Patent Publication Number: US-7899171-B2

Title: Voice call system and method of providing contents during a voice call

Description:
CLAIM OF PRIORITY 
     The present application claims priority from Japanese patent application JP 2005-265283 filed on Sep. 13, 2005, the content of which is hereby incorporated by reference into this application. 
     FIELD OF THE INVENTION 
     The present invention relates to a voice call system and more particularly to a technology for providing contents such as advertisement to a user in process of a voice call. 
     BACKGROUND OF THE INVENTION 
     There has been a conventional practice to provide advertisement using media such as television and radio broadcasting. The advertisement using television and radio broadcasting allocates time intervals for the advertisement between programs and between time-shared portions of a program. A broadcast signal for the advertisement is transmitted during the allocated time (the National Association of Commercial Broadcasters in Japan, ed. Broadcasting handbook—Practical knowledge about the civil law as a culture background: TOYO KEIZAI INC., August 1997, pp. 340-343). 
     SUMMARY OF THE INVENTION 
     The above-mentioned conventional broadcasting takes no count of using voice calls as media. When the time-sharing advertisement using television and radio broadcasting is applied to a voice call, the conversation is interrupted to cause an unnatural effect. 
     The present invention has been made in consideration of the foregoing. It is therefore an object of the present invention to provide contents such as advertisement for a user in process of voice call without interrupting the conversation. 
     To solve the above-mentioned problem, the invention inserts advertisement in a space division fashion instead of a time division fashion. A presence server is provided to manage positions of a user of each of the voice telecommunication terminals and a sound source for providing contents in a virtual space. The presence server stereophonically processes voice data for the other voice telecommunication terminals than a relevant voice telecommunication terminal correspondingly to a relative position between the each of the other voice telecommunication terminals and the user of the relevant voice telecommunication terminal. In addition, the presence server stereophonically processes acoustic data for the sound source correspondingly to a relative position between the sound source and the user of the relevant voice telecommunication terminal. In this manner, the presence server synthesizes the stereophonically processed voice data for each of the other voice telecommunication terminals with the stereophonically processed acoustic data for the sound source to generate voice call data for the relevant voice telecommunication terminal. At this time, the presence server configures a position of the sound source in the virtual space for each of the voice telecommunication terminals so that the user of the relevant voice telecommunication terminal can distinguish the position of the sound source from the position of the user of each of the other voice telecommunication terminals. 
     For example, the invention provides a voice call system that includes a plurality of voice telecommunication terminals, a content server to provide a sound source for each of the plurality of voice telecommunication terminals, and a presence server to manage positions of users of the plurality of voice telecommunication terminals and a sound source provided by the content server in a virtual space, the voice call system having: a presence acquisition unit that acquires information about positions of users of the plurality of voice telecommunication terminals and the sound source provided by the content server in a virtual space from the presence server; and an audio renderer provided for each of the voice telecommunication terminals. 
     The audio renderer performs a process for applying 
     a stereophonic process to voice data for each of voice telecommunication terminals other than a voice telecommunication terminal corresponding to the audio renderer in accordance with a relative position between each of users of the other voice telecommunication terminals and a user of the voice telecommunication terminal corresponding to the audio renderer, in which the presence acquisition unit acquires position information to specify the relative position and 
     a stereophonic process to acoustic data from a sound source provided by the content server in accordance with a relative position between the sound source and the user of the voice telecommunication terminal, in which the presence acquisition unit acquires position information to specify the relative position; and 
     a process for synthesizing the stereophonically processed voice data for each of the other voice telecommunication terminals other than the voice telecommunication terminal corresponding to the audio renderer with acoustic data for the sound source to generate voice call data for the voice telecommunication terminal corresponding to the audio renderer. 
     The presence server includes a position information management unit that determines a position of the sound source in a virtual space in terms of each of the plurality of voice telecommunication terminals so that a user of a relevant voice telecommunication terminal can distinguish the position of the sound source in the virtual space from positions of users of the other voice telecommunication terminals. 
     The position information management unit may determine a position of the sound source in the virtual space as follows so that the user of the relevant user can distinguish the position of the sound source in the virtual space from a position of the user of another voice telecommunication terminal. For example, a distance between the user of the voice telecommunication terminal and the sound source in the virtual space can be longer than a distance between the user of the relevant voice telecommunication terminal and a user of another nearest voice telecommunication terminal. 
     Alternatively, the position information management unit may determine a position of the sound source in the virtual space as follows so that the user of the relevant user can distinguish the position of the sound source in the virtual space from a position of the user of another voice telecommunication terminal. For example, a direction to the sound source viewed from the user of the voice telecommunication terminal can be configured to deviate from at least a direction to a user of the nearest another voice telecommunication terminal viewed from the relevant voice telecommunication terminal at a specified angle. 
     According to an embodiment of the invention, voice data for each of the other voice telecommunication terminal and acoustic data for the sound source are stereophonically processed to generate synthesized data for each voice telecommunication terminal based on relative positions in a virtual space among a user of a relevant voice telecommunication terminal, a user of each of the voice telecommunication terminals other than the relevant voice telecommunication terminal, and the sound source to provide contents the synthesized data is assumed to be voice call data for the relevant voice telecommunication terminal. An intended party and the sound source are placed in divided portions within the virtual space, i.e., at positions and/or orientations that allow the voice telecommunication terminal user to distinguish between the intended party and the sound source. Even when the user is simultaneously supplied with the voice data for the intended party and the acoustic data for the sound source and both data are synthesized in the-voice call data, the user can selectively or simultaneously hear them by distinguishing one from the other. Accordingly, it is possible to audiovisually provide contents such as advertisement for users in process of voice call without interrupting the conversation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a construction diagram of a voice telecommunication system according to a first embodiment of the invention; 
         FIG. 2  is a schematic construction diagram of a presence server  1 ; 
         FIG. 3  schematically shows a registration content of a position information storage unit  103 ; 
         FIG. 4  illustrates an operation flow of the presence server  1 ; 
         FIG. 5  illustrates a position and an orientation of as advertisement sound source in a virtual space; 
         FIG. 6  is a schematic construction diagram of a media server  2 ; 
         FIG. 7  illustrates processes of an audio renderer  208 ; 
         FIG. 8  schematically shows a two-dimensional image source method with a ceiling and a floor omitted; 
         FIG. 9  is a schematic construction diagram of an advertisement server  3 ; 
         FIG. 10  schematically shows a registration content of an advertisement information storage unit  305 ; 
         FIG. 11  shows an operational flow of an advertisement information position control unit  304 ; 
         FIG. 12  is a schematic construction diagram of a voice telecommunication terminal  4 ; 
         FIG. 13  shows an example of video for a virtual space map; 
         FIG. 14  exemplifies a hardware construction of devices constituting a voice call system; 
         FIG. 15  schematically shows operations of the voice call system as shown in  FIG. 1 ; 
         FIG. 16  schematically shows a registration content of an advertisement information storage unit  305 A; 
         FIG. 17  schematically shows a registration content of a position information storage unit  103 A; 
         FIG. 18  schematically shows a registration content of a position information storage unit  103 B; 
         FIG. 19  schematically shows a registration content of an advertisement information storage unit  305 C; 
         FIG. 20  schematically shows a registration content of a position information storage unit  103 C; 
         FIG. 21  shows an operational flow of a presence server  1 C; 
         FIG. 22  is a schematic construction diagram an advertisement server  3 D; 
         FIG. 23  schematically shows a registration content of an advertisement information storage unit  305 D; 
         FIG. 24  schematically shows a registration content of a request storage unit  307 ; 
         FIG. 25  shows an operational flow of an advertisement information position control unit  304 D; 
         FIG. 26  is a schematic construction diagram of a voice telecommunication terminal  4 D; 
         FIG. 27  shows an example of a request acceptance screen; 
         FIG. 28  shows a position of an advertisement sound source in a virtual space; and 
         FIG. 29  shows a position of an advertisement sound source in a virtual space. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will be described. 
     First Embodiment 
       FIG. 1  is a construction diagram of a voice call system according to a first embodiment of the invention. As shown in  FIG. 1 , the voice call system according to the embodiment includes a presence server  1 , a media server  2 , an advertisement server  3 , and multiple voice telecommunication terminals  4  that are connected to each other via an IP (Internet Protocol) network  5 . 
     The presence server  1  manages an advertisement sound source provided from the advertisement server  3  and position information about a user of each voice telecommunication terminal in a virtual space. A user of each voice telecommunication terminal  4  creates the virtual space for voice call communication. For example, virtual space properties include: a space size; a ceiling height; reflection coefficients, colors, textures, and resonance characteristics of a wall and a ceiling; and an absorption factor of sound due to air in the space. 
       FIG. 2  is a schematic construction diagram of the presence server  1 . 
     As shown in  FIG. 2 , the presence server  1  includes an IP network interface unit  101  for connection to an IP network  5 , a position information management unit  102 , and a position information storage unit  103 . 
