Patent Publication Number: US-8542856-B2

Title: Hearing aid

Description:
TECHNICAL FIELD 
     The present invention relates to a hearing aid. 
     Background Art 
     A hearing aid comprises a receiver that the user mount in the inlet to the ear canal or inserts into the ear canal, a control device that is connected to the receiver, and an external microphone that is connected to the control device. The hearing aid uses the control device to perform hearing aid processing on sound collected by the external microphone, and then supplies this sound to the ear canal through the receiver. The hearing aid processing performed by the control device is carried out according to the hearing aid function settings made during fitting prior to use of the hearing aid. As is well known, these hearing aid function settings during fitting are made according to how the user hears successively outputted sounds over the audible frequency band, such as from low sounds to high sounds. However, even though the hearing aid function setting has been performed, the hearing aid function may not be properly realized depending on the usage environment of the hearing aid (such as how it is mounted). 
     In view of this, Patent Literature 1 below proposes that hearing aid processing (amplification) be performed by a control device so that the sound pressure collected by the ear canal microphone will be constant, on the basis of the result of comparing the sound pressure of sound collected by the external microphone to the sound pressure collected by the ear canal microphone, during fitting before the hearing aid is used. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Laid-Open Patent Application H3-007498 
       
    
     SUMMARY 
     Technical Problem 
     However, the hearing aid processing discussed in Patent Literature 1 merely involves keeping the sound pressure constant, so when the user puts on the hearing aid the day after its fitting, for example, how the user hears sounds may be very different from that during fitting the day before, and this often causes the user discomfort. 
     This point will now be described in further detail. The mounting position of the hearing aid may become slightly offset every time it is attached, and this tiny difference in the mounting position of the hearing aid results in a volume difference within the ear canal between the receiver and the ear drum. This is easy to understand when considering a type of hearing aid in which the receiver is inserted into ear canal; the more deeply the receiver is inserted into the ear canal, the smaller is the volume inside the ear canal, and conversely the more shallowly the receiver is inserted into the ear canal, the larger is the volume inside the ear canal. This fluctuation in the volume inside the ear canal directly affects the acoustic characteristics (that is, the frequency characteristics). In particular, the distance from the receiver to the ear drum tends to vary with the position at which the receiver is inserted into the ear canal deviates, so the sound pressure fluctuation caused by ear canal resonance and distance attenuation has a strong effect. Therefore, since situations in which the characteristics at the time of fitting adjustment cannot necessarily be obtained, the user&#39;s hearing (sound quality) may seem to be very different from that during fitting the day before. As a result, the user&#39;s satisfaction with respect to hearing ends up being low. 
     It is an object of the present invention to provide a hearing aid with which it is possible to suppress fluctuation in the acoustic characteristics (that is, frequency characteristics) caused by slight deviation in the mounting position of the hearing aid. 
     Solution to Problem 
     The hearing aid pertaining to the present invention comprises an external microphone that collects sound outside the ear canal, an ear canal microphone that collects sound inside the ear canal, a hearing aid processor that subjects input sound data indicating the sound collected by the external microphone to hearing aid processing on the basis of fitting information that has been set by fitting, a correction-use sound output component that outputs correction-use sound on the basis of correction-use sound data, an interface that is operated by a user, a transmission characteristic calculator that calculates an at-fitting transmission characteristic on the basis of first sound data produced by collection at the ear canal microphone of the correction-use sound outputted from the correction-use sound output component during fitting, and second sound data corresponding to the correction-use sound data, the transmission characteristic calculator configured to calculate an in-usage transmission characteristic on the basis of third sound data produced by collection at the ear canal microphone of the correction-use sound outputted from the correction-use sound output component according to user operation after fitting, and fourth sound data corresponding to the correction-use sound data, a correction characteristic calculator that calculates a correction characteristic on the basis of the at-fitting transmission characteristic and the in-usage transmission characteristic, and a correction component that corrects the input sound data that has undergone hearing aid processing by the hearing aid processor, on the basis of the correction characteristic. 
     Advantageous Effects 
     With the present invention, a hearing aid can be provided with which it is possible to suppress fluctuation in the acoustic characteristics (that is, frequency characteristics) caused by slight deviation in the mounting position of the hearing aid. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an oblique view of a hearing aid pertaining to a first embodiment; 
         FIG. 2  is a diagram of the state when the hearing aid pertaining to the first embodiment is used; 
         FIG. 3  is a front view of the receiver portion pertaining to the first embodiment; 
         FIG. 4  is a block diagram of the receiver portion pertaining to the first embodiment; 
         FIG. 5  is a block diagram of the receiver portion pertaining to the first embodiment; 
         FIG. 6A  is a graph of second sound data pertaining to the first embodiment; 
         FIG. 6B  is a diagram of the state during fitting of the hearing aid pertaining to the first embodiment; 
         FIG. 6C  is a graph of first sound data pertaining to the first embodiment; 
         FIG. 7A  is a graph of fourth sound data pertaining to the first embodiment; 
         FIG. 7B  is a diagram of the state when the hearing aid pertaining to the first embodiment is used; 
         FIG. 7C  is a graph of third sound data pertaining to the first embodiment; 
         FIG. 8  is a schematic diagram of the method for calculating an at-fitting transmission characteristic pertaining to the first embodiment; 
