Patent Publication Number: US-8121310-B2

Title: Sound receiving apparatus and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2007-41289, filed on Feb. 21, 2007; the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a sound receiving apparatus and a method for determining a directivity of a microphone array of a mobile-phone. 
     BACKGROUND OF THE INVENTION 
     Microphone array technique is one of speech emphasis technique. Concretely, a signal received via a plurality of microphones is processed, and a directivity of the received signal is determined. Then, a signal from a direction along the directivity is emphasized while suppressing another signal. 
     For example, delay-and-sum array as the simplest method is disclosed in “Acoustic Systems and Digital Processing for Them, J. Ohga et al., Corona Publishing Co. Ltd., April 1995”. In this method, a predetermined delay is additionally inserted into a signal of each microphone. As a result, signals come from a predetermined direction are summed at the same phase and emphasized. On the other hand, signals come from other directions are weakened because their phases are different. 
     Furthermore, a method called “adaptive array” is also used. In this method, a filter coefficient is arbitrarily updated according to an input signal, and disturbance sounds come from various directions except for a target direction are electively removed. This method has high ability to suppress noise. 
     Recently, by installing this microphone onto a portable terminal such as a cellular-phone or a PDA, application to clearly catch user&#39;s voice becomes popular. In this case, it is an important problem that directivity is formed toward which direction. For example, in case of a cellular-phone, orientation of a user who speaks with the cellular-phone is already known. Accordingly, previous design that directivity is formed toward a direction of the user&#39;s mouth is correct. 
     However, for a mobile speech-to-speech translation device that a plurality of peoples input their voice, directivity should be suitably set to a target person who speaks at the moment. 
     In order to solve this problem, a terminal has a fixed direction of directivity, and a user moves the terminal in order to keep the directivity set to an appropriate speaker. For example, a reporter moves a microphone between himself and the other party in an interview. However, this method is very troublesome, and there is a possibility that a user cannot watch a screen of the terminal on a direction of the terminal. Furthermore, in case of PDA that orientation (angle) of the terminal changes during use, the user must operate the terminal with conscious of a fixed direction (directivity) of the terminal. 
     In this way, in case of a terminal having a microphone array that a plurality of speakers inputs their voice, the directivity should be set along a target sound direction which changes depending on various speakers. This operation is very troublesome, and the screen of the terminal cannot be viewed depending on directions of the terminal. Furthermore, in case that orientation of the terminal changes during utterance of different speakers, a directivity direction of the terminal is often shifted from a target sound direction. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a sound receiving apparatus and a method for constantly forming a directivity of a microphone of a terminal toward a predetermined direction while changing an orientation of the terminal. 
     According to an aspect of the present invention, there is provided an apparatus for receiving sound, comprising: an equipment body; a plurality of sound receiving units in the equipment body; an initial information memory configured to store an initial direction of the equipment body in a terminal coordinate system based on the equipment body; an orientation detection unit configured to detect an orientation of the equipment body in a world coordinate system based on a real space; a lock information output unit configured to output lock information representing to lock the orientation; an orientation information memory configured to store the orientation detected when the lock information is output; a direction conversion unit configured to convert the initial direction to a target sound direction in the world coordinate system by using the orientation stored in the orientation information memory; and a directivity forming unit configured to form a directivity of the plurality of sound receiving units toward the target sound direction. 
     According to another aspect of the present invention, there is also provided a method for receiving sound in an equipment body having a plurality of sound receiving units, comprising: storing an initial direction of the equipment body in a terminal coordinate system based on the equipment body; detecting an orientation of the equipment body in a world coordinate system based on a real space; outputting lock information representing to lock the orientation; storing the orientation detected when the lock information is output; converting the initial direction to a target sound direction in the world coordinate system by using the orientation stored; and forming a directivity of the plurality of sound receiving units toward the target sound direction. 
     According to still another aspect of the present invention, there is also provided a computer readable medium storing program codes for causing a computer to receive sound in an equipment body having a plurality of sound receiving units, the program codes comprising: a first program code to store an initial direction of the equipment body in a terminal coordinate system based on the equipment body; a second program code to detect an orientation of the equipment body in a world coordinate system based on a real space; a third program code to output lock information representing to lock the orientation, a fourth program code to store the orientation detected when the lock information is output; a fifth program code to convert the initial direction to a target sound direction in the world coordinate system by using the orientation stored; and a sixth program code to form a directivity of the plurality of sound receiving units toward the target sound direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a sound receiving apparatus according to a first embodiment. 
         FIG. 2  is a block diagram of the sound receiving apparatus according to a second embodiment. 
         FIG. 3  is a block diagram of the sound receiving apparatus according to a third embodiment. 
         FIG. 4  is a block diagram of the sound receiving apparatus according to a fourth embodiment. 
         FIG. 5  is a block diagram of the sound receiving apparatus according to a fifth embodiment. 
         FIGS. 6A ,  6 B and  6 C are schematic diagrams showing relationship between orientation of a sound receiving apparatus and a target sound direction. 
         FIGS. 7A and 7B  are schematic diagrams showing use status of the sound receiving apparatus according to the first embodiment. 