       FIG. 3  schematically shows a registration content of the position information storage unit  103 . As shown in  FIG. 3 , the position information storage unit  103  stores records  1030  about users of an advertisement sound source provided by the advertisement server  3  and the voice telecommunication terminals  4 . The record  1030  includes fields  1031 ,  1032 , and  1033 . The field  1031  registers a user/sound-source ID as identification information. The field  1032  registers an address (such as an SIP-URI or IP address) on the IP network  5 . The field  1033  registers virtual position information, i.e., position information in the virtual space about the user of the advertisement sound source or the voice telecommunication terminal identified by the user/sound-source ID. The virtual position information includes the following in the virtual space: coordinate information about the current position of the advertisement sound source or the user in the virtual space; and direction information about orientation (direction of utterance or sound generation) of the advertisement sound source or the user. 
     The position information management unit  102  receives virtual position information about a user of the voice telecommunication terminal  4  from the voice telecommunication terminal  4 . Based on the virtual position information, the position information management unit  102  updates the record  1030  about the user of the voice telecommunication terminal  4 . The record  1030  is registered in the position information storage unit  103 . The position information storage unit  103  registers the record  1030  about the user of each voice telecommunication terminal  4 . The record  1030  contains virtual position information. Based on the virtual position information, the position information management unit  102  determines virtual position information about an advertisement sound source provided from the advertisement server  3 . Based on the determined virtual position information, the position information management unit  102  registers the record  1030  about the advertisement sound source provided from the advertisement server  3  in the position information storage unit  103 . Further, the position information management unit  102  responds to a position information request from media server  2  or the voice telecommunication terminal  4 . The position information management unit  102  then transmits each record  1030  registered in the position information storage unit  103  to the transmission origin of the position information request. 
       FIG. 4  illustrates an operation flow of the presence server  1 . 
     The position information management unit  102  receives a position information registration request including the user/sound-source ID and the virtual position information from the voice telecommunication terminal  4  via the IP network interface unit (S 1001 ) . The position information management unit  102  searches the position information storage unit  103  for the record whose field  1031  registers the user/sound-source ID (S 1002 ). When the virtual position information is registered to the field  1033  in the retrieved record  1030 , the position information management unit  102  updates the virtual position information to virtual position information contained in the position information registration request (S 1003 ). 
     The position information management unit  102  receives a sound source addition request including the user/sound-source ID from the advertisement server  3  via the IP network interface unit  101  (S 1101 ). The position information storage unit  103  stores virtual position information about the user of each voice telecommunication terminal  4 . Based on the virtual position information, the position information management unit  102  generates virtual position information about the advertisement sound source provided from the advertisement server  2  as the request transmission origin (S 1102 ). 
     The position information storage unit  103  stores the record  1030  about the user of the voice telecommunication terminal  4 . Specifically, the position information management unit  102  performs the following process for each record  1030  to generate the virtual position information about the advertisement sound source. The virtual position information registered to the field  1033  in the focused record  1030  specifies a position in the virtual space. This position is assumed to be a focused position. 
     The virtual position information registered to the field  1033  specifies a position in the virtual space  106 . As shown in  FIG. 5A , the position information management unit  102  first detects the record  1030  about a user of another voice telecommunication terminal  4  whose position is nearest to the focused position. According to the example in  FIG. 5A , the position information management unit  102  detects position (jiro)  104   3  corresponding to focused position (taro)  104   1 . The position information management unit  102  detects position (taro)  104   1  corresponding to focused position (hanako)  104   2 . The position information management unit  102  detects position (taro)  104   1  corresponding to focused position (jiro)  104   3 . Viewed from the focused position, the position information management unit  102  detects an area distant from the position in the virtual space  106  specified by the virtual position information registered to the field  1032  in the detected record  1030 . The position information management unit  102  determines this area to be an advertisement sound source installation area candidate. According to the example in  FIG. 5A , the position information management unit  102  selects an advertisement sound source installation area candidate for the focused position (taro)  104   1  outside the range with radius r 1  around the focused position (taro)  104   1 . The position information management unit  102  selects an advertisement sound source installation area candidate for the focused position (hanako)  104   2  outside the range with radius r 1  around the focused position (hanako)  104   2 . The position information management unit  102  selects an advertisement sound source installation area candidate for the focused position (jiro)  104   3  outside the range with radius r 1  around the focused position (jiro)  104   3 . 
     As shown in  FIG. 5B , the position information management unit  102  finds an overlap range  107  of the advertisement sound source installation area candidates determined for the records  1030  about the users of the voice telecommunication terminals  4 , where the records  1030  are stored in the position information storage unit  103 . The position information management unit  102  determines a given position  105  within the range  107  as a position (coordinate) in the virtual space for the advertisement sound source (publicity A) provided by the advertisement server  3  as the sound source addition request transmission origin. The users of the voice telecommunication terminals  4  are viewed from the determined position to assume angle β between the left-end user (hanako) and the right-end user (jiro). So as to minimize angle β, the position information management unit  102  determines an orientation of the advertisement sound source (publicity A) in the virtual space. 
     In this manner, the position information management unit  102  generates the virtual position information about the advertisement sound source provided by the advertisement server  3  as the sound source addition request transmission origin. The position information management unit  102  then adds a new record  1030  to the position information storage unit  103 . The position information management unit  102  registers a user/sound-source ID contained in the field  1031  of the record  1030 . The position information management unit  102  registers the address of the request transmission origin. The position information management unit  102  then registers the generated virtual position information to the field  1033  (S 1103 ). 
     The position information management unit  102  receives a sound source deletion request containing the user/sound-source ID from the advertisement server  3  via the IP network interface unit  101  (S 1201 ). From the position information storage unit  103 , the position information management unit  102  retrieves the record whose field  1031  registers the user/sound-source ID. The position information management unit  102  then deletes that record  1030  from the position information storage unit  103  (S 1202 ). 
     The position information management unit  102  receives a position information request from the media server  2  or the voice telecommunication terminal  4  via the IP network interface unit  101  (S 1301 ) . The position information management unit  102  reads all the records  1030  from the position information storage unit  103  (S 1302 ) and returns the records to the requesting transmission origin (S 1303 ). 
     Let us return to  FIG. 1  for further description. The media server  2  receives voice data from the voice telecommunication terminals  4  other than the relevant voice telecommunication terminal  4 . The media server  2  applies a stereophonic process to the received voice data correspondingly to relative positions between the user of the relevant voice telecommunication terminal  4  and users of the other voice telecommunication terminals  4  managed by the presence server  1 . The media server  2  receives acoustic data for the advertisement sound source from the advertisement server  3 . The media server  2  applies a stereophonic process to the received acoustic data correspondingly to relative positions between the user of the relevant voice telecommunication terminal  4  and the advertisement sound source managed by the presence server  1 . In this manner, the media server  2  synthesizes the stereophonically processed voice data of the other voice telecommunication terminals  4  with the acoustic data of the advertisement sound source to generate voice call data for the relevant voice telecommunication terminal  4 . 
       FIG. 6  is a schematic construction diagram of the media server  2 . 
     As shown in  FIG. 6 , the media server  2  includes: an IP network interface unit  201  for connection to the IP network  5 ; an RTP (Real-time Transport Protocol) processing unit  202 ; an SIP (Session Initiation Protocol) processing unit  203 ; a presence acquisition unit  204 ; a space modeler  205 ; a user information generation unit  206 ; a voice distribution unit  207 ; and an audio renderer  208  provided for each voice telecommunication terminal  4 . 
     The SIP control unit  203  establishes a speech path between the advertisement server  3  and each voice telecommunication terminal  4  via the IP network interface unit  201 . 
     The RTP processing unit  202  receives acoustic data or voice data from the advertisement server  3  and the voice telecommunication terminal  4 , respectively. The RTP processing unit  202  outputs the received data as well as its transmission origin address to the voice distribution unit  207 . The audio renderer  208  outputs synthesized data corresponding to each of the voice telecommunication terminals  4 . The RTP processing unit  202  transmits the output synthesized data to each of the voice telecommunication terminals  4  via the speech path. 
     The presence acquisition unit  204  periodically transmits a position information request to the presence server  1  via the IP network interface unit  201 . As a response, the presence acquisition unit  204  receives the records (virtual position information)  1030  about the advertisement server  3  and the voice telecommunication terminals  4  from the presence server  1 . The presence acquisition unit  204  notifies the space modeler  205  of the received records  1030 . 
     The space modeler  205  receives the records  1030  about the advertisement server  3  and the voice telecommunication terminals  4  from the presence acquisition unit  204  and holds the received records  1030 . In addition, the space modeler  205  outputs the records  1030  to the user information generation unit  206 . 