         FIG. 9  is a schematic diagram of the method for calculating an in-usage transmission characteristic pertaining to the first embodiment; 
         FIG. 10  is a schematic diagram of the method for calculating a correction characteristic pertaining to the first embodiment; 
         FIG. 11  is an oblique view of a hearing aid pertaining to a second embodiment; 
         FIG. 12  is a control block diagram pertaining to the second embodiment; 
         FIG. 13  is a control block diagram pertaining to the second embodiment; 
         FIG. 14A  is a graph of the second sound data pertaining to the second embodiment; 
         FIG. 14B  is a diagram of the state during the fitting of the hearing aid pertaining to the second embodiment; 
         FIG. 14C  is a graph of the first sound data pertaining to the second embodiment; 
         FIG. 15A  is a graph of the fourth sound data pertaining to the second embodiment; 
         FIG. 15B  is a diagram of the state when the hearing aid pertaining to the second embodiment is used; 
         FIG. 15C  is a graph of the third sound data pertaining to the second embodiment; 
         FIG. 16  is a schematic diagram of the method for calculating an at-fitting transmission characteristic pertaining to the second embodiment; 
         FIG. 17  is a schematic diagram of the method for calculating an in-usage transmission characteristic pertaining to the second embodiment; 
         FIG. 18  is a schematic diagram of the method for calculating a correction characteristic pertaining to the second embodiment; and 
         FIG. 19  is a front view of the configuration of a through-hole T pertaining to an embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present invention will now be described through reference to the appended drawings. 
     First Embodiment 
     Configuration of Hearing Aid  100   
       FIG. 1  shows a hearing aid  100  pertaining to the first embodiment. The hearing aid  100  comprises a main body case  1  that is mounted so as to conform to the rear face side of the ear, and a receiver  3  (an example of a “correction-use sound output component”) that is linked to this main body case  1  via an ear hook  2 . A control device  4  and a battery  5  are housed inside the main body case  1 . A power switch  6 , a volume control  7 , an external microphone  8 , and a mounting correction switch  9  are provided on the surface of the main body case  1 . As shown in  FIGS. 2 and 3 , the receiver  3  is integrated along with an ear canal microphone  10  into a mounting piece  11  formed from a soft material. The receiver  3  and the ear canal microphone  10  respectively open toward the ear canal  14  via acoustic tubes  12  and  13  formed in the mounting piece  11 . 
     In other words, when the receiver  3  is mounted at the inlet to the ear canal  14  as shown in  FIG. 2 , or inserted into the ear canal  14 , the receiver  3  and the ear canal microphone  10  are in a state of being open toward the inside of the ear canal  14  via the acoustic tubes  12  and  13 . In  FIG. 2 , the ear hook  2  is not hooked over the ear (auricle)  15  so as to make it easier to understand the positional relation between the receiver  3  and the ear canal microphone  10  with respect to the ear canal  14 . During actual use, however, the receiver  3  is mounted at the inlet to the ear canal  14  as shown in  FIG. 2 , or is inserted into the ear canal  14 , in a state in which the ear hook  2  has been hooked over the ear (auricle)  15  and the main body case  1  has been disposed so as to conform to the rear face of the ear (auricle)  15 . 
     Configuration of Control Device  4   
       FIGS. 4 and 5  are electrical control block diagrams of the control device  4  pertaining to the first embodiment. In  FIGS. 4 and 5 , components that are operating are linked by solid lines, and components that are not operating are linked by broken lines. 
     The control device  4  comprises a hearing aid processor  16  that subjects input sound data indicating the sound collected by the external microphone  8  to hearing aid processing, a correction component  17  that corrects the output of this hearing aid processor  16  and then outputs the result to the receiver  3 , a transmission characteristic calculator  18  that is connected to the output side of the ear canal microphone  10 , an at-fitting transmission characteristic storage  19 , a correction-use sound data storage  20  that outputs the correction-use sound output to the transmission characteristic calculator  18  and the receiver  3 , an in-usage transmission characteristic storage  28  that storages the output of the transmission characteristic calculator  18 , a correction characteristic calculator  21  that calculates a correction characteristic H (ω) from the output of the at-fitting transmission characteristic storage  19  and the output of the in-usage transmission characteristic storage  28 , and a correction characteristic storage  29  provided on the output side of this correction characteristic calculator  21 . The mounting correction switch  9  is connected to this control device  4 .  22 ,  23 , and  24  are amplifiers,  25  and  26  are A/D converters,  27  is a D/A converter, and  30  is a sound reproduction processor. 
       FIGS. 6A ,  6 B, and  6 C show the state during the fitting of the hearing aid  100 . At this time, the hearing aid is placed on the ear (more specifically, the auricle)  15 , and the hearing aid function is set by an ordinary fitting procedure, namely, one in which audible frequency bands are successively outputted from lower sounds to higher sounds to check how well the user can hear those sounds. The fitting information determined by this fitting procedure is registered in the hearing aid processor  16  in  FIG. 4 . Immediately after this fitting, the mounting correction switch  9  is turned on by the user (see  FIG. 5 ). 
     The operation of the control device  4  is switched depending on how many times the mounting correction switch  9  is pressed within a specific period of time. If the mounting correction switch  9  is pressed once within the specific period of time, the operation of the control device  4  is switched to an operation in which the at-fitting transmission characteristic is stored in the at-fitting transmission characteristic storage  19 . When this happens, the mounting correction switch  9  is switched on, and a voice reports that “The at-fitting transmission characteristic has been stored.” Once the at-fitting transmission characteristic has thus been stored, the sound reproduction processor  30  acquires correction-use sound data (an example of “second sound data” pertaining to this embodiment, such as data about sound with low temporal strength over a wide band of 0 to 16 KHz, such as white noise) from the correction-use sound data storage  20 . The sound reproduction processor  30  then transmits the correction-use sound data (the spectrum X (ω) shown in  FIG. 6A ) to the transmission characteristic calculator  18  and outputs to the receiver  3  via the D/A converter  27  and the amplifier  24 . As a result, correction-use sound is emitted from the receiver  3 , and then the sound from the receiver  3  is collected by the ear canal microphone  10 . 