         FIGS. 8A and 8B  are schematic diagrams showing use status of the sound receiving apparatus according to the second embodiment. 
         FIGS. 9A and 9B  are schematic diagrams showing use status of the sound receiving apparatus according to the third embodiment. 
         FIGS. 10A and 10B  are schematic diagrams showing use status of the sound receiving apparatus according to the fifth embodiment. 
         FIG. 11  is a flow chart of processing of the sound receiving method according to the second embodiment. 
         FIG. 12  is a block diagram of the sound receiving apparatus according to a sixth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, various embodiments of the present invention will be explained by referring to the drawings. The present invention is not limited to the following embodiments. 
     First Embodiment 
     A sound receiving apparatus  100  of a first embodiment of the present invention is explained by referring to  FIGS. 1 ,  6  and  7 . 
     (1) COMPONENT OF THE SOUND RECEIVING APPARATUS  100   
       FIG. 1  is a block diagram of the sound receiving apparatus  100  of the first embodiment. The sound receiving apparatus  100  includes microphones  101 - 1 ˜M, input terminals  102  and  103 , an orientation information memory  104 , a target sound direction calculation unit  106 , a directivity direction calculation unit  107 , and a directivity forming unit  108 . The input terminal  102  receives orientation information of an equipment body  105  (shown in  FIGS. 6A ,  6 B and  6 C) of the sound receiving apparatus  100 . The input terminal  103  receives lock information representing timing to store the orientation information. The orientation information memory  104  stores the orientation information at the timing of the lock information. The target sound direction calculation unit  106  calculates a target sound direction based on the orientation information in a real space. The directivity direction calculation unit  107  determines directivity of the sound receiving apparatus  100  according to the orientation information and the target sound direction. The directivity forming unit  108  processes signals from the microphones  101 - 1 ˜m using the directivity direction, and outputs a signal from the directivity direction. Unit  101 ˜ 108  are packaged into the equipment body of a rectangular parallelepiped. 
     As the lock information, a user may push a lock button on the sound receiving apparatus  100 . The lock button may be shared with a button to push at speech start timing. Furthermore, at the time when a speaker&#39;s utterance is necessary in cooperation with an application, the application may voluntarily supply a lock signal. 
     (2) OPERATION OF THE RECEIVING APPARATUS  100   
     Next, operation of the receiving apparatus  100  is explained. 
     First, orientation of the equipment body  105  of the sound receiving apparatus  100  is provided to the input terminal  102  on, for example, an hourly basis. The orientation of the equipment body  105  can be detected using a three axes acceleration sensor or a three axes magnetic sensor. These sensors are small-sized chips installed onto the sound receiving apparatus  100 . 
     At the time when the lock information is provided to the input terminal  103 , orientation of the equipment body  105  of the sound receiving apparatus  100  is stored in the orientation information memory  104 . 
     The target sound direction calculation unit  106  calculates a target sound direction in real space by using an orientation of the equipment body  105  (of the sound receiving apparatus  100 ) and an initial direction preset on the equipment body  105 . The initial direction is, for example, a long side direction of the equipment body  105  if the equipment body of the sound receiving apparatus  100  is a rectangular parallelepiped. The target sound direction is, for example, a ceiling direction if the long side direction (initial direction) turns to the ceiling when lock information is input. 
     The directivity direction calculation unit  107  decides which direction of the equipment body  105  is a target sound direction while the orientation of the equipment body  105  is changing, for example, hourly. In this case, the direction of the equipment body  105  is calculated using orientation information (output from the input terminal  102 ) and the target sound direction (output from target sound direction calculation unit  106 ). In the above example, the target sound direction is the ceiling direction but assume that the equipment body  105  of the sound receiving apparatus  100  is moved to a horizontal direction. In this case, a target sound direction viewed from the equipment body  105  is controlled as a direction vertical to the long side direction. 
     The directivity forming unit  108  forms a directivity to the target sound direction, and processes input signals from the microphones  101 - 1 ˜M so that an input signal from the target sound direction is emphasized. 
     (3) EXAMPLE 
     (3-1) A First Example 
     The first example of the first embodiment is explained using  FIGS. 6A ,  6 B, and  6 C. Microphones  101 - 1 ˜ 4  are installed onto four corners of the equipment body  105  of the sound receiving apparatus  100 .  FIG. 6A  shows relationship between the equipment body  105  of the sound receiving apparatus  100  and a real space at activation timing. 
     At the activation timing, an orientation of the equipment body is captured using a stored sensor. For example, in a world coordinate system that X axis is the south direction, Y axis is the west direction, and Z axis is the ceiling direction, an orientation of the equipment body  105  is represented as a rotation angle (θx, θy, θz) of each axis. 
     On the other hand, a terminal coordinate system fixed to the equipment body  105  exists. As shown in  FIGS. 6A-6C , in the terminal coordinate system, x axis is a vertical direction (long side direction), y axis is a horizontal direction (short side direction), and z axis is a normal line direction. Furthermore, the initial direction is set as x axis direction, i.e., p=(1,0,0) in the terminal coordinate system. 
     Next, as shown in  FIG. 6B , a user inputs lock information to the sound receiving apparatus  100  by operation after moving the equipment body  105 . In response to the lock information, the sound receiving apparatus  100  sets the initial direction p (long side direction) to a target sound direction t in the terminal coordinate system. The target sound direction t is a directivity direction of the microphones  101 - 1 ˜M of the sound receiving apparatus  100 . 
     After locking the target sound direction t, the equipment body  105  is often moved. Accordingly, by converting the target sound direction t to the world coordinate system, the target sound direction t is fixed even if the equipment body  105  is moved. 
     Concretely, following coordinate conversion matrix from the terminal coordinate system to the world coordinate system is used. 
     
