Abstract:
A method and apparatus for mapping a moving direction by using sounds for people with visual impairments, in which a moving direction can be expressed multi-dimensionally by using sound information and can effectively assist people with visual impairments and the like in navigation tasks. A moving direction of a person carrying a device configured to output sounds is mapped by using a combination of sounds outputted from the device. A plurality of different sound information pieces are stored in association with three or more predetermined directions, respectively, a current position of the moving target device is identified, and then a moving direction of the device is identified. A sound obtained by combining two sounds in a ratio according to the identified moving direction is outputted on the basis of sound information pieces associated respectively with two adjacent directions sandwiching the identified moving direction among the predetermined directions.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 from Japanese Patent Application No. 2010-265981 filed Nov. 30, 2010, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method, a device and a computer program for mapping a moving direction by using sounds. 
     2. Description of Related Art 
     In recent years, numerous systems have been developed for assisting people with visual impairments to engage in activities and process information in ways comparable to those without visual impairments. For example, there are systems capable of estimating the direction in which a person with a visual impairment is moving, on the basis of information which the person with the visual impairment acquires by use of a sense other than sight, e.g. a sense of hearing, smelling, touch or the like. 
     A number of techniques have already been disclosed for techniques of indicating a traveling direction, navigational techniques and the like. For example, the navigation apparatus shown in U.S. Pat. No. 7,620,493 generates a movement instruction regarding a distance and a direction to move from a current position to a target position, on the basis of information on the surrounding environment, e.g. information acquired by use of the sense of hearing, smelling, touch or the like. 
     Moreover, techniques for identifying a direction and a distance by using sounds have also been proposed. For example, in Tooba Nasir, Jonathan C. Roberts, “Sonification of spatial data”, the 13th International Conference on Auditory Display, Montreal (Canada), Jun. 26-29, 2007, accurate positional information can be informed even to a person with visual impairment by use of stereo effects using two or more sound sources. The use of sounds is considered especially effective in guiding a person with visual impairment towards a dynamically changing direction. 
     Even though guiding a person with visual impairment by using sound is effective, the conventional techniques can express directions only one-dimensionally, thus, having difficulty in producing sound indicating a desired direction. For example, in the case of providing movement instructions by uttering meaningful words, the words each indicating a one-dimensional direction are repeated intermittently. Specifically, to provide an instruction to move forward to the right at a 45-degree angle, the words of “right” and “forward” are repeated as “right, forward, right, forward . . . . ” Accordingly, it is too complicated to provide an instruction of a detailed direction, and is too difficult for people with visual impairments to correctly catch a movement instruction if the instruction is overlapped with another sound. 
     Although accurate positional information can be informed by using stereo effects, this technique requires a large-scale system with the necessity of preparing two or more sound sources, and hence has a problem that it is difficult to reduce the total cost for system construction. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the above-described circumstances, and aims to provide a method, a device and a computer readable storage medium for mapping a moving direction by using sounds, with which a moving direction can be expressed multi-dimensionally, especially two-dimensionally, by using sound information, and can effectively assist people with visual impairments and the like in navigation tasks. 
     To achieve the above object, the first aspect of the present invention provides a method for mapping a moving direction of a moving target by outputting a plurality of sounds from a sound output device in combination. The method includes storing a plurality of different sound information pieces in association with three or more predetermined directions, respectively, identifying the current position of the moving target; identifying the moving direction of the moving target, and outputting a sound obtained by combining two sounds in a ratio according to the identified moving direction, on the basis of sound information pieces associated respectively with two adjacent directions sandwiching the identified moving direction among the predetermined directions. 
     In another aspect of the present invention, a device for mapping a moving direction of a moving target by outputting a plurality of sounds in combination is provided. The device includes a sound information storing unit configured to store a plurality of different sound information pieces in association with three or more predetermined directions, respectively, a current-position identifying unit configured to identify the current position of the moving target, a moving-direction identifying unit configured to identify the moving direction of the moving target, and a sound output unit configured to output a sound obtained by combining two sounds in a ratio according to the identified moving direction, on the basis of sound information pieces associated respectively with two adjacent directions sandwiching the identified moving direction among the predetermined directions. 