     As shown in  FIG. 5 , the first sound data (the spectrum Yf (ω) shown in  FIG. 6C ) produced when the correction-use sound is collected by the ear canal microphone  10  is supplied to the transmission characteristic calculator  18 . The transmission characteristic calculator  18  compares the first sound data (the spectrum Yf (ω) shown in  FIG. 6C ) produced by sound collection by the ear canal microphone  10 , with the correction-use sound data (an example of second sound data, the spectrum X (ω) shown in  FIG. 6A ), and calculates the at-fitting transmission characteristic Gf (ω) on the basis of this comparison result. The transmission characteristic calculator  18  stores the at-fitting transmission characteristic Gf (ω) in the at-fitting transmission characteristic storage  19 . The method for calculating the at-fitting transmission characteristic Gf (ω) will be discussed below. 
     Next, when the mounting correction switch  9  is pressed three times within the specific period of time, the mounting correction switch  9  is switched off as in  FIG. 4  (it is reported by voice from the receiver  3  that the mounting correction switch  9  has been switched off), and the hearing aid is used in that state for that day. That is, only the external microphone  8 , the amplifiers  23  and  24 , the A/D converter  26 , the D/A converter  27 , the hearing aid processor  16 , the correction component  17 , and the receiver  3  operate, and ordinary hearing aid operation is carried out, specifically, the hearing aid operation related to the fitting information registered to the hearing aid processor  16 . At this point, since no output from the correction characteristic calculator  21  is supplied to the correction characteristic storage  29 , the correction component  17  does not perform a correction operation, and the signal is merely passed through. 
       FIGS. 7A ,  7 B, and  7 C show a state in which the user has put on the hearing aid  100  the next day, and as is clear from a comparison of  FIGS. 6B and 7B , the mounting position of the receiver  3  has shifted deeper into the ear canal  14 . At this point the volume inside the ear canal is smaller than that in  FIG. 6B  (conversely, the volume inside the ear canal increases if the receiver  3  is inserted more shallowly into the ear canal  14 ). This fluctuation in the volume inside the ear canal directly affects acoustic characteristics (frequency characteristics). As a result, the user experiences the discomfort of having hearing that is quite different from that during the fitting on the previous day, so the user feels less satisfied with his hearing. 
     If the user presses the mounting correction switch  9  twice within the specific period of time, the mounting correction switch  9  is switched on as in  FIG. 5  (it is reported by voice from the receiver  3  that the mounting correction switch  9  has been switched on and correction processing is being executed). When this happens, the sound reproduction processor  30  acquires correction-use sound data (such as data about sound with low temporal strength over a wide band of 0 to 16 KHz, such as white noise) from the correction-use sound data storage  20 . The sound reproduction processor  30  then transmits the correction-use sound data (an example of the “fourth sound data” pertaining to this embodiment, the spectrum X (ω) shown in  FIG. 7A ) to the transmission characteristic calculator  18  and outputs to the receiver  3  via the D/A converter  27  and the amplifier  24 . 
     As a result, correction-use sound is emitted from the receiver  3 , and this correction-use sound is collected by the ear canal microphone  10 . Third sound data (the spectrum Yu (ω) shown in  FIG. 7C ) produced by sound collection by the ear canal microphone  10  is supplied to the transmission characteristic calculator  18 . The transmission characteristic calculator  18  compares the third sound data (the spectrum Yu (ω) shown in  FIG. 7C ) produced by sound collection by the ear canal microphone  10 , with the correction-use sound data transmitted from the sound reproduction processor  30  (an example of the “fourth sound data” pertaining to this embodiment, the spectrum X (ω) shown in  FIG. 7A ), and calculates the in-usage transmission characteristic Gu (ω) on the basis of this comparison result. The transmission characteristic calculator  18  stores the in-usage transmission characteristic Gu (ω) thus calculated in the in-usage transmission characteristic storage  28 . The method for calculating the in-usage transmission characteristic Gu (ω) will be discussed below. 
     After this, the correction characteristic calculator  21  calculates a correction characteristic H (ω) from the in-usage transmission characteristic Gu (ω) stored in the in-usage transmission characteristic storage  28  and the at-fitting transmission characteristic Gf (ω) stored in the at-fitting transmission characteristic storage  19 , and stores this correction characteristic H (ω) in the correction characteristic storage  29 . The method for calculating the correction characteristic H (ω) will be discussed below. 
     Next, when the mounting correction switch  9  is pressed three times within the specific period of time, the mounting correction switch  9  is switched off as in  FIG. 4  (it is reported by voice from the receiver  3  that the mounting correction switch  9  has been switched off). At this point, as shown by the solid lines in  FIG. 4 , the external microphone  8 , the amplifiers  23  and  24 , the A/D converters  26  and  27 , the hearing aid processor  16 , the correction component  17 , and the receiver  3  operate, and the correction component  17  corrects the input sound data that has undergone hearing aid processing by the hearing aid processor  16 , on the basis of the correction characteristic H (ω) stored in the correction characteristic storage  29 . 
     Method for Calculating At-Fitting Transmission Characteristic Gf (ω) 
       FIG. 8  is a schematic diagram illustrating the method for calculating the at-fitting transmission characteristic Gf (ω) by the transmission characteristic calculator  18 . The at-fitting transmission characteristic Gf (ω) is calculated by dividing the first sound data (the spectrum Yf (ω) shown in  FIG. 6C ) produced when the ear canal microphone  10  collects the correction-use sound outputted from the receiver  3  during fitting, by the correction-use sound data from the correction-use sound data storage  20  (an example of the “second sound data” pertaining to this embodiment, the spectrum X (ω) shown in  FIG. 6A ). The at-fitting transmission characteristic Gf (ω) here is calculated, for example, on the basis of the following Calculation Formula 1 or 2.
 
