Abstract:
A communication apparatus for adjusting a received voice signal in accordance with an ambient noise, the communication apparatus includes: a microphone for receiving an ambient noise and input voice and outputting a voice input signal corresponding to a level of the input voice and the ambient noise; a receiver for receiving the voice signal; a processer for extracting a voice component originated by a sender and an ambient noise component originated by the ambient noise, determining the ratio between the voice component and the ambient noise component, and adjusting the amplitude of the received voice signal in accordance with the ratio; and a speaker for outputting a reception voice corresponding to the adjusted reception voice signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2008-093763 filed on Mar. 31, 2008, the entire contents of which are incorporated herein by reference. 
     FIELD 
     A certain aspect of the embodiments discussed herein is related to a communication apparatus. 
     BACKGROUND 
     A cellular phone and an IP phone are often used in a place where ambient noise is large. Accordingly, it is necessary for the communication terminals to adjust a reception sound in consideration for a usage environment of the user (more to the point, ambient noise). As a technique for adjusting the reception sound, there are a technique for varying the sound amount of the reception sound (AGC: Auto Gain Control) and a technique for emphasizing a formant of the reception sound. 
     However, listenability of the reception sound depends on auditory property of the user. Consequently, it is not necessary the case that uniform variation of the sound volume of the reception sound in accordance with an ambient noise enables the user to hear well. That is, in a conventional communication terminal, it is impossible to adjust the reception sound only when the user feels that it is hard to hear. 
     Japanese Laid-open Patent Publication No. 04-328798, Japanese Laid-open Patent Publication No. 2002-185572, and Japanese Laid-open Patent Publication No. 2004-165865 disclose techniques for adjusting the reception sound in the communication apparatus. 
     SUMMARY 
     According to an aspect of an embodiment, a communication apparatus for adjusting a received voice signal in accordance with an ambient noise, the communication apparatus includes: a microphone for receiving an ambient noise and input voice and outputting a voice input signal corresponding to a level of the input voice and the ambient noise; a receiver for receiving the voice signal; a processer for extracting a voice component originated by a sender and an ambient noise component originated by the ambient noise, determining the ratio between the voice component and the ambient noise component, and adjusting the amplitude of the received voice signal in accordance with the ratio; and a speaker for outputting a reception voice corresponding to the adjusted reception voice signal. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory and are not respective of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing an outline of a first voice transmission system according to an embodiment; 
         FIG. 2  is a block diagram showing an outline of a second voice transmission system according to the embodiment; 
         FIG. 3  is a block diagram showing a structure of a speech control effect calculating function according to the embodiment; 
         FIG. 4  is a flowchart showing a processing performed by the first voice transmission system; 
         FIG. 5  is a flowchart showing a processing performed by the second voice transmission system according to the embodiment; 
         FIG. 6  is a flowchart showing a processing performed by the speech control effect calculating function according to the embodiment; 
         FIGS. 7A and 7B  are a flowchart that is processed by a speech control effect applying function according to the embodiment; 
         FIG. 8  is a diagram schematically showing an application processing of a power dynamic range variation amount according to the embodiment; 
         FIG. 9  is a diagram schematically showing an application processing of a spectrum inclination variation amount according to the embodiment; 
         FIG. 10  is a diagram schematically showing an application processing of a pause length variation amount according to the embodiment; 
         FIG. 11  is a diagram schematically showing an application processing of a pitch frequency dynamic range variation amount according to the embodiment; 
         FIG. 12  is a hard block diagram showing a communication terminal according to the embodiment; and 
         FIG. 13  is a functional block diagram showing a voice processing unit according to the embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
     1. Outline of Voice Transmission System According to Embodiment 
     First, an outline of a voice transmission system  100  according to the embodiment will be described with reference to  FIGS. 1 to 4 . The voice transmission system  100  is a system that is mounted and provided in a communication terminal  1200  shown in  FIG. 12 . 
     There is, for example, a cellular phone as the communication terminal  1200 . The cellular phone may be used at a place where ambient noise is loud, so that a reception sound is often deteriorated by the ambient noise. The cellular phone (communication terminal  1200 ) does not uniformly emphasize the reception sound when the reception sound is deteriorated, but adjusts the reception sound in accordance with the auditory property of the user. Specifically, the cellular phone emphasizes the reception sound when it is judged that a ratio of the ambient noise with respect to the reception sound is large and the user feels that it is difficult to hear due to the ambient noise, and outputs the reception sound without change when it is judged that the user does not feel that it is difficult to hear (transmission voice is hardly changed). Herewith, the user of the cellular phone can comfortably perform communication as compared with a conventional cellular phone. 
     To be more specific, each function (a speech control effect calculating function  101 , a speech control effect applying function  102 ) in the voice transmission system  100  performs a processing to be described below.  FIG. 1  is a block diagram showing an outline of the voice transmission system  100  according to the embodiment. The voice transmission system  100  is equipped with the speech control effect calculating function  101 , the speech control effect applying function  102 , a microphone  103 , a receiving unit  104 , and a speaker  105 . The speech control effect calculating function  101  calculates a variation amount  111  of a transmission voice that is varied due to a speech control effect, and the speech control effect applying function  102  adjusts a reception voice signal  110  by applying the variation amount  111 . Herein, the speech control effect denotes a phenomenon in which a voice that is spoken by a person is varied in the case where the person who is speaking is difficult to hear a voice of the other party due to the ambient noise. Accordingly, in the embodiment, a function for calculating the variation amount of the transmission voice that is varied due to the ratio of the ambient noise with respect to the reception voice is referred to as the voice control effect calculating function  101 . 
     First, the microphone  103  receives a sound  106 . The microphone  103  outputs a sound signal  107  to the speech control effect calculating function  101 . The sound signal  107  is an electrical signal corresponding to the sound signal  106 . The sound signal  107  is constituted by an ambient noise  108  and a transmission voice signal  109 . A reception voice signal  110  is received by the receiving unit  104 . The sound signal  107  of the sound  106  received by the microphone  103  and the reception voice signal  110  received by the receiving unit  104  are input to the speech control effect calculating function  101 , and the varied amount (variation amount)  111  of the transmission voice signal  109  that is varied due to the speech control effect is calculated by using the signals (step S 401 ). The reception voice signal  110  received by the receiving unit  104  is input to the speech control effect applying function  102 . The speech control effect applying function  102  applies the variation amount  111  to the reception voice signal  110  (step S 402 ), and outputs a reception voice signal  112  that is adjusted by the speaker  105  (step S 403 ). 
