Abstract:
A hearing optimization device and hearing optimization method having a high boost frequency characteristic reference live for high frequency range enhancement and a low boost frequency characteristic reference live for low frequency range enhancement to achieve separate gain control of input audio signal according to frequency. An audio signal processing and generating means is also included, along with synthesized audio signal output structure.

Description:
FIELD OF THE INVENTION 
     The present invention relates to hearing optimization device and hearing optimization method, which are hearing optimization technologies adjustable to hearing characteristic of an individual and his/her hearing situation (including sound environment such as noises), the technologies being designed to be adjustable to hearing of the individual who may be a person with impaired hearing or one with normal hearing, whereby he/she can enjoy clear, comfortable and smooth conversation (including telephone conversation) in any kind of situation. 
     BACKGROUND OF THE INVENTION 
     A various conventional hearing aids, designed for hearing impaired persons, have been proposed. However, hearing differs greatly between individuals, and also it is affected from time to time by other factors such as physical condition of a user and his/her sound environment. 
     Solutions have been addressed to aid hearing impairment in such a way that hearing characteristic of an individual hearing impaired user is measured at specific frequency ranges using an audiometer or the like for example, the result being used to calculate preferable correction and output characteristic for a hearing aid, so that the hearing impaired user can select a hearing aid which provides preferable characteristic (by controlling output for specific frequency ranges) to him/her, or he/she can adjust characteristic on the hearing aid. However, such methods have their own limits because of the difficulty to measure hearing impairment condition or such precisely by using a measuring instrument. 
     For example, in Japanese published unexamined application No. 2000-165483, because of the possible audible difficulty for a hearing impaired user, a digital phone adjusts its audio output comprising steps including: a step wherein a user parameter, which represents haring spectrum of an individual user, is obtained; a step wherein digital input signal, which represents information heard by a user, is received; a step wherein, in order to generate hearing-adjusted digital signal, digital input signal is adjusted according to the user parameter; and a step wherein analog output signal is generated based on the hearing-adjusted digital signal. However, a special place and highly complicated processes are required in order to obtain hearing characteristic of impaired persons. 
     Moreover, individual hearing impaired persons would go to various places in their daily lives, which situation requires correction adjustment over output characteristic of a hearing aid, corresponding to sound environment of the place where the user is in, because hearing characteristic is subject to the present sound environment. However, the fact is that there was no such device which can be easily adjusted to the aforementioned situation. 
     Also, hearing is affected by physical condition of an individual and so on, so that correction over the similar output characteristic to that of the last time may not necessarily work out the best even if the sound environment is the same as before. 
     Further issue is that hearing is of human aesthesia, so that it is only understood by a hearer and difficult to explain verbally to other people including doctors and specialists. However, in order to measure the hearer&#39;s hearing characteristic, his/her personal perception, which cannot be shared with anyone else, needs to be taken out, which is very difficult to do. 
     An ideal but not realistic solution is a hearing aid being provided with an equalizer, which can adjust input audio corresponding to each user, place, and time, for each user to adjust at the place and time of use of the device. Very possibly this issue would also suffer persons with normal hearing that in noisy environment voice of other people as well as other sounds are hard to hear, resulting in unsmooth conversation, including telephone conversation. 
     Also one of other demands, in audio field including music listening for example, is for preferable acoustic characteristic which can be adjusted by means of adjusting frequency continuously over various frequency ranges of sound source, corresponding to hearing characteristic of an individual, a place or other factors. 
     Patent Document 1: Japanese published unexamined application No. 2000-165483 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     There has been a demand for hearing optimization device and method which can be adjusted easily by an individual user corresponding to his/her hearing characteristic of the day, his/her sound environment, and so on. Conventional hearing aids for hearing impaired persons are designed to measure hearing characteristic by using a special measuring device or the like, to adjust output characteristic suited for the hearer. However, as aforementioned, hearing of an individual is not only being accurately understood by the hearer alone but also differs according to his/her physical condition and the place he/she is in. Therefore, conventional technologies have not necessarily been satisfactory. 
     Likewise, even persons with normal hearing have sometimes suffered from insufficient voice output of a person on the other side of a mobile phone, or the like, which is used in various outdoor situations, of which usability can be greatly improved if optimized voice output can be heard according to factors such as the place where it is used. Specifically, in noisy environment such as airport or railway station, by easy adjustment to hearing characteristic of the mobile phone user in accordance with his/her sound environment, conversation over mobile phone can be easy in a bad sound environment. 
     Particularly, hearing (how a sound is heard) is a perceptive matter, and is neither easy to explain verbally to other people nor measurable without limitation by an equipment, therefore a hearer needs some kind of means he can easily adjust. Such an adjustable means is what easily adjusts a difference between individuals and/or sound environments. 
     Moreover, for audio equipment and the like, if there is a continuous adjustment mechanism, more corresponding adjustment to human hearing than before becomes available. 
     Means of Solving the Problems 
     The present invention, in view of the aforementioned conventional drawbacks, provides hearing optimization device and hearing optimization method such as hearing aid and mobile phone, wherein optimization and correction can be easily done corresponding to hearing of each high frequency range and low frequency range without changing output loudness (perceptive sound volume) of audio signal, and further wherein being combined with a user-adjustable technology whereby a hearer can adjust by him/herself while hearing or listening. 
     In order to solve the aforementioned issues, the inventors of this present invention have adopted the following means after keen examination. That is, in order for separate gain control of input audio signal according to frequency, the present invention is preliminarily provided with a high boost (high frequency boosting) frequency characteristic reference line (DEFINITION: reference line according to which increase and decrease amount of gain of the original audio signal according to frequency range is determined) for high frequency range enhancement and a low boost (low frequency boosting) frequency characteristic reference line for low frequency range enhancement. 
     The present invention is also provided with an audio signal processing and generating means (DEFINITION: means by which, a single frequency is dual distributed, one for high frequency enhancement and the other for low frequency enhancement, each of which references its corresponding frequency characteristic reference line, and generates the original audio signals), whereby the input audio signal is dual distributed, and the two audio signal processings are carried out for the high boost (high frequency boosting) audio signal to enhance a high frequency range according to the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) audio signal to enhance a low frequency range according to the low boost (low frequency boosting) frequency characteristic reference line. 
     The present invention is further provided with: the synthesized audio signal output means, wherein the two input audio signals are generated by the audio signal processing and generating means to be used as an audio signal output; and a synchronous adjustment means for the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line to synchronously adjust the two characteristic reference lines—namely the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line—by a pair of adjustment means. The high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference lines are crossed at a memorized frequency. 
     Synchronous enhancement is carried out by changing inclinations of the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line, the crossing point being a rotation center. A memorized crossing frequency range for the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line is between 500 Hz and 2 kHz. 
     As aforementioned, the adjustment means, which synchronously adjusts the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line with each other, adjusts said high boost (high frequency boosting) frequency characteristic reference line and said low boost (low frequency boosting) frequency characteristic reference line in symmetrical inclination to each other, the crossing point being a center where the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) characteristic reference line are crossed with each other at a memorized frequency. In this way, easy simultaneous enhancement is possible by a pair of adjustment means for the high frequency range and the low frequency range. 
     Described hereinafter is a method on how to make automatic adjustment. The present invention is provided with: an input audio signal analysis and memory means, whereby the input audio signal is analyzed and input audio situation is memorized; a memory means for input audio situation and inclinations of high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines, which memorizes inclinations of high boost (high frequency boosting) frequency characteristic reference line and low boost (low frequency boosting) frequency characteristic reference line, adjusted by a user using the adjustment means, simultaneously with the input audio signal analysis and memory means; and an automatic adjustment means for inclinations of high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines, whereby the input audio signal is analyzed, and whereby an audio situation pattern similar to that of corresponding input audio situation is selected from the memory means for input audio situation and inclinations of high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines, and whereby inclinations of the high and low boost (high and low frequency boosting) frequency characteristic reference lines are determined without any user adjustment. 
     In this way, a user can obtain clear and comfortable audio signal output without any adjustment when he/she is in the same sound environment. 
     The automatic inclination adjustment means for the high boost (high frequency boosting) and low boost (low frequency boosting) frequencies reference lines is provided with a learning function, so that optimized inclinations for high boost (high frequency boosting) and low boost (low frequency boosting) characteristic reference lines can be obtained more easily and automatically as memories are accumulated for places where the user is likely to go to. The analysis means to analyze the input audio signal is a frequency analysis means. 