     In yet another aspect of the present invention, a computer readable storage medium for mapping a moving direction of a moving target by outputting a plurality of sounds in combination is provided. The computer readable storage medium carries out the steps of a method comprising storing a plurality of different sound information pieces in association with three or more predetermined directions, respectively, identifying the current position of the moving target, identifying the moving direction of the moving target, and outputting a sound obtained by combining two sounds in a ratio according to the identified moving direction, on the basis of sound information pieces associated respectively with two adjacent directions sandwiching the identified moving direction among the predetermined directions. 
     According to the present invention, a moving direction of a moving target, e.g. a device main body, an imaginary object on a screen or the like, can be expressed multi-dimensionally, especially two-dimensionally, by using sounds, and a change of the moving direction can be expressed by changing sounds outputted successively. Even when information on a moving direction is overlapped with other audio information, the user can identify the moving direction while understanding the contents of the audio information. Further, since preparation of multiple sound sources is not required, guiding, for example, a person with visual impairment properly to a direction in which the person is to move, is enabled at a low cost. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram schematically showing a configuration of information processor according to an embodiment of the present invention. 
         FIG. 2  is a functional block diagram of the information processor according to the embodiment of the present invention. 
         FIGS. 3A to 3D  are views each showing an example of directions which are associated respectively with sound information pieces. 
         FIGS. 4A to 4C  are views showing examples of sound information pieces stored in a storage of the information processor according to the embodiment of the present invention. 
         FIGS. 5A and 5B  are views showing sound information pieces outputted for a given path. 
         FIG. 6  is a flowchart showing a procedure of processing performed by a CPU of the information processor according to the embodiment of the present invention. 
         FIG. 7  is a functional block diagram showing a configuration of a moving-direction identifying unit according to the embodiment of the present invention. 
         FIGS. 8A and 8B  are views showing an example of a method for identifying a target point according to a moving speed. 
         FIG. 9  is a flowchart showing a procedure of processing for identifying a moving direction performed by the CPU of the information processor according to the embodiment of the present invention. 
         FIG. 10  is a view showing an example of an overview of processing performed in the case of outputting colored noise. 
         FIG. 11  is a flowchart showing a procedure of processing for outputting the colored noise performed by the CPU of the information processor according to the embodiment of the present invention. 
         FIGS. 12A and 12B  are views showing an example of a case in which a sound to be outputted is changed for each spot located in a path. 
         FIG. 13  is a functional block diagram showing a configuration of the moving-direction identifying unit according to the embodiment of the present invention for checking a path. 
         FIG. 14  is a flowchart showing a procedure of processing for checking a moving path performed by the CPU of the information processor according to the embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Detailed descriptions will be given below of a device according to an embodiment of the present invention for mapping a moving direction of a moving target by outputting multiple sounds in combination, on the basis of the accompanying drawings. Naturally, the embodiment to be given below is not to limit the invention described in the scope of claims, and not all the combinations of the characteristic features described in the embodiment are essential for solving means. 
     In addition, the present invention can be carried out by a number of different embodiments, and should therefore not be understood as is limited to what is described in the embodiment. Throughout the embodiment, the same components bear the same reference numerals. 
     In the following embodiment, descriptions will be given of a device in which a computer program is installed in a computer system. However, as is apparent to those skilled in the art, the present invention can be carried out as a computer program part of which can be executed by a computer. Accordingly, the present invention can be carried out in an embodiment as hardware serving as a device, an embodiment as software and an embodiment in combination of software and hardware, for mapping a moving direction of a moving target by outputting multiple sounds in combination. The computer program can be recorded in any computer-readable recording medium such as a hard disk, a DVD, a CD, an optical storage, a magnetic storage or the like. 
     According to the embodiment of the present invention, a moving direction can be expressed two-dimensionally by using sounds, and a change of the moving direction can be expressed by changing sounds outputted successively. Moreover, even when information on a moving direction is combined with different audio information, the moving subject can identify the moving direction while understanding the contents of the audio information. Further, since preparation of multiple sound sources is not required, guiding, for example, a person with a visual impairment properly to a direction in which the person is to move, is enabled at a low cost. 
       FIG. 1  is a block diagram schematically showing a configuration of an information processor according to an embodiment of the present invention. An information processor  1  according to the embodiment of the present invention includes at least a central processing unit (CPU)  11 , a memory  12 , storage  13 , an I/O interface  14 , a video interface  15 , a portable disk drive  16 , a communication interface  17  and an internal bus  18  connecting the above-described hardware units with each other. 