     As described above, the vice transmission system  100  applies the variation amount  111  of the transmission voice signal  109  that is varied due to the ambient noise  108  to the reception voice signal  110 , so that the reception voice can be converted to a voice that is easy to hear for a user, and a reception sound that is easy to hear than a conventional transmission system can be created. 
     1.1. Communication Terminal  1200   
     Next, a communication terminal  1200  in which the voice transmission system  100  is mounted will be described.  FIG. 12  is a hard block diagram of the communication terminal  1200  according to the embodiment. The communication terminal  1200  includes a transmission/reception antenna  1201 , a baseband processor  1202 , a CPU  1203 , an input unit  1204 , a display unit  1205 , the receiving unit  104 , a transmitting unit  1206 , a duplexer  1207 , the microphone  103 , and the speaker  105 . The baseband processor  1202  includes a demodulator  1208 , a communication control unit  1209 , a modulator  1210 , a voice processing unit  1211 , and an interface unit  1212 . 
     The communication terminal  1200  receives the reception voice signal  110  from another communication terminal via the transmission/reception antenna  1201 . Further, the communication terminal  1200  transmits the transmission voice signal  109  to another communication terminal via the transmission/reception antenna  1201 . Then the duplexer  1207  mounted in the communication terminal  1200  electrically separates a transmission pathway and a reception path way of the signals. The duplexer  1207  separates the reception voice signal  110  received by the transmission/reception antenna  1201  and transmission voice signal  109  transmitted by the transmission/reception antenna  1201 . 
     The communication terminal  1200  receives the reception voice signal  110  by the receiving unit  104  via the transmission/reception antenna  1201 . The receiving unit  104  transfers the reception voice signal  110  to the demodulator  1208  of the baseband processor  1202 . The demodulator  1208  demodulates the reception voice signal  110  and transmits to the communication control unit  1209 . The communication control unit  1209  decodes the demodulated reception voice signal  110 . Then, the communication control unit  1209  transfers the decoded reception voice signal  110  to the vice processing unit  1211 . 
     The voice processing unit  1211  provides the processing of the speech control effect calculating function  101  and the processing of the speech control effect applying function  102 .  FIG. 13  is a functional block diagram of the voice processing unit  1211 . The voice processing unit  1211  includes the speech control effect calculating function  101  and the speech control effect applying function  102 . Then, the speech control effect calculating function  101  includes an ambient noise separating function  301 , a characteristic amount calculating function  302 , a reception voice calculating function  303 , a normal statistic calculating function  304 , a deterioration statistic calculating function  305 , and a variation amount calculating function  306 . The functions owned by the voice processing unit  1211  are cooperated to adjust the reception voice signal  110  as shown in  FIGS. 1 ,  3 . Schematically, the voice processing unit  1211  performs the following processing. First, the voice processing unit  1211  receives the voice signal  17  output by the microphone  13  via the interface unit  1212 , and receives the reception voice signal  110  received by the receiving unit  104 . Then, the voice processing unit  1211  performs the processing of the speech control effect calculating function  101  and the processing of the speech control effect applying function  102 . The communication terminal  120  outputs the adjusted reception voice signal  112  from the speaker  105 . The details of the processing of the speech control effect calculating function  101  and the processing of the speech control effect applying function  102  will be described below with reference to  FIGS. 3 ,  6 , and  7 . 
     The CPU  1203  performs a control of a communication protocol and an execution control of an application mounted in the communication terminal  1200 . 
     The input unit  104  is a unit with which a user of the communication terminal  1200  operates a key input. Further, the display unit  1205  is a display that displays an operation screen or a content of the communication terminal  1200 . 
     2. Advantage of Communication Terminal  1200   
     The communication terminal  1200  according to the embodiment has an advantageous effect as compared with a conventional communication terminal. For example, a reception voice can be adjusted in accordance with the auditory property of the user as shown in the above description. The advantageous effect is provided by the function owned by the voice processing unit  1211 . Accordingly, hereinafter, the structure of and the processing performed by the speech control effect calculating function  101  and the speech control effect applying function  102  will be described. 
     3. Speech Control Effect Calculating Function  101   
       FIG. 3  is a functional block diagram showing a structure of the speech control effect calculating function  101  according to the embodiment. The speech control effect calculating function  101  is a function that is provided by the voice processing unit  1211  by a hardware, and a function constituting the speech control effect calculating function  101  is also a function that is provided by the voice processing unit  1211 . The voice control effect calculating function  101  includes the ambient noise separating function  301 , the characteristic amount calculating function  302 , the reception voice deterioration level calculating function  303 , the normal statistic calculating function  304 , the deterioration statistic calculating function  305 , and the variation amount calculating function  306 . Further,  FIG. 6  is a flowchart showing a processing that is performed by the speech control effect calculating function  101 . 
     The sound signal  107  is input to the ambient noise separating function  301 . The sound signal  17  is constituted by the ambient noise  108  and the transmission voice signal  109 . The ambient noise separating function  301  separates the sound signal  107  into the ambient noise  108  and the transmission voice signal  109 . In the embodiment, the ambient noise separating function  301  estimates SNR of the ambient noise  108  and the transmission voice signal  109 . Then the ambient noise separating function  301  multiplies a power spectrum of the transmission voice signal  109  by a gain in accordance with the SNR to separate from the ambient noise  108  (step S 601 ). To be more specific, the ambient noise separating function  301  performs time division on a frame of the sound signal  107  to be received. The ambient noise separating function  301  estimates the transmission voice signal  109  from the periodicity owned by the transmission voice signal  109 . The ambient noise separating function  301  estimates the ambient noise  108  from the information of the time divided frame that does not include the transmission voice signal  109 . Then, the ambient noise separating function  301  separates the received sound signal  107  into the ambient noise  108  and the transmission voice signal  109 . 