       
         
           
             
               
                 
                   
                     
                       
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     In above equation (1), “*” represents product, and “RL” is 3×3 conversion matrix from a terminal coordinate to a world coordinate at lock timing. “RL” is represented as a product of rotation matrixes around x axis, y axis and z axis as follows. 
     
       
         
           
             
               
                 
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     In the above matrixes, (φx, φy, φz) is a rotation angle around each coordinate axis at lock timing. 
       FIG. 6C  shows operation of the equipment body  105  after locking. A microphone array of the sound receiving apparatus  100  is controlled so that the directivity direction always turns to the target sound direction locked. Accordingly, while the orientation of the sound receiving apparatus is changing, it is important to decide which direction in the terminal coordinate system is the target sound direction. 
     A decision method is explained. A target sound direction t in the terminal coordinate system is calculated using a target sound direction T (stored at lock timing) and an orientation (θx, θy, θz) of the sound receiving apparatus  100  at present timing as follows. 
     
       
         
           
             
               
                 
                   
                     
                       
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     In above equation (5), “R” is a conversion matrix from the terminal coordinate system to the world coordinate system, “inv(R)” is an inverse matrix of the matrix “R” (i.e., a conversion matrix from the world coordinate system to the terminal coordinate system), and “Rx, Ry, Rz” are rotation matrixes around each axis (i.e., (φx, φy, φz) in equations (2) (3) (4) is replaced with rotation angle (θx, θy, θz) of present orientation). 
     In this way, the target sound direction in the world coordinate system is stored, and converted to the terminal coordinate system by referring to the present orientation of the equipment body  105 . As a result, irrespective of change of orientation of the equipment body  105 , a target sound direction in the terminal coordinate system can be calculated. 
     (3-2) A Second Example 
     The second example is explained. In the first example, a target sound direction T is stored and converted to a terminal coordinate. However, by detecting a difference of orientation of the equipment body  105  between the present timing and the lock timing, a target sound direction t can be directly calculated, not using a target sound direction T. This example is explained by equation. 
     A coordinate conversion matrix at some timing after locking is represented as follows.
 