 Gf (ω)= Yf (ω)/ X (ω)  (1)
 
 Gf (ω)=[Σ{ Yf (ω)/ X (ω)}]/ N   (2)
 
     Method for Calculating In-Usage Transmission Characteristic Gu (ω) 
       FIG. 9  is a schematic diagram illustrating the method for calculating the in-usage transmission characteristic Gu (ω) by the transmission characteristic calculator  18 . The in-usage transmission characteristic Gu (ω) is calculated by dividing the third sound data (the spectrum Yu (ω) shown in  FIG. 7C ) produced when the ear canal microphone  10  collects the correction-use sound outputted from the receiver  3  when the user presses the mounting correction switch  9  twice within the specific period of time, by the correction-use sound data from the correction-use sound data storage  20  (an example of the “fourth sound data” pertaining to this embodiment, the spectrum X (ω) shown in  FIG. 7A ). The in-usage transmission characteristic Gu (ω) here is calculated, for example, on the basis of the following Calculation Formula 3 or 4.
 
 Gu (ω)= Yu (ω)/ X (ω)  (3)
 
 Gu (ω)=[Σ{ Yu (ω)/ X (ω)}]/ N   (4)
 
     Method for Calculating Correction Characteristic H (ω) 
       FIG. 10  is a schematic diagram illustrating the method for calculating the correction characteristic H (ω) by the correction characteristic calculator  21 . The correction characteristic H (ω) is calculated by dividing the at-fitting transmission characteristic Gf (ω) in  FIG. 8  by the in-usage transmission characteristic Gu (ω) in  FIG. 9 . This correction characteristic H (ω) is calculated, for example, on the basis of the following Calculation Formula 5, etc.
 