     The transmission voice signal  109  is input to the characteristic amount calculating function  302 , and a characteristic amount  307  of the input transmission voice signal  109  is calculated (step S 602 ). 
     The ambient noise  108  and the reception voice signal  110  are input to the reception voice deterioration level calculating function  303 . Then, the reception voice deterioration level calculating function  303  calculates a deterioration level (step S 603 ). The deterioration level shows the level of the reception voice signal  110  that becomes hard to hear due to the influence of the ambient noise  108 . The reception voice deterioration level calculating function  303  performs calculation so that the deterioration level of the reception voice signal  110  becomes larger as the SNR of the reception voice signal  110  and the ambient noise  108  becomes smaller. For example, the deterioration level=−SNR, SNR=power (dB) of the reception voice signal 110-power (dB) of the ambient noise  108 . Further, the reception voice deterioration level calculating function  303  may perform time frequency conversion such as Fourier transform or the like on the reception voice signal  110  and the ambient noise  108  to perform calculation from the average value of the SNR that is calculated for every band. The reception voice deterioration level calculating function  303  performs any one of the normal statistic calculating function  304  and the deterioration statistic calculating function  305  in accordance with the deterioration level of the reception voice signal  110 . In other words, the reception voice deterioration level calculating function  303  judges whether or not the ratio of the ambient noise  108  with respect to the reception voice signal  110  is not less than a predetermined threshold value. The reception voice deterioration level calculating function  303  performs any of the normal statistic calculating function  304  and the deterioration statistic calculating function  305  in accordance with the result of whether the ratio of the ambient noise  108  with respect to the reception voice signal  110  is not less than a predetermined threshold value or not. The reception voice deterioration level calculating function  303  judges that whether the deterioration level of the reception voice signal  110  is not less than the predetermined threshold value or not (S 604 ). The threshold value shall be preliminarily provided. 
     When the reception voice deterioration level calculating function  303  judges that the deterioration level of the reception voice signal  110  is not less than the threshold value (step S 604  YES), the deterioration statistical calculating function  305  is performed, and the characteristic amount  307  of the transmission voice signal  109  is input to the deterioration statistic calculating function  305  by the characteristic amount calculating function  302 . Then the deterioration statistic calculating function  305  calculates the statistic of the characteristic amount  307  of the transmission voice signal  109  of the present frame (step S 605 ). The deterioration statistic calculating function  305  newly adds the characteristic amount  307  of the present frame to the statistic that is calculated before the characteristic amount  307  of the transmission voice signal  109  of the present frame is received by the deterioration statistic calculating function  305 , and calculates the average, dispersion, standard error of the average, and 95% reliable interval of the average value. When there is a plurality of types of the characteristic amount of the transmission voice signal  109 , the deterioration statistic calculating function  305  performs the similar processing to each of them. The statistic that is calculated by the deterioration statistic calculating function  305  is a statistic of the characteristic amount  307  of the transmission voice signal  109  in the case where the reception voice signal  110  is deteriorated, and hereinafter referred to as a deterioration statistic  308 . When the reception voice deterioration level calculating function  303  judges that the deterioration level of the reception voice signal  110  is less than the threshold value, (No in step S 604 ), the normal statistic calculating function  304  is performed, and the characteristic amount  307  of the transmission voice signal  109  is input to the normal statistic calculating function  304  by the characteristic amount calculating function  302 . Then the normal statistic calculating function  304  calculates the statistic of the characteristic amount  307  (step S 606 ). The normal statistic calculating function  304  newly adds the characteristic amount  307  of the present frame to the statistic that is calculated before the characteristic amount  307  of the transmission voice signal  109  of the present frame is received by the normal statistic calculating function  304 , and calculates the average, dispersion, standard error of the average, and 95% reliable interval of the average value. When there is a plurality of types of the characteristic amount of the transmission voice signal  109 , the normal statistic calculating function  304  performs the similar processing to each of them. The statistic that is calculated by the normal statistic calculating function  304  is a statistic of the characteristic amount  307  of the transmission voice signal  109  in the case where it is judged that the reception voice signal  110  is not deteriorated, and hereinafter referred to as a normal statistic  309 . 
     The variation amount calculating function  306  calculates the variation amount  111  of the characteristic amount  307  (step S 607 ). The normal statistic calculating function  304  inputs the normal statistic  308  to the variation amount calculating function  306 . The deterioration statistic calculating function  305  inputs the deterioration statistic  309  to the variation amount calculating function  306 . The variation amount calculating function  306  calculates the variation amount  111  by comparing the normal statistic  308  and the deterioration statistic  309 . 
     In the embodiment, the statistic (normal statistic  308 , deterioration statistic  309 ) of the characteristic value  307  of the transmission voice signal  109  shall be average, dispersion, number of sample, standard error of the average, standard variation, and 95% reliable interval. 
     The variation amount calculating function  306  compares the normal statistic  308  and deterioration statistic  309 , and judges whether or not there is a difference between the normal statistic  308  and deterioration statistic  309 . when the variation amount calculating function  306  judges that the 95% reliable intervals of the normal statistic  308  and deterioration statistic  309  are matched to each other, the variation amount calculating function  306  judges that there is statistically no significant difference, regards the variation amount  111  as “0”, and outputs the transmission voice signal  109 . When the variation amount calculating function  306  judges that the 95% reliable intervals of the normal statistic  308  and deterioration statistic  309  are not matched to each other, the variation amount calculating function  306  judges that the characteristic amount  307  of the transmission voice signal  109  is varied due to the deterioration of the reception voice signal  110 , and outputs the difference between the average value of the characteristic amount  307  when the reception voice signal  110  is deteriorated and the average value of characteristic amount  307  when the reception voice signal  110  is not deteriorated (normal time) as the variation amount  111  (step S 608 ). Note that a 99% reliable interval of the average or the like may be used in stead of the 95% reliable interval of the average. The 95% reliable interval is calculated by formula (1). SE, m included in formula (1) that shows the 95% reliable interval are respectively calculated by formula (2), (3), and (4). 
     