 R=RL*Rd  
 
     In above equation, “RL” is a conversion matrix at lock timing (in the same way as the equation (1)), and “Rd” is a conversion matrix to calculate a difference of orientation after lock timing. A target sound direction t is represented as follows.
 
 t =inv( R ) T  
 
=inv( RL*Rd ) T  
 
=inv( Rd )inv( RL ) T  
 
=inv( Rd ) p  
 
     Briefly, the target sound direction t is calculated using an initial direction p (stored at lock timing) and a conversion matrix Rd (representing a difference of orientation after the lock timing). 
     (3-3) A Third Example 
     As mentioned-above, methods to calculate relationship between a target sound direction t of a terminal coordinate and a target sound direction T of a world coordinate are considered. The first embodiment does not limit such method. Furthermore, as to a coordinate system in the first embodiment, a coordinate axis is defined as a left-handed coordinate system. However, it may be defined as a right-handed coordinate system that Z axis is set along an opposite direction. 
     Furthermore, in the equation (1), a target sound direction t is converted to a target sound direction T. However, the target sound direction T is converted to the target sound direction t. In this case, a rotation angle (θx, θy, θz) and signs in equations (2)˜(4) often change, which is not an essential problem. Briefly, any one definition may be used. 
     (4) OPERATION OF THE DIRECTIVITY FORMING UNIT  108   
     Next, operation example of the directivity forming unit  108  in  FIG. 1  is explained. 
     (4-1) A First Method 
     The directivity direction calculation unit  107  calculates a target sound direction t in the terminal coordinate system at the present timing. By using a microphone array, directivity (directivity direction) is formed toward the target sound direction. 
     As an example of Adaptive type array, Directionally Constrained Minimization of Power (DCMP) is disclosed in “Adaptive Signal Processing with Array Antenna, N. Kikuma, Science and Technology Publishing Company, Inc., 1999”. In this case, by calculating a vector “c” of array along a directivity direction, an array weight w is calculated as follows.
 
 w =inv( Mxx ) c/cH *inv( Mxx ) c  
 
     In the above equation, “inv(Mxx)” is an inverse matrix of a correlation matrix Mxx among microphones, and “cH” is a complex conjugate transposition of “c”. 
     In case of delay-and-sum array, the array weight is calculated as follows.
 
 w=c/cH*c  
 
     This equation represents signal-delaying so that a difference of arriving time of signals among each microphone  101  is “0” for a directivity direction. 
     Furthermore, weight prepared may be selected according to the directivity direction. For example, in case of two microphones, any one of following weights is used.
 
w=(1,0)′ or (0,1)′ (′: transposition)
 
     The above equation represents selection of any one from two microphones. 
     Selection basis is determined by relationship between directivity and microphones-array location. For example, a microphone located where an angle between a straight line of the microphones-array and the directivity direction is an acute angle is set as “1” of weight w. In case of using directivity microphone, a microphone that an angle between its directivity characteristic and a directivity direction is narrower is set as “1” of weight w. 
     By using the weight w (obtained as mentioned-above), signals a 1 ˜aM received at microphones  101 - 1 ˜M are summed (weighted sum). A processed signal b having directivity same as target sound direction is obtained as follows.
 
 b=wH*a  
 
 a =( a 1 ,a 2 , . . . , aM )
 
 w =( w′ 1 ,w′ 2 , . . . , w′M )
 
