Patent Publication Number: US-2022215854-A1

Title: Speech sound response device and speech sound response method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-000096, filed on Jan. 4, 2021, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a speech sound response device and a speech sound response method. 
     BACKGROUND 
     A speech sound dialogue device (a speech sound response device) such as an artificial intelligence (AI) speaker (smart speaker) inputs a voice uttered by the user as an input speech sound and performs speech sound recognition on the content of the received input speech sound. The speech sound dialogue device outputs response content generated in response to the result of the speech sound recognition with respect to the input speech sound as a response speech sound. Generally, if the volume of the input speech sound is too loud, or the volume of the input speech sound is too low, it is difficult for the speech sound dialogue device to obtain a correct recognition result by the speech sound recognition. It is considered that the speech sound dialogue device is likely to control the loudness of the voice uttered by a talker (user) by controlling the volume of the output response speech sound. This is because the talker may control the loudness of the voice to be uttered in response to the loudness of a voice of a partner to talk to. 
     However, the speech sound dialogue device in the related art cannot flexibly change the volume of the response speech sound because the response speech sound has a preset volume or a volume defined by the user. Further, the speech sound dialogue device uses a microphone to collect not only the talker&#39;s voice but also sounds other than the talker&#39;s voice. Therefore, the speech sound dialogue device has a problem that it is difficult to improve the accuracy of speech sound recognition even if the volume of the response speech sound can be simply set in response to the volume of the input speech sound. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram schematically illustrating a configuration example of a speech sound response device according to an embodiment; 
         FIG. 2  is a block diagram illustrating a configuration example of a control system; 
         FIG. 3  is a diagram illustrating an example of a function for determining a response volume from an input volume if an environmental volume is less than a threshold value; 
         FIG. 4  is a diagram illustrating an example of a function for determining the response volume from the input volume if the environmental volume is the threshold value or more; 
         FIG. 5  is a diagram illustrating an example of a table for selecting a function in response to the environmental volume and the input volume; 
         FIG. 6  is a flowchart for explaining an operation example; 
         FIG. 7  is a flowchart for explaining a calculating process of a response volume; and 
         FIG. 8  is a flowchart for explaining the calculating process of the response volume. 
     
    
    
     DETAILED DESCRIPTION 
     In order to solve the above problem, a speech sound response device and a speech sound response method that can realize a highly accurate speech sound response are provided. 
     In general, according to one embodiment, a speech sound response device includes a microphone, a processor, and a speaker. The microphone inputs a sound. The processor generates a response content by a speech sound in response to a voice uttered by a user to be detected from the sound input by the microphone and determines a volume for outputting the response content as a response speech sound in response to an input volume as a volume of the voice uttered by the user and a volume of an environmental sound other than the voice uttered by the user. The speaker outputs the response speech sound in the volume determined by the processor. 
     Hereinafter, the embodiment is described with reference to the drawings. 
       FIG. 1  is a diagram schematically illustrating the speech sound response device  1  according to the embodiment. As illustrated in  FIG. 1 , the speech sound response device  1  according to the embodiment includes a microphone  2  and a speaker  3 . The speech sound response device  1  is a device that outputs a response speech sound from the speaker  3  in response to the speech sound of the talker input to the microphone  2 . 
     The speech sound response device  1  is, for example, a speech sound dialogue device referred to as an AI speaker. The speech sound response device  1  may be an information process device such as a smartphone, a tablet terminal, or a personal computer. The speech sound response device  1  may be a device obtained by connecting any one or both of the microphone  2  and the speaker  3  to the information process device. 
     The speech sound response device  1  collects a sound including a voice uttered by a talker (speech sound) and the environmental sound with the microphone  2 . The speech sound response device  1  detects the voice uttered by the talker (input speech sound) from the sound collected with the microphone  2 . The speech sound response device  1  recognizes the content of the input speech sound (the content of the talk uttered by the talker) by performing speech sound recognition on the detected input speech sound. The speech sound response device  1  generates the response content uttered as the response speech sound in response to the content of the recognized input speech sound. 