       
         
           
             
               
                 
                   Formula 
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                   1 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     95 
                     ⁢ 
                     % 
                     ⁢ 
                     
                         
                     
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                     reliable 
                     ⁢ 
                     
                         
                     
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                     interval 
                   
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                   SE 
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                   3 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   SD 
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                   4 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   m 
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     m is the average value, k is a constant number that is determined by the number of sample (1.96 when the number of sample is ∞) SE is the standard error of the average, SD is the standard variation, and n is the number of sample. 
     4. Characteristic Amount  307   
     Next, the characteristic amount  307  calculated by the characteristic amount calculating function  302  will be described in detail. The characteristic amount  307  according to the embodiment is constituted by the power, power dynamic range, power spectrum inclination, speaking speed, pause length, pitch frequency, pitch frequency dynamic range, and vocal length of the transmission voice signal  109  which are described below. 
     4.1 Power of Transmission Voice Signal  109   
     The power of the transmission voice signal  109  of the characteristic amount  307  will be described. 
     The characteristic amount calculating function  302  calculates the power of the transmission voice signal  109  by formula (5). 
     
       
         
           
             
               
                 
                   Formula 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   5 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   p 
                   = 
                   
                     10 
                     * 
                     log 
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                     10 
                     ⁢ 
                     
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     p is frame electric power (dB), N is the number of sample of a frame, and xi is the amplitude of ith sample. 
     4.2. Power Dynamic Range of Transmission Voice Signal  109   
     The power dynamic range of the transmission voice signal  109  of the characteristic value  307  will be described. 
     The characteristic amount calculating function  302  calculates the power dynamic range (p_range) of the transmission voice signal  109  by formula (6).
 
Formula 6
 
 p _range=max( pt−k )−min( pt−k ) K= 0 , . . . ,M− 1  (6)
 
     pj is jth frame power (dB). t is the present frame, M is the number of frame in an observation interval of the dynamic range. max( ) is a function that outputs the maximum value in the interval, min( ) is a function that outputs the minimum value in the interval. 
     4.3. Power Spectrum Inclination of Transmission Voice Signal  109   
     The power spectrum inclination of the transmission voice signal  109  of the characteristic amount  307  will be described. 
     (1) The characteristic amount calculating function  302  calculates a power spectrum by performing a time frequency conversion on the transmission voice signal  109  from which the ambient noise  108  is removed. The time frequency conversion is a method of such as Fourier transform or the like. 
     (2) The characteristic amount calculating function  302  calculates the inclination of the power spectrum. 
     The characteristic amount calculating function  302  expresses the power spectrum for every frequency by (xi, yi) and calculates the power spectrum inclination as a real inclination when a least square method is applied to a linear function. 
     xi is the frequency (HZ) of ith power spectrum, and yi is the magnitude (dB) of ith power spectrum. 
     4.4. Speaking Speed of Transmission Voice Signal  109   
     The speaking speed of the transmission voice signal  109  of the characteristic amount  307  will be described. 
     The characteristic amount calculating function  302  detects a vocal of the input voice, counts the number of the vocal in a predetermined time, and calculates the speaking speed by the number of the vocal. 
     4.5. Pause Length of Transmission Voice Signal  109 . 
     The pause length of the transmission voice signal  109  of the characteristic amount  307  will be described. 
     (1) The characteristic amount calculating function  302  performs a sound detection processing of the transmission voice signal  109  from which the ambient noise  108  is removed. The characteristic amount calculating function  302  detects the frame power by comparing with a threshold value. The threshold value is a long-term average of the frame power. 
     (2) The characteristic amount calculating function  302  calculates a continuous length of a no-sound interval as the pause length. 
     4.6. Pitch Frequency of Transmission Voice Signal  109   
     The pitch frequency of the transmission voice signal  109  of the characteristic amount  307  will be described. 
     The characteristic amount calculating function  302  calculates the pitch frequency by formula (8). Further, the characteristic amount calculating function  302  calculates a correlation coefficient when a shifted position is “a” by formula (7). 
     
       
         
           
             
               
                 
                   Formula 
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                   7 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     corr 
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                   8 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   pitch 
                   = 
                   
                     freq 
                     / 
                     a_max 
                   
                 
               
               
                 
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     X is an input signal, M is a length (sample) of an interval in which the correlation coefficient is calculated, a is a starting position of a signal that calculates the correlation coefficient, pitch is the pitch frequency (Hz), corr(a) is the correlation coefficient in the case where the shifted position is “a”, a_max is “a” corresponding to maximum correlation coefficient, i is an index (sample) of the signal, and freq is a sampling frequency (Hz). 
     4.7. Pitch Frequency Dynamic Range of Transmission Voice Signal  109   
     The pitch frequency dynamic range of the transmission voice signal  109  of the characteristic amount  307  will be described. 
     The characteristic amount calculating function  302  calculates the pitch frequency dynamic range by formula (9).
 
Formula 9
 
 p _range=max( pt−k )−min( pt−k ) k= 0 , . . . ,M− 1  (9)
 