     Or possibly, the present invention is provided with: an input audio signal analysis means to analyze the input audio signal and to recognize the input audio situation; and/or a memory means for inclinations of the high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines corresponding to memorized input audio situation, wherein inclinations of the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) characteristic reference line are preliminarily memorized. In this case, inclinations of high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines are memorized, using preliminarily gathered data from average persons with normal hearing, suitable for each memorized sound environment. The analysis means to analyze the audio signal is a frequency analysis means. 
     Described hereinbefore is a method on how to simultaneously adjust two frequency characteristic reference lines (high boost (high frequency boosting) and low boost (low frequency boosting)), each for high frequency range and low frequency range. Described hereinafter is about a method on how to enhance core voice frequencies in human conversations. 
     The present invention is preliminary provided with: frequency characteristic reference lines in order to gain control an input audio signal according to frequency; and an audio signal processing and generating means to gain control the input audio signal according to the frequency characteristic reference lines. 
     The frequency characteristic reference lines are provided with an adjustment means which adjusts inclinations of frequency characteristic reference lines, wherein a reference frequency is a rotation center. The reference frequency range of the rotation center is between 500 Hz and 2 kHz. 
     The aforementioned description is about the method on how to automatically adjust a high frequency range and a low frequency range, i.e. the two frequency characteristic reference lines (high boost (high frequency boosting) and low boost (low frequency boosting)), simultaneously. 
     Described hereinafter is a method on how to automatically adjust single frequency characteristic reference line. The present invention is provided with: the input audio signal analysis and memory means to analyze the input audio signal and memorize the input audio situation; a memory means for input audio situation and inclinations of frequency characteristic reference lines, whereby inclinations of frequency characteristic reference lines adjusted by a user using the adjustment means are memorized simultaneously with aforementioned input audio signal analysis and memory means; and an automatic adjustment means for inclinations, whereby input audio signal is analyzed, corresponding input audio situation is selected from the memory means for input audio situation and inclinations, and whereby inclinations of the frequency characteristic reference lines are determined without any user adjustment. 
     The automatic inclination adjustment means for frequency characteristic reference line is more useful by providing a learning function. The analysis means to analyze the input audio signal is a frequency analysis. 
     Or possibly, the present invention is provided with: an input audio signal analysis means to analyze the input audio signal and to recognize input audio situation; and a memory means for inclinations of frequency characteristic reference lines corresponding to input audio situation, whereby inclinations of frequency characteristic reference lines, corresponding to the memorized audio situation, are preliminarily memorized. Just like the aforementioned case of two frequency characteristic reference lines, inclinations of high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines are memorized, using preliminarily gathered data from average persons with normal hearing, suitable for each memorized sound environment. Further likewise, the analysis means to analyze the input audio signal is a frequency analysis means. 
     Described hereinafter is a method on how to apply the aforementioned method to hearing aid. This method is applicable to both the former case of two frequency characteristic reference lines (high boost (high frequency boosting) and low boost (low frequency boosting)) and the latter case of single frequency characteristic reference line. The hearing optimization device and the hearing optimization method are applied to hearing aids. 
     Also, the adjustment means is controllable independently from an audio signal output adjustment means, wherein the audio signal output adjustment means and the adjustment means are adjusted by the same mechanical adjustment device, and further wherein the mechanical adjustment device is provided with either one of the audio signal output adjustment means, a volume control which selects the adjustment means, or the mechanical adjustment and selection means which controls and selects frequency. 
     The hearing aid has a unified construction attached to/in an ear, wherein the adjustment means is provided within the unified construction. Or possibly, the hearing aid is composed of a hearing aid remote control unit and an ear attachment unit, each of the hearing aid remote control unit and the ear attachment unit is provided with a communication means to communicate with each other either by wired or short-range radio communication, the adjustment means being provided within the hearing aid remote control unit. 
     Described hereinbefore is an application method to hearing aid. 
     Described hereinafter is an application method to communication device including mobile phone. This method is applicable to both the former case of two frequency characteristic reference lines (high boost (high frequency boosting) and low boost (low frequency boosting)) and the latter case of single frequency characteristic reference line. The aforementioned hearing optimization device and the hearing optimization method are applied to a telecommunication means. The telecommunication means is a telephone such as mobile phone and land line, or further can be site-specific telephone equipment such as intercommunication system. 
     The hearing optimization device and the telecommunication means are of unified construction, wherein the adjustment means is provided within the unified construction. Or possibly, the hearing optimization device is independent from the telecommunication means, and the hearing optimization device and the telecommunication means are interfaced with a wired or short-range radio communication means. 
     Described hereinafter is a further application for use in noisy environments. This method is applicable to both the former case of two frequency characteristic reference lines (high boost (high frequency boosting) and low boost (low frequency boosting)) and the latter case of single frequency characteristic reference line. 
     The hearing optimization device and the hearing optimization method are provided with: a background-noise adjustment means which decreases gain of a memorized frequency range of memorized background noises; and a background noise adaptation activation means with which a user can activate the background noise adaptation means over the input audio. In this way, a user can hear in good conditions in noisy environments by using the activation means freely. 
     Or possibly, in order to be used in noisy environments, the hearing optimization device and the hearing optimization method is provided with: a background-noise recognition means to measure whether or not any background-noise of a memorized frequency is present; a background-noise adjustment means which decreases gain of a memorized frequency range; and an automatic background-noise muting activation means to activate the background-noise adjustment means when the background-noise recognition means recognizes that there is some noise. In this way, background-noise adaptation is possible when memorized background-noise is identified. A memorized frequency range of the background noises for the background-noise adaptation means is between 20 Hz and 500 Hz, and preferably between 20 Hz and 200 Hz. 
     Described hereinafter is an adjustment method, adapted to factors such as personal hearing characteristic or locations, continuously corresponding to various frequency ranges. 
     In order for gain control according to frequency of input audio signal, the present invention is preliminarily provided with a high boost (high frequency boosting) frequency characteristic reference line to enhance a high frequency range and a low boost (low frequency boosting) frequency characteristic reference line to enhance a low frequency range, wherein two audio signals are generated by dual distributing the input audio signal, one of the dual distributed input audio signal being used as a high boost (high frequency boosting) audio signal generated by a high boost (high frequency boosting) audio signal processing and generating means to enhance a high frequency range referring to the high boost (high frequency boosting) frequency characteristic reference line, and the other of the dual distributed input audio signal being used as a low boost (low frequency boosting) audio signal generated by a low boost (low frequency boosting) audio signal processing and generating means to enhance a low frequency range referring to the low boost (low frequency boosting) frequency characteristic reference line, and further provided with a synthesized audio signal output means, which makes an output audio signal by synthesizing two audio signals, which are: a high boost (high frequency boosting) audio signal coefficient-multiplying means which multiplies coefficient to adjust a ratio for synthesizing the high boost (high frequency boosting) audio signal with memorized two audio signals; and a low boost (low frequency boosting) audio signal coefficient-multiplying means which multiplies coefficient to adjust a ratio for synthesizing the low boost (low frequency boosting) audio signal with memorized two audio signals. 
     Audio signal synthesis becomes available by adjusting ratio of the high boost (high frequency boosting) audio signal and the low boost (low frequency boosting) audio signal in such a way that: the memorized coefficient for the high boost (high frequency boosting) audio signal is set by the high boost (high frequency boosting) coefficient input adjustment means; and, likewise, the memorized coefficient for the low boost (low frequency boosting) audio signal is set by the low boost (low frequency boosting) coefficient input adjustment means. Therefore, it becomes possible to output desired audio signal because the high boost (high frequency boosting) audio signal according to the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) audio signal according to the low boost (low frequency boosting) frequency characteristic reference line are adjustable at any desired ratio. 
     The high boost (high frequency boosting) frequency characteristic reference line is provided with an adjustment means for high boost (high frequency boosting) frequency characteristic reference line to adjust its inclination, a memorized frequency being as a rotation center, and the low boost (low frequency boosting) frequency characteristic reference line is provided with an adjustment means for low boost (low frequency boosting) frequency characteristic reference line to adjust its inclination, a memorized frequency being as a rotation center 
     The present invention is further provided with: the high boost (high frequency boosting) center position adjustment means to adjust a center position, its rotation center being a memorized frequency for the high boost (high frequency boosting) frequency characteristic reference line; and the low boost (low frequency boosting) center position adjustment means to adjust a center position, its rotation center being a memorized frequency for the low boost (low frequency boosting) frequency characteristic reference line. 
     Greater adjustment flexibility is offered if the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line are adjusted independently from each other. A frequency range of a rotation center of the high boost (high frequency boosting) frequency characteristic reference line is between 1000 Hz and 8000 Hz, and a frequency range of a rotation center of the low boost (low frequency boosting) frequency characteristic reference line is between 400 Hz and 1000 Hz. By arranging this plurality of adjustments, frequency hearing environment becomes adjustable in continuous fashion, which is essential for audio equipments. 