     Further, the speech sound response device  1  according to the present embodiment measures (calculates) the volume of the voice uttered by the talker (input speech sound) and the volume of the sound other than the voice uttered by the talker (environmental sound). The speech sound response device  1  holds a plurality of functions (or tables) for determining the volume of the response speech sound. The plurality of functions in order to determine the volume of the response speech sound is set in response to the combination of the loudness of the environmental sound and the loudness of the input speech sound. The speech sound response device  1  selects the function (or the table) based on the volume of the input speech sound and the volume of the environmental sound measured from the sound collected with the microphone  2 . The speech sound response device  1  determines the volume of the response speech sound in response to the volume of the input speech sound according to the selected function. The speech sound response device outputs the response content generated in response to the content of the input speech sound as the response speech sound of the volume determined from the volume of the input speech sound and the volume of the environmental sound from the speaker  3 . 
     Subsequently, the configuration of the speech sound response device  1  according to the embodiment is described.  FIG. 2  is a block diagram illustrating the configuration example of the speech sound response device  1  according to the embodiment. As illustrated in  FIG. 2 , the speech sound response device  1  includes a processor  11 , a main storage device  12 , an auxiliary storage device  13 , a speech sound processing circuit  14 , the microphone  2 , and the speaker  3 . 
     The processor  11  controls the entire speech sound response device  1 . The processor  11  is, for example, a central processing unit (CPU). The processor  11  performs various processes described below by executing programs. For example, the processor  11  performs various processes such as operation control of the speech sound response device  1 , speech sound detection, speech sound recognition, response sentence generation, input speech sound volume measurement, environmental sound volume measurement, response speech sound volume calculation, and response waveform generation. 
     The main storage device  12  is a main memory that stores data. The main storage device  12  is, for example, configured with a random-access memory (RAM). The main storage device  12  temporarily stores data during the process by the processor  11 . The main storage device  12  may store data required for executing a program and an execution result of the program. The main storage device  12  also operates as a buffer memory for temporarily holding data. 
     For example, the main storage device  12  functions as a memory that stores, for example, information indicating the volume of the environmental sound calculated from the sound collected with the microphone. For example, the main storage device  12  stores data of the speech sound obtained by processing the sound collected with the microphone  2  by the speech sound processing circuit  14 . Further, the main storage device  12  may store the calculation result of the volume of the voice uttered by talker (input speech sound) included in the sound collected with the microphone  2 . The main storage device  12  may store the information indicating the volume of the response speech sound determined in response to the volume of the input speech sound and the volume of the environmental sound. 
     The auxiliary storage device  13  is storage that stores data. The auxiliary storage device  13  includes a non-rewritable non-volatile memory such as a read-only memory (ROM), a rewritable non-volatile memory, and the like. Examples of the rewritable non-volatile memory include a hard disk drive (HDD), a solid state drive (SSD), an electrically erasable programmable read-only memory (EEPROM) (registered trademark), or a flash ROM. 
     The auxiliary storage device  13  stores a program executed by the processor  11  and control data. For example, the auxiliary storage device  13  stores a speech sound response program in order to output the response speech sound in response to the input speech sound. The speech sound response program includes programs that perform various processes as described below such as speech sound detection, speech sound recognition, intention analysis, response sentence generation, input volume calculation, environmental volume calculation, response volume calculation, and response waveform generation. In addition, a portion or all of the processes performed by executing the programs by the processor  11  described below may be performed by hardware such as processing circuits. 
     In the example illustrated in  FIG. 2 , the auxiliary storage device  13  adds the volume of the environmental sound (environmental volume) and stores a function table  13   a  in order to select a function for determining the volume of the response speech sound in response to the volume of the input speech sound (input volume). The function table  13   a  is specifically described below. 
     The microphone  2  collects (acquires) a sound. The microphone  2  inputs, for example, a collected sound as an analog signal (analog waveform) and outputs the analog signal of the input sound to the speech sound processing circuit  14 . The speech sound processing circuit  14  receives the analog signal of the sound collected by the microphone  2  and outputs sound data as digital data obtained by digitalizing the analog signal of the input sound. The speech sound processing circuit  14  includes an AD converter or the like that digitalizes an analog waveform. The microphone  2  may be an external device connected to the speech sound response device  1 . 
     If the microphone  2  is an external device, the speech sound processing circuit  14  may include an interface that connects the microphone  2  for receiving a speech sound. 