     p_range is the pitch frequency dynamic range (Hz), pj is jth pitch frequency (Hz). t is the present frame, M is the number of frame of an observation interval of the dynamic range, max( ) is a function for outputting the maximum value in the interval, and min( ) is a function for outputting the minimum value in the interval. 
     4.8. Vocal Length of Transmission Voice Signal  109   
     The vocal length of the transmission voice signal  109  of the characteristic value  307  will be described. 
     The characteristic amount calculating function  302  calculates the vocal length of the transmission voice signal  109 . A vocal detection processing of an input (transmission sound from which ambient noise is removed) is performed. 
     (1) The characteristic amount calculating function  302  calculates a pitch correlation (corr(a_max)), compares with a predetermined threshold value, and judges the present frame as a vocal when larger than the threshold value. 
     (2) The characteristic amount calculation function  302  calculates the length of the vocal (frame) as a continuous length of a vocal interval. 
     5. Speech Control Effect Applying Function  102   
     Next, a processing of the speech control effect applying function  102  will be described.  FIGS. 7A and 7B  are a flowchart of a processing performed by the speech control effect applying function  102  according to the embodiment. As shown in  FIGS. 7A and 7B , in the embodiment, the variation amount  111  applied to the reception voice signal  110  by the speech control effect applying function  102  is constituted by a power deformation amount  71 , power dynamic range  72 , spectrum inclination  73 , speaking speed deformation amount  74 , pause length  75 , pitch frequency deformation amount  76 , pitch frequency dynamic range  77 , and vocal length deformation amount  78 . 
     The speech control effect applying function  102  applies the deformation amounts  71  to  78  constituting the variation amount  111  to the reception voice signal  110  in accordance with the processing flow shown in  FIGS. 7A and 7B . 
     The speech control effect calculating function  101  inputs the variation amount  111  to the speech control effect applying function  102 . In the embodiment, the speech control effect calculating function  101  inputs the deformation amounts  71  to  77  constituting the variation amount  111  to the speech control effect applying function  102  in series. 
     The speech control effect applying function  102  receives the power deformation amount  71  (step S 701 ). 
     The speech control effect applying function  102  judges whether or not the power deformation amount  71  is not less than a threshold value (step S 702 ). The threshold value  79  shall be predetermined. When the speech control effect applying function  102  judges that the power deformation amount  71  is not less than the threshold value  79  (YES in step S 702 ), the speech control effect applying function  102  applies the power deformation amount  71  to the reception voice signal  110 . (step S 703 ). When the speech control effect applying function  102  judges that the power deformation amount  71  is less than the threshold value  79  (No in step S 702 ), the speech control effect applying function  102  receives the power dynamic range deformation amount  72  (step S 704 ). 
     The speech control effect applying function  102  judges whether or not the power dynamic range deformation amount  72  is not less than a threshold value  80  (step S 705 ). The threshold value  80  shall be predetermined. When the speech control effect applying function  102  judges that the power dynamic range deformation amount  72  is not less than the threshold value  80  (YES in step S 705 ), the speech control effect applying function  102  applies the power dynamic range deformation amount  72  to the reception voice signal  110  (step S 706 ). When the speech control effect applying function  102  judges that the power dynamic range deformation amount  72  is less than the threshold value  80  (No in step S 705 ), the speech control effect applying function  102  receives the spectrum inclination deformation amount  73  (step S 707 ). 
     The speech control effect applying function  102  judges whether or not the spectrum inclination deformation amount  73  is not less than a threshold value  81  (step S 708 ). The threshold value  81  shall be predetermined. When the speech control effect applying function  102  judges that the spectrum inclination deformation amount  73  is not less than the threshold value  81  (YES in step S 708 ), the speech control effect applying function  102  applies the spectrum inclination deformation amount  73  to the reception voice signal  110  (step S 709 ). When the speech control effect applying function  102  judges that the spectrum inclination deformation amount  73  is less than the threshold value  81  (No in step S 708 ), the speech control effect applying function  102  receives the speaking speed deformation amount  74  (step S 710 ). The speech control effect applying function  102  judges whether or not the speaking speed deformation amount  74  is not less than a threshold value  82  (step S 711 ). The threshold value  82  shall be predetermined. When the speech control effect applying function  102  judges that the speaking speed deformation amount  74  is not less than the threshold value  82  (YES in step S 711 ), the speech control effect applying function  102  applies the speaking speed deformation amount  74  to the reception voice signal  110  (step S 712 ). When the speech control effect applying function  102  judges that the speaking speed deformation amount  74  is less than the threshold value  82  (No in step S 711 ), the speech control effect applying function  102  receives the pause length deformation amount  75  (step S 713 ). 
     The speech control effect applying function  102  judges whether or not the pause length deformation amount  75  is not less than a threshold value  83  (step S 714 ). The threshold value  83  shall be predetermined. When the speech control effect applying function  102  judges that the pause length deformation amount  75  is not less than the threshold value  83  (YES in step S 714 ), the speech control effect applying function  102  applies the pause length deformation amount  75  to the reception voice signal  110  (step S 715 ). When the speech control effect applying function  102  judges that the pause length deformation amount  75  is less than the threshold value  83  (No in step S 714 ), the speech control effect applying function  102  receives the pitch frequency deformation amount  76  (step S 716 ). 
     The speech control effect applying function  102  judges whether or not the pitch frequency deformation amount  76  is not less than a threshold value  84  (step S 717 ). The threshold value  84  shall be predetermined. When the speech control effect applying function  102  judges that the pitch frequency deformation amount  76  is not less than the threshold value  84  (YES in step S 717 ), the speech control effect applying function  102  applies the pitch frequency deformation amount  76  to the reception voice signal  110  (step S 718 ). When the speech control effect applying function  102  judges that the pitch frequency deformation amount  76  is less than the threshold value  84  (No in step S 717 ), the speech control effect applying function  102  receives the pitch frequency dynamic range deformation amount  77  (step S 719 ). 
     The speech control effect applying function  102  judges whether or not the pitch frequency dynamic range deformation amount  77  is not less than a threshold value  85  (step S 720 ). The threshold value  85  shall be predetermined. When the speech control effect applying function  102  judges that the pitch frequency dynamic range deformation amount  77  is not less than the threshold value  85  (YES in step S 720 ), the speech control effect applying function  102  applies the pitch frequency dynamic range deformation amount  77  to the reception voice signal  110  (step S 721 ). When the speech control effect applying function  102  judges that the pitch frequency dynamic range deformation amount  77  is less than the threshold value  85  (No in step S 720 ), the speech control effect applying function  102  receives the vocal length deformation amount  78  (step S 722 ). 
     The speech control effect applying function  102  judges whether or not the vocal length deformation amount  78  is not less than a threshold value  86  (step S 723 ). The threshold value  86  shall be predetermined. When the speech control effect applying function  102  judges that the vocal length deformation amount  78  is not less than the threshold value  86  (YES in step S 723 ), the speech control effect applying function  102  applies the vocal length deformation amount  78  to the reception voice signal  110  (step S 724 ), and finishes the processing. When the speech control effect applying function  102  judges that the vocal length deformation amount  78  is less than the threshold value  86  (No in step S 723 ), the speech control effect applying function  102  finishes the processing. 
     6. Embodiment of Speech Control Effect Applying Function  102   
     Next, a concrete application of each deformation amount  71  to  78  to the reception voice signal  110  performed by the speech control effect applying function  102  will be described. 
     First, an application processing of the power deformation amount  71  performed by the speech control effect applying function  102  will be described. 
     (1) The speech control effect applying function  102  calculates the power of the reception voice signal  110 . In the embodiment, the speech control effect applying function  102  calculates by a dB value. 
     (2) The speech control effect applying function  102  adds the power deformation amount  71  to the power of the reception voice signal  110 . The speech control effect applying function  102  increases/decreases the power of the reception voice signal  110  by the deformation amount  71  of the transmission voice signal  109 . The speech control effect applying function  102  may multiply the deformation amount  71  by a predetermined coefficient value to increase/decrease the power of the reception voice signal  110  at a predetermined rate. 
     Specifically, the speech control effect applying function  102  performs calculation by using formula (10) for amplitude pr′ of the reception voice signal  110 .
 
Formula 10
 
 Pr′=pr+Δp   (10)
 
     Pr′ is the power (dB) of the reception voice signal  110  to which the deformation amount  71  is applied, pr is the power (dB) of the reception voice signal  110 , and Δp is the power deformation amount  71  (dB). 
     The speech control effect applying function  102  adjusts the reception voice signal  110  by adding the deformation amount  71  to the reception voice signal  110 . 
     Next, an application processing of the power dynamic range deformation amount  72  performed by the speech control effect applying function  102  will be described. 
     (1) The speech control effect applying function  102  calculates a power dynamic range pr_range of the reception voice signal  110  by using formula (11).
 