     The user information generation unit  206  performs the following process for each of the voice telecommunication terminals  4 . That is, the user information generation unit  206  specifies the record  1030  containing the address of the relevant voice telecommunication terminal  4  from the records  1030  received from the space modeler  205 . The user information generation unit  206  transmits the specified record  1030  as own-user information to the voice distribution unit  207 . The user information generation unit  206  assumes the records other than the specified record  1030  to be other-user/sound-source information. The user information generation unit  206  associates the other-user/sound-source information with the own-user information and transmits the other-user/sound-source information to the voice distribution unit  207 . 
     The voice distribution unit  207  receives acoustic data and voice data from the RTP processing unit  202  for each voice telecommunication terminal  4 . Out of these acoustic data and voice data, the voice distribution unit  207  extracts data used for synthesized data to be transmitted to the relevant voice telecommunication terminal  4 . Specifically, the voice distribution unit  207  performs the following process for each voice telecommunication terminal  4 . 
     Out of the own-user information received from the user information generation unit  206 , the voice distribution unit  207  detects own-user information containing the user/sound-source ID of the targeted voice telecommunication terminal  4 . The voice distribution unit  207  assumes the detected own-user information to be own-user information about the relevant voice telecommunication terminal  4 . The voice distribution unit  207  outputs the own-user information to the audio renderer  208  associated with the relevant voice telecommunication terminal  4 . Out of the other-user/sound-source information received from user information generation unit  206 , the voice distribution unit  207  detects other-user/sound-source information associated with the relevant own-user information. The voice distribution unit  207  detects acoustic data and voice data from those received from the RTP processing unit  502  so that the detected acoustic data and voice data can be used for synthesized data to be transmitted to the relevant voice telecommunication terminal  4 . The voice distribution unit  207  detects the acoustic data and voice data based on addresses contained in the other-user/sound-source information associated with the own-user information. The voice distribution unit  207  associates the detected acoustic data and voice data with the other-user/sound-source information containing the address used for the data detection. The voice distribution unit  207  outputs the acoustic data and voice data to the audio renderer  208  associated with the relevant voice telecommunication terminal  4 . 
     The audio renderer  208  receives each acoustic data and voice data as well as other-user/sound-source information from the voice distribution unit  508 . The audio renderer  208  receives the own-user information from the voice distribution unit  508 . The audio renderer  208  buffers the received acoustic data and voice data to synchronize (associate) them with each other. The audio renderer  208  stereophonically processes the synchronized acoustic data and voice data based on relative positions among the advertisement sound source, the other users, and the own user. The acoustic data and voice data are provided with virtual position information about the other-user/sound-source information and the relevant own-user information. The virtual position information specifies the relative position. The synthesized data (3D audio data) contains signal data (signal string) for two channels (left and right channels). The audio renderer  208  outputs the synthesized data to the RTP processing unit  202 . 
     The audio renderer  208  will be described in more detail. 
     The 3D audio technology represents the sound direction and distance using an HRIR (Head Related Impulse Response) and artificial echo. The HRIR (Head Related Impulse Response) mainly represents an impulse response, i.e., how the sound varies around a human head. The artificial echo is generated from the virtual environment such as a room. The HRIR is determined by a distance between the sound source and the human head and angles (horizontal and vertical angles) therebetween. It is assumed that the audio renderer  208  previously stores HRIR values measured for the distances and angles using a dummy head. The HRIR values are measured for a left channel (the dummy head&#39;s left ear) and a right channel (the dummy head&#39;s right ear). Different HRIR values are used to represent the sense of directions such as left and right, forward and backward, and up and down. 
       FIG. 7  illustrates processes of the audio renderer  208 . The audio renderer  208  performs the following calculation with respect to each of the acoustic data and voice data as well as the other-user/sound-source information transmitted from the voice distribution unit  207 . 
     The audio renderer  208  accepts each of the other-user/sound-source information and signal string s i [t] (t=1, 2, 3, and so on) of the acoustic data or voice data associated with the other-user/sound-source information from the voice distribution unit  207 . In addition, the audio renderer  208  accepts the own-user information from the voice distribution unit  207 . The virtual position information is contained in each of the other-user/sound-source information and the own-user information. The audio renderer  208 . configures these virtual position information as parameters used for the 3D audio process (stereophonic process) applied to signal string s i [t] (t=1, 2, 3, and so on) of the acoustic data or voice data associated with the other-user/sound-source information (S 2001 ). 
     The audio renderer  208  calculates direct sound and reflected sound as echo in the acoustic data or voice data for each of the other-user/sound-source information. With respect to the direct sound, the audio renderer  208  uses the position information configured to be parameters to calculate a distance and an angle (azimuth) between the own user and the advertisement sound source having the other-user/sound-source information or between the own user and the other user in the virtual space (S 2002 ). The audio renderer  208  then specifies an HRIR corresponding to the distance and the angle for the own user out of the prestored HRIR values (S 2003 ). The audio renderer  208  may use an HRIR value calculated by interpolating the prestored HRIR value. 
     The audio renderer  208  performs the convolution calculation using the signal string provided at S 2001  and the HRIR for the left channel specified at S 2003  to generate a left channel signal (S 2004 ). Similarly, the audio renderer  208  performs the convolution calculation using the signal string provided at S 2001  and the HRIR for the right channel specified at S 2003  to generate a right channel signal (S 2005 ). 
     With respect to the reverberating sound, the audio renderer  208  calculates an echo to be added using the position information configured to be parameters at S 2001  (S 2006  and S 2007 ). That is, the audio renderer  208  calculates the echo based on how the sound varies (impulse response) due to virtual space attributes. The echo calculation will be described below. 
     An echo is composed of early reflection (early reflection) and late echo (late reverberation). The early reflection is generally considered to be more important than the late echo in terms of the sense formation (recognition) as to a distance to another user or the size of a room (virtual space). Reportedly, it is possible to hear several tens of early reflections from a wall, ceiling, and floor in a room as an actual space depending on conditions several to 100 milliseconds after hearing the direct sound, i.e. . , the sound directly generated from a sound source. A cubic room causes only six early reflections at a time. When a room is complexly shaped or contains furniture and the like, the number of reflected sounds increases. Further, it is possible to hear the sound reflected several times against the wall and the like. 
     An example of calculating the early reflection is the image source method. For example, see Allen, J. B. and Berkley, A., “Image Method for efficiently Simulating Small-Room Acoustics”, J. Acoustical Society of America, Vol. 65, No. 4, pp. 943-950, April 1979. A simple image source method assumes that the room&#39;s wall, ceiling, and floor have mirror surfaces. The method calculates the reflected sound as the sound from an image of the sound source opposite the mirror surface. 
       FIG. 8  schematically shows a two-dimensional image source method with a ceiling and a floor omitted for simplicity of description. An original virtual space  2081  exists at the center. The virtual space  2081  contains the own user and the advertisement sound source (or another user) . Twelve mirror images including room walls  2082  are drawn around the sound room  2081 . The number of mirror images is not limited to 12 and may be larger or smaller. 
     The audio renderer  208  calculates the distance and the direction between each image of the advertisement sound sources (or other users) and the own user. At this time, it is assumed that the sound directly travels to the own user (audience) from each image of the advertisement sound sources (or the other users) in the mirror images. Since the sound intensity is inversely proportional to the distance, the audio renderer  208  attenuates each sound volume in accordance with the distance. Let us suppose that the wall reflectivity is α (0&lt;α&lt;1) . When a sound sample is reflected n times against the wall, the audio renderer  208  further attenuates its sound volume by multiplying it and α n  together. 
     The value for reflectivity α is assumed to be approximately 0.6. A reason for using the value of approximately 0.6 is to acquire an echo (i.e., a ratio between the direct sound and the reflected sound) sufficient for the own user to recognize a distance up to the advertisement sound source (or the other user) . As another reason, using too large a value for α blurs the own user&#39;s sense of direction. 
     Out of the prestored HRIR values, the audio renderer  208  specifies an HRIR value corresponding to the distance and the angle between the own user and each image of the advertisement sound source (or another user) (S 2007 ). Since the reflected sound reaches the human head from different directions, the HRIR value to be applied needs to differ from the HRIR value for the direct sound specified at S 2003 . 
     A large amount of calculation is needed when the convolution is performed (S 2007  and S 2008 ) for each of many reflected sounds using different HRIR values to be described later. To prevent the calculation amount from increasing, the reflected sound calculation may use an HRIR value corresponding to the sound source provided at the front irrespectively of actual sound source directions. A small amount of calculation is needed to replace the HRIR calculation by calculating only a time difference (ITD: interaural time difference) and an intensity difference (IID: interaural intensity difference). 
     The audio renderer  208  performs the convolution calculation using the signal string provided at S 2001  and the HRIR for the left channel specified at S 2007  to generate an echo for the left channel signal (S 2008 ). Similarly, the audio renderer  208  performs the convolution calculation using the signal string provided at S 2001  and the HRIR for the right channel specified at S 2007  to generate an echo for the right channel signal (S 2009 ). 
