Abstract:
A hearing aid stores a plurality of sets of hearing aid parameters in built-in memories, and tailors suitable hearing aid parameters through an interpolation between the sets of hearing aid parameters so as to cope with new working conditions, thereby allowing a user to adjust the hearing aid to his hearing sense.

Description:
FIELD OF THE INVENTION 
     This invention relates to a hearing aid and, more particularly, to a hearing aid for controlling hearing sense compensation with suitable parameters internally tailored. 
     DESCRIPTION OF THE RELATED ART 
     A provider usually regulates device characteristics of a conventional analog hearing aid to a user before delivery to the user. The regulation is called as &#34;fitting&#34;. First, the provider measures the hearing sense of the user, and represents the measured hearing sense by an audiogram. Then, the provider fits the device characteristics to the audiogram, and delivers the analog hearing aid to the user. 
     A hearing aid digitally processes a signal representative of an input sound wave, and the digital signal processing unit is provided between an analog-to-digital converter and a digital-to-analog converter. Such a digitally signal processing hearing aid is called as &#34;digitally programmable hearing aid&#34;, and the provider also fits the device characteristics of the digitally programmable hearing aid to the hearing sense of a user through the fitting work. 
     If a time variant filter is incorporated in the digital signal processing unit, the provider further gives parameters for defining the filtering characteristics to the digitally programmable hearing aid through the fitting work. The parameters for the time variant filter is hereinbelow referred to &#34;hearing aid parameters&#34;. 
     Japanese Patent Publication of Unexamined Application No. 3-284000 discloses the digitally programmable hearing aid with the time variant filter. In this instance, the time variant filter is implemented by a frequency sampling structure type filter circuit, and the frequency sampling structure type filter circuit is responsive to an input signal for varying the filtering characteristics on the basis of the hearing aid characteristics given through the fitting work. However, the parameters given through the fitting work are so many and hardly imaged. For this reason, it is difficult for a user to carry out a fine control on the digitally programmable hearing aid. 
     Japanese Patent Publication of Unexamined Application No. 4-242400 discloses a volume controller for a hearing aid. The volume controller automatically regulates the volume to the fitting level of a user. However, if the user is getting more difficult in hearing, it is necessary to measure the hearing sense so as to fit the hearing aid to the user again. 
     Although the digitally programmable hearing aid disclosed in Japanese Patent Publication of Unexamined Application No. 3-284000 changes the filtering characteristics with the input signal level, the hearing aid parameters are unchanged, and the digitally programmable hearing aid can not cope with progression of hardness of hearing. The fitting work is required again. 
     The hearing aid equipped with the volume controller disclosed in Japanese Patent Publication of Unexamined Application No. 4-242400 automatically changes the volume. However, the loudness is merely one of the hearing characteristics, and other hearing characteristics relate to the hardness of hearing. Therefore, it is impossible to cope with the hardness of hearing, and the fitting work is required again. 
     SUMMARY OF THE INVENTION 
     It is therefore an important object of the present invention to provide a hearing aid the device characteristics of which is easily changeable. 
     To accomplish the object, the present invention proposes to internally produce suitable hearing aid parameters from sets of hearing aid parameters stored in a memory unit. 
     In accordance with the present invention, there is provided a hearing aid comprising: an acoustic signal-to-electric signal converting means for converting a first sound to a first electric signal; an electric signal-to-acoustic signal converting means for converting a second acoustic signal to a second sound; a signal modifying means connected between the acoustic signal-to-electric signal converting means and the electric signal-to-acoustic signal converting means, and responsive to a third electric signal representative of hearing aid parameters so as to modify the first electric signal to the second electric signal; a memory means including a plurality of memory sub-means for respectively storing a plurality of pieces of hearing aid data information in a readable manner; a working condition modifying means responsive to an instruction for working conditions for producing a fourth electric signal representative of a ratio of interpolation; and a parameter generating means responsive to the fourth electric signal so as to produce the third electric signal from pieces of hearing aid data information selected from the plurality of pieces of hearing aid data information through an interpolation at the ratio represented by the fourth electric signal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and advantages of the hearing aid according to the present invention will be more clearly understood from the following description taken in conjunction with the accompanying drawing in which FIGURE is a block diagram showing the arrangement of a hearing aid according to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the FIGURE, a hearing aid embodying the present invention is designated by reference numeral 1. The hearing aid comprises a microphone 2, an earphone 3, a digital signal processing unit 4, an analog-to-digital converter 5 connected between the microphone 2 and the digital signal processing unit 4, a digital-to-analog converter 6 connected between the digital signal processing unit 4 and the earphone 3, a memory unit 7 associated with the digital signal processing unit 4 and a manipulating board 8. 