Formula 11
 
 pr _range=max( prt−k )−min( prt−k ) k= 0, . . . , M− 1  (11)
 
     pr_range is a power dynamic range, prj is a jth frame power of the reception voice signal  110 , t is the present frame, M is the number of frames in an observation interval of the dynamic range, max( ) is a function for outputting the maximum value in the interval, and min( ) is a function for outputting the minimum value in the interval. 
     (2) The speech control effect applying function  102  applies the power dynamic range deformation amount  72  to the power dynamic range of the reception voice signal  110 .  FIG. 8  is a diagram schematically showing the application processing of the power dynamic range deformation amount  72 . The power dynamic range is the one obtained by reducing the power minimum value from the power maximum value in a predetermined observation interval. The power dynamic range shows an intonation of the sound shown by the power.  FIG. 8  shows the magnitude of the power of the present frame in the power dynamic range. 
     The speech control effect applying function  102  applies the power dynamic range deformation amount  72  to the power of the present frame of the reception voice signal  110  by using formula (12) to calculate the power pr′ (dB) of the reception voice signal  110 .
 
Formula 12
 
 pr ′=min+( pr− min)×( pr _range+Δ p _range)/ pr _range  (12)
 
     pr′ is the power (dB) of the reception voice signal  110  after applying the deformation amount  72 , min is the minimum power (dB) of the reception voice signal  110 , pr is the power (dB) of the reception voice signal  110 , Δp is the power deformation amount  72  (dB). As shown in  FIG. 8 , the speech control effect applying function  102  performs an adjustment so that a magnitude  801  of the present frame before applying the power dynamic range deformation amount  72  and a magnitude  802  of the present frame after applying the power dynamic range deformation amount  72  become relatively the same by using Formula (12). That is, the speech control effect applying function  102  performs adjustment so that the position of the magnitude  801  of the present frame in the power dynamic range before applying the deformation amount  72  and the position of magnitude  802  of the present frame in the power dynamic range after applying the deformation amount  72  become relatively the same. 
     Next, an application processing of the spectrum inclination deformation amount  73  performed by the speech control effect applying function  102  will be described.  FIG. 9  is a diagram schematically showing an application processing of the spectrum inclination deformation amount  73 . The spectrum inclination is an inclination with respect to the time frequency of the power spectrum. Generally, it becomes easy to hear for a human being as the power of high time frequency becomes larger. Accordingly, the speech control effect applying function  102  can perform adjustment so that it becomes easy to hear the reception voice signal  110  by increasing the power of high time frequency by adjusting the spectrum inclination. 
     (1) The speech control effect applying function  102  calculates the power spectrum of the reception voice signal  110 . The power spectrum is a frequency component of each of the power. The speech control effect applying function  102  performs a time frequency conversion on the power spectrum of the reception voice signal  110 . 
     (2) The speech control effect applying function  102  calculates the power spectrum inclination of the reception voice signal  110 . 
     (3) The speech control effect applying function  102  corrects the power spectrum pri′ of the reception voice signal  110  as shown in formula (13).
 
Formula 13
 
 pri′−pri+Δaxi   (13)
 
     pri′ is the ith band power spectrum after applying the power spectrum inclination deformation amount  73 , Δa is the power spectrum inclination deformation amount  73  (dB), and i is an index of the power spectrum band. 
     (4) The speech control effect applying function  102  performs a frequency time conversion on the power spectrum of the reception voice signal  110  that is calculated and corrected by formula (13). 
     Next, an application processing of the speaking speed deformation amount  74  performed by the speech control effect applying function  102  will be described. 
     (1) The speech control effect applying function  102  calculates the speaking speed of the received vice signal  110 . For example, the speaking speed is calculated as described below. The speech control effect applying function  102  detects a vocal in the reception voice signal  110 . The communication terminal  1200 , for example, stores standard patterns of vocals and consonants in a memory (not shown in  FIG. 12 ). Then, the speech control effect applying function  102  compares a detected sound and the standard patterns stored in the memory. The speech control effect applying function  102  judges whether the detected sound is a vocal or not by selecting a sound having a Euclidean distance that is the shortest to the detected sound among the standard patterns, thereby detecting vocal. The speech control effect applying function  102  replaces the number of vocal in a predetermined time interval by the number of syllables in the predetermined time interval. The speech control effect applying function  102  divides the reception voice signal  11  in the predetermined time interval by the replaced number of syllables in the predetermined time interval to calculate the speaking speed. 
     (2) The speech control effect applying function  102  adjusts the speaking speed (speed′) of the reception voice signal  110  by using formula (14)
 
Formula 14
 
speed′=speed+Δspeed  (14)
 
     speed is the speaking speed of the reception voice signal  110  before applying the deformation amount  74 , Δspeed is the deformation amount  74  of the speaking speed (speed), speed′ is the speaking speed of the reception voice signal  110  after applying the deformation amount  74 . The speech control effect applying function  102  judges the periodicity of the speaking speed (speed) of the reception voice signal  110 . Then, the speech control effect applying function  102  adjusts the speaking speed (speed) of the reception voice signal  110  by increasing or decreasing the reception voice signal  110  by one cycle. 
     Next, an application processing of the pause length deformation amount  75  performed by the speech control effect applying function  102  will be described.  FIG. 10  is a diagram schematically showing the application processing of the pause length deformation amount  75 . 
     (1) The speech control effect applying function  102  calculates pause lengths of the reception voice signal  110  (T 1 , T 2 , T 3 , T 4 , T 5  described in  FIG. 10 ). For example, the speech control effect applying function  102  compares the frame power of the reception voice signal  110  to a threshold value (for example, a long term average of the frame power). Then, the length of the interval in which the speech control effect applying function  102  judges that the frame power of the reception voice signal  110  is not more than the threshold value is calculated as the pause length. Further, the speech control effect applying function  102  may calculate an interval having no periodicity that is included in the reception voice signal  110  as a no-sound interval. The interval in which the speech control effect applying function  102  judges that the frame power of the reception voice signal  110  is larger than the threshold value is voice presence intervals  101  to  1012  of the reception voice signal  110  described in  FIG. 10 . Each of the voice presence intervals  1007  to  1012  is the voice presence interval corresponding to the corresponding one of the voice presence intervals  1001  to  1006 . 
     (2) The pause length of the reception voice signal  110  is calculated by using formula (15).
 
