In detail, if the first voice information is determined as an execution command through the execution command determiner  143 , the controller  140  performs the control operation according to a control command corresponding to the first voice information determined as the execution command among control commands corresponding to a plurality of pieces of voice information stored in the storage  150 . If the second voice information is determined as an execution command through the execution command determiner  143 , the controller  140  transmits the second voice information to the interactive server  300  through the communicator  120  to receive response information related to the second voice information from the interactive server  300 . If the response information related to the second voice information is received, the display  160  may display a voice recognition result of the received response information on the screen according to the control command of the controller  140 . 
     If an uttered voice of a user is input as described above, the display apparatus  100  according to the present exemplary embodiment performs a voice recognition process with respect to the inputted uttered voice and simultaneously receives a voice recognition result of the uttered voice from the voice recognition apparatus  200 . After that, the display apparatus  100  performs an operation based on a voice recognition result appropriate for an intent of the user among a voice recognition result that is internally recognized and a voice recognition result that is received from the voice recognition apparatus  200  to actively cope with various types of utterances made by the user. 
     A structure of the interactive server  300  will now be described in detail. 
       FIG. 7  is a block diagram of the interactive server  300 , according to an exemplary embodiment. 
     Referring to  FIG. 7 , the interactive server  300  includes a communicator  310 , an extractor  320 , a storage  330 , and a controller  340 . 
     The communicator  310  may communicate with the display apparatus  100  to receive second voice information, which is converted into text information in relation to an uttered voice of a user, from the display apparatus  100 . The extractor  320  extracts utterance factors from the second voice information received from the display apparatus  100  through the communicator  310 . The second voice information may include a first utterance factor indicating an execution object and a second utterance factor indicating an execution command. In detail, the first utterance factor indicating the execution object is an utterance factor that is classified as a main feature in the uttered voice of the user, and the second utterance factor indicating the execution command is an utterance factor that is classified as a user action in the uttered voice of the user. For example, in an uttered voice “Search for action movie!”, “action” may be a first utterance factor classified as a main feature, and “Search for” may be a second utterance factor classified as a user action. 
     If these utterance factors are extracted, the controller  340  generates response information related to the uttered voice of the user based on functions classified according to the extracted utterance factors and transmits the response information to the display apparatus  100 . Here, the functions classified according to the utterance factors may include at least one of a content recommendation function, an electronic program guide (EPG)-related function, and an operation control function for controlling an operation of the display apparatus  100 . Therefore, the controller  340  may generate response information corresponding to the uttered voice of the user based on the utterance factors extracted from the second voice information of the uttered voice of the user. 
     For example, if second voice information “Search for ∘∘∘ (content name)” of an uttered voice of the user is received, the extractor  320  may extract a first utterance factor “∘∘∘ (content name)” and a second utterance factor “Search for”. If the first and second utterance factors are extracted from the uttered voice “Search for ∘∘∘ (content name)”, the controller  340  determines that an execution area is a content based on the extracted first utterance factor. The controller  340  may also acquire an execution word “$∘∘∘ (content name)$” corresponding to the first utterance factor “∘∘∘ (content name)” with reference to execution words that are respectively defined according to first utterance factors stored in the storage  330 . Also, the controller  340  determines that a type of the second utterance factor “Search for” is related to a content search, based on the execution area determined as the content. Therefore, the controller  340  may acquire a command “content_search” corresponding to the content search among commands that are respectively defined according to second utterance factors stored in the storage  330 . The controller  340  may combine the execution word “$∘∘∘ (content name)$” and the command “content_search” corresponding to the first and second utterance factors to generate an execution command script “content_search($∘∘∘ (content name)$)”. If such an execution command script is generated, the controller  340  transmits response information including the generated execution command script to the display apparatus  100 . Therefore, the display apparatus  100  may receive content information of each episode of “∘∘∘ (content name)” from a content providing server (not shown) based on the execution command script included in the response information received from the interactive server  300  and display a content list of the received content information of each episode on a screen. 
     As another example, the extractor  320  may extract a first utterance factor “bedtime reservation” and a second utterance factor “make” from second voice information of an uttered voice “Make bedtime reservation.” If first and second utterance factors are extracted from the uttered voice “Make bedtime reservation.”, the controller  340  determines that an execution area is an apparatus control, based on the extracted first utterance factor. The controller  340  may also acquire an execution word “$bedtime reservation$” corresponding to the first utterance factor “bedtime reservation” with reference to execution words that are respectively defined according to first utterance factors stored in the storage  330 . Also, the controller  340  determines that a type of the second utterance factor “make” corresponds to an apparatus function execution, based on the execution area determined as the apparatus control. Therefore, the controller  340  may acquire a command “device_execute” corresponding to the apparatus function execution among commands that are respectively defined according to second utterance factors stored in the storage  330 . The controller  340  may combine the execution word “$bedtime reservation$” and the command “device_execute” corresponding to the first and second utterance factors to generate an execution command script. If the execution command script is generated, the controller  340  transmits response information including the generated execution command script to the display apparatus  100 . Therefore, the display apparatus  100  may set a bedtime reservation based on the execution command script included in the response information received from the interactive server  300  and output a notification message for notifying the interactive server  300  that the bedtime reservation is set, through at least one of a voice notification and a text notification. 