     The CPU  11  is connected to the above-described hardware units of the information processor  1  via the internal bus  18 , and is configured to control operations of the above-described hardware units while performing various software functions in accordance with a computer program  100  stored in the storage  13 . A volatile memory such as an SRAM, an SDRAM or the like, is used as the memory  12 , and a load module is loaded into the memory  12  in executing the computer program  100 . The memory  12  is configured to store temporary data and the like generated in executing the compute program  100 . 
     A built-in stationary storage (hard disk), a ROM or the like is used as the storage  13 . The computer program  100  stored in the storage  13  is downloaded from a portable recording medium  90 , such as a DVD, a CD-ROM or the like, in which a program, data and the like are recorded, by the portable disk drive  16 , and is loaded from the storage  13  into the memory  12  to be executed. Naturally, a computer program downloaded from an external computer connected to the hardware units via the communication interface  17  can be used, instead. 
     The communication interface  17  is connected to the internal bus  18 , and is capable of exchanging data with an external computer and the like by being connected to an external network such as the Internet, a LAN, a WAN or the like. 
     The I/O interface  14  is connected to input devices such as a keyboard  21 , a mouse  22  and the like, and is configured to receive data inputs. Moreover, the I/O interface  14  is also connected to an audio output device  24  such as a speaker or the like, and is configured to output desired sounds on the basis of an instruction by the CPU  11 . The video interface  15  is connected to a display  23  such as a CRT display, a liquid-crystal display or the like, and is configured to display desired images. 
       FIG. 2  is a functional block diagram of the information processor  1  according to the embodiment of the present invention. In  FIG. 2 , a sound information storing unit  201  of the information processor  1  stores multiple different sound information pieces in the storage  13  in association with three or more predetermined directions, respectively. 
     Here, the number of the predetermined directions is defined as three or more, and this enables two-dimensional expression of a moving direction. Specifically, in the case where only two different sound information pieces are stored in association with two predetermined directions, respectively, a person hearing an outputted sound encounters a difficulty in accurately identifying whether the sound indicates a forward direction, a backward direction, a rightward direction or a leftward direction, and requires assistance of different information, e.g. a word having a meaning or the like. 
     In the case where multiple different sound information pieces are stored in association with three or more predetermined directions, respectively, on the other hand, a person can uniquely determine the direction to move on the basis of the combination of outputted sounds.  FIGS. 3A to 3D  are views each showing an example of predetermined directions stored in association with sound information pieces, respectively. In  FIGS. 3A to 3D , the mark ● indicates the current position of a moving subject. Here, the term “moving subject” means a person who moves while holding a sound output device (the information processor  1 ). 
     As shown in  FIG. 3A , when sound information pieces are stored in association with two directions, respectively, a person can be able to determine whether the moving direction is forward or backward, but cannot determine rightward or leftward. Naturally, if each of the arrows is turned 90°, the person can determine whether the moving direction is right ward or leftward, but then cannot determine forward or backward. Thus, it is not possible to uniquely determine the moving direction by using sound information pieces for two directions only. 
     When sound information pieces are stored in association with three directions, respectively, as shown in  FIG. 3B , a person can determine whether the moving direction is forward or backward and also can determine whether the moving direction is rightward or leftward. In this case, the person can determine the moving direction only by recognizing a sound information piece or a combination of sound information pieces. 
     Generally, to facilitate a person to determine the direction to move, four directions as shown in  FIG. 3C  or eight directions as shown in  FIG. 3D  are used desirably. The four or eight directions are considered to agree with the sense of directions in an everyday life and thus to allow quick determination. 
       FIGS. 4A to 4C  show examples of sound information pieces stored in the storage  13  of the information processor  1  according to the embodiment of the present invention. As shown in  FIG. 4A , sound information pieces are stored in association with four directions, i.e. a forward direction, a rightward direction, a backward direction and a leftward direction, respectively. 