Formula 15
 
pause′=pause+Δpause  (15)
 
     pause is the pause length of the reception voice signal  110  before applying the deformation amount  75 , Δpause is the pause length deformation amount  75 , pause′ is the pause length of the reception voice signal  110  after applying the deformation amount  75 . 
     The speech control effect applying function  102  adds Δpause  75  to adjust the pause length after a pause of the reception voice signal  110  is finished. Pause lengths adjusted by the speech control effect applying function  102  are T′ 1 , T′ 2 , T′ 3 , T′ 4 , T′ 5  described in  FIG. 10 . The speech control effect applying function  102  applies the deformation amount  75  to the pause lengths T 1 , T 2 , T 3 , T 4 , T 5  to calculates the pause lengths T′ 1 , T′ 2 , T′ 3 , T′ 4 , T′ 5 . Note that the speech control effect applying function  102  performs adjustment so that no-sound interval does not become longer than a fixed length. This is to prevent that the delay time from the original reception signal  110  becomes long when the no-sound interval becomes long to seriously increase the delay by adjusting the pause length by the speech control effect applying function  102 . The speech control effect applying function  102  judges that whether the no-sound interval becomes not less than a fixed length or not, and contracts the no-sound interval to eliminate time delay when it is judged that the no-sound interval is not less than the fixed length. For example, the pause length T 3  described in  FIG. 10  is the pause length (no-sound interval) that is judged to be not less than the fixed length by the speech control effect applying function  102 . The speech control effect applying function  102  shortens the pause length T 3  to the pause length T′ 3 . 
     Next, an application processing of the pitch frequency deformation amount  76  performed by the speech control effect applying function  102  will be described. 
     (1) The speech control effect applying function  102  calculates the pitch frequency of the reception voice signal  110 . The pitch frequency is a physical value showing an intonation of sound. The speech control effect applying function  102  performs calculation by formulas (7) and (8). That is, the frequency at which a correlation coefficient shown by formula (7) becomes the maximum is the pitch frequency. 
     (2) The speech control effect applying function  102  calculates the pitch frequency pitch′ of the reception voice signal  110  by using formula (16).
 
Formula 16
 
pitch′=pitch+Δpitch  (16)
 
     pitch is the pitch frequency of the reception voice signal  110  before applying the deformation amount  76 , Δpitch is the pitch frequency deformation amount  76 , and pitch′ is the pitch frequency of the reception voice signal  110  after applying the pitch frequency deformation amount  76 . The pitch frequency is adjusted by adding the pitch frequency of the reception voice signal  110  to the pitch frequency deformation amount  76 . The sound of the reception voice signal  110  becomes higher as the pitch becomes higher. 
     Next, an application processing of the deformation amount  77  of a pitch frequency dynamic range pitch_r_range performed by the speech control effect applying function  102  will be described.  FIG. 11  is a diagram schematically showing the application processing of the pitch frequency dynamic range deformation amount  77 . 
     (1) The pitch frequency dynamic range of the reception voice signal  110  is calculated by using formula (17)
 
Formula 17
 
pitch —   r _range=max(pitch —   rt−k )−min(pitch —   rt−k ) k= 0, . . . , M− 1  (17)
 
     pitch_r_range is the pitch frequency dynamic range of the reception voice signal  110 , pitch_rj is the pitch frequency of jth frame of the reception voice signal  110 , t is the present frame, M is the number of frames in an observation interval of the dynamic range, max( ) is a function for outputting the maximum value in the interval, and min( ) is a function for outputting the minimum value in the interval. 
     (2) The speech control effect applying function  102  corrects the pitch frequency dynamic range of the reception voice signal  110  by the pitch frequency dynamic range deformation amount  77 . 
     The speech control effect applying function  102  applies the pitch frequency dynamic range deformation amount  77  to the pitch frequency of the present frame of the reception voice signal  110 . The speech control effect applying function  102  performs calculation so that the pitch frequency of the reception voice signal  110  becomes pitch_r′ by using formula (18). 
     
       
         
           
             
               
                 
                   Formula 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   18 
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     pitch_r 
                     ′ 
                   
                   = 
                   
                     pitch_min 
                     + 
                     
                       
                         ( 
                         
                           pitch_r 
                           - 
                           pitch_min 
                         
                         ) 
                       
                       × 
                       
                         
                           ( 
                           
                             pitch_range 
                             + 
                             Δpitch_range 
                           
                           ) 
                         
                         / 
                         pitch_range 
                       
                     
                   
                 
               
               
                 
                   ( 
                   18 
                   ) 
                 
               
             
           
         
       
     
     pitch_r′ is the pitch frequency (Hz) of the reception voice signal  110  after application, pitch_min is the minimum pitch frequency (Hz) of the reception voice signal  110 , pitch_r is the pitch frequency (Hz) of the reception voice signal  110 , Δpitch_range is the pitch frequency dynamic range deformation amount  77  (Hz). As shown in  FIG. 11 , the speech control effect applying function  102  performs an adjustment so that a pitch frequency  1101  of the present frame before applying the modulation amount  77  to the pitch frequency dynamic range and a pitch frequency  1102  of the present frame after applying the deformation amount  77  to the pitch frequency dynamic range become relatively the same by formula (18). That is, the speech control effect applying function  102  performs an adjustment so that the position of the pitch frequency  1101  of the present frame in the pitch frequency dynamic range before applying the deformation amount  77  and the position of the pitch frequency  1102  of the present frame in the pitch frequency dynamic range after applying the deformation amount  77  become relatively the same. 
     Next, an application processing of the vocal deformation amount  78  performed by the speech control effect applying function  102  will be described. 
     (1) The speech control effect applying function  102  calculates the vocal length of the reception voice signal  110 . 
     (2) The speech control effect applying function  102  adds the vocal length deformation amount  78  to the vocal length of the reception voice signal  110 . The speech control effect applying function  102  calculates vocal length vl′ of the reception voice signal  110  by using formula (19).
 