     The audio renderer  208  calculates left channel signals for all the advertisement sound sources and the other users in this manner and then sums the signals (S 2010 ) . The left channel signal contains the direct sound calculated at S 2004  and the reflected sound calculated at S 2008 . The audio renderer  208  calculates right channel signals for all the advertisement sound sources and the other users in this manner and then sums the signals (S 2011 ). The right channel signal contains the direct sound calculated at S 2005  and the reflected sound calculated at S 2009 . 
     The HRIR calculation (S 2003  and S 2007 ) is performed for each data equivalent to one RTP packet. However, the convolution calculation (S 2004 , S 2005 , S 2008 , and S 2009 ) causes a portion carried over to the next one packet of data. For this reason, the audio renderer  208  needs to hold the specified HRIR or the input signal string until processing the next one packet of data. 
     In this manner, the voice distribution unit  207  transmits acoustic data and voice data for the advertisement sound source and the other users. The audio renderer  208  processes the transmitted acoustic data and voice data to perform the above-mentioned calculations such as adjusting the sound volume, superposing an echo or a reverberating sound, and filtering. The audio renderer  208  provides acoustic effects to sounds audible at positions in the own user&#39;s virtual space. That is, the audio renderer  208  performs the process consequent to virtual space attributes and relative positions in terms of the advertisement sound source and the other users to generate a stereophonic effect that orients sounds. 
     Let us return to  FIG. 1  for further description. The advertisement server  3  transmits acoustic data of the advertisement sound source to the media server  2  via the speech path established between advertisement server  3  and the media server  2 . The transmitted acoustic data is supplied to each of the voice telecommunication terminals  4 . 
       FIG. 9  is a schematic construction diagram of the advertisement server  3 . 
     As shown in  FIG. 9 , the advertisement server  3  includes: an IP network interface unit  301  for connection with the IP network  5 ; an RTP processing unit  302 ; an SIP processing unit  303 ; and an advertisement information storage unit  305 . 
     The SIP control unit  303  establishes a speech path between the advertisement server  3  and the media server  2  via the IP network interface unit  301 . 
     As will be described later, acoustic data of the advertisement sound source is received from the advertisement information transmission control unit  304 . The RTP processing unit  302  transmits the received acoustic data to the media server  2  via the speech path established between the advertisement server  3  and the media server  2 . 
     The advertisement information storage unit  305  registers acoustic data of the advertisement sound source as well as an advertisement condition.  FIG. 10  schematically shows the advertisement information storage unit  305 . As shown in  FIG. 10 , a record  3050  is registered correspondingly to each acoustic data of the advertisement sound source. The record  3050  contains fields  3051 ,  3052 , and  3053 . The field  3051  registers a user/sound-source ID as identification information about acoustic data of the advertisement sound source. The field  3052  registers acoustic data of the advertisement sound source. The field  3053  registers a transmission time slot for acoustic data of the advertisement sound source. The embodiment registers the records  3050  in the order of transmission time slots. 
     While the advertisement information storage unit  305  stores acoustic data of the advertisement sound source, the advertisement information transmission control unit  304  controls transmission of the stored acoustic data to the media server  2 .  FIG. 11  shows an operational flow of the advertisement information position control unit  304 . 
     The advertisement information transmission control unit  304  sets counter value n to 1 (S 3001 ). 
     The advertisement information transmission control unit  304  focuses on the nth record  3050  stored in the advertisement information storage unit  305  and determines it to be a focused record (S 3002 ). Using a built-in timer and the like, the advertisement information transmission control unit  304  determines whether or not the current time reaches the start time of an advertisement time slot registered in the field  3053  of the focused record (S 3003 ). 
     When the current time reaches the start time of the advertisement time slot (YES at S 3003 ), the advertisement information transmission control unit  304  generates a sound source addition request containing the user/sound-source ID registered in the field  3050  of the focused record. The advertisement information transmission control unit  304  transmits the generated sound source addition request to the presence server  1  via the IP network interface unit  301  (S 3004 ). 
     The advertisement information transmission control unit  304  allows the SIP control unit  303  to establish a speech path (S 3550 ). In response to this, the SIP control unit  303  performs an SIP-compliant call control procedure in connection with the media server to establish a speech path to the media server  2 . The advertisement information transmission control unit  304  reads the acoustic data registered in the field  3052  of the focused record from the advertisement information storage unit  350  and outputs the acoustic data to the RTP processing unit  302  (S 3006 ). In response to this, the RTP processing unit  302  uses the speech path to the media server  2  to transmit the acoustic data received from the advertisement information transmission control unit  304  to the media server  2 . Thereafter, the advertisement information transmission control unit  304  periodically repeats output of acoustic data stored in the field  3052  of the focused record to the RTP processing unit  302 . As a result, the acoustic data is repeatedly transmitted to the media server  2 . 
     Using a built-in timer and the like, the advertisement information transmission control unit  304  determines whether or not the current time reaches the end time of the advertisement time slot registered in the field  3053  of the focused record (S 3007 ). When the current time reaches the end time of the advertisement time slot (YES at S 3007 ), the advertisement information transmission control unit  304  stops the transmission of the acoustic data registered in the field  3052  of the focused record to the media server  2  using the speech path (S 3008 ). The advertisement information transmission control unit  304  allows the SIP control unit  303  to disconnect the speech path (S 3009 ). In response to this, the SIP control unit  303  disconnects the speech path to the media server  2  in accordance with SIP. 
     The advertisement information transmission control unit  304  generates a sound source deletion request containing the user/sound-source ID of the own advertisement server  3  and transmits the sound source deletion request to the presence server  1  via the IP network interface unit  301  (S 3010 ). Thereafter, the advertisement information transmission control unit  304  increments counter value n by one (S 3011 ) and then returns to S 3002 . 
     Let us return to  FIG. 1  for further description. The voice telecommunication terminal  4  transmits virtual position information about the own user to the presence server  1 . In addition, the voice telecommunication terminal  4  receives virtual position information about the advertisement sound source of the advertisement server  3  and virtual position information about the user of each voice telecommunication terminal  4  from the presence server  1 . Based on the received virtual position information, the voice telecommunication terminal  4  generates and outputs a map that shows positions and orientations of users of the voice telecommunication terminals  4  and advertisement sound source of the advertisement server  3  in the virtual space. 
     The voice telecommunication terminal  4  transmits the own user&#39;s voice data to the media server  2  and receives synthesized data (3D audio data) from the media server  2 . The voice telecommunication terminal  4  reproduces and outputs the received synthesized data. 
       FIG. 12  is a schematic construction diagram of the voice telecommunication terminal  4 . 
     As shown in  FIG. 12 , the voice telecommunication terminal  4  includes: an voice input unit  401 ; an voice output unit  402 ; a video output unit  403 ; an operation acceptance unit  404 ; an audio encoder  405 ; an audio decoder  406 ; an IP network interface unit  407  for connection to the IP network  5 ; an SIP control unit  408 ; an RTP control unit  409 ; a presence provider  410 ; and a virtual space map generation unit  411 . 
     The voice input unit  401  is supplied with an audio signal collected by a microphone  421 . The voice output unit  402  is connected to a headphone (or a speaker)  422  compliant with the 3D audio (e.g., pseudo 5.1-channel audio). The video output unit  403  displays video of a virtual space map on a display  423 . The virtual space map is output from the virtual space map generation unit  411  to be described later. The operation acceptance unit  404  accepts a user operation of a pointing device  424 . 
     The audio encoder  405  encodes a voice signal supplied to the voice input unit  401  and outputs voice data to the RTP processing unit  409 . The audio decoder  406  decodes synthesized data output from the RTP processing unit  409  and outputs  3 D audio compliant voice signal to the voice output unit  402 . 
     The SIP control unit  408  establishes a speech path to the media server  3  via the IP network interface unit  407 . The RTP processing unit  409  stores voice data output from the audio encoder  405  in an RTP packet and transmits the RTP packet to the media server  2  via the speech path established by the SIP processing unit  408 . The RTP processing unit  409  extracts the synthesized data (3D audio data) from the RTP packet received from the media server  2  via the speech path and outputs the synthesized data to the audio decoder  406 . 
     The presence provider  410  determines own user&#39;s position (coordinate) and the line of sight (azimuth direction) in the relevant virtual space according to the predetermined virtual space attributes and own user&#39;s operation of the pointing device  424 . The operation acceptance unit  404  accepts the own user&#39;s operations. The presence provider  410  transmits the own user&#39;s virtual position information including the determined position and line of sight to the virtual space map generation unit  411  and to the presence server  1  via the IP network interface unit  407 . The presence provider  410  periodically transmits a position information request to the presence server  1  via the IP network interface unit  212 . As its response, the presence provider  410  receives the records  1030  about the advertisement sound source and the other users from the presence server  1 . The presence provider  410  notifies the received record  1030  to the virtual space map generation unit  411 . 