     The elements of the interactive server  300  according to the present exemplary embodiment have been described in detail. A method of controlling the display apparatus  100  according to an exemplary embodiment will now be described in detail. 
       FIG. 8  is a flowchart of a method of controlling the display apparatus  100 , according to an exemplary embodiment. 
     Referring to  FIG. 8 , if an uttered voice of a user is input, the display apparatus  100  samples the inputted uttered voice and converts the uttered voice into a digital voice signal in operation S 810 . In operation S 820 , the display apparatus  100  performs a voice recognition process with respect to the uttered voice converted into the voice signal to generate first voice information and calculates a reliability value of the first voice information. The first voice information may be text information into which the voice signal of the uttered voice of the user is converted. According to exemplary embodiments, the display apparatus  100  may convert the uttered voice of the user into a text by using an STT algorithm. In detail, the display apparatus  100  may generate the first voice information related to the uttered voice of the user based on a candidate group of a plurality of pieces of pre-stored voice information and calculate a reliability value of the first voice information. 
     In operation S 830 , the display apparatus  100  transmits the uttered voice of the user converted into the digital voice signal to the voice recognition apparatus  200 . However, the exemplary embodiment is not limited thereto, and the display apparatus  100  may simultaneously perform operations S 820  and  830 . 
     If a voice recognition result of the uttered voice of the user is received from the voice recognition apparatus  200 , the display apparatus  100  compares the reliability value of the first voice information calculated in operation S 820  and a reliability value of second voice information included in the voice recognition result received from the voice recognition apparatus  200  with a preset first threshold value in operation S 840 . The second voice information may be text information into which the voice signal of the uttered voice of the user is converted. 
     If the reliability value of the first voice information or second voice information is greater than or equal to the first threshold value, the display apparatus  100  determines one of the first voice information or the second voice information which has a reliability value greater than or equal to the first threshold value as an execution command of the uttered voice of the user in operation S 850 . If it is determined in operation S 860  that the first voice information among the first voice information and the second voice information is determined to be the execution command of the uttered voice of the user, the display apparatus  100  performs a control operation according to a control command corresponding to the first voice information among control commands corresponding to the plurality of pre-stored pieces of voice information, in operation S 870 . 
     If it is determined in operation S 860  that the second voice information among the first voice information and the second voice information is determined to be the execution command of the uttered voice of the user, the display apparatus  100  transmits the second voice information determined to be the execution command to the interactive server  300  in operation S 880 . If response information related to the second voice information is received from the interactive server  300 , the display apparatus  100  generates a voice recognition result related to the received response information and displays the voice recognition result on a screen in operation S 890 . 
     If the reliability values of the first voice information and the second voice information are greater than or equal to the first threshold value in operation S 840 , the display apparatus  100  may determine the first or second voice information to be an execution command of the uttered voice of the user according to the following method. 
       FIG. 9  is a flowchart of a method of determining first or second voice information as an execution command of an uttered voice of a user if reliability values of the first voice information and the second voice information are greater than or equal to or lower than a preset first threshold value in the display apparatus  100 , according to an exemplary embodiment. 
     Referring to  FIG. 9 , in operation S 910 , the display apparatus  100  determines whether reliability values of first voice information and second voice information are greater than or equal to a preset first threshold value. If it is determined in operation S 910  that the reliability values of the first voice information and the second voice information are greater than or equal to the preset first threshold value, the display apparatus  100  generates character strings from text information of the first voice information and the second voice information and compares lengths of the character strings to determine whether the lengths of the character strings are the same in operation S 915 . If it is determined in operation S 915  that the lengths of the character strings generated from the text information of the first voice information and the second voice information are different from each other, the display apparatus  100  determines one of the first voice information or the second voice information which has the longer character string to be an execution command of an uttered voice of a user in operation S 920 . 
     If it is determined in operation S 915  that the lengths of the character strings generated from the text information of the first voice information and the second voice information are the same, the display apparatus  100  calculates a similarity value of pronunciation strings generated from the text information of the first voice information and the second voice information by using a predefined similarity algorithm in operation S 925 . Here, the predefined similarity algorithm may be a confusion matrix. However, the present exemplary embodiment is not limited thereto, and the display apparatus  100  may compare the pronunciation strings generated from the text information of the first voice information and the second voice information to calculate the similarity value based on how many of the same pronunciation characters the pronunciation strings include. 