     The speaker  3  outputs a speech sound. The speaker  3  utters a response speech sound based on the response waveform supplied from the processor  11 . The speaker  3  controls a volume by the processor  11 . For example, the speaker  3  utters a response speech sound based on the response waveform of which the amplitude is adjusted by the processor  11  in response to the volume of the response speech sound. The speaker  3  may be an external device connected to the speech sound response device  1 . If the speaker  3  is an external device, the speech sound response device  1  may include an interface that outputs a signal indicating a waveform of a sound to be output to the speaker  3 . 
     Subsequently, a function for determining a volume of a response speech sound (response volume) by the speech sound response device  1  according to the embodiment is described. The speech sound response device  1  recognizes the voice uttered by the talker and outputs a response to the speech uttered by the talker (input sentence) by a speech sound. The speech sound response device  1  generates the response content with respect to the voice uttered by the talker and also determines the response volume by using the function selected in response to the volume of the input speech sound (input volume) and the volume of the environmental sound (environmental volume). That is, the speech sound response device  1  holds the plurality of functions in response to the loudness of the environmental sound as the function for determining the response volume from the input volume. The speech sound response device  1  selects the function appropriate for the loudness of the environmental sound from the plurality of functions and determines the response volume from the input volume. 
       FIGS. 3 and 4  are diagrams illustrating examples of functions (filters) for determining the volume of the response speech sound (response volume) in response to a volume V of the input speech sound (input volume).  FIG. 3  illustrates an example of a function (first function) for determining a response volume from the input volume if a volume (environmental volume) S of the environmental sound is less than the threshold value T S  (S&lt;T S ).  FIG. 4  illustrates an example of a function (second function) for determining a response volume from the input volume if the environmental volume S is a threshold value T S  or more (S≥T S ). 
     In the example illustrated in  FIG. 3 , a function FA is a function for determining the response volume from the input volume if the environmental volume S is less than the threshold value T S  (S&lt;T S ). The function FA changes characteristics by threshold values Tva, Tvb, Tvc, and Tvd with respect to the input volume V. The function FA includes functions FAa, FAb, FAc, FAd, and FAe in five sections separated by four threshold values Tva, Tvb, Tvc, and Tvd with respect to the input volume V. 
     The function FAa is a function for determining the response volume from the input volume if the environmental volume S is less than the threshold value T S  (S&lt;T S ), and the input volume V is less than the threshold value Tva (V&lt;Tva). The function FAb is a function for determining the response volume from the input volume if the environmental volume S is less than the threshold value T S  (S&lt;T S ), and the input volume V is the threshold value Tva or more and less than the threshold value Tvb (Tva≤V&lt;Tvb). 
     The function FAc is a function for determining the response volume from the input volume if the environmental volume S is less than the threshold value T S  (S&lt;T S ), and the input volume V is the threshold value Tvb or more and less than the threshold value Tvc (Tvb≤V&lt;Tvc). The function FAd is a function for determining the response volume from the input volume if the environmental volume S is less than the threshold value T S  (S&lt;T S ), and the input volume V is the threshold value Tvc or more and less than the threshold value Tvd (Tvc≤V&lt;Tvd). The function FAe is a function for determining the response volume from the input volume if the environmental volume S is less than the threshold value T S  (S&lt;T S ), and the input volume V is the threshold value Tvd or more (Tvd≤V). 
     In the example illustrated in  FIG. 4 , a function FB is a function for determining the response volume from the input volume if the environmental volume S is the threshold value T S  or more (T S ≤S). The function FB changes characteristics by three threshold values Tvi, Tvj, and Tvk with respect to the input volume V. The function FB includes the functions FBa, FBb, FBc, and FBd in four sections separated by three threshold values Tvi, Tvj, and Tvk with respect to the input volume V. 
     The function FBa is a function for determining the response volume from the input volume if the environmental volume S is the threshold value T S  or more (T S ≤S), and the input volume V is less than the threshold value Tvi (V&lt;Tvi). The function FBb is a function for determining the response volume from the input volume if the environmental volume S is the threshold value T S  or more (T S ≤S), and the input volume V is the threshold value Tvi or more and less than the threshold value Tvj (Tvi≤V&lt;Tvj). 
