| Piezoelectric material has found an increasingly wide utilization in most fields due to its satisfactory performance,and the bone-conduction technology is also more and more used in headphones,mobile phones,and other hearing device.Combinating with Specialized Research Fund for the Doctoral Program of Higher Education Project " Research on the Piezoelectric Bone-conduction Hearing-aid Device with Frequency Division" and Ministry of Education of Higher Education Science and Technology Innovation Project Major Projects to Foster Capital " Research on the New Piezoelectric Drive Mechanism with Integration of Driven Testing and Control",Combinating with the converse piezoelectric effect of the piezoelectric material and the principle of bone-conduction,we have developed the bone-conduction hearing device with two-way circular piezoelectric vibrators.As the core of the hearing device,the vibration model of the vibration system with two-way piezoelectric vibrators was carried on the theoretical derivation,and the overall structure of the hearing device and electronic amplifier circuit with two-way were developed,the function of frequency division and amplification and hearing-aid were verified through the clinical experiment.The main research work of the article is as follows:1.The theoretical research on the bone-conduction hearing device with two-way circular piezoelectric vibratorsAt the field of audiology,composition of hearing system and voice transmission were researched,and the function of the ear were analyzed,design idea of bone-conduction hearing device has been put forward;the level of hearing loss and different hearing compensation methods were definitude,the bone-conduction hearing device was designed.The converse piezoelectric effect of piezoelectric materials and the performance parameters related to the piezoelectric drive ability were analyzed,and the deformations of piezoelectric vibrator with different vibration modes and its resonant characteristics were studied,and compared with frequency response characteristics of cochlear basement membrane,the design scheme of the bone-conduction hearing device with two-way circular piezoelectric vibrators was confirmed.2.The theoretical modeling and simulation analysis of the bone-conduction hearing device with two-way circular piezoelectric vibratorsSimulation analysis was carried on the circular piezoelectric vibrators with clamped around and center clamped,so the resonance frequency of the two kinds of piezoelectric vibrator was found respectively,simulation results indicated that the piezoelectric vibrator with clamped around was sensitive to high-frequency signal and the piezoelectric vibrator with clamped center was sensitive to low-frequency signal.In order to broaden range of frequency response of hearing device,the piezoelectric vibrators with two kinds of support ways were connected in series.The mathematical model of the vibration system was established with analytic method,the inherent vibration mode and the parameters influence on amplitude were inferred,and it was proved that the rationality was feasible.Through the simulation analysis on the circular piezoelectric vibrator with clamped center,the influence of the diameter and thickness of the piezoelectric vibrator and the size of the conductive column on the oscillator output displacement and on the fundamental frequency was indicated.The theoretical foundation was provided for the design on the size of hearing device.3.The prototype production of the bone-conduction hearing device with two-way circular piezoelectric vibratorsDesign of the vibration system of the bone-conduction hearing device with two-way circular piezoelectric vibrators was completed considering its functional and practical,the dimensions of the high-frequency of piezoelectric vibrator with clamped around and structure size of its supporting frame and conduction column were determined,and the dimensions of the low-frequency of piezoelectric vibrator with clamped center and structure size of its supporting column and conduction column were determined too.As well as other design of structures including the device cover,base,conductor hole,acoustic processing was carried on.Finally the prototype production of the hearing device was completed.The coupling problem of the vibration system of prototype was analyzed and researched by analytical method,it was verified that the influence of the coupling on the frequency response of vibration system was very small.4.Research on frequency division and amplifying circuit of the bone-conduction hearing device with two-way circular piezoelectric vibratorsIn order to the hign-frequency piezoelectric vibrator of the vibration system made response to the hign frequency signal,and the low-frequency piezoelectric vibrator of the vibration system made response to the low frequency signal,the range of frequency responseof hearing device was broaden,and the output of the vibration system was gained,so the circuit with frequency division and amplification function was developed to deal with the signal before it entered the hearing device.After the basic principle of frequency division and the common frequency division circuit were researched and analyzed,integrated amplifier chip NE5532 was adopted on the core component of the circuit,the design of electronic frequency division and amplifying circuit was carried.Simulation experiment of the circuit was completed through Multisim software and it was verified that the design was rational.So the circuit was producted and the experiment of circuit wan carried,the experiment concluded that the crossover point of the circuit is 2000 Hz,magnification of 20 times,frequency response range from 30 Hz to 30 k Hz,and frequency division and amplification function of the circuit was satisfied with the use of the hearing device.5.Experimental research of bone-conduction hearing device with two-way circular piezoelectric vibratorsTest system of hearing compensation ability of hearing aid in the current was analyzed,based on the design purpose of bone-conduction hearing device with two-way circular piezoelectric vibrators,combined with the existing experimental conditions the experimental method that is suitable for the device was formulated.Under three different sound fields,the experimental test was proved to person with different degree of hearing loss,the test contents included that test of listening to perceiving ability(if hear the sound),test of auditory resolution ability(tell music or speech)as well as test of the preliminary hearing recognition ability.On the basis of the analysis of experimental results,it was confirmed that the hearing compensation ability of the hearing device was satisfied.The study work on the bone-conduction hearing device with two-way circular piezoelectric vibrators involved the acoustics and vibration of mechanical and electrical knowledge,the development of the hearing device and the external frequency division amplifying circuit provided the basis of research on the bone conduction hearing device with piezoelectric for the practical application,and has a very good reference significance to improve the frequency response of bone-conduction hearing device and output ability. |
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