     The virtual space map generation unit  411  receives the records  1030  about the own user, the advertisement sound source, and the other users from the presence provider  410 . The records  1030  register the virtual position information. According to the virtual position information, the virtual space map generation unit  411  generates a virtual space map that presents positions and orientations of the own user, the advertisement sound source, and the other users. The virtual space map generation unit  411  outputs the video of the virtual space map to the video output unit  403 .  FIG. 13  shows an example of video for the virtual space map. As shown in  FIG. 13 , the display  423  displays the video of the virtual space map so as to be able to visualize positions and orientations of own user  4121 , the other users  4122 , and an advertisement sound source  4123 . 
     A general computer system as shown in  FIG. 14  can be used for the presence server  1 , the media server  2 , and the advertisement server  3  according to the above-mentioned construction. Such computer system includes: a CPU  601  to process and calculate data according to programs; memory  602  where the CPU  601  can directly read and write data; an external storage device  603  such as a hard disk drive; and a communication device  604  for data communication with an external system via the IP network  5 . Specifically, the system represents a sever, a host computer, and the like. 
     The general computer system as shown in  FIG. 14  can be used also for the voice telecommunication terminal  4  according to the above-mentioned construction. Such computer system includes: the CPU  601  to process and calculate data according to programs; the memory  602  where the CPU  601  can directly read and write data; the external storage device  603  such as a hard disk drive; the communication device  604  for data communication with an external system via the IP network  5 ; an input device  605  such as a keyboard and a mouse; and an output device  606  such as an LCD. Specifically, the computer system represents a PDA (Personal Digital Assistant), a PC (Personal Computer), and the like. 
     The CPU  601  executes specified programs loaded into or stored in the memory  602  to implement functions of the above-mentioned devices. 
       FIG. 15  schematically shows operations of the voice call system according to the first embodiment of the invention. Let us suppose that the voice telecommunication terminal  4  already establishes a speech path to the media server  2 . Although  FIG. 15  shows one voice telecommunication terminal  4 , it is assumed that multiple voice telecommunication terminals  4  establish speech paths to the media server  2 . The voice telecommunication terminals  4  are assumed to perform operations as shown in  FIG. 15 . 
     When a user operation changes a user position and orientation in the virtual space, the voice telecommunication terminal  4  generates new virtual position information. The voice telecommunication terminal  4  transmits a position information registration request including the virtual position information to the presence server  1  (S 5401 ). 
     The presence server  1  receives the position information registration request from the voice telecommunication terminal  4 . The presence server  1  then searches the position information storage unit  103  for the record  1030  that contains the requested transmission origin terminal&#39;s user/sound-source ID and the request transmission origin address. The presence server  1  updates the retrieved record  1030  using the virtual position information contained in the request (S 5101 ). 
     The advertisement server  3  detects that the current time reaches the start time of the advertisement time slot registered in the record  3050  (focused record) that is stored in the advertisement information storage unit  305  and is to be processed next (S 5301 ). The advertisement server  3  then transmits the sound source addition request containing the user/sound-source ID registered in the focused record to the presence server  1  (S 5302 ). Thereafter, the advertisement server  3  transmits an INVITE message to the media server  2  (S 5303 ) to establish a speech path to the media server  2  (S 5304 ). 
     When receiving the sound source addition request from the advertisement server  3 , the presence server  1  generates virtual position information about the advertisement sound source. The presence server  1  registers the virtual position information and the record  1030  containing the user/sound-source ID contained in the request to the position information storage unit  103  (S 5102 ). 
     The media server  2  periodically transmits the position information request to the presence server  1  (S 5201 ). Similarly, the voice telecommunication terminal  4  periodically transmits the position information request to the presence server  1  (S 5402 ). 
     When receiving the position information request from the media server  2 , the presence server  1  reads all records  1030  from the position information storage unit  103  and transmits them to the media server  2  (S 5103 ). Similarly, when receiving the position information request from the voice telecommunication terminal  4 , the presence server  1  reads all records  1030  from the position information storage unit  103  and transmits them to the voice telecommunication terminal  4  (S 5104 ). 
     The voice telecommunication terminal  4  transmits own user&#39;s voice data to the media server  2  via the established speech path to the media server  2  (S 5403 ). Similarly, the. advertisement server  3  transmits the acoustic data registered in the focused record to the media server  2  via the speech path (established at S 5304 ) to the media server  2  (S 5403 ). 
     The media server  2  applies the 3D audio process to the acoustic data and the voice data received from the advertisement server  3  and the voice telecommunication terminal  4  based on the virtual position information about the advertisement sound source of the advertisement server  3  and about users of the voice telecommunication terminals  4 . The virtual position information is received from the presence server  1 . The media server  2  synthesizes the acoustic data and the voice data treated with the 3D audio process to generate synthesized data (S 5202 ). The media server  2  also transmits the synthesized data to the voice telecommunication terminal  4  via the established speech path to the voice telecommunication terminal  4  (S 5203 ). 
     The advertisement server  3  detects that the current time reaches the end time of the advertisement time slot registered in the focused record (S 5306 ) . The advertisement server  3  then transmits a sound source deletion request containing the user/sound-source ID registered in the focused record to the presence server  1  (S 5307 ). Thereafter, the advertisement server  3  transmits an BYE message to the media server  2  (S 5308 ) to disconnect the speech path to the media server  2 . 
     When receiving the sound source deletion request from the advertisement server  3 , the presence server  1  searches the position information storage unit  103  for the record  1030  containing the user/sound-source ID contained in the request or containing the transmission origin address of the request. The presence server  1  deletes the record  1030  from the position information storage unit  103  (S 5105 ). 
     The first embodiment of the invention has been described. 
     The embodiment performs the 3D audio process to synthesize voice data for each of the other voice telecommunication terminals  4  with acoustic data for the advertisement server  3  correspondingly to each of the voice telecommunication terminals  4 . The process is based on relative positions in the virtual space among users of the other voice telecommunication terminals  4 , the advertisement sound source of the advertisement server  3 , and the user of the relevant voice telecommunication terminal  4 . The synthesized data is used as voice call data for the relevant voice telecommunication terminal  4 . The following describes positions of the advertisement sound source and the voice telecommunication terminals  4  in the virtual space for the advertisement sound source. A distance between the user of the relevant voice telecommunication terminal  4  and the advertisement sound source in the virtual space is longer than a distance between the user of the relevant voice telecommunication terminal  4  and at least a user of another nearest voice telecommunication terminal  4 . Accordingly, the user of the voice telecommunication terminal  4  can distinguish intended party&#39;s voice data synthesized with the call data from acoustic data of the advertisement sound source based on the relative positional relationship between the intended party and the advertisement sound source in the virtual space. The acoustic data of the advertisement sound source can be heard farther than the voice data of the user as the intended party. Consequently, it is possible to audiovisually provide the advertisement for users in process of voice call without interrupting the conversation. 
     Second Embodiment 
     While the first embodiment specifies a distance between the user of the voice telecommunication terminal  4  and the advertisement sound source provided by the advertisement server  3 , the second embodiment varies that distance according to the user&#39;s preference. 
     The voice telecommunication system according to the second embodiment differs from that according to the first embodiment in that the presence server  1  and the advertisement server  3  are replaced by a presence server  1 A and an advertisement server  3 A. The other parts of the construction are the same as those of the first embodiment. 
     The advertisement server  3 A differs from the advertisement server  3  according to the first embodiment in that the advertisement information transmission control unit  304  and the advertisement information storage unit  305  are replaced by an advertisement information transmission control unit  304 A and an advertisement information storage unit  305 A. The other parts of the construction are the same as those of the advertisement server  3 . 
     The advertisement information storage unit  305 A registers acoustic data of the advertisement sound source as well as advertisement conditions and categories.  FIG. 16  schematically shows a registration content of the advertisement information storage unit  305 A. As shown in  FIG. 16 , a record  3050 A is registered for each acoustic data of the advertisement sound source. The record  3050 A differs from the record  3050  according to the first embodiment (see  FIG. 10 ) in that the record contains an additional field  3054  for registering an advertisement category. 
     At S 3004  in  FIG. 11 , the advertisement information transmission control unit  304 A transmits a sound source addition request to the presence server  1 . At this time, the sound source addition request contains a category registered in the field  3054  of the focused record. The other operations are the same as those for the advertisement information transmission control unit  304  according to the first embodiment. 
     The presence server  1 A differs from the presence server  1  according to the first embodiment in that the position information management unit  102  and the position information storage unit  103  are replaced by a position information management unit  102 A and a position information storage unit  103 A. The other parts of the construction are the same as those of the presence server  1 . 
       FIG. 17  schematically shows a registration content of the position information storage unit  103 A. As shown in  FIG. 17 , a record  1030 A is recorded for each advertisement sound source provided by the advertisement server  3 A and each user of the voice telecommunication terminal  4 . The record  1030 A differs from the record  1030  (see  FIG. 3 ) according to the first embodiment in that the record contains an additional field  1034  for registering a user preference. 