 H (ω)= Gf (ω)/ Gu (ω)  (5)
 
     The correction characteristic H (ω) in  FIG. 10  obtained in this manner is stored in the correction characteristic storage  29 , and the correction characteristic H (ω) stored in the correction characteristic storage  29  is supplied to the correction component  17 . The correction component  17  then corrects the output from the hearing aid processor  16  on the basis of the correction characteristic H (ω). 
     Action and Effect 
     With the hearing aid  100  pertaining to the first embodiment, the control device  4  comprises the transmission characteristic calculator  18 , the correction characteristic calculator  21 , and the correction component  17 . The transmission characteristic calculator  18  calculates the at-fitting transmission characteristic Gf (ω) on the basis of the first sound data (the spectrum Yf (ω) shown in  FIG. 6C ) produced when the ear canal microphone  10  collects the correction-use sound outputted from the receiver  3  (an example of a correction-use sound output component) during fitting, and the correction-use sound data (an example of the “second sound data” pertaining to this embodiment, the spectrum X (ω) shown in  FIG. 6A ). The transmission characteristic calculator  18  calculates the correction characteristic G (ω) on the basis of the third sound data (the spectrum Yu (ω) shown in  FIG. 7C ) produced when the ear canal microphone  10  collects the correction-use sound outputted from the receiver  3  according to a user operation after fitting, and the correction-use sound data (an example of the “fourth sound data” pertaining to this embodiment, the spectrum X (ω) shown in  FIG. 7A ). The correction characteristic calculator  21  calculates the correction characteristic H (ω) on the basis of the at-fitting transmission characteristic Gf (ω) and the in-usage transmission characteristic Gu (ω). The correction component  17  corrects the input sound data that has undergone hearing aid processing by the hearing aid processor  16 , on the basis of the correction characteristic H (ω). 
     Thus, the correction component  17  corrects the input sound data that has undergone hearing aid processing, on the basis of the correction characteristic H (ω), which was calculated on the basis of the in-usage transmission characteristic Gu (ω) calculated according to a user request and the at-fitting transmission characteristic Gf (ω) already acquired at the time of fitting. Therefore, even if the volume inside the ear canal should fluctuate due to minute deviation in the mounting position of the hearing aid  100  from that during fitting, the input sound data that has undergone hearing aid processing will be corrected according to this fluctuation in the volume inside the ear canal. Accordingly, there will be less fluctuation in the acoustic characteristics (frequency characteristics) accompanying deviation in the mounting position of the hearing aid  100 , so the user can be more satisfied with his hearing. 
     Second Embodiment 
     Configuration of Hearing Aid  100 A 
       FIG. 11  shows a hearing aid  100 A pertaining to the second embodiment. As shown in  FIG. 11 , the hearing aid  100 A differs from the hearing aid  100  pertaining to the first embodiment above in that it comprises a correction sound-use speaker  31  (an example of a “correction-use sound output component”) provided to the surface of the main body case  1 . 
     Control Device  4 A 
       FIGS. 12 and 13  are electrical control block diagrams for the control device  4 A pertaining to the second embodiment. In  FIGS. 12 and 13 , components that are operating are linked by solid lines, and components that are not operating are linked by broken lines. 
     The control device  4 A differs from the control device  4  pertaining to the first embodiment above in that a sound reproduction processor  30 A is connected to the correction sound-use speaker  31 . The sound reproduction processor  30 A is connected to the correction sound-use speaker  31  via a D/A converter  32  and an amplifier  33 . 
       FIGS. 14A ,  14 B, and  14 C show the state of the hearing aid  100 A during fitting. At this point, the hearing aid is placed on the ear (more specifically, the auricle)  15 , and the hearing aid function is set by an ordinary fitting procedure, namely, one in which audible frequency bands are successively outputted from lower sounds to higher sounds to check how well the user can hear those sounds. The fitting information determined by this fitting procedure is registered in the hearing aid processor  16  in  FIG. 12 . Immediately after this fitting, the mounting correction switch  9  is turned on by the user (see  FIG. 13 ). 
     The operation of the control device  4 A is switched depending on how many times the mounting correction switch  9  is pressed within the specific period of time. If the mounting correction switch  9  is pressed once within the specific period of time, the operation of the control device  4 A is switched to an operation in which the at-fitting transmission characteristic is stored in the at-fitting transmission characteristic storage  19 . When this happens, the mounting correction switch  9  is switched on, and a voice reports that “The at-fitting transmission characteristic has been stored.” Once the at-fitting transmission characteristic has thus been stored, the sound reproduction processor  30 A acquires correction-use sound data (such as data about sound with low temporal strength over a wide band of 0 to 16 KHz, such as white noise) from the correction-use sound data storage  20 . The sound reproduction processor  30 A then outputs the correction-use sound data to the correction sound-use speaker  31  via the D/A converter  32  and the amplifier  33 . As a result, correction-use sound is emitted from the correction sound-use speaker  31 , and then the sound from the correction sound-use speaker  31  is collected by the external microphone  8  and the ear canal microphone  10 . 
     As shown in  FIG. 13 , the first sound data (the spectrum Yf (ω) shown in  FIG. 14C ) produced when the correction-use sound is collected by the ear canal microphone  10 , and the second sound data produced when the correction-use sound is collected by the external microphone  8  (an example of the “second sound data” pertaining to this embodiment, the spectrum X (ω) shown in  FIG. 14A ) is supplied to the transmission characteristic calculator  18 . 
     The transmission characteristic calculator  18  compares the first sound data (the spectrum Yf (ω) shown in  FIG. 14C ) with the second sound data (the spectrum X (ω) shown in  FIG. 14A ), and calculates the at-fitting transmission characteristic Gf (ω) on the basis of this comparison result. The transmission characteristic calculator  18  stores the at-fitting transmission characteristic Gf (ω) in the at-fitting transmission characteristic storage  19 . The method for calculating the at-fitting transmission characteristic Gf (ω) will be discussed below. 