     The function FBc is a function for determining the response volume from the input volume if the environmental volume S is the threshold value T S  or more (T S ≤S), and the input volume V is the threshold value Tvj or more and less than the threshold value Tvk (Tvj≤V&lt;Tvk). The function FBd is a function for determining the response volume from the input volume if the environmental volume S is the threshold value T S  or more (T S ≤S), and the input volume V is the threshold value Tvk or more (Tvk≤V). 
       FIG. 5  is a diagram illustrating a configuration example of the function table  13   a  for selecting a function appropriate for the loudness of the environmental volume S and the input volume V by the speech sound response device  1  according to the embodiment. The function table  13   a  illustrated in  FIG. 5  shows functions to be selected in response to the loudness of the environmental volume S and the input volume V from the functions illustrated in  FIGS. 3 and 4 . The function table  13   a  illustrated in  FIG. 5  is stored, for example, in the auxiliary storage device  13  in the speech sound response device  1  as illustrated in  FIG. 2 . The speech sound response device  1  selects one function in response to the environmental volume S and the input volume V with reference to the function table  13   a.  The speech sound response device  1  determines the response volume from the input volume by using the function selected in response to the environmental volume S and the input volume V. 
     For example, if S&lt;T S  and V&lt;Tva, the speech sound response device  1  determines the response volume from input volume by using the function FAa. If S&lt;T S  and Tva≤V&lt;Tvb, the speech sound response device  1  determines the response volume from input volume by using the function FAb. If S&lt;T S  and Tvb≤V&lt;Tvc, the speech sound response device  1  determines the response volume from input volume by using the function FAc. If S&lt;T S  and Tvc≤V&lt;Tvd, the speech sound response device  1  determines the response volume from input volume by using the function FAd. If S&lt;T S  and Tvd≤V, the speech sound response device  1  determines the response volume from input volume by using the function FAe. 
     If T S ≤S and V&lt;Tvi, the speech sound response device  1  determines the response volume from input volume by using the function FBa. If T S ≤S and Tvi≤V&lt;Tvj, the speech sound response device  1  determines the response volume from input volume by using the function FBb. If T S ≤S and Tvj≤V&lt;Tvk, the speech sound response device  1  determines the response volume from input volume by using the function FBc. If T S ≤S and Tvk≤V, the speech sound response device  1  determines the response volume from input volume by using the function FBd. 
     Subsequently, the operation of the speech sound response device  1  according to the embodiment is described.  FIG. 6  is a flowchart for explaining an operation example of a process of outputting a response speech sound to a voice of a talker (user) by the speech sound response device  1  according to the embodiment. The processor  11  of the speech sound response device  1  inputs the sound collected by the microphone  2  as the sound data of the input sound (ACT  11 ). The microphone  2  supplies the signal indicating the analog waveform of the collected sound to the speech sound processing circuit  14 . The speech sound processing circuit  14  digitalizes the signal indicating the analog waveform input from the microphone  2 . The speech sound processing circuit  14  supplies the digitalized digital signal as sound data to the processor  11 . The processor  11  acquires the sound data of the input sound obtained by digitalizing the sound collected by the microphone  2  with the speech sound processing circuit  14 . 
     If the sound data of the input sound is acquired, the processor  11  detects whether the voice uttered by the talker (talker&#39;s voice) is included in the sound data of the input sound by the speech sound detection process (ACT  12 ). The processor  11  performs the speech sound detection process of detecting whether the voice uttered by the talker is included in the input sound by executing the speech sound detection program. 
     If the talker&#39;s voice is not detected from the input sound (ACT  12 , NO), the processor  11  calculates (measures) the volume of the environmental sound (environmental volume) from the sound data of the input sound (ACT  13 ). If the talker&#39;s voice is not detected from the input sound, the input sound is set as an environmental sound (a sound other than the talker&#39;s voice) not including the talker&#39;s voice. If the input sound is the environmental sound, the processor  11  calculates the volume from the sound data of the input sound. If the input sound is the environmental sound, the processor  11  stores the volume of the calculated input sound to the main storage device  12  or the auxiliary storage device  13  as the environmental volume S (ACT  14 ). 
     In the present embodiment, the processor  11  stores the volume calculated from the input sound (environmental sound) in a period if the talker&#39;s voice is not included as the environmental volume S in order to estimate the environmental volume if the talker utters a voice. Therefore, the processor  11  may overwrite and store the environmental volume previously stored (the environmental volume in the past) with the calculated environmental volume S. The processor  11  may store the environmental volume S in a predetermined period from the present (e.g., periodically). Further, the processor  11  may store an average value of the environmental volume calculated in the predetermined period from the present as the environmental volume S. 