     Described further hereinafter is a method, particularly a method to be added to the aforementioned mechanism, to arrange optimized hearing environment corresponding to audio input situation. 
     The present invention is provided with: an input audio signal analysis and memory means whereby the input audio signal is analyzed and the input audio situation is memorized; a memory means for input audio situation and inclinations of high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines, whereby inclinations of the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line, which are adjusted by a user using the adjustment means, are memorized simultaneously with the input audio signal analysis and memory means; and further an automatic adjustment means for inclinations of the high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines, wherein the automatic adjustment means analyzes the input audio signal, and selects corresponding input audio situation from the memory means for input audio situation and inclinations of high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines, and further determines inclinations of the high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines without any user adjustment. In this way, optimized inclination information of high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines is automatically called to arrange hearing status corresponding to input audio. 
     The present invention is further provided with: a memory means for input audio situation and rotation center position of high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines to memorize rotation center position which is simultaneously adjusted with inclinations of the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line; and an automatic adjustment means for rotation center position and inclinations of the high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines, wherein the automatic adjustment means analyzes input audio signal, and selects corresponding input audio situation from the memory means for input audio situation and rotation center position and inclinations of high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines, and further determines rotation center position and inclinations of the high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines without any user adjustment. 
     The present invention is further provided with: an input audio signal analysis and memory means, whereby the input audio signal is analyzed and the input audio situation is memorized; a memory means for input audio situation and high boost (high frequency boosting) and low boost (low frequency boosting) coefficients to memorize high boost (high frequency boosting) coefficient and low boost (low frequency boosting) coefficient, which are adjusted by a user using the adjustment means, simultaneously with the input audio signal analysis and memory means; and an automatic adjustment means for high boost (high frequency boosting) and low boost (low frequency boosting) coefficients, whereby an input audio signal is analyzed, and a corresponding input audio situation is selected from the memory means for input audio situation and high boost (high frequency boosting) and low boost (low frequency boosting) coefficients, and the high boost (high frequency boosting) and low boost (low frequency boosting) coefficients are determined without any adjustment by a user. The analysis means to analyze the input audio signal is a frequency analysis means. 
     The present invention is provided with: in order for gain control according to frequency of input audio signal, a high boost (high frequency boosting) frequency characteristic reference line to enhance high frequency range and a low boost (low frequency boosting) frequency characteristic reference line to enhance low frequency range; a high boost (high frequency boosting) audio signal processing and generating means, whereby the input audio signal is dual distributed, one of the dual distributed signal refers to the high boost (high frequency boosting) frequency characteristic reference line, controls gain according to frequency, and enhances high frequency range; a low boost (low frequency boosting) audio signal processing and generating means, wherein the high boost (high frequency boosting) audio signal, generated by the aforementioned audio signal processing and generating means, and the other half of the dual distributed input audio signals is gain controlled according to frequency range, and low frequency range is enhanced referring to the aforementioned low boost (low frequency boosting) frequency characteristic reference line, wherein the low boost (low frequency boosting) audio signal generated by the low boost (low frequency boosting) audio signal processing and generating means and the aforementioned high boost (high frequency boosting) audio signal generated by the high boost (high frequency boosting) audio signal processing and generating means are generated; a high boost (high frequency boosting) audio signal coefficient-multiplying means, whereby coefficient-multiplying is carried out to adjust a ratio to synthesize two memorized audio signals with the high boost (high frequency boosting) audio signal; a low boost (low frequency boosting) audio signal coefficient-multiplying means, whereby coefficient-multiplying is carried out to adjust a ratio to synthesize two memorized audio signals with the low boost (low frequency boosting) audio signal; and a synthesized audio signal output means, whereby two audio signals generated by the high boost (high frequency boosting) audio signal coefficient-multiplying means and the low boost (low frequency boosting) acoustic coefficient-multiplying means are synthesized to be used as an audio output. 
     The high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line are provided with: an adjustment means for inclination of high boost (high frequency boosting) frequency characteristic reference line, which adjusts inclination using a memorized frequency as a rotation center; an adjustment means for inclination of low boost (low frequency boosting) frequency characteristic reference line, which adjusts inclination using a memorized frequency as a rotation center; a high boost (high frequency boosting) center position adjustment means, which adjusts center position using a memorized frequency of the high boost (high frequency boosting) frequency characteristic reference line as a rotation center; and a low boost (low frequency boosting) center position adjustment means, which adjusts center position using a memorized frequency of the low boost (low frequency boosting) frequency characteristic reference line as a rotation center. 
     Further, it becomes possible to generate continuous audio signal corresponding to a user&#39;s hearing, his/her sound environment, and so on by providing the present invention with at least one adjustment means selected from the followings: a high/low boost (high/low frequency boosting) rotation center position adjustment means; a high boost (high frequency boosting) coefficient input adjustment means which adjusts coefficient, to be coefficient-multiplied on the high boost (high frequency boosting) audio signal; or a low boost (low frequency boosting) coefficient input adjustment means which adjusts coefficient, to be coefficient-multiplied on the low boost (low frequency boosting) audio signal. 
     The high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line are adjusted independently from each other. The frequency range of a rotation center of the high boost (high frequency boosting) frequency characteristic reference line is between 1000 Hz and 8000 Hz, and the frequency range of a rotation center of the low boost (low frequency boosting) frequency characteristic reference line is between 400 Hz and 1000 Hz. 
     The frequency characteristic reference line can be single. In that case, the present invention is provided with: a frequency characteristic reference line in order for gain control according to frequency of input audio signal; and an audio signal processing and generating means whereby the input audio signal is gain controlled according to frequency referring to the frequency characteristic reference lines. 
     The hearing optimization device and the hearing optimization method, whereby audio signal is generated and output by the audio signal processing and generating means, wherein the a frequency range of the reference rotation center is between 500 Hz and 2 kHz, are provided with: an inclination adjustment means for the frequency characteristic reference lines to adjust its inclinations using a reference frequency as a rotation center; and a rotation center position adjustment means which adjusts the rotation center position of the reference frequency. 
     Advantageous Effect of the Invention 
     As described hereinbefore, for hearing aids designed for hearing impaired persons the present invention enables hearing correction corresponding to hearing characteristic of each user without making any complicated adjustment, and moreover, hearing correction is possible with easy adjustment in various places of various sound environments. A user can make optimized hearing correction regardless of time and place because the present invention allows him/her to adjust it easily, independent of his/her hearing condition of the day, his/her location at the moment, etc., according to his/her own hearing perception that only he/she can understand exactly. 
     The present invention is also beneficial for a person with normal hearing by allowing him/her clear and comfortable conversation in noisy environment or similar situation—he/she makes optimized correction with easy adjustment on his/her mobile phone etc. according to the location when he/she talks over the phone in various sound environments where various background noises are present. Further, the present invention enables easy and continuous hearing optimization corresponding to various hearings, sound environments, and locations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram showing an embodiment of the present invention; 
         FIG. 2  is a graph showing adjustments of frequency characteristic reference lines, according to the present invention; 
         FIG. 3  is a flow diagram, according to the present invention; 
         FIG. 4  is a block diagram showing adjustments corresponding to surrounding sound environments, according to the present invention; 
         FIG. 5  is a flow diagram showing adjustments suited to user&#39;s specific sound environments, according to the present invention; 
         FIG. 6  is a memory reading flow diagram showing adjustments corresponding to surrounding sound environments, according to the present invention; 
         FIG. 7  is a schematic diagram showing an embodiment of a hearing aid, according to the present invention; 
         FIG. 8  is a schematic diagram showing an example of control buttons, according to the present invention; 
         FIG. 9  is a flow diagram showing control button determination, according to the present invention; 
         FIG. 10  is a schematic block diagram showing an embodiment of a mobile phone, according to the present invention; 
         FIG. 11  is a schematic diagram showing control input of a mobile phone, according to the present invention; 
         FIG. 12  illustrates graphs showing gain control corresponding to background noises, according to the present invention; 
         FIG. 13  is a schematic block diagram showing another embodiment of the present invention; 
         FIG. 14  is a graph showing frequency characteristic reference lines, according to the present invention; 
         FIG. 15  is a flow diagram, according to the present invention; 
         FIG. 16  is a block diagram showing automatic adjustments, according to the present invention; 
         FIG. 17  is a block diagram showing adjustments by a user, according to the present invention; 
         FIG. 18  is a block diagram showing learning ability, according to the present invention; 
         FIG. 19  is a schematic block diagram of another embodiment of construction of a hearing aid, according to the present invention; 
         FIG. 20  is a schematic diagram showing an example of control buttons, according to the present invention; 
         FIG. 21  is a flow diagram showing control button determination, according to the present invention; 
         FIG. 22  is another embodiment of a mobile phone, according to the present invention; 
         FIG. 23  is a schematic diagram showing control input, according to the present invention; 
         FIG. 24  illustrates graphs showing gain control corresponding to background noises, according to the present invention; 
         FIG. 25  is a schematic diagram showing an embodiment which has a plurality of adjustment mechanisms, according to the present invention; 
         FIG. 26  is a graph showing adjustments of high boost (high frequency boosting) frequency characteristic reference lines, according to the present invention; 
         FIG. 27  is a graph showing adjustments of low boost (low frequency boosting) frequency characteristic reference lines, according to the present invention; 
         FIG. 28  is a graph showing other adjustments of low boost (low frequency boosting) frequency characteristic reference lines, according to the present invention; 
         FIG. 29  is a flow diagram of an embodiment which has a plurality of adjustment mechanisms, according to the present invention; 
         FIG. 30  is a block diagram showing adjustments corresponding to surrounding sound environments, according to the present invention; 
         FIG. 31  is a flow diagram showing adjustments suited to user&#39;s specific sound environments, according to the present invention; 
         FIG. 32  is a flow diagram showing adjustments suited to user&#39;s other specific sound environments, according to the present invention; 
         FIG. 33  is a schematic block diagram showing an embodiment of which frequency characteristic reference line is a single line, according to the present invention; 
         FIG. 34  is a graph showing adjustments of frequency characteristic reference lines, according to the present invention; and 
         FIG. 35  is a flow diagram showing an embodiment of which frequency characteristic reference line is a single line, according to the present invention. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The drawings are described in greater detail below. 