     When the at-fitting transmission characteristic Gf (ω) is calculated, the transmission characteristic calculator  18  is selectively connected not to the in-usage transmission characteristics storage  28  (discussed below), but to the at-fitting transmission characteristic storage  19 . 
     In the first embodiment above, the correction-use sound data itself was used as an example of the “second sound data,” but in the second embodiment, an example will be described in which the “second sound data” is data indicating correction-use sound collected by the external microphone  8  during fitting. 
     Next, when the mounting correction switch  9  is pressed three times within the specific period of time, the mounting correction switch  9  is switched off as in  FIG. 13  (it is reported by voice from the receiver  3  that the mounting correction switch  9  has been switched off), and the hearing aid is used in that state for that day. That is, only the external microphone  8 , the amplifiers  23  and  24 , the A/D converter  26 , the D/A converter  27 , the hearing aid processor  16 , the correction component  17 , and the receiver  3  operate, and ordinary hearing aid operation is carried out, specifically, the hearing aid operation related to the fitting information registered to the hearing aid processor  16 . At this point, since no output from the correction characteristic calculator  21  is supplied to the correction characteristic storage  29 , the correction component  17  does not perform a correction operation, and the signal is merely passed through. 
       FIGS. 15A ,  15 B, and  15 C show a state in which the user has put on the hearing aid  100 A the next day, and as is clear from a comparison of  FIGS. 14B and 15B , the mounting position of the receiver  3  has shifted deeper into the ear canal  14 . At this point the volume inside the ear canal is smaller than that in  FIG. 14B  (conversely, the volume inside the ear canal increases if the receiver  3  is inserted more shallowly into the ear canal  14 ). This fluctuation in the volume inside the ear canal directly affects acoustic characteristics (frequency characteristics). As a result, the user experiences the discomfort of having hearing that is quite different from that during the fitting on the previous day, so the user feels less satisfied with his hearing. 
     If the user presses the mounting correction switch  9  twice within the specific period of time, the mounting correction switch  9  is switched on as in  FIG. 13  (it is reported by voice from the receiver  3  that the mounting correction switch  9  has been switched on and correction processing is being executed). When this happens, the sound reproduction processor  30 A acquires correction-use sound data (such as data about sound with low temporal strength over a wide band of 0 to 16 KHz, such as white noise) from the correction-use sound data storage  20 . The sound reproduction processor  30 A then outputs the correction-use sound data to the correction sound-use speaker  31  via the D/A converter  27  and the amplifier  24 . 
     As a result, correction-use sound is emitted from the correction sound-use speaker  31 , and this correction-use sound is collected by the ear canal microphone  10  and the external microphone  8 . Third sound data (the spectrum Yu (ω) shown in  FIG. 15C ) produced by sound collection by the ear canal microphone  10 , and fourth sound data (the spectrum X (ω) shown in  FIG. 15A ) produced by sound collection by the external microphone  8  are supplied to the transmission characteristic calculator  18 . The transmission characteristic calculator  18  compares the third sound data (the spectrum Yu (ω) shown in  FIG. 15C ) with the fourth sound data (the spectrum X (ω) shown in  FIG. 15A ), and calculates the in-usage transmission characteristic Gu (ω) on the basis of this comparison result. The transmission characteristic calculator  18  stores the in-usage transmission characteristic Gu (ω) thus calculated in the in-usage transmission characteristic storage  28 . The method for calculating the in-usage transmission characteristic Gu (ω) will be discussed below. 
     When the in-usage transmission characteristic Gu (ω) is calculated, the transmission characteristic calculator  18  is selectively connected not to the at-fitting transmission characteristic storage  19 , but to the in-usage transmission characteristics storage  28 . 
     In the first embodiment above, the correction-use sound data itself was used as an example of the “fourth sound data,” but in the second embodiment, an example will be described in which the correction sound-use speaker  31  outputs according to user operation, and the “fourth sound data” is data indicating correction-use sound collected by the external microphone  8 . 
     After this, the correction characteristic calculator  21  calculates a correction characteristic H (ω) from the in-usage transmission characteristic Gu (ω) stored in the in-usage transmission characteristic storage  28  and the at-fitting transmission characteristic Gf (ω) stored in the at-fitting transmission characteristic storage  19 , and stores this correction characteristic H (ω) in the correction characteristic storage  29 . The method for calculating the correction characteristic H (ω) will be discussed below. 
     Next, when the mounting correction switch  9  is pressed three times within the specific period of time, the mounting correction switch  9  is switched off as in  FIG. 12  (it is reported by voice from the receiver  3  that the mounting correction switch  9  has been switched off). At this point, as shown by the solid lines in  FIG. 12 , the external microphone  8 , the amplifiers  23  and  24 , the A/D converters  26  and  27 , the hearing aid processor  16 , the correction component  17 , and the receiver  3  operate, and the correction component  17  corrects the input sound data that has undergone hearing aid processing by the hearing aid processor  16 , on the basis of the correction characteristic H (ω) stored in the correction characteristic storage  29 . 
     Method for Calculating At-Fitting Transmission Characteristic Gf (ω) 
       FIG. 16  is a schematic diagram illustrating the method for calculating the at-fitting transmission characteristic Gf (ω) by the transmission characteristic calculator  18 . The at-fitting transmission characteristic Gf (ω) is calculated by dividing the first sound data (the spectrum Yf (ω) shown in  FIG. 14C ) produced when the ear canal microphone  10  collects the correction-use sound outputted from the correction sound-use speaker  31  during fitting, by the second sound data (the spectrum X (ω) shown in  FIG. 14A ) produced when correction-use sound is collected by the external microphone  8 . The at-fitting transmission characteristic Gf (ω) here is calculated, for example, on the basis of the following Calculation Formula 6 or 7.
 