     If the talker&#39;s voice is detected from the input sound (ACT  12 , YES), the processor  11  performs the process of generating the response content (response sentence) (ACTS  15  to  17 ) and the process of calculating the response volume (ACTS  18  to  19 ). 
     As the process of generating the response content, the processor  11  performs processes such as a speech sound recognition process, a content analysis process, and a response sentence generation process. That is, the processor  11  performs the speech sound recognition of recognizing the talker&#39;s voice (input speech sound) included in the input sound (ACT  15 ). The processor  11  extracts the talker&#39;s voice from the input sound and recognizes the speech uttered by the talker (input sentence) from the extracted talker&#39;s voice. For example, the processor  11  recognizes the speech uttered by the talker by referring to the pronunciation of a preset language (word). 
     When obtaining the input sentence as the speech sound recognition result of the voice uttered by the talker, the processor  11  performs the intention analysis process of analyzing the meaning of the input sentence obtained as the speech sound recognition result (ACT  16 ). The processor  11  analyzes the meaning of the input sentence (the intention of the user included in the input sentence) based on the recognition result of the word included in the input sentence as the intention analysis process. 
     For example, the processor  11  determines whether the input sentence is a question sentence, a request or a wish, a greeting, or the like. If the input sentence is determined to be the question sentence, the processor  11  specifies the question content included in the input sentence. In addition, if it is determined that the input sentence is a request, the processor  11  specifies the content of the request included in the input sentence. If it is determined that the input sentence is a greeting, the processor  11  specifies the content of the greeting included in the input sentence. 
     If the meaning of the voice uttered by the talker (input sentence) is analyzed, the processor  11  generates the response content (response sentence) with respect to the input sentence (ACT  17 ). For example, if the question content included in the input sentence is specified, the processor  11  generates the response sentence in response to the question content. If the request of the talker included in the input sentence is specified, the processor  11  generates the response sentence according to the request of the talker. If the greeting included in the input sentence is specified (if it is understood that the input sentence is a greeting from the talker), the processor  11  generates a response sentence as the greeting in response to the greeting from the talker. 
     Meanwhile, the processor  11  performs the calculating process of the input volume V and the calculating process of the response volume as the process of calculating the response volume. The processor  11  calculates the volume V of the talker&#39;s voice detected from the input sound (input speech sound) (ACT  18 ). For example, the processor  11  extracts the component of the talker&#39;s voice from the sound data of the input sound (input speech sound) and calculates the volume V of the extracted input speech sound (input volume). 
     If the input volume V is calculated, the processor  11  performs a process of calculating the response volume based on the calculated input volume V and the environmental volume S (ACT  19 ). The processor  11  calculates the response volume with respect to the input volume based on the function to be selected in response to the input volume V and the environmental volume S. The process of calculating the response volume (the calculating process of the response volume) is specifically described below. 
     The processor  11  generates the response waveform to be the response speech sound uttered from the speaker  3  based on the response sentence generated in ACT  17  and the response volume calculated in ACT  19  (ACT  20 ). For example, the processor  11  generates the response waveform for uttering the response sentence generated in ACT  17  as the response speech sound. The processor  11  adjusts the amplitude of the response waveform for uttering the generated response speech sound in response to the response volume calculated in ACT  19 . If the response waveform is generated, the processor  11  outputs the generated response waveform from the speaker  3  (ACT  21 ). 
     Subsequently, the calculating process of the response volume in the speech sound response device  1  according to the embodiment is specifically described.  FIGS. 7 and 8  are flowcharts for explaining the calculating process of the response volume in the speech sound response device  1  according to the embodiment. In the calculating process of the response volume, the processor  11  acquires the input volume V in the present to be calculated in ACT  18  described above (ACT  31 ). The processor  11  acquires the environmental volume S stored in the main storage device  12  or the auxiliary storage device  13  (ACT  32 ). 