       FIG. 1  is a schematic block diagram showing an embodiment of the present invention.  FIG. 2  shows frequency characteristic reference lines which determine enhancement level of input audio signal according to frequency range. 
     In  FIG. 1 , the input audio signal is dual distributed to be used for audio signal generation. High frequency enhancing signal processing method is to refer to a high boost (high frequency boosting) frequency reference line  102 , and, by a high boost (high frequency boosting) audio signal processing and generating means  101 , generates high boost (high frequency boosting) audio signal. Low frequency enhancing signal processing method is to refer to a low boost (low frequency boosting) frequency reference line  104 , and, by a low boost (low frequency boosting) audio signal processing and generating means  105 , generates low boost (low frequency boosting) audio signal. Audio signal synthesizing method is to synthesize the generated high boost (high frequency boosting) audio signal and low boost (low frequency boosting) audio signal by a synthesis means  106  for high/low boost (high/low frequency boosting) audio signal to make an audio signal output. 
     Adjustment of frequency characteristic reference line is explained here in some details. By using a synchronous adjustment means  103  as shown in  FIG. 1 , a user synchronously adjusts the high boost (high frequency boosting) frequency characteristic reference line  102  and the low boost (low frequency boosting) frequency characteristic reference line  104 . 
     In an adjustment method as shown in  FIG. 2 , preliminarily set high boost (high frequency boosting) frequency characteristic reference line and low boost (low frequency boosting) frequency characteristic reference line are numbered as  201  and  204  respectively. 
     In order to increase the inclination by the synchronous adjustment means  103  as shown in  FIG. 1 , a user gradually adjusts a high boost (high frequency boosting) frequency characteristic reference line  201  and a low boost (low frequency boosting) frequency characteristic reference line  204  until they reach  202  and  206  respectively, with crossing point  210  being user-adjusted at 1000 Hz as a center point, where each frequency characteristic reference line crosses. 
     In order to decrease the inclination by the synchronous adjustment means  103  as shown in  FIG. 1 , a user gradually adjusts the low boost (low frequency boosting) frequency characteristic reference line  201  and the low boost (low frequency boosting) frequency characteristic reference line  204  until they reach  203  and  205  respectively, with crossing point  210  being user-adjusted at 1000 Hz as a center point, where each frequency characteristic reference line crosses. 
     Now going into details.  FIG. 3  is a flow diagram of the foregoing description. First, audio signal input is analog-to-digital converted in  301  as needed, and then the digital audio signal is dual distributed in  302 . One of the dual distributed digital audio signals is used for high boost (high frequency boosting) audio signal generation  303  in a way that high frequency is enhanced referring to high boost (high frequency boosting) frequency characteristic reference line  305 . The other is used for low boost (low frequency boosting) audio signal generation  304  in a way that low frequency is enhanced referring to a low boost (low frequency boosting) frequency characteristic reference line  306 . 
     A more detailed explanation is given by using  FIG. 2 . Gain is controlled independently according to frequency range, more specifically; gain of digital audio signal is increased or decreased according to the user-adjusted high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines. 
     For the high boost (high frequency boosting) frequency characteristic reference line  201 , which enhances high frequency, gain increase will enhance high frequency referring to the high boost (high frequency boosting) characteristic reference line  201  of each frequency range. For example, in frequency range A as displayed in  FIG. 2 , gain increase amount ah (between baseline  209  and point  207  on frequency characteristic reference line  201 ) is added to. 
     For the low boost (low frequency boosting) frequency characteristic reference line  204 , which enhances low frequency, gain decrease will enhance low frequency referring to the low boost (low frequency boosting) characteristic reference line  204  of each frequency range. For example, in frequency range A as displayed in  FIG. 2 , gain decrease amount al (between baseline  209  and point  208  on frequency characteristic reference line  204 ) is decreased from. 
     The generated high frequency enhanced high boost (high frequency boosting) audio signal and low frequency enhanced low boost (low frequency boosting) audio signal are synthesized in  307 , digital-to-analog converted in  308  as needed, and output as an audio signal. 
     Explained next is a method which requires no adjustment in such a case that surrounding sound environment situation (frequency pattern) is similar to that of preliminarily memorized one.  FIG. 4  displays its schematic block diagram. The input audio signal is frequency analyzed by an input audio signal analysis means  401  to be made as an input audio situation (frequency pattern) and through a control means  404 , is memorized in an input audio situation (frequency pattern) and high/low boost (high/low frequency boosting) frequency characteristic reference line inclination memory means  405 . to memorize the input audio situation (frequency pattern), being frequency analyzed by the input audio signal analysis means  401 , in input audio situation (frequency pattern) and the high/low frequency characteristic reference line inclination memory means  405  by the control means  404 . 
     In the above mentioned process, audio signal output is made by a high/low boost (high/low frequency boosting) audio signal processing and generating means  406  as aforementioned and as in  FIG. 3 , according to inclinations of high boost (high frequency boosting) frequency characteristic reference line and low boost (low frequency boosting) frequency characteristic reference line. 
     While listening to the output audio, a user, through a user interface  403 , then by high/low frequency characteristic reference line adjustment means  402 , adjusts inclinations of the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line, then by the control means  404 , together with an input audio situation (frequency pattern) which is frequency analyzed by the aforementioned input audio signal analysis means  401 , to be memorized in input audio situation (frequency pattern) and the high/low frequency characteristic reference line inclination memory means  405 . 
       FIG. 5  shows a flow of memorization into input audio situation (frequency pattern) and high/low boost (high/low frequency boosting) frequency characteristic reference line inclination memory means. Input audio signal is frequency analyzed in an input audio signal analysis  501  to be output as an input audio situation (frequency pattern). 
     Output audio, being generated in a high/low boost (high/low frequency boosting) audio signal processing and generating means  502 , is, through a user interface  504 , then by a high/low boost (high/low frequency boosting) frequency characteristic reference line adjustment  503 , adjusting inclinations of the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line, then by a control means  505 , together with the aforementioned input audio situation (frequency pattern)  501 , memorized in an input audio situation (frequency pattern) and high/low boost (high/low frequency boosting) frequency characteristic reference line inclination memory  506 . 
     Described next is a method which makes suitable audio output adapted to the frequency pattern (surrounding sound environment situation) by calling inclinations of high/low boost (high/low frequency boosting) frequency characteristic reference lines from optimum input audio situation (frequency pattern) and high/low frequency characteristic reference line inclination memory means. Input audio signal is frequency analyzed by the input audio signal analysis means  401  in  FIG. 4 , to be made as an frequency pattern, and by the control means  404 , examines whether a set of corresponding frequency pattern is being memorized in input audio situation (frequency pattern) and the high/low frequency characteristic reference line inclination memory means  405 , and if there is one, calls and sends to the high/low boost (high/low frequency boosting) audio signal processing and generating means  406  to make an audio output. 