 Gf (ω)= Yf (ω)/ X (ω)  (6)
 
 Gf (ω)=[Σ{ Yf (ω)/ X (ω)}]/ N   (7)
 
     Method for Calculating In-Usage Transmission Characteristic Gu (ω) 
       FIG. 17  is a schematic diagram illustrating the method for calculating the in-usage transmission characteristic Gu (ω) by the transmission characteristic calculator  18 . The in-usage transmission characteristic Gu (ω) is calculated by dividing the third sound data (the spectrum Yu (ω) shown in  FIG. 15C ) produced when the ear canal microphone  10  collects the correction-use sound outputted from the receiver  3  when the user presses the mounting correction switch  9  twice within the specific period of time, by the fourth sound data (the spectrum X (ω) shown in  FIG. 15A ) produced when the correction-use sound is collected by the external microphone  8 . The in-usage transmission characteristic Gu (ω) here is calculated, for example, on the basis of the following Calculation Formula 8 or 9.
 
 Gu (ω)= Yu (ω)/ X (ω)  (8)
 
 Gu (ω)=[Σ{ Yu (ω)/ X (ω)}]/ N   (9)
 
     Method for Calculating Correction Characteristic H (ω) 
       FIG. 18  is a schematic diagram illustrating the method for calculating the correction characteristic H (ω) by the correction characteristic calculator  21 . The correction characteristic H (ω) is calculated by dividing the at-fitting transmission characteristic Gf (ω) in  FIG. 16  by the in-usage transmission characteristic Gu (ω) in  FIG. 17 . This correction characteristic H (ω) is calculated, for example, on the basis of the following Calculation Formula 10, etc.
 
 H (ω)= Gf (ω)/ Gu (ω)  (10)
 