     For example, in  FIG. 4B , as the sound information pieces, instrument sounds are stored in association with the four directions, respectively. In the example of  FIG. 4B , the sound of “flute”, the sound of “violin”, the sound of “oboe” and the sound of “cello” are stored in association with the forward direction (#), the rightward direction (%), the backward direction ($) and the leftward direction (&amp;), respectively. A direction between two of the above directions, e.g. the forward right direction, is expressed by outputting a sound obtained by combining the sound for the forward direction and the sound for the rightward direction in the ratio of 1:1. Specifically, when the sound obtained by combining the sound of “flute” and the sound of “violin” in the ratio of 1:1 is outputted, the moving subject can recognize that he/she is to move in the forward right direction. 
     Similarly, in  FIG. 4C , as sound information pieces, voices respectively pronouncing vowels are stored in association with the four directions, respectively. In the example of  FIG. 4C , the voice of “e”, the voice of “a”, the voice of “u” and the voice of “i” are stored in association with the forward direction (#), the rightward direction (%), the backward direction ($) and the leftward direction (&amp;), respectively. A direction between two of the above directions, e.g. the frontward right direction, is expressed by outputting a voice obtained by combining the voice for the forward direction and the voice for the rightward direction in the ratio of 1:1. Specifically, when the voice obtained by combining the voice of “e” and the voice of “a” in the ratio of 1:1, i.e., a voice pronouncing a sound between “a” and “e”, is outputted, the person can recognize that he/she is to move in the forward right direction. 
     In the case of using voices respectively pronouncing vowels, the vowel outputted by combining voices pronouncing two vowels is often one the user is used to hearing in his/her everyday life. For this reason, in such a case, the user can easily differentiate between the voices and can quickly notice a change in successive sounds, compared with the case of using other types of sounds such as instrument sounds or the like. 
       FIGS. 5A and 5B  are views showing an example of sound information pieces outputted for a given path.  FIG. 5A  shows a moving path, where the mark ● indicates the current position of the moving target, and the moving subject moves along the path in the direction indicated by the arrow. 
       FIG. 5B  shows sound information pieces corresponding respectively to sounds to be outputted, by using a series of symbols respectively indicating directions. The moving subject moves in the forward direction for a while after starting from the mark ●, and this movement is expressed by showing a series of the symbols “#” indicating the forward direction. This means that the sound corresponding to the sound information piece stored in association with the forward direction (#) is outputted successively. 
     Then, similarly, sounds corresponding to the sound information pieces stored in association with moving directions, i.e. the rightward direction (%), the backward direction ($), the leftward direction (&amp;), the backward direction ($), the rightward direction (%) and then the forward direction (#), are outputted sequentially. 
     Returning to  FIG. 2 , a current-position identifying unit  202  identifies a current position of the moving target, e.g. the information processor  1 . The identified current position can be an absolute position such as coordinate values based on a GPS or the like, or can be a relative position showing a relative displacement from a predetermined reference point. 
     A moving-direction identifying unit  203  identifies a moving direction from the current position identified by the current-position identifying unit  202  to a next target point to move to. The next target point to move to is identified according to a moving speed. Hence, the moving direction is changed as needed. 
     A sound output device  204  extracts sound information pieces stored respectively in association with two adjacent directions sandwiching the identified moving direction, among the forward direction (#), the rightward direction (%), the backward direction ($) and the leftward direction (&amp;), and then outputs the two sounds combined in a ratio according to the moving direction on the basis of the extracted sound information pieces. For example, when the moving direction is the forward right direction, the sound output device  204  outputs sounds corresponding to the sound information pieces stored respectively in association with the forward direction (#) and the rightward direction (%), the sounds being combined in the ratio based on the proportional distribution of the two adjacent directions sandwiching the moving direction. 
       FIG. 6  is a flowchart showing a procedure of processing performed by the CPU  11  of the information processor  1  according to the embodiment of the present invention. In  FIG. 6 , the CPU  11  of the information processor  1  stores, in the storage  13 , multiple different sound information pieces in association with three or more predetermined directions (Step S 601 ). 
     The CPU  11  identifies a current position of a moving target, e.g. the information processor  1  (Step S 602 ). The identified current position can be an absolute position such as coordinate values based on a GPS or the like, or can be a relative position showing a relative displacement from a predetermined reference point. 
     The CPU  11  identifies a moving direction from the identified current position to a next target point to move to (Step S 603 ). The next target point to move to is identified according to a moving speed. Hence, the moving direction is changed as needed along a predetermined path. 