     This input audio situation (frequency pattern) and high/low frequency characteristic inclination memory, by being provided with a learning function, automatically adjusts to a user&#39;s specific sound environments as he/she continues to use the adjustment function. 
     However, an automatically called adjustment may not necessarily fit a user&#39;s hearing characteristic. In this case, adjustment is made through the user interface  403  and by the high/low boost (high/low frequency boosting) frequency characteristic reference line adjustment means  402 . The control means  404  monitors whether there is such an adjustment and when there is one, without referring to input audio situation (frequency pattern) and the high/low boost (high/low frequency boosting) frequency characteristic reference line inclination memory means  405 , inclinations of high boost (high frequency boosting) frequency characteristic reference line and low boost (low frequency boosting) frequency characteristic reference line, being adjusted by the high/low boost (high/low frequency boosting) frequency characteristic reference line inclination adjustment means  402 , are forwarded to the high/low boost (high/low frequency boosting) audio signal processing and generating means  406  to be used as an audio signal output. 
     In a flow diagram as shown in  FIG. 6 , a user, through a user interface  604 , monitors whether a high/low boost (high/low frequency boosting) frequency characteristic reference line adjustment  603  is being activated, and if it is, inclinations of a high boost (high frequency boosting) frequency characteristic reference line and a low boost (low frequency boosting) frequency characteristic reference line, being adjusted in the high/low boost (high/low frequency boosting) frequency characteristic line adjustment  603 , are sent to a high/low boost (high/low frequency boosting) audio signal processing and generating  602  to be used as an audio signal output. 
     If a control means  606 , in its monitoring, determines that the high/low boost (high/low frequency boosting) frequency characteristic reference line adjustment  603  is not being made, then input audio signal is frequency analyzed in  601 , the input audio situation (frequency pattern) by the control means  606  and in  605 , searches any corresponding data to this audio situation (frequency pattern), from user-adjusted memories of input audio situation (frequency pattern) and high/low boost (high/low frequency boosting) frequency characteristic reference line inclinations. Called inclinations, if any, of a high boost (high frequency boosting) frequency characteristic reference line and a low boost (low frequency boosting) frequency characteristic reference line are sent to the high/low boost (high/low frequency boosting) frequency audio signal processing and generating  602  to be used as an audio output. 
     In this way, adjusted inclinations of high boost (high frequency boosting) frequency characteristic reference line and low boost (low frequency boosting) frequency characteristic reference line for each frequency pattern are memorized, so that if an input audio is similar to any of the preliminarily memorized surrounding sound environment situation (frequency pattern), there is no need for adjustment. Inclinations of high boost (high frequency boosting) frequency characteristic reference line and low boost (low frequency boosting) frequency characteristic reference line, being memorized together with the corresponding surrounding sound environment situation (frequency pattern), are called to be used as an audio output by high/low boost (high/low frequency boosting) audio signal processing and generating means. 
     This embodiment requires a user to adjust according to the sound environment he/she is in. However, it is also possible to preliminarily measure and memorize inclinations of high boost (high frequency boosting) frequency characteristic reference line and low boost (low frequency boosting) frequency characteristic reference line by sound environments suited for average persons with normal hearing, and then, when needed, analyze an input audio signal to call inclinations of corresponding high boost (high frequency boosting) characteristic reference line and low boost (low frequency boosting) characteristic reference line. 
     Explained next is an application of this embodiment to hearing aid.  FIG. 7  is a configuration example. The hearing aid in this example is composed of an ear attachment unit  701  and a hearing aid remote control unit  706 . The two units interface with each other by short range radio communication such as Bluetooth or ZigBee. Communication portions may be wired instead of wireless. 
     The ear attachment unit  701  is provided with an audio signal input portion  702 , a processing portion  705  wherein the aforementioned audio signal processing is performed, a communication portion  704  to radio communicate with the remote control unit, and an audio signal output portion  703 . The hearing aid remote control Unit  706  is provided with an adjustment portion  708  to perform adjustment, and a communication portion  707  to communicate with the ear attachment unit. An example of the adjustment portion of a hearing aid is shown in  FIG. 8 , which is provided with a function button  801  displayed as F, an up button  802  displayed as UP, and a down button  803  displayed as DWN. Volume is adjustable by UP and DWN buttons. 
     The aforementioned frequency adjustment is performed in such ways that holding down the F button and pressing the UP button will increase inclination of frequency characteristic reference line, and holding down the F button and pressing the DWN will decrease inclination of frequency characteristic reference line.  FIG. 9  displays a flow of how different functions of the UP and DWN buttons can be activated. Cognition whether the F button is being held down is made in  901 : when it is being held down, the UP and DWN buttons will adjust inclinations of frequency characteristic reference lines to adjust frequency characteristic according to a user&#39;s hearing characteristic; and when it is not being held down, the UP and DWN buttons will adjust volume. 
     This embodiment provides the audio signal input portion within the ear attachment unit and the adjustment portion within the remote control unit of the hearing aid. However, other configurations of embodiment are possible. For example, all functions may be housed in the ear attachment unit. Any combination may be used unless it is against the spirit of the present invention. 
     Explained next is an embodiment for mobile phone, of which configuration is displayed in  FIG. 10 . An audio signal from telephone voice output unit  1001  is processed by the aforementioned method. An adjustment portion  1002  adjusts inclination of the frequency characteristic reference lines, adjusts frequency characteristic of a user&#39;s hearing characteristic, a processing portion  1003  processes audio signal, and an audio signal output portion  1004  outputs audio signal. Since mobile phones are preinstalled with user input interface, their existing control portions can be assigned with individual adjustment function. As shown in  FIG. 11 , the audio signal output is adjusted by volume increase/decrease and/or inclination increase/decrease of high/low boost (high/low frequency boosting) frequency characteristic reference lines. This embodiment is further provided with a noise compression function, which significantly decreases gain of a specific frequency range in order to make human voice frequency range more clearly hearable when the user is in a noisy environment. 
     Explained next is a method for noise compression. When a user is on the mobile phone, some environmental background noises may mask the voice of a person who is on the other side of the phone. By compressing these noises the voice of the other party becomes more hearable.  FIG. 12  shows about background noise compression, wherein graph (a) displays an audio situation  1201  before background noise compression, whereas graph (b) displays an audio situation after background noise compression, wherein gain of a frequency range between 20 Hz and 300 Hz is decreased to a level numbered as  1202 , the frequency range being where human voice masking noises are on. 
     This embodiment activates background noise compression manually by a user, however, it is also available to have it done automatically, i.e., the specific frequency range (between 20 Hz and 300 Hz in this graph) is monitored to activate the compression function automatically when sound pressure exceeds a certain level. 
     This embodiment is about the background noise compression for a mobile phone. However, the embodiment is not limited to this particular application but is also applicable to a hearing aid. Further, this embodiment houses an adjustment portion and a processing portion within a mobile phone unit. However, the embodiment is not limited to this particular configuration but is also possible to house the adjustment portion and the processing portion within a headset, or within a set of a microphone and an earphone, for communication with a mobile phone. Or other telephone call applications than a mobile phone, such as a personal computer or the like being connected to an IP phone or other kinds of communication lines, are possible. Any combination may be used unless it is against the spirit of the present invention. 
     Explained next is about another embodiment of the present invention.  FIG. 13  is a schematic block diagram showing another embodiment of the present invention.  FIG. 14  is a graph showing frequency characteristic reference lines in accordance which enhancement level of input audio signal is determined according to a frequency range. As shown in  FIG. 13 , signal processing method of input audio signal is to refer to a frequency characteristic reference line  1302 , and then, by a frequency-adjusted audio signal processing and generating means  1301 , to generate audio signal. 
     Now explaining about frequency characteristic reference line adjustment, a frequency characteristic reference line  1302  is adjustable by a frequency characteristic reference line adjustment means  1303  as shown in  FIG. 13 . As shown in  FIG. 14 , a preliminarily set frequency characteristic reference line is numbered as  1401 . In order to increase the inclination by the synchronous adjustment means  1303  as shown in  FIG. 13 , a user gradually adjusts the frequency characteristic reference line until it reaches  1402 , with the rotation center  1406  being user-adjusted at 1000 Hz. 
     Likewise, in order to decrease the inclination by the synchronous adjustment means  1303  as shown in  FIG. 13 , a user adjusts the frequency characteristic reference line until it reaches  1403 , with the rotation center  1406  being user-adjusted at 1000 Hz. Going into details now with  FIG. 15  which is a flow diagram of the above mentioned. Input audio is analog-to-digital converted as needed in  1501 , and then the converted digital audio signal is processed in frequency characteristic adjustment audio signal generation  1502  by referring to a frequency characteristic reference line  1504 . 