     If the input volume V and the environmental volume S are acquired, the processor  11  selects the function in response to the input volume V and the environmental volume S with reference to the function table illustrated in  FIG. 5 . In the process examples illustrated in  FIGS. 7 and 8 , the processor  11  selects the function according to the function table  13   a  illustrated in  FIG. 5 . The functions for adding the environmental volume and determining the response volume from the input volume are not limited to those illustrated in  FIGS. 3 and 4  and can be appropriately set in response to operation forms. In addition, the threshold value with respect to the environmental volume and the threshold value with respect to the input volume are not limited to those illustrated in  FIGS. 3, 4, and 5 , and may be appropriately set in response to the functions. 
     In the process examples illustrated in  FIGS. 7 and 8 , the processor  11  refers to the table illustrated in  FIG. 5  and determines whether the environmental volume S is less than the threshold value T S  (ACT  33 ). If the environmental volume S is less than the threshold value T S  (S&lt;T S ) (ACT  33 , YES), the processor  11  applies the function FA (i.e., if the environmental volume S is low). According to the example illustrated in  FIG. 3 , the function FA includes five functions FAa, FAb, FAc, FAd, and FAe separated by the threshold values Tva, Tvb, Tvc, and Tvd. Based on the table illustrated in  FIG. 5 , the processor  11  compares the input volume V with the threshold values Tva, Tvb, Tvc, and Tvd and selects one function from the functions FAa, FAb, FAc, FAd, and FAe. 
     That is, if S&lt;T S  (ACT  33 , YES), the processor  11  determines whether the input volume V is less than the threshold value Tva (ACT  41 ). If it is determined that the input volume V is less than the threshold value Tva (ACT  41 , YES), the processor  11  specifies that S&lt;T S , and V&lt;Tva. If S&lt;T S , and V&lt;Tva, the processor  11  selects the function FAa (ACT  42 ). 
     If it is determined that the input volume V is not less than the threshold value Tva (ACT  41 , NO), the processor  11  determines whether the input volume V is less than the threshold value Tvb (ACT  43 ). If it is determined that the input volume V is less than the threshold value Tvb (ACT  43 , YES), the processor  11  specifies that S&lt;T S , and Tva≤V&lt;Tvb. If S&lt;T S , and Tva≤V&lt;Tvb, the processor  11  selects the function FAb (ACT  44 ). 
     If it is determined that the input volume V is not less than the threshold value Tvb (ACT  43 , NO), the processor  11  determines whether the input volume V is less than the threshold value Tvc (ACT  45 ). If it is determined that the input volume V is less than the threshold value Tvc (ACT  45 , YES), the processor  11  specifies that S&lt;T S , and Tvb≤V&lt;Tvc. If S&lt;T S , and Tvb≤V&lt;Tvc, the processor  11  selects the function FAc (ACT  44 ). 
     If it is determined that the input volume V is not less than the threshold value Tvc (ACT  45 , NO), the processor  11  determines whether the input volume V is less than the threshold value Tvd (ACT  47 ). If it is determined that the input volume V is less than the threshold value Tvd (ACT  47 , YES), the processor  11  specifies that S&lt;T S , and Tvc≤V&lt;Tvd. If S&lt;T S , and Tvc≤V&lt;Tvd, the processor  11  selects the function FAd (ACT  48 ). 
     If it is determined that the input volume V is not less than the threshold value Tvd (ACT  47 , NO), since the input volume V is the threshold value Tvd or more, the processor  11  specifies that S&lt;T S , and Tvd≤V. If S&lt;T S , and Tvd≤V, the processor  11  selects the function FAe (ACT  49 ). 
     Meanwhile, if the environmental volume S is not less than the threshold value T S , that is, if the environmental volume S is the threshold value T S  or more (ACT  33 , NO), the processor  11  applies the function FB (i.e., when the environmental volume S is high). According to the example illustrated in  FIG. 4 , the function FB includes four functions FBa, FBb, FBc, and FBd separated by the threshold values Tvi, Tvj, and Tvk with respect to the input volume V. Based on the function table  13   a  illustrated in  FIG. 5 , the processor  11  compares the input volume V with the threshold values Tvi, Tvj, and Tvk and selects one function from the functions FBa, FBb, FBc, and FBd. 