     The microphone 2 picks up voice and/or sound, and generates an analog sound signal AS1 representative of the voice and/or sound. The analog sound signal AS1 is supplied to the analog-to-digital converter 5, and is converted to digital sound signal DS1 equivalent thereto. The digital sound signal DS1 is supplied to the digital signal processing unit 4, and the digital signal processing unit 4 processes the pieces of sound information represented by the digital sound signal. The digital signal processing unit 4 modifies attributes of the voice and/or sound as will be described hereinlater in detail, and generates a digital sound signal DS2 representative of the modified voice and/or sound. The digital sound signal DS2 is supplied to the digital-to-analog converter 6, and is converted to an analog sound signal equivalent thereto. The analog sound signal AS2 is supplied to the earphone 3, and the modified voice and/or sound is reproduced from the earphone 3. 
     The digital signal processing unit 4 includes a signal modifier 4a, an amplifier 4b and a controller 4c. A data signal DT1 represents suitable hearing characteristics or suitable hearing aid parameters, and is supplied to the controller 4c. When the data signal DT1 representative of the suitable hearing characteristics is supplied to the controller 4c, the controller 4c produces the hearing aid parameters from the suitable hearing characteristics, and forms a control signal CTL1 representative of the hearing aid parameters. On the other hand, when the data signal DT1 is representative of the suitable hearing aid parameters, the controller 4c directly forms the control signal CTL1 representative of the suitable hearing aid parameters. 
     The control signal CTL1 is supplied from the controller 4c to the signal modifier 4a, and the signal modifier 4a is responsive to the control signal CTL1 for processing the digital sound signal DS1. The signal modifier 4a supplies a digital sound signal DS3 to the amplifier 4b, and the amplifier 4b produces the digital sound signal DS2 from the digital sound signal DS3 through an amplification. 
     The digital signal processing unit 4 further includes an instructor 4d, an interpolator 4e and a controller 4f. The instructor 4d is connected to the manipulating board 8, and supplies instruction signals INS1 and INS2 to the interpolator 4e and the controller 4f, respectively. Various switches (not shown) are provided on the manipulating board 8. A user communicates with the instructor 4d through the switches, and informs the instructor 4d of user&#39;s requests. 
     One of the switches is assigned a selection of operation mode. The hearing aid 1 has a plurality of hearing aid modes for compensating the hearing sense of a user. The hearing aid 1 compensates the hearing sense at home through one of the hearing aid modes, on a street through another hearing aid mode and at night through yet another hearing aid mode. In order to compensate the hearing sense in different environments, the hearing aid stores a plurality of program sequences, and the voice and/or sound is differently processed by the digital signal processing unit 4 depending upon the selected mode. Another switch is used for changing working conditions such as, for example, user&#39;s hearing sense. 
     When the user requests the instructor 4d to change the operation mode, the instructor 4d supplies the instruction signal INS2 representative of the operation mode to be requested to the controller 4f. On the other hand, when the user changes the working conditions, the instructor 4d determines a ratio of interpolation, and supplies the instruction signal INS1 representative of the new ratio of interpolation to the interpolator 4e. 
     The memory unit 7 has a plurality of memory sub-units 70, 71, . . . and 7n, and the plurality of memory sub-units 70 to 7n respectively store a plurality of sets of hearing aid data representative of hearing aid characteristics or hearing aid parameters. The memory unit 7 further stores the control data defining the function of the hearing aid 7. The plurality of sets of hearing aid data and the control data are addressable, and are read out from the memory unit 7 to the interpolator 4e. 
     The interpolator 4e tailors suitable hearing aid parameters or suitable hearing aid characteristics from the hearing aid data stored in the memory unit 7. Namely, the interpolator 4e determines the suitable hearing aid characteristics or the suitable hearing aid parameters through an interpolation between the sets of hearing aid characteristics or the sets of hearing aid parameters at the ratio represented by the instruction signal INS1, and produces the data signal DT1 representative of the suitable hearing aid characteristics or the suitable hearing aid parameters. 