     A more detailed explanation is given by using  FIG. 14 . Gain is controlled independently according to frequency range. More specifically, gain of digital audio signal is increased or decreased according to the user-adjusted frequency characteristic reference lines. When a frequency characteristic reference line is being adjusted at  1401 , gain is increased or decreased according to the frequency characteristic reference line  1401 . For example, in frequency range A as displayed in  FIG. 14 , gain increase amount a (between baseline  1405  and point  1404  on frequency characteristic reference line  1401 ) is added to. The generated audio signal is then digital-to-analog converted in  1503  as shown in  FIG. 15 , as needed, to be output as an audio. 
     Explained next is a method which requires no adjustment in such a case that a surrounding sound environment situation (frequency pattern) is similar to that of preliminarily memorized one.  FIG. 16  displays its schematic block diagram. Here, input audio signal is frequency analyzed by an input audio signal analysis means  1601 , and an input audio situation (frequency pattern) is, through a control means  1604 , memorized in an input audio situation (frequency pattern) and frequency characteristic reference line inclination memory means  1605 . 
     In the above mentioned process, an audio output is made by audio signal generating means  1606  as aforementioned and as in  FIG. 15 , according to inclinations of frequency characteristic reference lines. 
     While listening to the output audio, a user is, through a user interface  1603 , then by a frequency characteristic reference line adjustment means  1602 , adjusts inclinations of the frequency characteristic reference lines, then by control means  1604 , together with an input audio situation (frequency pattern) which is frequency analyzed by the aforementioned input audio signal analysis means  1601 , to be memorized in input audio situation (frequency pattern) and frequency characteristic reference line inclination memory means  1605 . 
       FIG. 17  shows a flow of memorization into input audio situation (frequency pattern) and frequency characteristic reference line inclination memory means. Input audio signal is frequency analyzed in input audio signal analysis  1701  to be output as an input audio signal. Output audio, being generated in audio signal processing and generating  1702 , is, through a user interface  1704 , then by frequency characteristic reference line adjustment  1703 , adjusting inclinations of the frequency characteristic reference lines, then by control means  1705 , together with the aforementioned input audio situation (frequency pattern)  1701 , memorized in an input audio situation (frequency pattern) and frequency characteristic reference line inclination memory means  1706 . 
     Described next is a method which makes suitable audio signal output adapted to the surrounding sound environment situation (frequency pattern) by calling inclinations of frequency characteristic reference lines from optimum input audio situation (frequency pattern) and frequency characteristic reference line inclination memory means according to the surrounding sound environment situation. 
     Audio input is frequency analyzed by the input audio signal analysis means  1601  in  FIG. 16 , and an input audio situation (frequency pattern), by control means  1604 , examines whether a set of corresponding input audio situation (frequency pattern) is being memorized in input audio situation (frequency pattern) and frequency characteristic reference line inclination memory means  1605 , and if there is one, calls and sends to the audio signal processing and generating means  1606  to make an audio output. 
     This input audio situation (frequency pattern) and frequency characteristic inclination memory, by being provided with a learning function, automatically adjusts to a user&#39;s specific sound environment as he/she continues to use the adjustment function. However, an automatically called adjustment may not necessarily fit a user&#39;s hearing characteristic. In this case, adjustment is made through the user interface  1603  and by the frequency characteristic reference line adjustment means  1602 . Control means  1604  monitors whether there is such an adjustment, and when there is one, without referring to an input audio situation (frequency pattern) and the frequency characteristic reference line inclination memory means  1605 , inclinations of frequency characteristic reference lines, being adjusted by the frequency characteristic reference line inclination adjustment means  1602 , are forwarded directly to the audio signal processing and generating means  1606  to be used as an audio output. 
     In a flow diagram as shown in  FIG. 18 , in a control means  1806 , a user, through a user interface  1806 , monitors whether frequency characteristic reference line adjustment  1803  is being activated, and if it is, inclinations of frequency characteristic reference lines, being adjusted in  1803 , are sent to an audio signal processing and generating means  1802  to be used as an audio output. 
     If the control means  1806 , in its monitoring, determines that the frequency characteristic reference line adjustment  1803  is not being made, then input audio signal is frequency analyzed in  1801  to be made as an input audio situation (frequency pattern) then by the control means  1806  and in  1805 , searches any corresponding data to this input audio situation (frequency pattern), from memories of input audio signal and frequency characteristic reference line inclinations. Called inclinations, if any, frequency characteristic reference lines are sent to the audio signal processing and generating means  1802  to be used as an audio output. 
     In this way, adjusted inclinations of frequency characteristic reference lines for each surrounding sound environment situation (frequency pattern) are memorized, so that if an input audio is similar to any of the preliminarily memorized surrounding sound environment situation (frequency pattern), there is not any need for adjustment. Inclinations of frequency characteristic reference line, being memorized together with the corresponding surrounding sound environment situation (frequency pattern), are called to be used as an audio output by audio signal processing and generating means. 
     This embodiment requires a user to adjust according to sound environment. However, it is also possible to preliminarily measure and memorize inclinations of frequency characteristic reference lines suited for sound environment of average persons with normal hearing, and then, when needed, analyze input audio signals to call inclinations of corresponding frequency characteristic reference lines. 
     Explained next is an application of this embodiment to hearing aid.  FIG. 19  is a configuration example. The hearing aid in this example is composed of an ear attachment unit  1901  and a hearing aid remote control unit  1904 . The two units interface with each other by short range radio communication such as Bluetooth or ZigBee. The ear attachment unit  1901  is provided with a communication portion  1903  to radio communicate with the remote control unit  1904 , and an audio output portion  1902 . 
     The hearing aid remote control Unit  1904  is provided with an audio input portion  1906 , an adjustment portion  1907  to perform adjustment, a processing portion  1908 , and a communication portion  1905  to communicate with the ear attachment unit  1901 . This embodiment provides the audio signal input portion within the ear attachment unit, however, it may be housed in the ear attachment unit. Any combination may be used unless it is against the spirit of the present invention. An example of the adjustment portion of a hearing aid is shown in  FIG. 20 , which is provided with a function button  2001  displayed as F, an up button  2002  displayed as UP, and a down button  2003  displayed as DWN. Volume is adjustable by UP and DWN buttons. 
     The aforementioned frequency adjustment is performed in such ways that holding down the F button and pressing the UP button will increase inclination of frequency characteristic reference line, and holding down the F button and pressing the DWN will decrease inclination of frequency characteristic reference line.  FIG. 21  displays a flow of how different functions of the UP and DWN buttons can be activated. Cognition whether the F button is being held down is made in  2101 : when it is being held down, the UP and DWN buttons will adjust inclinations of frequency characteristic reference lines to adjust frequency characteristic according to a user&#39;s hearing characteristic; and when it is not being held down, the UP and DWN buttons will adjust volume. 
       FIG. 22  shows another embodiment of construction of a mobile phone, which comprises a mobile phone unit  2201  and a headset  2204 . The mobile phone unit  2201  comprises a telephone voice output portion  2202 , and a communication portion  2203  to communicate with the headset  2204 . The headset  2204  comprises an audio signal input portion (not indicated in the figure), a communication portion  2208  which communicates with the mobile phone unit  2201 , an adjustment portion  2205  which adjusts input frequency characteristic by adjusting inclination of frequency characteristic reference line, a processing portion  2206  which processes audio signal according to adjustment result from the processing adjustment portion, and an audio signal output portion  2207 . 
     Explained next is further another embodiment of a mobile phone, as shown in  FIG. 23 , wherein an adjustment portion is housed within a headset unit, the adjustment portion being provided with a function button  2301  displayed as F, an up button  2302  displayed as UP, a down button  2303  displayed as DWN, and a noise compression button  2304  displayed as C. Volume is adjustable by UP and DWN buttons. 
     The aforementioned frequency adjustment is performed in such ways that holding down the F button and pressing the UP button will increase inclination of frequency characteristic reference line, holding down the F button and pressing the DWN will decrease inclination of frequency characteristic reference line, and pressing the C button will compress the frequency range of compress level of background noise. 
     Explained next is a method for noise compression. When a user is on the mobile phone, some environmental background noises may mask the voice of a person who is on the other side of the phone. By compressing these noises the voice of the other party becomes more hearable.  FIG. 24  shows about background noise compression, wherein graph (a) displays an audio situation  2401  before background noise compression, whereas graph (b) displays an audio situation after background noise compression, wherein gain of a frequency range between 30 Hz and 350 Hz is decreased to a level numbered as  2402 , the frequency range being where human voice masking noises are on. 