     w′H: complex conjugate transposition of w′ 
     Another method for forming directivity toward the target sound direction is proposed. In case of Adaptive type array, Griffiths-Jim type array is disclosed in “An Alternate Approach to Linearly Constrained Adaptive Beamforming, L. J. Griffiths and C. W. Jim, IEEE Trans. Antennas &amp; Propagation, Vol. AP-30, No. 1, January 1982”. 
     (4-2) A Second Method 
     Furthermore, by setting a predetermined tracking range (for example, ±20°) toward a target sound direction, a signal from the tracking range may be emphatically operated. This method is disclosed in “Two-Channel Adaptive Microphone Array with Target Tracking, Y. Nagata, The Institute of Electronics, Information and Communication Engineers, Transcription A, J82-A, No. 6, pp. 860-866, 1999”. In this method, signal-emphasis within the tracking range is realized by tracking a target signal in combination with prior type algorithm. 
     Application of this algorithm to the directivity forming unit  108  of the first embodiment is effective. By setting a tracking range, an error from orientation detection of the equipment body  105  or a discrepancy from assumption that a sound source is not strictly a plane wave can be reduced. 
     As mentioned-above, various means for forming directivity are applicable. The first embodiment does not limit the method for forming directivity. Another prior technique can be used. 
     (5) USE METHOD 
       FIGS. 7A and 7B  show schematic diagrams of using the sound receiving apparatus  100  of the first embodiment. In this example, two persons face each other, and the left side person has the equipment body  105  of the sound receiving apparatus  100 . 
     As shown in  FIG. 7A , in case of inputting the right side person&#39;s voice, the left side person pushes a lock button of the sound receiving apparatus  100  by pointing a long side direction of the equipment body  105  to the right side person. The long side direction of the equipment body  105  is already set as an initial direction. Accordingly, a target sound direction is set as an arrow in  FIG. 7A . 
     Then, as shown in  FIG. 7B , the left side person changes orientation of the equipment body  105  in order to watch a screen of the equipment body  105 . In this case, the target sound direction is already fixed as an arrow direction toward the right side person. Accordingly, directivity of microphones-array of the sound receiving apparatus  100  is not shifted from the target sound direction. 
     Second Embodiment 
     Next, the sound receiving apparatus  100  of the second embodiment is explained by referring to  FIGS. 2 ,  8  and  11 . 
     (1) Component of the Sound Receiving Apparatus  100 : 
       FIG. 2  is a block diagram of the sound receiving apparatus  100  according to the second embodiment. A different feature of the second embodiment compared with the first embodiment is an initial direction dictionary  201 . In the first embodiment, the initial direction is such as a long side direction of the equipment body  105 . However, in the second embodiment, a plurality of initial directions are prepared and selected by output from the orientation information memory  104 . 
     (2) Use Method: 
     A use method is explained by referring to  FIGS. 8A and 8B . In this use method, the equipment body  105  of the sound receiving apparatus  100  has two initial directions, i.e., a long side direction and a normal line direction. 
     As shown in  FIG. 8A , when the left side person pushes a lock button by laying the equipment body  105 , the long side direction is selected as the initial direction, and a directivity direction is formed toward voice direction of the right side person. 
     On the other hand, as shown in  FIG. 8B , when the left side person pushes a lock button by standing the equipment body  105 , the normal line direction is selected as the initial direction, and a directivity direction is formed toward voice direction of the left side person (operator himself). 
     (3) Processing Method: 
       FIG. 11  is a flow chart of processing method of the second embodiment. At S 1 , it is decided whether lock information is input. In case of inputting the lock information, orientation of the equipment body  105  of the sound receiving apparatus  100  is detected at S 2 . At S 3 , an initial direction p is selected according to the orientation. At S 4 , the initial direction p is converted to a world coordinate, and a target sound direction T is calculated. At S 5 , a target sound direction t (directivity direction) in the terminal coordinate system is calculated according to the orientation of the equipment body  105 . 
     At S 6 , parameter of microphones-array is set so that an input signal from the directivity direction is emphasized. At S 7 , the input signal is processed. Accordingly, a signal from the target sound direction is emphasized irrespective of orientation of the equipment body  105 . At S 8 , it is decided whether processing is continued. In case of “no”, processing is completed. In case of “yes”, processing is forwarded to S 1 . 
     In case of “no” at S 1 , a target sound direction is not calculated, and processing is forwarded to S 5 . At S 5 , a present directivity direction p is calculated according to the target sound direction (previously calculated) and an orientation of the equipment body  105  of the sound receiving apparatus  100 . In case of first processing of S 1  as an exception, the processing waits until the lock information is input. 
     (4) Effect: 
     As mentioned-above, by setting a plurality of initial directions, even if an operator locates at  1800  direction from a long side direction of the equipment body  105  as shown in  FIG. 8A , an angle for the operator to move the equipment body  105  to lock is only 90° as shown in  FIG. 8B . As a result, the operator&#39;s usability improves. 