     The CPU  11  extracts sound information pieces stored respectively in association with two adjacent directions sandwiching the identified moving direction, among the forward direction (#), the rightward direction (%), the backward direction ($) and the leftward direction (&amp;) (Step S 604 ), and then outputs the two sounds combined in a ratio according to the moving direction on the basis of the extracted sound information pieces (Step S 605 ). 
     Here, it is preferable that the moving-direction identifying unit  203  identify, as a moving direction, the direction from the current position identified by the current-position identifying unit  202  to the target point to move to according to a moving speed. This configuration makes it possible to change the moving direction as needed along the predetermined path. In this case, a distance from the current position to the target point needs to be larger as the moving speed becomes faster, since the moving amount per unit time is larger. 
       FIG. 7  is a functional block diagram showing a configuration of the moving-direction identifying unit  203  according to the embodiment of the present invention. In  FIG. 7 , a target-point identifying unit  701  identifies a target point to move to according to a moving speed. 
       FIGS. 8A and 8B  are views showing an example of a method for identifying a target point according to a moving speed.  FIG. 8A  is an example of identifying a target point when the moving speed is slow. As shown in  FIG. 8A , when the moving speed of a current position  81  of the moving target is slow, the moving amount (distance) of the current position  81  is small, and a target point  83  only moves to a target point  84 . Accordingly, a direction  85  from the current position  81  to the target point  84  is identified as a moving direction. 
       FIG. 8B  is an example of identifying a target point when the moving speed is fast. As shown in  FIG. 8B , when the moving speed of the current position  81  of the moving target is fast, the moving amount (distance) of the current position  81  is large, and hence the target point  83  moves a longer distance to a target point  86 . Accordingly, a direction  87  from the current position  81  to the target point  86  is identified as a moving direction. 
     Returning to  FIG. 7 , a direction identifying unit (identifying unit)  702  identifies the direction from the current position to a target point as a moving direction. With this configuration, the moving subject is instructed to move relatively quickly in a linear path while moving relatively slowly in a path including many curves, and can thereby move without diverging a lot from the predetermined path. 
       FIG. 9  is a flowchart showing a procedure of processing for identifying a moving direction performed by the CPU  11  of the information processor  1  according to the embodiment of the present invention. In  FIG. 9 , the CPU  11  of the information processor  1  detects a moving speed (Step S 901 ), and identifies a distance from the current position of the moving target to a target point according to the detected speed (Step S 902 ), in Step S 603  in  FIG. 6 . The CPU  11  identifies the target point in a predetermined path on the basis of the identified distance (Step S 903 ). Then, the CPU  11  returns the processing to Step S 604  in  FIG. 6 , and repeats the above-described processing. 
     Here, it is preferable that colored noise be outputted as warning if a current position of the moving target deviates a lot from the predetermined path. To enable this, a shortest-path calculation unit  205  shown in  FIG. 2  calculates a shortest path from the current position of the moving target to the predetermined path every time the moving target moves a certain distance in order to move along the predetermined path. A judging unit  206  judges whether or not the length of the calculated shortest path is above a predetermined value. When the judging unit  206  judges that the length is above the predetermined value, the sound output unit  204  outputs colored noise. 
       FIG. 10  is a view showing an example of an overview of processing performed in the case of outputting colored noise. In  FIG. 10 , to see how much a current position  101  is deviating from a predetermined path  102 , the normal line to the predetermined path  102  is drawn from the current position  101  of the moving target, and a linear distance  103  is calculated. If the value of the linear distance  103  is above a predetermined value  104  of the distance from the predetermined path  102 , it is judged that the current position  101  is deviating a lot, and hence colored noise  105  is outputted. 
       FIG. 11  is a flowchart showing a procedure of processing for outputting colored noise performed by the CPU  11  of the information processor according to the embodiment of the present invention. In  FIG. 11 , after Step S 603  in  FIG. 6 , the CPU  11  of the information processor  1  calculates a shortest path from a current position of the moving target to the predetermined path (Step S 1101 ), and then judges whether or not the length of the shortest path is above the predetermined value (Step S 1102 ). 