     This embodiment activates background noise compression manually by a user, however, it is also available to have it done automatically, i.e., the specific frequency range (between 30 Hz and 350 Hz in this graph) is monitored to activate the compression function automatically when sound pressure exceeds a certain level. 
     In this embodiment, noise compression is applied to only audio signal output; however, it can also be applied to audio signal input. In this case, the voice of a user talking on the mobile phone can be transmitted to a person on the other side of the line with background noise in the voice frequency range being compressed. 
     This embodiment is about the background noise compression for a mobile phone. However, the embodiment is not limited to this particular application but is also applicable to a hearing aid. Further, this embodiment houses an adjustment portion and a processing portion within a mobile phone unit. However, the embodiment is not limited to this particular configuration but is also possible to house the adjustment portion and the processing portion within a headset, or a set of a microphone and an earphone, for communication with a mobile phone. 
     Or other telephone call applications than a mobile phone, such as a personal computer or the like being connected to an IP phone or other kinds of communication lines, are possible. Any combination may be used unless it is against the spirit of the present invention. 
       FIG. 25  is a schematic block diagram of further another embodiment of the present invention.  FIG. 26  shows a high boost (high frequency boosting) frequency characteristic reference line, in accordance which enhancement level of input audio signal is determined to enhance a high frequency range.  FIG. 27  shows a low boost (low frequency boosting) frequency characteristic reference line, in accordance which enhancement level of input audio signal is determined to enhance a low frequency range. 
     In  FIG. 25 , the input audio signal is dual distributed to be used for audio signal generation. High frequency enhancing signal processing method is to refer to a high boost (high frequency boosting) frequency reference line  2502 , and, by a high boost (high frequency boosting) audio signal processing and generating means  2501 , generate high boost (high frequency boosting) audio signal. Low frequency enhancing signal processing method is to refer to a low boost (low frequency boosting) frequency reference line  2507 , and, by a low boost (low frequency boosting) audio signal processing and generating means  2508 , generate low boost (low frequency boosting) audio signal. 
     The generated high boost (high frequency boosting) audio signal is, by referring to a high boost (high frequency boosting) audio signal coefficient-multiplying adjustment means  2510 , coefficient-multiplied by a high boost (high frequency boosting) audio signal coefficient-multiplying means  2509 . The coefficient may be any numeric value between 0.01 and 10. 
     Likewise, the generated low boost (low frequency boosting) audio signal is, by referring to a low boost (low frequency boosting) audio signal coefficient-multiplying adjustment means  2512 , coefficient-multiplied by low boost (low frequency boosting) audio signal coefficient-multiplying means  2511 . Likewise, the coefficient may be any numeric value between 0.01 and 10. These coefficient-multiplied audio signals are synthesized by a synthesis means  2513  for high and low boost (high and low frequency boosting) coefficient-multiplied audio signal to make an audio signal output. 
     Explained now is about adjustment of high boost (high frequency boosting) frequency characteristic reference lines. As shown in  FIG. 25 , a high boost (high frequency boosting) frequency characteristic reference line rotation center adjustment means  2503  adjusts rotation center of inclination, and a low boost (low frequency boosting) frequency characteristic reference line inclination adjustment means  2504  adjusts inclination. 
       FIG. 26  shows an example wherein a rotation center  2601  is set at 1000 Hz. Inclination of a user-adjusted high boost (high frequency boosting) frequency characteristic reference line  2602  may be adjusted to be as  2603  or  2604  by the inclination adjustment means.  FIG. 26  also shows another example wherein a rotation center  2605  is set at 3000 Hz. Inclination of a user-adjusted high boost (high frequency boosting) frequency characteristic reference line  2606  may be adjusted to be as  2603  or  2604  by the inclination adjustment means. 
     The aforementioned high boost (high frequency boosting) frequency characteristic reference line inclination rotation center adjustment means is performed by the high boost (high frequency boosting) frequency characteristic reference line rotation center adjustment means  2503  as shown in  FIG. 25 , and high boost (high frequency boosting) frequency characteristic reference line inclination adjustment is performed by the high boost (high frequency boosting) frequency characteristic reference line inclination adjustment means  2504  also as shown in  FIG. 25 . 
     Explained now is about adjustment of low boost (low frequency boosting) frequency characteristic reference lines. As shown in  FIG. 25 , a low boost (low frequency boosting) frequency characteristic reference line rotation center adjustment means  2505  adjusts rotation center of inclination, and a low boost (low frequency boosting) frequency characteristic reference line inclination adjustment means  2506  adjusts inclination. 
       FIG. 27  shows an example wherein a rotation center  2701  is set at 400 Hz. Inclination of a user-adjusted low boost (low frequency boosting) frequency characteristic reference line  2702  may be adjusted to be as  2703  or  2704  by the inclination adjustment means.  FIG. 27  also shows another example wherein a rotation center  2705  is set at 800 Hz. Inclination of a user-adjusted low boost (low frequency boosting) frequency characteristic reference line  2706  may be adjusted to be as  2707  or  2708  by the inclination adjustment means. 
     The aforementioned low boost (low frequency boosting) frequency characteristic reference line inclination rotation center adjustment means is performed by the low boost (low frequency boosting) frequency characteristic reference line rotation center adjustment means  2505  as shown in  FIG. 25 , and low boost (low frequency boosting) frequency characteristic reference line inclination adjustment is performed by the low boost (low frequency boosting) frequency characteristic reference line inclination adjustment means  2506  also as shown in  FIG. 25 . 
     This embodiment explains that a rotation center of frequency characteristic inclination may be moved from one frequency range to another as shown in  FIG. 26  and  FIG. 27 . However, another possibility is that a rotation center may be on a frequency characteristic reference line as shown in  FIG. 28 . If a point  2802  on a frequency characteristic reference line  2801  is used as a rotation center, the inclination may be adjusted to be as  2803  or  2804 . Likewise, if a point  2806  on a frequency characteristic reference line  2801  is used as a rotation center, the inclination may be adjusted to be as  2807  or  2808 . 
     Explained in more detail now of the aforementioned using a flow diagram as shown in  FIG. 29 , wherein, in sequence, audio signal input is analog-to-digital converted in  2901 , the converted digital audio signal is dual distributed in  2902  to be used for audio signal generation. For the dual distributed digital audio signal, high frequency enhancing signal processing method is to refer to a high boost (high frequency boosting) frequency reference line  2905 , and, by  2903 , generates a high boost (high frequency boosting) audio signal, and a low frequency enhancing signal processing method is to refer to low boost (low frequency boosting) frequency reference line  2906 , and, by  2904 , generates a low boost (low frequency boosting) audio signal. 
     Gain control is made independently according to frequency range. Gain control of digital audio signal is made by increasing or decreasing according to user-adjusted high boost (high frequency boosting) and low boost (low frequency boosting) frequency characteristic reference lines, as described in the aforementioned embodiment. 
     Then, the generated high frequency enhanced high boost (high frequency boosting) audio signal refers to a high boost (high frequency boosting) audio signal coefficient  2909 , and generates high boost (high frequency boosting) coefficient-multiplied audio signal at  2907 . Likewise, the generated low frequency enhanced low boost (low frequency boosting) audio signal refers to a low boost (low frequency boosting) audio signal coefficient  2910 , and generates low boost (low frequency boosting) coefficient-multiplied audio signal at  2908 . And then, in  2911 , the high boost (high frequency boosting) coefficient-multiplied audio signal and the low boost (low frequency boosting) coefficient-multiplied audio signal are synthesized and, as appropriate, is digital-to-analog converted at  2912  to be output as an audio signal. 
     Explained next is a method which requires no adjustment in such a case that a surrounding sound environment is similar to that of a preliminarily memorized frequency pattern.  FIG. 30  displays its schematic block diagram. The input audio signal is frequency analyzed by an input audio signal analysis means  3001  and, through a control means  3010 , is memorized in a memory means for input audio situation (frequency pattern), rotation center and inclinations of high/low frequency characteristic reference lines, and audio signal multiple coefficients  3008 . In the above mentioned process, in sequence, rotary canters and inclinations of high boost (high frequency boosting) frequency characteristic reference line and low boost (low frequency boosting) frequency characteristic reference line are referred to, high/low boost (high/low frequency boosting) audio signals are generated, audio signal multiple coefficient is referred to, and high/low boost (high/low frequency boosting) audio signals are coefficient-multiplied to be synthesized to make an audio signal output. 
     The output audio, through a user interface  3003 , and by a high/low boost (high/low frequency boosting) frequency characteristic reference line adjustment means, and a high/low boost (high/low frequency boosting) audio signal coefficient-multiplying adjustment means, adjusts high/low frequency characteristic reference lines and high/low boost (high/low frequency boosting audio signal multiple coefficient, as shown in  3002 . 