     If the similarity value of the pronunciation strings generated from the text information of the first voice information and the text information of the second voice information is calculated as described above, the display apparatus  100  compares the calculated similarity value with a preset second threshold value to determine whether the calculated similarity value is greater than or equal to the preset second threshold value in operation S 930 . 
     If it is determined in operation S 930  that the similarity value is greater than or equal to the preset second threshold value, the display apparatus  100  determines the first voice information among the first voice information and the second voice information as a voice recognition result which is similar to the uttered voice of the user, and determines the first voice information to be an execution command of the uttered voice of the user in operation S 935 . If it is determined in operation S 930  that the similarity value is lower than the preset second threshold value, the display apparatus  100  determines the second voice information among the first voice information and the second voice information to be a voice recognition result which is similar to the uttered voice of the user, and determines the second voice information to be an execution command of the uttered voice of the user in operation S 940 . 
     According to another exemplary embodiment, the display apparatus  100  may determine whether voice information determined as an execution command in the above-described operation is determined to be a final execution command. 
     For this, if the first or second voice information is determined to be the execution command of the uttered voice of the user, the display apparatus  100  determines a domain of the first or second voice information determined to be the execution command and a domain of a current operation mode of the display apparatus  100  in operation S 945 . In operation S 950 , the display apparatus  100  determines the first or second voice information which has a domain corresponding to the domain of the current operation mode of the display apparatus  100  to be a final execution command. 
     In detail, the display apparatus  100  determines whether the domain of the first voice information or the second voice information determined to be the execution command, and the domain of the current operation mode of the display apparatus  100  correspond to each other. If it is determined that the two domains correspond to each other, the display apparatus  100  may determine the first voice information or the second voice information determined to be the execution command as a final execution command. If it is determined that the two domains do not correspond to each other, the display apparatus  100  determines whether the domain of first voice information or the second voice information that is not determined as an execution command corresponds to the domain of the current operation mode of the display apparatus  100 . If it is determined that the two domains correspond to each other, the display apparatus  100  may determine the first or second voice information that is not determined as the execution command, as a final execution command. 
     If it is determined in operation S 910  that the reliability values of the first voice information and the second voice information are lower than the preset first threshold value, the display apparatus  100  determines domains of the first voice information and the second voice information in operation S 955 . If the domains of the first voice information and the second voice information are determined, the display apparatus  100  applies a weight to a reliability value of the first or second voice information which has a domain corresponding to the domain of the current operation mode of the display apparatus  100  in operation S 960 . Here, the weight may be a value enough to secure a reliability value greater than or equal to the first threshold value. If the weight is applied to the reliability value of the first or second voice information having the domain corresponding to the domain of the current operation mode of the display apparatus  100  as described above, the display apparatus  100  may determine the corresponding first or second voice information as an execution command of the uttered voice of the user. 
     However, the present exemplary embodiment is not limited thereto, and the weight that is applied to the reliability value of the first or second voice information having the domain corresponding to the domain of the current operation mode of the display apparatus  100  may be a preset fixed value. In this case, if a weight having a value of fixed size is applied to the reliability value of the first or second voice information having the domain corresponding to the domain of the current operation mode of the display apparatus  100 , the display apparatus  100  re-determines whether the reliability value of the first or second voice information to which the weight is applied is greater than or equal to the preset first threshold value. If it is determined that the reliability value of the first or second voice information to which the weight is applied is greater than or equal to the first threshold value, the display apparatus  100  determines the corresponding first or second voice information as an execution command of the uttered voice of the user. If it is determined that the reliability value of the first voice information or the second voice information to which the weight is applied is lower than the first threshold value, the display apparatus  100  displays a notification message on the screen, requesting re-uttering of the voice input by the user. Therefore, the user may perform re-uttering of the voice input, and the display apparatus  100  may perform a voice recognition process with respect to a re-uttered voice of the user. 
     According to various exemplary embodiments as described above, if a display apparatus and an external apparatus simultaneously recognize an uttered voice of a user in an interactive system, the display apparatus may select a voice recognition result proximate to an intent of the user from two voice recognition results. 
     The foregoing exemplary embodiments and advantages are merely exemplary and are not to be construed as limiting. The present teaching can be readily applied to other types of apparatuses. Also, the description of the exemplary embodiments is intended to be illustrative, and not to limit the scope of the claims, and many alternatives, modifications, and variations will be apparent to those skilled in the art.