     When judging that the length is equal to or below the predetermined value (Step S 1102 : NO), the CPU  11  advances the processing to Step S 604  in  FIG. 6 . When judging that the length is above the predetermined value (Step S 1102 : YES), the CPU  11  outputs colored noise (Step S 1103 ), and advances the processing to Step S 604  in  FIG. 6 . 
     The sound outputted from the sound output unit  204  is not limited to a fixed sound. If there are various spots in a path, the sound output unit  204  can output a sound corresponding to the characteristics of each spot. 
       FIGS. 12A and 12B  are views showing an example in which different sounds are outputted depending on the characteristics of the spots located in the path.  FIGS. 12A and 12B  are basically the same as  FIGS. 5A and 5B . What is different is that, in the case of  FIGS. 12A and 12B , there are a railroad crossing  121 , traffic lights  122  and a store  126  in the path and the width of the path varies. 
       FIG. 12A  shows a moving path where the mark ● shows a current position of the moving target, and the moving subject moves along the path in the direction indicated by the allow.  FIG. 12B  shows sound information pieces corresponding respectively to the sounds to be outputted, by a series of symbols each indicating a direction. The existences of the railroad crossing  121 , the traffic lights  122  and the like are informed by a sound not existing in the real world, e.g. “beep” or the like, outputted by so-called earcons  123  and  124  shown in  FIG. 12B , respectively. The existence of the store  126  can be informed by a store name or the like pronounced by a synthetic voice outputted by a so-called spearcon  127  shown in  FIG. 12B . 
     Additionally, in  FIG. 12B , the change of the pitch, volume or the like of the sounds for a section  125  is expressed by showing the symbols in bold. Specifically, the variation of the width of the path can be informed by the change of the pitch, volume or the like of the sounds as shown in the section  125 . 
     As described above, according to the embodiment of the present invention, a moving direction of a moving target can be expressed two-dimensionally by using sounds, and a change of the moving direction can be expressed by changing sounds outputted successively. Moreover, even when information on a moving direction is overlapped with other audio information, the moving subject can identify the moving direction while understanding the contents of the audio information. Further, since preparation of multiple sound sources is not required, guiding, for example, a person with a visual impairment properly to a direction in which the person is to move, is enabled at a low cost. 
     Here, sounds can be outputted for the purpose of informing a person with a visual impairment of a predetermined path in advance, instead of guiding a person with a visual impairment to a direction to move. In this case, it is preferable that a start point and an end point of a predetermine path be identified, and that the person be informed of the path between the points by sounds indicating moving directions. 
       FIG. 13  is a functional block diagram showing a configuration of the moving-direction identifying unit  203  according to the embodiment of the present invention for checking a moving path. In  FIG. 13 , a start-point/end-point identifying unit  131  identifies a start point from which moving is to be started and an end point at which the moving is to be finished, in a predetermined path. 
     A position designation receiving unit  132  receives designation of a certain position located between the start point and the end point in the path. A direction identifying unit (identifying unit)  133  identifies a moving direction from the designated position. Specifically, the direction identifying unit  133  identifies a direction from the current position of the moving target to a target point as the moving direction. In this way, the moving subject can check the moving direction from any position in the path by listening to the sounds, and can hence certainly understand an approximate outline of the path. 
       FIG. 14  is a flowchart showing a procedure of processing for checking a moving path performed by the CPU  11  of the information processor  1  according to the embodiment of the present invention. In  FIG. 14 , after Step S 601  in  FIG. 6 , the CPU  11  of the information processor  1  identifies the start point and the end point of a predetermined path (Step S 1401 ), and then receives designation of a certain position in the path (Step S 1402 ). A method for receiving designation of a certain position is not limited to any particular method, and can be any method as long as designation of a certain position in the path can be received by using a slider or the like. 
     The CPU  11  identifies a moving direction from the received designated position (Step S 1403 ), and advances the processing to Step S 604  in  FIG. 6 . In this way, the moving subject can check the moving direction from a certain position by listening to the sounds, and can easily understand an approximate outline of the path. 
     It is to be noted that the present invention is not limited to the above-described embodiment, and various alternations, improvements and the like are possible within the scope of the spirit of the present invention. For example, a moving target can be an imaginary object displayed on a screen. In this case, sounds indicating a moving direction can be outputted with respect to a position of a finger on a touch panel, for example.