       3004  in  3002  is a high boost (high frequency boosting) frequency characteristic reference line adjustment means. For drawing simplification purpose, rotation center adjustment and inclination adjustment for high boost (high frequency boosting) frequency characteristic reference line are described within a same text box. However, these are two different functions. 
     Likewise,  3005  in  3002  is a low boost (low frequency boosting) frequency characteristic reference line adjustment means. For drawing simplification purpose, rotation center adjustment and inclination adjustment for low boost (low frequency boosting) frequency characteristic reference line are described within a same text box. However, these are two different functions. 
       3006  in  3002  is a high boost (high frequency boosting) audio signal multiple coefficient adjustment means.  3007  in  3002  is a low boost (low frequency boosting) audio signal multiple coefficient adjustment means. 
     Information which is processed by the high/low boost (high/low frequency boosting) frequency characteristic adjustment means and also by the high/low boost (high/low frequency boosting) audio signal multiple coefficient adjustment means in  3002  is, by a control means  3010 , together with the input audio situation (frequency pattern) which is frequency analyzed by the input audio signal analysis means  3001 , memorized in a memory means  3008  for the input audio situation (frequency pattern) and the rotation center and inclinations of high/low boost (high/low frequency boosting) frequency characteristic reference lines, and audio signal multiple coefficients. 
       FIG. 31  is a flow diagram, illustrating how an input audio signal is memorized in memory means for input audio signal (input frequency pattern), rotation center and inclinations of high/low boost (high/low frequency boosting) frequency characteristic reference lines and audio signal multiple coefficients. The input audio signal is frequency analyzed by an input audio signal analysis means  3101  and is output as an input audio situation (frequency pattern). A user, while listening to the output audio generated by a high/low boost (high/low frequency boosting) audio signal processing and generating means  3102 , through a user interface  3104 , by an adjustment means  3103  for high/low boost (high/low frequency boosting) frequency characteristic reference lines and an adjustment means  3105  for high/low boost (high/low frequency boosting) audio signal multiple coefficient, adjusts high/low boost (high/low frequency boosting) frequency characteristic reference line rotation center, inclinations and audio signal multiple coefficients. The high/low boost (high/low frequency boosting) frequency characteristic reference line rotation center, inclinations and audio signal multiple coefficients, adjusted by the  3103  and the  3105 , is, together with the input audio signal analysis means  3101 , memorized in a memory means  3107  for input audio situation (frequency pattern), high/low boost (high/low frequency boosting) frequency characteristic reference lines rotation centers and inclinations, and high/low boost (high/low frequency boosting) audio signals multiple coefficients. 
     Explained next is a method, wherein surrounding sound environment situation (frequency pattern) is memorized in most suitable input audio situation and high/low boost (high/low frequency boosting) frequency reference lines rotation center and inclinations and audio signal multiple coefficient memory means, and then call the rotation center and inclinations of the high boost (high frequency boosting) frequency characteristic reference line and the low boost (low frequency boosting) frequency characteristic reference line, and high/low boost (high/low frequency boosting) audio signal multiple coefficient, and then an audio suitable to the corresponding surrounding sound environment is output. 
     Input audio signal is frequency analyzed by the input audio signal analysis means  3001  in  FIG. 30 , and by the control means  3010 , examines whether a set of corresponding audio situation (frequency pattern) is being memorized in a memory means  3008  for input audio situation (frequency pattern) and high/low boost (high/low frequency boosting) frequency characteristic reference lines rotation centers and inclinations and audio signal multiple coefficients, and if there is one, calls and sends to a high/low boost (high/low frequency boosting) audio signal processing and generating means  3009  to make an audio output. 
     This input audio situation (frequency pattern) and high/low boost (high/low frequency boosting) frequency characteristic reference line inclination memory means, by being provided with a learning function, automatically adjusts to a user&#39;s specific sound environment as he/she continues to use the adjustment function. 
     However, an automatically called adjustment may not necessarily fit a user&#39;s hearing characteristic. In this case, adjustment is made through the user interface  3003  and by the adjustment means  3002 . Control means  3010  monitors whether there is such an adjustment, and when there is one, without referring to the input audio situation (frequency pattern) and the high/low boost (high/low frequency boosting) frequency characteristic reference line inclination and audio signal multiple coefficient memory means  3008 , audio signal is directly output by the high/low boost (high/low frequency boosting) audio signal processing and generating means  3009  after being adjusted by the adjustment means  3002 . 
     In a flow diagram as shown in  FIG. 32 , in a control means  3206 , a user, through a user interface  3203 , monitors whether a high/low boost (high/low frequency boosting) frequency characteristic reference line adjustment  3202  and a high/low boost (high/low frequency boosting) audio signal multiple coefficient adjustment  3204  are being activated, and if they are, refers to information adjusted by adjustment means  3202  and  3204 , controls in  3206 , and outputs an audio signal by a high/low boost (high/low frequency boosting) audio signal processing, generating and synthesis means  3207 . 
     If control means  3206 , in its monitoring, determines that no adjustment is being made by  3202  and/or  3204 , then audio signal being frequency analyzed in  3201  is recognized to measure input audio situation (frequency pattern) then by control means  3206 , searches any corresponding data to this input audio situation (frequency pattern), from a memory means  3205  for an input audio situation (frequency pattern) and high/low boost (high/low frequency boosting) frequency reference lines rotation center and inclinations and high/low boost (high/low frequency boosting) audio signal multiple coefficients. Called data, if any, are sent to a high/low boost (high/low frequency boosting) audio signal processing, generating and synthesis means  3207  to be used as an audio signal output. 
     The memory means already memorizes input audio situation (frequency pattern) and high/low boost (high/low frequency boosting) frequency reference lines rotation center and inclinations and audio signal multiple coefficients, for various surrounding sound environment situation (frequency pattern), so that if an input audio is similar to any of the preliminarily memorized surrounding sound environment situation (frequency pattern), there is no need for adjustment, input audio signal and high/low boost (high/low frequency boosting) frequency reference lines rotation center and inclinations and audio signal multiple coefficients, being memorized together with the corresponding surrounding sound environment situation (frequency pattern), are called to be used as an audio output by the high/low boost (high/low frequency boosting) audio signal processing and generating means. 
     This embodiment requires a user to adjust according to his/her sound environment, however, it is also possible to preliminarily measure and memorize inclinations of high boost (high frequency boosting) frequency characteristic reference line and low boost (low frequency boosting) frequency characteristic reference line of a sound environment suited for average persons with normal hearing, and then, when needed, analyze input audio signal to call inclinations of corresponding high boost (high frequency boosting) characteristic reference line and low boost (low frequency boosting) characteristic reference line. 
     Explained next is about a case for a single frequency characteristic reference line.  FIG. 33  is a schematic block diagram of another embodiment of the present invention.  FIG. 34  shows frequency characteristic reference lines in accordance which enhancement level of input audio signal is determined according to frequency ranges. In  FIG. 33 , signal processing method of input audio signal is to refer to a frequency characteristic reference line  3302 , and, by an audio signal processing and generating means  3301 , generate an audio signal.  FIG. 34  shows an example of frequency characteristic reference lines, wherein  3401  and  3405  are examples of rotation centers on frequency characteristic reference lines, which are adjusted by a frequency characteristic reference line rotation center adjustment means  3303 , and a frequency characteristic reference line inclination adjustment means  3304 , as shown in  FIG. 33 . 
     For adjustment of inclination, with a rotation center  3401  in  FIG. 34 , a frequency characteristic reference line  3402  may shift to  3403  by increasing the inclination, or may shift to  3404  by decreasing the inclination, likewise, with a rotation center  3406  in  FIG. 34 , a frequency characteristic reference line  3406  may shift to  3407  by increasing the inclination, or may shift to  3408  by decreasing the inclination, These adjustments are performed by a frequency characteristic reference line inclination adjustment means  3304  in  FIG. 33 . 
     Explained in more detail now of the aforementioned using a flow diagram as shown in  FIG. 35 , wherein, in sequence, audio signal input is analog-to-digital converted in  3501  as needed, and the converted digital audio signal is, referring to a frequency characteristic reference line  3503 , audio signal generated in  3502 . Gain is adjusted independently according to frequency range, of which digital audio signal may be increased or decreased according to user-adjusted frequency characteristic reference line, which is shown in the aforementioned embodiment. Digital-to-analog conversion may be made in  3504 , as needed, to make an audio output. 
     The aforementioned embodiment shows straight frequency characteristic reference lines to make explanations simple; however, those are not limited to straight lines but may be curved ones as appropriate.