     The interpolator 4e is further operative to transfer the control data to the controller 4f. When the control data is read out from the memory unit 7 to the interpolator 4e, the interpolator 4e produces a data signal DT2 representative of the control data, and supplies the data signal DT2 to the controller 4f. The controller 4f supplies control signals CTL2 to CTLx to the signal modifier 4a, the controller 4c, the instructor 4d, the interpolator 4e and the memory unit 7. 
     The hearing aid 1 behaves as follows. Assuming now that a user wants to modify the working conditions, the user manipulates the switch, and the instructor 4d determines the ratio of interpolation on the basis of new working conditions. The instructor 4d further supplies the instruction signal INS2 representative of the change of working conditions, and the memory unit 7, the interpolator 4e and the controller 4c behave under the control of the controller 4f as follows. 
     Sets of hearing aid characteristics or sets of hearing aid parameters are read out from the selected memory sub-units to the interpolator 4e. The interpolator 4e produces suitable hearing aid characteristics or suitable hearing aid parameters from the sets of hearing aid characteristics or the sets of hearing aid parameters read out from the memory unit 7 through an interpolation at the ratio represented by the instruction signal INS1. The interpolator 4e supplies the data signal DT1 representative of the suitable hearing aid characteristics or the suitable hearing aid parameters to the controller 4c. If the data signal DT1 represents the suitable hearing aid characteristics, the controller 4c determines hearing aid parameters, and supplies the control signal CTL1 representative of the hearing aid parameters to the signal modifier 4a. On the other hand, if the data signal DT1 is representative of the suitable hearing aid parameters, the controller 4c produces the control signal CTL1 representative of the suitable hearing aid parameters, and supplies it to the signal modifier 4a. 
     Thus, a user easily modifies the device characteristics of the hearing aid 1 through the ratio of interpolation by changing the working conditions. The change of working conditions may be carried out as follows. Using a timer (not shown), the hearing aid 1 is linearly changed from a set of hearing aid characteristics to another set of hearing aid characteristics with time, and determines the amount of change in the day time. The amount of change is slightly given back in the night time. Using the present hearing aid characteristics, an extrapolation may be carried out so as to cope with a progression of hardness of hearing. 
     If the user does not change the working conditions, a set of hearing aid characteristics or a set of hearing aid parameters at the latest fitting is supplied to the controller 4c without an interpolation. 
     When the suitable hearing aid parameters are supplied to the signal modifier 4a, the hearing aid 1 appropriately compensates the hearing sense of the user. Sounds 1 is converted to the analog sound signal AS1, and the analog-to-digital converter 5 supplies the digital sound signal DS1 representative of the sounds SD1 to the signal modifier 4a. The suitable hearing aid parameters determines the circuit characteristics of the signal modifier 4a, and the digital sound signal DS1 is changed to the digital sound signal DS3 slightly different from the digital sound signal DS1. The amplifier 4b amplifies the digital sound signal DS3, and supplies the digital sound signal DS2 to the digital-to-analog converter 6. The digital-to-analog converter 6 converts the digital sound signal DS2 to the analog sound signal AS2, and the analog sound signal AS2 causes the earphone to reproduce sounds SD2 slightly modified from the sounds SD1. 
     In this instance, the acoustic signal-to-electric signal converting means and the electric signal-to-acoustic signal converting means are implemented by the microphone 2 and the earphone 3, respectively. The analog-to-digital converter 5, the signal modifier 4a, the amplifier 4b and the digital-to-analog converter 6 as a whole constitute the signal modifying means, and the manipulating board 8, the instructor 4d, the controller 4f form in combination the working condition modifying means. The controller 4c and the interpolator as a whole constitute the parameter generating means, respectively. 
     As will be appreciated from the foregoing description, the hearing aid according to the present invention tailors suitable hearing aid parameters on the basis of the plurality of pieces of hearing aid data information corresponding to the heading aid data, and a user easily carries out a fine control to the hearing aid. 
     Although a particular embodiment of the present invention has been shown and described, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention. 
     For example, the hearing aid data may be supplied from a fitting system through an electric signal to a data port connected to the memory unit.