Formula 19
 
vl′=vl+Δvl  (19)
 
     vl is the vocal length (frame) of the reception voice signal  110  before application, vl′ is the vocal length (frame) of the reception voice signal  110  after application, and Δvl is the variation amount (frame) of the vocal length. 
     The speech control effect applying function  102  performs converts the vocal length so that the speaking speed becomes vl′/vl times in the interval that is judged as a vocal interval. 
     Second Embodiment 
     7. Outline of Voice Transmission System  200   
     Next, another embodiment that adjusts a voice output that reflects the speech control effect will be described.  FIG. 2  is a block diagram showing an outline of a voice transmission system  200  according to the embodiment. 
     The voice transmission system  200  is equipped with a speech control effect calculating function  201 , a speech control effect applying function  202 , a speech control effect judging function  203 , a microphone (MIKE)  204 , a receiving unit  205 , and a speaker  206 . The voice transmission system is also a processing system that can be provided by a communication terminal corresponding to the communication terminal  1200 . A voice processing unit  207  corresponding to the voice processing unit  1211  is a unit that provides a processing of the speech control effect calculating function  201 , the speech control effect applying function  202 , and the speech control effect judging function  203 . 
     The speech control effect calculating function  201  and the speech control effect applying function  202  have the same structure as the speech control effect calculating function  101  and the speech control effect applying function  102  in the first embodiment. 
     The voice transmission system  200  according to the embodiment has the speech control effect judging function  203 , which is the different point from the voice transmission system  100 . Accordingly, the speech control effect judging function  203  will be mainly described below. 
     The speech control effect calculating function  201  calculates the variation amount of the transmission voice that is varied due to the speech control effect, and the speech control effect applying function  202  applies the variation amount to adjust a reception voice signal  212 . 
     Further, in the voice transmission system  200  according to the embodiment, the speech control effect judging function  203  judges whether or not the present transmission voice is varied due to the speech control effect. When the speech control effect judging function  203  judges that a present transmission voice signal  211  is varied due to the speech control effect, the speech control effect applying function  202  applies a variation mount  213  of the characteristic amount of the reception voice signal  212  that is varied due to the speech control effect to the reception voice signal  212  for adjustment. That is, in the voice transmission system  200  according to the embodiment, the presence or absence of the speech control effect is judged and the reception voice is adjusted when there is the speech control effect. 
     8. Processing Flowchart of Voice Transmission System  200   
       FIG. 5  is a processing flow performed by the voice transmission system  200 . The processing that is performed by the voice transmission system  200  will be described in detail by using  FIG. 5 . 
     The microphone  204  receives a sound  208  and the receiving unit  205  receives the reception voice signal  212  from outside of the voice transmission system  200 . A sound signal  209  and the reception voice signal  212  are input to the speech control effect calculating function  201 . The speech control effect calculating function  201  calculates an amount (varied amount)  213  of the transmission voice signal  211  that is varied by the speech control effect and a characteristic amount  214  of the transmission voice signal  211  which is the present frame of the transmission voice signal  111  and from which an ambient noise  210  is removed by using the signals (step S 501 ). Note that the sound signal  209  is an electrical signal corresponding to the sound  208  input to the microphone  204 . 
     The speech control effect judging function  203  receives the characteristic amount  214  of the transmission voice signal  211  contained in the sound signal  209  of the present frame from the speech control effect calculating function  201 . Then, the speech control effect judging function  203  judges whether or not the transmission voice signal  211  of the present (present frame) is varied due to the speech control effect (step S 502 ). When the speech control effect judging function  203  judges that the transmission voice signal  211  is varied due to the speech control effect (YES in step S 502 ), the speech control effect applying function  202  applies the variation amount  213  of the characteristic amount of the reception voice signal  212  that is varied by the speech control effect to the reception voice signal  212  (step S 503 ). The speech control effect applying function  202  outputs a reception voice signal  216  to which the variation amount  213  is applied (step S 504 ). When the speech control effect judging function  203  judges that the transmission voice signal  211  is not varied by the speech control effect (No in step S 502 ), the speech control effect applying function  202  outputs the reception voice signal  212  (step S 505 ). In step S 502 , the judgment of whether or not the transmission voice signal  211  is varied due to the speech control effect is judged from the characteristic amount  214  output from the speech control effect calculating function  201 . The speech control effect judging function  203  calculates a judgment result  215  of whether the characteristic amount  214  of the transmission voice signal  211  of the present frame is varied by the speech control effect or not by a following processing. 
     The speech control effect judging function  203  calculates a distance S 1  between the characteristic amount of the present frame of the transmission voice signal  211  and the transmission voice signal  211  when the reception voice signal  212  is not less than a predetermined ratio with respect to the ambient noise  210 , and a distance S 2  between the characteristic amount of the present frame of the transmission voice signal  211  and the transmission voice signal  211  when the reception voice signal  212  is not deteriorated. S 1 , S 2  can be expressed by formulas (20), (21).
 
Formula 20
 
 S 1 =|Mn−Mc|   (20)
 
Formula 21
 
 S 2=| Md−Mc|   (21)
 
     Mn is an average of the transmission voice signal  211  when the reception voice signal  212  is not deteriorated, Md is an average of the transmission voice signal  211  when the reception voice signal  212  is not deteriorated, and Mc is an average of the transmission voice signal of the present frame. 
     When the speech control effect judging function  203  judges that S 1 &lt;S 2 , it is judged that the transmission voice signal  211  of the present frame is varied due to the speech control effect. When the speech control effect judging function  203  judges that S 1 &gt;S 2 , it is judged that the transmission voice signal  211  of the present frame is not varied due to absence of the speech control effect. That is, the speech control effect judging function  203  compares S 1  and S 2  and judges that the present frame of the transmission voice signal  211  belongs to the smaller one. Note that, when there is a plurality of the characteristic amounts in the transmission voice signal  211 , S 1  and S 2  are calculated and compared for every characteristic amount. Further, a weight may be changed in accordance with the characteristic amount when the speech control effect judging function  203  averages the characteristic amount. 
     According to the voice transmission system of the embodiment, the following effect can be obtained. In the voice transmission system according to the embodiment, the variation amount of the transmission voice that is varied due to the speech control effect is calculated. The voice transmission system applies the variation amount to the reception voice signal, so that it becomes possible to emphasize the reception voice signal in accordance with auditory property of the user. Accordingly, in the voice transmission system according to the embodiment, a reception voice which is easy to hear for the user as compared with a conventional voice transmission system can be created. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and condition, nor does the organization of such examples in the specification relate to a showing of superiority and inferiority of the invention. Although the embodiment of the present inventions have been described in detail, it should be understood that the various changes, substitutions, and alternations could be made hereto without departing from the spirit and scope of the invention.