     That is, if S&lt;T S  is not satisfied (ACT  33 , NO), the processor  11  determines whether the input volume V is less than the threshold value Tvi (ACT  51 ). If it is determined that the input volume V is less than the threshold value Tvi (ACT  51 , YES), the processor  11  specifies that S≥T S , and V&lt;Tvi. If S≥T S , and V&lt;Tvi, the processor  11  selects the function FBa (ACT  52 ). 
     If it is determined that the input volume V is not less than the threshold value Tvi (ACT  51 , NO), the processor  11  determines whether the input volume V is less than the threshold value Tvj (ACT  53 ). If it is determined that the input volume V is less than the threshold value Tvj (ACT  53 , YES), the processor  11  specifies that S≥T S , and Tvi≤V&lt;Tvj. If S≥T S , and Tvi≤V&lt;Tvj, the processor  11  selects the function FBb (ACT  54 ). 
     If it is determined that the input volume V is not less than the threshold value Tvj (ACT  53 , NO), the processor  11  determines whether the input volume V is less than the threshold value Tvk (ACT  55 ). If it is determined that the input volume V is less than the threshold value Tvk (ACT  55 , YES), the processor  11  specifies that S≥T S , and Tvj≤V&lt;Tvk. If S&lt;T S , and Tvj≤V&lt;Tvk, the processor  11  selects the function FBc (ACT  56 ). 
     If it is determined that the input volume V is not less than the threshold value Tvk (ACT  55 , NO), since the input volume V is the threshold value Tvk or more, the processor  11  specifies that S≥T S , and Tvk≤V. If S≥T S , and Tvk≤V, the processor  11  selects the function FBd (ACT  57 ). 
     If the function is selected in response to the environmental volume S and the input volume V, the processor  11  determines the response speech sound based on the selected function (ACT  60 ). That is, the processor  11  calculates the response volume in response to the input volume V in the selected function. Accordingly, the processor  11  can add the environmental volume and calculate the response volume in response to the input volume. 
     As above, the speech sound response device according to the embodiment detects the voice uttered by the user from the sound input to the microphone. The speech sound response device generates the response content (response sentence) to be output as the response speech sound with respect to the voice uttered by the user. Further, the speech sound response device calculates the response volume in response to the input volume as the volume of the voice uttered by the user and the volume of the environmental sound other than the voice uttered by the user. The speech sound response device outputs the response speech sound from the speaker in the calculated response volume. 
     That is, the speech sound response device according to the embodiment can add the loudness of the environmental sound and output the response speech sound of the response volume in response to the input volume. Accordingly, it can be expected that the loudness of the voice uttered by the talker (user) is controlled in response to the volume of the response speech sound output by the speech sound response device. The speech sound response device can guide the loudness of the voice uttered by the user to the volume appropriate for the speech sound recognition so that the speech sound recognition with the high accuracy can be realized. 
     The speech sound response device according to the embodiment holds the plurality of functions selected in response to the loudness of the environmental volume. The speech sound response device determines the volume of the response speech sound from the input volume based on the first function if the environmental volume is less than the threshold value and determines the volume of the response speech sound from the input volume based on the second function different from the first function if the environmental volume is less than the threshold value. Accordingly, the speech sound response device according to the embodiment can set the response volume in response to the loudness of the environmental sound. As a result, even in an environment where the environmental volume cannot be predicted in advance, the speech sound response device can guide the loudness of the voice uttered by the user to the volume appropriate for the speech sound recognition. 
     The speech sound response device according to the embodiment stores the plurality of functions to be selected in response to the loudness of the environmental volume and the loudness of the input volume in the storage device. The speech sound response device determines the volume of the response speech sound from the input volume based on one function selected in response to the environmental volume and the input volume from the plurality of functions. Accordingly, the speech sound response device can select the function in response to the environmental volume and the input volume and can guide the loudness of the voice uttered by the user to the volume appropriate for the speech sound recognition. 
     In the above embodiment, the case where the program executed by the processor is stored in advance in the memory in the device is described. However, the program executed by the processor may be downloaded from the network to the device or may be installed from the storage medium to the device. The storage medium may be a storage medium that can store a program such as a CD-ROM and can be read by the device. Further, the functions obtained by installation or download in advance may be realized in cooperation with the operating system (OS) or the like inside the device. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. These embodiments and modifications of the embodiments are included in the scope and gist of the invention and included in the inventions described in claims and the scope of equivalents of the inventions.