     The correction characteristic H (ω) in  FIG. 18  obtained in this manner is stored in the correction characteristic storage  29 , and the correction characteristic H (ω) stored in the correction characteristic storage  29  is supplied to the correction component  17 . The correction component  17  then corrects the output from the hearing aid processor  16  on the basis of the correction characteristic H (ω). 
     Action and Effect 
     With the hearing aid  100 A pertaining to the second embodiment, the control device  4 A comprises the transmission characteristic calculator  18 , the correction characteristic calculator  21 , and the correction component  17 . The transmission characteristic calculator  18  calculates the at-fitting transmission characteristic Gf (ω) on the basis of the first sound data (the spectrum Yf (ω) shown in  FIG. 14C ) produced when the ear canal microphone  10  collects the correction-use sound outputted from the correction sound-use speaker  31  (an example of a “correction-use sound output component”) during fitting, and the second sound data (the spectrum X (ω) shown in  FIG. 14A ) produced by collection by the external microphone  8 . The transmission characteristic calculator  18  calculates the in-usage transmission characteristic Gu (ω) on the basis of third sound data produced when the ear canal microphone  10  collects the correction-use sound outputted from the correction sound-use speaker  31  according to user operation after fitting, and fourth sound data (the spectrum X (ω) shown in  FIG. 15A ) produced by collection by the external microphone  8 . The correction characteristic calculator  21  calculates the correction characteristic H (ω) on the basis of the at-fitting transmission characteristic Gf (ω) and the in-usage transmission characteristic Gu (ω). The correction component  17  corrects the input sound data that has undergone hearing aid processing by the hearing aid processor  16 , on the basis of the correction characteristic H (ω). 
     Thus, the correction component  17  corrects the input sound data that has undergone hearing aid processing, on the basis of the correction characteristic H (ω), which was calculated on the basis of the in-usage transmission characteristic Gu (ω) calculated according to a user request and the at-fitting transmission characteristic Gf (ω) already acquired at the time of fitting. Therefore, even if the volume inside the ear canal should fluctuate due to minute deviation in the mounting position of the hearing aid  100 A from that during fitting, the input sound data that has undergone hearing aid processing will be corrected according to this fluctuation in the volume inside the ear canal. Accordingly, there will be less fluctuation in the acoustic characteristics (frequency characteristics) accompanying deviation in the mounting position of the hearing aid  100 A, so the user can be more satisfied with his hearing. 
     Other Embodiments 
     (A) In the above embodiments, the correction characteristic calculator  21  calculated the correction characteristic H (ω) from the in-usage transmission characteristic Gu (ω) stored in the in-usage transmission characteristics storage  28  and the at-fitting transmission characteristic Gf (ω) stored in the correction-use sound data storage  20 . However, since the in-usage transmission characteristic Gu (ω) is outputted from the transmission characteristic calculator  18 , the correction characteristic H (ω) may be calculated from the output of the transmission characteristic calculator  18  as the in-usage transmission characteristic Gu (ω) and the at-fitting transmission characteristic stored in the at-fitting transmission characteristic storage  19 . 
     (B) Although not specifically mentioned in the second embodiment above, as shown in  FIG. 19 , the hearing aid  100  may comprise an ear plug  34  in which the receiver  3  and the ear canal microphone  10  are embedded, and a through-hole T that is formed in the ear plug  34  and communicates between the inside of the ear canal  14  and the outside of the ear canal  14 . In this case, the correction-use sound emitted from the correction sound-use speaker  31  is guided through the through-hole T into the ear canal  14 . Therefore, the correction-use sound emitted from the correction sound-use speaker  31  can be accurately reflected in the first sound data (the spectrum Yf (ω) shown in  FIG. 14C ) and the third sound data (the spectrum Yu (ω) shown in  FIG. 15C ). Furthermore, providing the through-hole T reduces the sensation of sound being trapped inside the ear canal  14 , and therefore further improves the user&#39;s hearing. 
     (C) In the second embodiment above, the second sound data (the spectrum X (ω) shown in  FIG. 14A ) and the fourth sound data (the spectrum X (ω) shown in  FIG. 15A ) were produced by collection of sound at the external microphone  8 , but this is not the only option. The correction-use sound data stored in the correction-use sound data storage  20  can be used as the second sound data and/or the fourth sound data. 
     INDUSTRIAL APPLICABILITY 
     With the present invention, after the user puts the hearing aid on an ear, if the user operates a mounting correction switch upon sensing something unsatisfactory, the feeling that there is something wrong with the user&#39;s hearing caused by a minute difference in how the hearing aid is mounted will be eliminated, and this improves the user&#39;s sense of satisfaction with his hearing. Accordingly, the present invention is expected to find wide application as a hearing aid. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  main body case 
               2  ear hook 
               3  receiver 
               4  control device 
               5  battery 
               6  power switch 
               7  volume control 
               8  external microphone 
               9  mounting correction switch 
               10  ear canal microphone 
               11  mounting piece 
               12 ,  13  acoustic tube 
               14  ear canal 
               15  ear (auricle) 
               16  hearing aid processor 
               17  correction component 
               18  transmission characteristic calculator 
               19  at-fitting transmission characteristic storage 
               20  correction-use sound data storage 
               21  correction characteristic calculator 
               22 ,  23 ,  24  amplifier 
               25 ,  26  A/D converter 
               27  D/A converter 
               28  in-usage transmission characteristics storage 
               29  correction characteristic storage 
               30  sound reproduction processor 
               31  correction sound-use speaker 
               32  D/A converter 
               33  amplifier 
               34  ear plug 
             T through-hole