     Third Embodiment 
     Next, the sound receiving apparatus  100  of the third embodiment is explained by referring to  FIGS. 3 and 9 . Different feature of the third embodiment compared with the second embodiment is an initial range dictionary  301  instead of the initial direction dictionary  201 . In the second embodiment, an initial direction is selected in response to lock information. However, in the third embodiment, an initial range is selected. 
     (1) Component of the Sound Receiving Apparatus: 
       FIG. 3  is a block diagram of the sound receiving apparatus  100  according to the third embodiment. The sound receiving apparatus  100  includes microphones  101 - 1 ˜M, input terminals  102  and  103 , an orientation information memory  104 , a target sound direction calculation unit  106 , a directivity direction calculation unit  107 , a directivity forming unit  108 , an initial range dictionary, a target sound range calculation unit  302 , a decision unit  303 , and a sound source direction estimation unit  305 . 
     The input terminal  102  receives orientation information of the equipment body  105  of the sound receiving apparatus  100 . The input terminal  103  receives lock information representing timing to store the orientation information. The orientation information memory  104  stores the orientation information at the timing of the lock information. The initial range dictionary  301  stores a plurality of target sound ranges prepared. The target sound range calculation unit  302  selects a target sound range (initial range) from the initial range dictionary  301  according to output of the orientation information memory  104 . The sound source direction estimation unit  305  estimates a sound source direction from signals input to the microphones  101 - 1 ˜M. The decision unit  303  decides whether the sound source direction is within the target sound range (selected by the target sound range calculation unit  302 ), and outputs the sound source direction as the initial direction when the sound source direction is within the target sound range. 
     The target sound direction calculation unit  106  calculates a target sound direction according to the decision result (from the decision unit  303 ) and the orientation information (from the input terminal  102 ). The directivity direction calculation unit  107  determines directivity of the sound receiving apparatus  100  according to output from the target sound direction calculation unit  106 . The directivity forming unit  108  processes signals from the microphones  101 - 1 ˜m using the directivity direction, and outputs a signal from the directivity direction. 
     (2) Operation of the Sound Receiving Apparatus  100 : 
     Next, operation of the sound receiving apparatus  100  of the third embodiment is explained. When an operator locks the sound receiving apparatus  100  by directing the equipment body  105  to a speaker, an initial direction of the equipment body  105  is often shifted from the speaker&#39;s direction. Accordingly, instead of the initial direction, an initial range having a small space centered around the initial direction (For example, ±20° from a long side direction of the equipment body  105 ) is set. 
     Then, the sound source direction estimation unit  305  estimates an utterance direction of the speaker (the equipment body  105  is directed), and sets the utterance direction as the initial direction. The target sound direction calculation unit  106  calculates a target sound direction according to the initial direction, and the directivity is formed in the same way as in the second embodiment. 
     In this case, in a period from set timing of the initial range to utterance timing of the speaker, noise often comes from another direction. The decision unit  303  decides whether a sound source direction is within the initial range. If the sound source direction is not within the initial range, a target sound direction is not calculated. 
     (3) Use Method: 
       FIGS. 9A and 9B  are schematic diagrams of use situation of the sound receiving apparatus  100  according to the third embodiment. As show in  FIG. 9A , an initial range (represented by two arrows) for the other party (speaker) is set. Next, as shown in  FIG. 9B , an initial direction in the initial range is determined based on an utterance direction of the speaker. The initial direction is regarded as a target sound direction. Under this component, the initial direction need not be strictly directed to the speaker. In other words, the initial direction may be roughly directed to the speaker. 
     Fourth Embodiment 
     Next, the sound receiving apparatus  100  of the fourth embodiment is explained by referring to  FIG. 4 .  FIG. 4  is a block diagram of the sound receiving apparatus  100  according to the fourth embodiment. The fourth embodiment does not include the directivity direction calculation unit  107  of the second embodiment. Furthermore, output from the target sound direction calculation unit  306  is directly supplied to the directivity forming unit  108 . 
     In the second embodiment, a target sound direction t (input to the directivity forming unit  108 ) in the terminal coordinate space is calculated by the equation (5). This calculation is occasionally executed based on a rotation angle (θx, θy, θz) of a present orientation. On the other hand, if a target sound direction “t” does not change largely, a value “t” occasionally calculated by the present orientation (θx, θy, θz) is not so different from a value “t” calculated by a rotation angle (φx, φy, φz) at lock timing. In the fourth embodiment, a target sound direction “t” is fixed at the lock timing. As a result, subsequent occasional calculation is not necessary. 