     At S 1103  in  FIG. 4 , the position information management unit  102 A generates the virtual position information about the advertisement sound source provided by the advertisement server  2  as the relevant request transmission origin. This operation is based on the virtual position information about and the preference of the user of each voice telecommunication terminal  4  stored in the position information storage unit  103 A and based on the category contained in the sound source addition request. Similarly to the first embodiment (see  FIG. 5 ), the position information management unit  102 A determines an advertisement sound source installation area candidate for each record  1030  about the user of the voice telecommunication terminal  4  and finds the overlap range  107  for the advertisement sound source installation area candidate. It should be noted that the position information storage unit  103 A stores the record  1030 . Thereafter, the position information management unit  102 A checks whether or not the preference registered in the field  1034  belongs to the category contained in the sound source addition request in terms of each record  1030  about the user of the voice telecommunication terminal  4 . It should be noted that the position information storage unit  103 A stores the record  1030 . The position information management unit  102 A determines a position  105  in the virtual space for the advertisement sound source (publicity A) provided by the advertisement server  3  as the request transmission origin as follows. That is, the advertisement sound source is expected to be positioned closer to a position in the virtual space  106  specified by the virtual position information registered in the field  1033  of the record  1030  having the field  1034  assigned with the preference belonging to the category contained in the request than a position in the virtual space  106  specified by the virtual position information registered in the field  1033  of the record  1030  having the field  1034  assigned with the preference belonging to the category NOT contained in the request. In  FIG. 5B , for example, let us suppose that the preference of the user (taro) belongs to the category of the advertisement sound source (publicity A) and that the preferences of the other users (jiro and hanako) do not belong to the category of the advertisement sound source (publicity A) . In this case, the position information management unit  102 A determines the position of the advertisement sound source (publicity A) in the virtual space to be within an area  107 A in the overlap range  107 . The users of the voice telecommunication terminals  4  are viewed from the determined position to assume angle β between the left-end user (hanako) and the right-end user (jiro) . So as to minimize angle β, the position information management unit  102 A determines an orientation of the advertisement sound source (publicity A) in the virtual space. 
     At S 1103  in  FIG. 4 , the position information management unit  102 A adds a new record  1030 A to the position information storage unit  103 . The position information management unit  102 A registers the user/sound-source ID contained in the request in the field  1031  of the record  1030 A, registers the address of the request transmission origin, registers the generated virtual position information in the field  1033 , and registers the category contained in the request in the field  1034 . 
     The second embodiment of the invention has been described. 
     The second embodiment provides the following effect in addition to the effect of the first embodiment. The advertisement sound source is disposed in the virtual space closer to a user having the preference belonging to the category of the advertisement sound source than a user not having the same. Accordingly, the advertisement is issued with a relatively small sound volume to a user who does not have the preference belonging to the category of the advertisement sound source. In addition, the advertisement is issued with a relatively large sound volume to a user who has the preference belonging to the category of the advertisement sound source. The advertising effectiveness can be improved. 
     Third Embodiment 
     The third embodiment enables each of the voice telecommunication terminals  4  to determine whether or not to output acoustic data from the advertisement sound source provided by the advertisement server  3  according to the above-mentioned first embodiment. 
     The voice telecommunication system according to the third embodiment differs from the voice telecommunication system in  FIG. 1  according to the first embodiment in that the presence server  1  and the media server  2  are replaced by a presence server  1 B and a media server  2 B. The other parts of the construction are the same as those of the first embodiment. 
     The presence server  1 B differs from the presence server  1  according to the first embodiment in that the position information management unit  102  and the position information storage unit  103  are replaced by a position information management unit  102 B and a position information storage unit  103 B. The other parts of the construction are the same as those of the presence server  1 . 
       FIG. 18  schematically shows a registration content of the position information storage unit  103 B. As shown in  FIG. 18 , a record  1030 B is recorded for each advertisement sound source provided by the advertisement server  3  and each user of the voice telecommunication terminal  4 . The record  1030 B differs from the record  1030  (see  FIG. 3 ) according to the first embodiment in that the record  1030 B contains an additional field  1035  for registering an advertisement policy. The advertisement policy determines whether or not to output acoustic data of the advertisement sound source. Each user of the voice telecommunication terminal  4  is provided with the record  1030 B. The field  1035  in the record  1030 B registers “advertisement provided” to output acoustic data of the advertisement sound source or “no advertisement” not to output the same. A blank (null data) is placed in the field  1035  of the record  1030 B for the advertisement sound source provided by the advertisement server  3 . 
     At S 1103  in  FIG. 4 , the position information management unit  102 B adds a new record  1030 B to the position information storage unit  1 b 3 . The position information management unit  102 B registers the user/sound-source ID contained in the request in the field  1031  of the record  1030 B, registers the address of the request transmission origin, registers the generated virtual position information in the field  1033 , and registers null data in the field  1035 . 
     The media server  2 B differs from the media server  2  in that the user information generation unit  206  is replaced by a user information generation unit  206 B. The other parts of the construction are the same as those of the media server  2 . 
     The user information generation unit  206 B performs the following process for each of the voice telecommunication terminals  4 . Out of records  1030 B received from the space modeler  205 , the user information generation unit  206 B specifies the record  1030 B that contains the address of the voice telecommunication terminal  4 . The user information generation unit  206 B transmits the specified record  1030 B as own-user information to the voice distribution unit  207 . The user information generation unit  206 B checks for the advertisement policy registered in the field  1035  of the record  1030 B as own-user information. When the advertisement policy indicates “advertisement provided,” the user information generation unit  206 B assumes the records  1030 B other than the record  1030 B as own-user information to be other-user/sound-source information. The user information generation unit  206 B associates the records  1030 B assumed to be other-user/sound-source information with the own-user information and transmits these records  1030 B to the voice distribution unit  207 . When the advertisement policy indicates “no advertisement,” the user information generation unit  206 B specifies the record  1030 B whose field  1035  contains null data, i.e., the record  1030 B for the advertisement sound source provided by the advertisement server  3 . The user information generation unit  206 B assumes this record  1030 B and the records  1030 B other than the record as the own-user information to be other-user/sound-source information. The user information generation unit  206 B associates the records  1030 B assumed to be other-user/sound-source information with the own-user information and transmits these records  1030 B to the voice distribution unit  207 . 
     The third embodiment of the invention has been described. 
     The third embodiment provides the following effect in addition to the effect of the first embodiment. That is, the third embodiment enables each of the voice telecommunication terminals  4  to determine whether or not to output acoustic data for the advertisement sound source provided by the advertisement server  3 . It is possible to prevent advertisement acoustic data from being output from the voice telecommunication terminal of the user who refuses to receive the advertisement. 
     Fourth Embodiment 
     The fourth embodiment automatically moves the position in the virtual space for the advertisement sound source provided by the advertisement server  3  according to the first embodiment. 
     The voice telecommunication system according to the fourth embodiment differs from the voice telecommunication system according to the first embodiment in that the presence server  1  and the advertisement server  3  are replaced by a presence server  1 C and an advertisement server  3 C. The other parts of the construction are the same as those of the first embodiment. 
     The advertisement server  3 C differs from the advertisement server  3  according to the first embodiment in that the advertisement information transmission control unit  304  and the advertisement information storage unit  305  are replaced by an advertisement information transmission control unit  304 C and an advertisement information storage unit  305 C. The other parts of the construction are the same as those of the advertisement server  3 . 
     The advertisement information storage unit  305 C stores not only acoustic data of the advertisement sound source, but also advertisement conditions and movement rules for the advertisement sound source.  FIG. 19  schematically shows a registration content of the advertisement information storage unit  305 C. As shown in  FIG. 19 , a record  3050 C is registered for each acoustic data of the advertisement sound source. The record  3050 C differs from the record  3050  (see  FIG. 10 ) as described in the first embodiment in that the record  3050 C contains an additional field  3055  for registering a movement rule for the advertisement sound source. The movement rules registered in the field  3055  include “Fix,” “Update,” and “Cycle.” The “Fix” rule maintains the virtual position information determined when the record  3050 C is registered. The “Update” rule periodically updates the virtual position information. The “Cycle” rule cycles through multiple specified positions in the virtual space. When “Cycle” is applied, the field  3055  also registers a cyclic schedule that specifies coordinate information in the virtual space, a cyclic sequence, and duration of stay for each of the multiple specified positions. 
     At S 3004  in  FIG. 11 , the advertisement information transmission control unit  304 C transmits a sound source addition request including the movement rule registered in the field  3055  of the focused record to the presence server  1 C. The other operations are the same as those for the advertisement information transmission control unit  304  according to the first embodiment. 
     The presence server  1 C differs from the presence server  1  according to the first embodiment in that the position information management unit  102  and the position information storage unit  103  are replaced by a position information management unit  102 C and a position information storage unit  103 C. The other parts of the construction are the same as those of the presence server  1 . 
       FIG. 20  schematically shows a registration content of the position information storage unit  103 C. As shown in  FIG. 20 , a record  1030 C is registered for the advertisement sound source provided by the advertisement server  3 C and each of the voice telecommunication terminals  4 . The record  1030 C differs from the record  1030  (see  FIG. 3 ) as described in the first embodiment in that the record  1030 C contains an additional field  1035  for registering a movement rule for the advertisement sound source. A blank (null data) is placed in the field  1035  of the record  1030 B for the user of each of the voice telecommunication terminals  4 . 
     The position information management unit  102 C performs the following process in addition to the process performed by the position information management unit  102  according to the first embodiment. Depending on needs, the position information management unit  102 C updates the virtual position information registered in the field  1033  according to the movement rule registered in the field  1035  of the record  1030 C for the advertisement sound source provided by the advertisement server  3 C. It should be noted that the position information storage unit  103  registers the record  1030 C. 
       FIG. 21  shows an operational flow of the presence server  1 C. 
     The following process is the same as that shown in  FIG. 4  according to the first embodiment. The position information management unit  102 C performs the process at S 1002  and S 1003  when receiving a position information registration request from the voice telecommunication terminal  4  via the IP network interface unit  101  (YES at S 1001 ). The position information management unit  102 C performs the process at S 1202  when receiving a sound source deletion request from the advertisement server  3 C from the IP network interface unit  101  (YES at S 1201 ). The position information management unit  102 C performs the process at S 1302  and S 1303  when receiving a position information request from the media server  2  or the voice telecommunication terminal  4  via the IP network interface unit  101  (YES at S 1301 ). 
     The position information management unit  102 C performs the process at S 1102  and S 1103  in  FIG. 4  according to the first embodiment when receiving a sound source addition request from the advertisement server  3 C via the IP network interface unit  101  (YES at S 1101 ). In addition, the position information management unit  102 C starts a built-in timer, though not shown (S 1104 ). 
     Further, the presence server  1 C according to the embodiment performs the following process. That is, the position information management unit  102 C checks whether or not the position information storage unit  103 C registers the record  1030 C (whose field  1035  contains the movement rule other than null data) for the advertisement sound source. When that record  1030 C is registered, the position information management unit  102 C checks whether or not the field  1035  of the record  1030 C registers the “Update” movement rule (S 1401 ). When the movement rule is “Update” (YES at S 1401 ), the position information management unit  102 C further checks whether or not the built-in timer indicates the elapse of specified time (S 1402 ). When the built-in timer indicates the elapse of specified time (YES at S 1402 ), the position information management unit  102 C regenerates the virtual position information for the advertisement sound source similarly to S 1102  in  FIG. 4  (S 1403 ). The position information management unit  102 C updates the virtual position information registered in the field  1033  of the record  1030 C for the advertisement sound source to the regenerated virtual position information (S 1404 ). The position information management unit  102 C resets the built-in timer (S 1405 ) and returns to S 1001 . When the built-in timer does not indicate the elapse of specified time (NO at S 1402 ), the position information management unit  102 C immediately returns to S 1001 . 
     There may be a case where the position information storage unit  103 C registers the record  10301 C for the advertisement sound source and the field  1035  of the record  1030 C does not register the “Update” movement rule (NO at S 1401 ). In such case, the position information management unit  102 C checks whether or not the field  1035  registers the “Cycle” movement rule (S 1501 ). When the movement rule is “Cycle” (YES at S 1501 ), the position information management unit  102 C checks whether or not the built-in timer indicates the elapse of specified time (S 1502 ). When the built-in timer indicates the elapse of specified time (YES at S 1502 ), the position information management unit  102 C follows the movement rule registered in the field  1035  of the record  1030 C for the advertisement sound source. The position information management unit  102 C specifies the next virtual position according to the order of virtual positions contained in the virtual position information registered in the field  1033 . The position information management unit  102 C determines the orientation of the advertisement sound source at the virtual position similarly to S 1102  in  FIG. 4 . The position information management unit  102 C regenerates the virtual position information containing the specified virtual position and the determined orientation (S 1503 ). The position information management unit  102 C updates the virtual position information registered in the field  1033  of-the record  1030 C for the advertisement sound source to the regenerated virtual position information (S 1504 ). The position information management unit  102 C then resets the built-in timer (S 1505 ) and returns to S 1001 . When the built-in timer does not indicate the elapse of specified time (NO at S 1502 ), the position information management unit  102 C immediately returns to S 1001 . 
     The fourth embodiment of the invention has been described. 
     The fourth embodiment provides the following effect in addition to the effect of the first embodiment. That is, the advertisement sound source automatically moves in the virtual space and enables more users in the virtual space to hear acoustic data for the advertisement sound source. The advertising effectiveness can be improved. 
     Fifth Embodiment 
     The fifth embodiment allows a user of a voice telecommunication terminal  4 D to request acoustic data for the advertisement sound source provided by an advertisement server  3 D in the first embodiment. 
     The voice telecommunication system according to the fifth embodiment differs from the voice telecommunication system according to the first embodiment in that the advertisement server  3  and the voice telecommunication terminal  4  are replaced by the advertisement server  3 D and the voice telecommunication terminal  4 D. The other parts of the construction are the same as those of the first embodiment. 
       FIG. 22  is a schematic construction diagram the advertisement server  3 D. 
     As shown in  FIG. 22 , the advertisement server  3 D differs from the advertisement server  3  according to the first embodiment in that the advertisement information transmission control unit  30  and the advertisement information storage unit  305  are replaced by an advertisement information transmission control unit  304 D and an advertisement information storage unit  305 D and a request acceptance unit  306  and a request storage unit  307  are provided. The other parts of the construction are the same as those of the advertisement server  3 . 
     The advertisement information storage unit  305 D stores not only acoustic data for the advertisement sound source, but also advertisement guide information.  FIG. 23  schematically shows a registration content of the advertisement information storage unit  305 D. As shown in  FIG. 23 , a record  3050 D is registered for each acoustic data of the advertisement sound source. The record  3050 D differs from the record  3050  (see  FIG. 10 ) according to the first embodiment in that the record  3050 D is provided with a field  3056  for registering the advertisement guide information instead of the field  3053  for registering the transmission time slot for acoustic data of the advertisement sound source. 
     The request storage unit  307  registers a request for acoustic data of the advertisement sound source when the request is accepted from the voice telecommunication terminal  4 .  FIG. 24  schematically shows a registration content of the request storage unit  307 . As shown in  FIG. 24 , a record  3070  is registered for each request accepted from the voice telecommunication terminal  4 . The record  3070  contains fields  3071 ,  3072 , and  3073 . The field  3071  registers the date and time the request was accepted. The field  3072  registers the user/sound-source ID for the voice telecommunication terminal as the request transmission origin. The field  3073  registers the user/sound-source ID for acoustic data of the requested advertisement sound source. 
     The request acceptance unit  306  follows a list request accepted by the voice telecommunication terminal  4  via the IP network interface unit  301 . The request acceptance unit  306  generates an advertisement list that contains the user/sound-source ID and the guide information registered in the fields  3051  and  3056  in each record  3050 D registered in the advertisement information storage unit  305 D. The request acceptance unit  306  transmits the advertisement list to the voice telecommunication terminal  4  as the list request transmission origin. When accepting the request from the voice telecommunication terminal  4  via the IP network interface unit  301 , the request acceptance unit  306  adds a new record  3070  to the request storage unit  307 . The request acceptance unit  306  registers the current date and time in the field  3071  of the added record  3070 . The request acceptance unit  306  registers, in the field  3072 , the user/sound-source ID for the request transmission origin contained in the request. The request acceptance unit  306  registers, in the field  3073 , the user/sound-source ID of acoustic data for the advertisement sound source as a request target contained in the request. 
     The advertisement information storage unit  305 D stores acoustic data for the advertisement sound source. A request stored in the request storage unit  305  specifies the acoustic data. The advertisement information transmission control unit  304 D controls transmission of the acoustic data to the media server  2 .  FIG. 25  shows an operational flow of the advertisement information position control unit  304 D. 
     The advertisement information transmission control unit  304 D searches the request storage unit  307  for the record  3070  that registers the earliest reception date and time in the field  3071 . The advertisement information transmission control unit  304 D assumes this record to be a focused record (S 3101 ) . The advertisement information transmission control unit  304 D then generates a sound source addition request containing the user/sound-source ID registered in the field  3073  of the focused record. The advertisement information transmission control unit  304 D transmits the generated sound source addition request to the presence server  1  via the IP network interface unit  301  (S 3102 ). 
     The advertisement information transmission control unit  304 D allows the SIP control unit  303  to establish a speech path (S 3103 ) . In response to this, the SIP control unit  303  performs an SIP-compliant call control procedure to establish a speech path to the media server  2 . 