     The fourth embodiment is unsuitable for the case that orientation of the equipment body  105  changes largely after locking. However, in case that the orientation does not change largely, the target sound direction “t” need not occasionally update, and calculation quantity can be reduced. 
     Fifth Embodiment 
     Next, the sound receiving apparatus  100  of the fifth embodiment is explained by referring to  FIGS. 5 and 10 .  FIG. 5  is a block diagram of the sound receiving apparatus  100  according to the fifth embodiment. In the fifth embodiment, the input terminal  103  and the orientation information memory  104  of the fourth embodiment are removed. In the fifth embodiment, an initial direction is selected according to orientation (changing hourly) of the equipment body  105  of the sound receiving apparatus  100 . The initial direction is used as a directivity direction. 
     For example, in case that the sound receiving apparatus  100  is applied to a speech translation apparatus (explained as a sixth embodiment afterwards), operator of the sound receiving apparatus  100  talks with an opposite speaker via the sound receiving apparatus  100 . As shown in  FIG. 10B , when the operator inputs voice to the sound receiving apparatus  100 , the operator holds the equipment body  105  in his hand. As shown in  FIG. 10A , when the opposite speaker input voice to the sound receiving apparatus  100 , the operator lays down the equipment body  105 . 
     In this way, if a target sound direction closely relates to an operational angle of the equipment body  105 , input of lock information is not necessary. A directivity direction can be changed by orientation of the equipment body  105 . For example, by using a gravity-acceleration sensor of three axes, a gravity-acceleration direction (a lower direction) can be detected. 
     As shown in  FIG. 10A , if an angle between the lower direction (vector g) and a long side direction (vector r) of the equipment body  105  is below a threshold, an initial direction p 1  (preset along the long side direction of the equipment body  105 ) is selected to turn a directivity direction to the opposite speaker&#39;s voice. On the other hand, as shown in  FIG. 10B , if the angle is above the threshold, an initial direction p 2  (preset along a normal line direction to the long side direction) is selected. 
     Under this component, an operator can change a directivity by movement of the equipment body  105  of the sound receiving apparatus  100 . Accordingly, the operator can smoothly use the sound receiving apparatus  100 . 
     Sixth Embodiment 
     Next, a translation apparatus  200  of the sixth embodiment is explained by referring to  FIGS. 7A and 12 . In the sixth embodiment, the sound receiving apparatus  100  of the first embodiment is applied to a translation apparatus. 
       FIG. 12  is a block diagram of the translation apparatus  200 . In  FIG. 12 , a translation unit  210  translates speech emphasized along a directivity direction (output from the sound receiving apparatus  100 ) to a predetermined language (For example, from English to Japanese). In this case, as shown in  FIG. 7A , an operator locks an initial direction (target sound direction) of the equipment body  105 . The sound receiving apparatus  100  picks up an English speech from an opposite speaker. The translation unit  210  translates the English speech to a Japanese speech, and replays or displays the Japanese speech. 
     Modification Example 
     In above embodiments, a microphone is used as a speech input means. However, various means for inputting speech are applicable. For example, a signal previously recorded may be replayed and input. Furthermore, a signal generated by calculation simulation may be used. Briefly, the speech input means is not limited to the microphone. 
     In the disclosed embodiments, the processing can be accomplished by a computer-executable program, and this program can be realized in a computer-readable memory device. 
     In the embodiments, the memory device, such as a magnetic disk, a flexible disk, a hard disk, an optical disk (CD-ROM, CD-R, DVD, and so on), an optical magnetic disk (MD and so on) can be used to store instructions for causing a processor or a computer to perform the processes described above. 
     Furthermore, based on an indication of the program installed from the memory device to the computer, OS (operation system) operating on the computer, or MW (middle ware software), such as database management software or network, may execute one part of each processing to realize the embodiments. 
     Furthermore, the memory device is not limited to a device independent from the computer. By downloading a program transmitted through a LAN or the Internet, a memory device in which the program is stored is included. Furthermore, the memory device is not limited to one. In the case that the processing of the embodiments is executed by a plurality of memory devices, a plurality of memory devices may be included in the memory device. The component of the device may be arbitrarily composed. 
     A computer may execute each processing stage of the embodiments according to the program stored in the memory device. The computer may be one apparatus such as a personal computer or a system in which a plurality of processing apparatuses are connected through a network. Furthermore, the computer is not limited to a personal computer. Those skilled in the art will appreciate that a computer includes a processing unit in an information processor, a microcomputer, and so on. In short, the equipment and the apparatus that can execute the functions in embodiments using the program are generally called the computer. 
     Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.