     The advertisement information transmission control unit  304 D searches the advertisement information storage unit  305 D for the record  3050 D whose field  3051  registers the user/sound-source ID registered in the field  3073  of the focused record. The advertisement information transmission control unit  304 D output the acoustic data registered in the field  3052  of the retrieved record  3050 D to the RTP processing unit  302  (S 3104 ). In response to this, the RTP processing unit  302  uses the speech path to the media server  2  to transmit the acoustic data received from the advertisement information transmission control unit  304 b to the media server  2 . Thereafter, the advertisement information transmission control unit  304 D periodically repeats output of the acoustic data to the RTP processing unit  302 . As a result, the acoustic data is repeatedly transmitted to the media server  2 . 
     The advertisement information transmission control unit  304 D uses the built-in timer and the like to detect that the specified time has elapsed from the time to start the process at S 3104 , i.e., repeatedly reproducing the acoustic data, (YES at S 3105 ). In this case, the advertisement information transmission control unit  304 D stops transmitting the acoustic data to the media server  2  using the speech path (S 3106 ). The advertisement information transmission control unit  304 D then allows the SIP control unit  303  to disconnect the speech path (S 3107 ). In response to this, the SIP control unit  303  disconnects the speech path to the media server  2  in accordance with the SIP. 
     The advertisement information transmission control unit  304 D generates a sound source deletion request containing the user/sound-source ID of the own advertisement server  3 . The advertisement information transmission control unit  304 D transmits the generated sound source deletion request to the presence server  1  (S 3108 ). Thereafter, the advertisement information transmission control unit  304 D deletes the focused record from the request storage unit  307  (S 3109 ) and then returns to S 3101 . 
       FIG. 26  is a schematic construction diagram of the voice telecommunication terminal  4 D. 
     As shown in  FIG. 26 , the voice telecommunication terminal  4 D according to the embodiment differs from the voice telecommunication terminal  4  according to the first embodiment in that a request acceptance unit  412  is newly provided. The other parts of the construction are the same as those of the voice telecommunication terminal  4 . 
     According to a list browse instruction accepted from the user via the operation acceptance unit  404 , the request acceptance unit  412  generates a list request containing the user/sound-source ID for the own voice telecommunication terminal  4 D. The request acceptance unit  412  transmits the generated list request to the advertisement server  3 D via the IP network interface unit  407 . The request acceptance unit  412  follows the advertisement list received from the advertisement server  3 D via the IP network interface unit  407  to generate video data for a request acceptance screen  4120  as shown in  FIG. 27  and output the video date from the video output unit  403 . The request acceptance screen  4120  lists sets of a user/sound-source ID  4121  for the acoustic data of the advertisement sound source and guide information  4122 . The request acceptance screen  4120  is used to accept a request for the acoustic data of the advertisement sound source from the user. The user may operate the pointing device  424  to select a set of the user/sound-source ID  4121  and the guide information  4122  from the request acceptance screen  4120 . In this case, the request acceptance unit  412  accepts the set of the user/sound-source ID  4121  and the guide information  4122 , generates a request containing the set, and transmits the request to the advertisement server  3 D via the IP network interface unit  407 . 
     The fifth embodiment of the invention has been described. 
     The fifth embodiment provides the following effect in addition to the effect of the first embodiment. That is, it is possible to allow any user to hear acoustic data of the advertisement sound source according to his or her request. The advertising effectiveness can be improved. 
     It is to be distinctly understood that the invention is not limited to the above-mentioned embodiments but may be otherwise variously embodied within the spirit and scope of the invention. 
     There have been described the embodiments where the media server  2  or  2 B performs the 3D audio process and the synthesis process for acoustic data of the advertisement sound source and voice data for each user. However, the invention is not limited thereto. The voice telecommunication terminal  4  or  4 D may perform the 3D audio process and the synthesis process for acoustic data of the advertisement sound source and voice data for each user. In this case, the voice telecommunication terminal  4  or  4 D establishes speech paths to the voice telecommunication terminals  4  and  4 D other than the own terminal, and to the advertisement servers  3 ,  3 A, and  3 D. The voice telecommunication terminal  4  or  4 D transmits the own terminal user&#39;s voice data to the voice telecommunication terminals  4  and  4 D other than the own terminal. In addition, the voice telecommunication terminal  4  or  4 D receives the voice data and the acoustic data from the voice telecommunication terminals  4  and  4 D other than the own terminal and from the advertisement servers  3 ,  3 A,  3 C, and  3 D. The voice telecommunication terminal  4  or  4 D performs the 3D audio process for the received voice data and acoustic data and synthesizes these pieces of data based on: virtual position information, received from the presence servers  1 ,  1 A,  1 B, and  1 C, about the voice telecommunication terminals  4  and  4 D other than the own terminal and about the advertisement servers  3 ,  3 A,  3 C, and  3 D; and virtual position information about the own terminal. In this manner, the media servers  2  and  2 B are unnecessary. 
     According to the above-mentioned embodiments, the presence server  1  determines a virtual position of the advertisement sound source in the virtual space so that the distance between the advertisement sound source and a user of the voice telecommunication terminal  4  is longer than at least the distance between the user of the relevant voice telecommunication terminal  4  and another user of the nearest voice telecommunication terminal  4 . However, the invention is not limited thereto. The user of the voice telecommunication terminal only needs to be able to distinguish the virtual position of the advertisement sound source in the virtual space from a virtual position of a user of another voice telecommunication terminal  4 . For example, it may be preferable to determine the virtual position of the advertisement sound source in the virtual space so that a specified angle is formed between the orientation of the advertisement sound source (sound output direction) viewed from the user of the voice telecommunication terminal  4  and at least the orientation of another user of the nearest voice telecommunication terminal  4  viewed from the user of the voice telecommunication terminal  4 . 
     Specifically, the position information management unit  102  of the presence server  1  performs the following process. As shown in  FIG. 28A , a given voice telecommunication terminal  4  is selected. The user of this voice telecommunication terminal  4  is assumed to view a user of another voice telecommunication terminal  4  from that user&#39;s virtual position along direction d. The position information management unit  102  estimates angular range γ along direction d as center from the viewing user. The position information management unit  102  finds an area not belonging to the angular range γ for each of the other voice telecommunication terminals  4 . As shown in  FIG. 28B , the position information management unit  102  performs this process for all the voice telecommunication terminals  4  and finds a region  107 A where all the resulting areas overlap. When multiple regions  107 A are available, the position information management unit  102  selects any one of them. When no region  107 A is available, the position information management unit  102  decreases the angular range γ. Alternatively, the position information management unit  102  recalculates the region  107 A by excluding a user of another voice telecommunication terminal  4  farthest from the virtual position for the user of the relevant voice telecommunication terminal  4  for each of the voice telecommunication terminals  4 . The position information management unit  102  determines the orientation of the advertisement sound source in the virtual space similarly to the above-mentioned embodiments (see  FIG. 5B ). 
     The human hearing has a weakness of difficulty in identifying sound sources positioned symmetrically about a line connecting both ears. That is, it is difficult to distinguish sound sources symmetrically positioned forward and backward, top and bottom, and the like with respect to that line. The sound sources can be arranged by avoiding these positions as follows. As shown in  FIG. 28A , a given voice telecommunication terminal  4  is selected. The user of this voice telecommunication terminal  4  is assumed to view a user of another voice telecommunication terminal  4  from that user&#39;s virtual position along direction d. The position information management unit  102  estimates specified angular range γ along direction d as center from the viewing user. In addition, line f (a line connecting both ears of the user) is assumed to be orthogonal to orientation e of the user of the voice telecommunication terminal  4 . The specified angular range γ and range γ′ are assumed to be symmetrical with respect to the line f. The position information management unit  102  finds an area not belonging to γ nor to γ′ for each of the other voice telecommunication terminals. As shown in  FIG. 29B , the position information management unit  102  performs this process for all the voice telecommunication terminals  4  and finds a region  107 B where all the resulting areas overlap. 
     The above-mentioned embodiments have been described using SIP to establish speech paths. However, the invention is not limited thereto. For example, it may be preferable to use call the other control protocols such as H.323 than SIP. 
     The above-mentioned embodiments have been described so as to provide users of the voice telecommunication terminals  4  with contents such as acoustic data of the advertisement sound source. However, the invention is not limited thereto. For example, the invention can be used for a case of providing users with the other acoustic data including musical compositions as contents. 
     While the above-mentioned embodiments have been described using the audio advertisement as an example, the invention is not limited thereto. There may be a case of using a terminal that displays 3D graphics for the user and the advertisement sound source positioned in the virtual space instead of or in addition to output voice from the user and the advertisement sound source positioned in the virtual space. When the advertisement uses image or image and voice, the invention can determine the arrangement of the advertisement and display the advertisement using 3D graphics. In this case, however, placing the advertisement backward of the user provides little effect. It is necessary to determine the arrangement of the advertisement so that as many users as possible can view the advertisement. When taking a user preference into consideration, the advertisement needs to be positioned so that a highly-prioritized user can view the advertisement.